diff --git a/.cargo/config.toml.in b/.cargo/config.toml.in
index 3f6f8e2dca56..f9adc255437a 100644
--- a/.cargo/config.toml.in
+++ b/.cargo/config.toml.in
@@ -60,9 +60,9 @@ git = "https://github.com/mozilla-spidermonkey/jsparagus"
 rev = "61f399c53a641ebd3077c1f39f054f6d396a633c"
 replace-with = "vendored-sources"
 
-[source."git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"]
+[source."git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16"]
 git = "https://github.com/mozilla/application-services"
-rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16"
 replace-with = "vendored-sources"
 
 [source."git+https://github.com/mozilla/audioipc?rev=e6f44a2bd1e57d11dfc737632a9e849077632330"]
diff --git a/Cargo.lock b/Cargo.lock
index f097456de7c2..9807db848a01 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -826,7 +826,7 @@ version = "4.5.13"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "501d359d5f3dcaf6ecdeee48833ae73ec6e42723a1e52419c79abf9507eec0a0"
 dependencies = [
- "heck 0.5.0",
+ "heck",
  "proc-macro2",
  "quote",
  "syn",
@@ -1708,7 +1708,7 @@ dependencies = [
 [[package]]
 name = "error-support"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "error-support-macros",
  "lazy_static",
@@ -1720,7 +1720,7 @@ dependencies = [
 [[package]]
 name = "error-support-macros"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "proc-macro2",
  "quote",
@@ -2411,9 +2411,9 @@ dependencies = [
 
 [[package]]
 name = "glean"
-version = "60.5.0"
+version = "61.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "4cc81e8412d413d9f97ab91cce6a7d40bf11b0a03f8dcd3112cd1334a5e61086"
+checksum = "873a0621989a5eac9c9a23f47c217a74a1b1587fdc0c6c764c06567ba286e027"
 dependencies = [
  "glean-core",
  "inherent",
@@ -2424,9 +2424,9 @@ dependencies = [
 
 [[package]]
 name = "glean-core"
-version = "60.5.0"
+version = "61.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "8de1ecd4c5de0b0ecad949e29f6973bfaa4d53b668ebccdd5bc1a1f2591d0271"
+checksum = "bfd39741d1790f1022b0bf65d7b4a73fbb7a646158e0c96a0c845b097cce2ba2"
 dependencies = [
  "android_logger",
  "bincode",
@@ -2664,13 +2664,6 @@ dependencies = [
  "http",
 ]
 
-[[package]]
-name = "heck"
-version = "0.4.999"
-dependencies = [
- "heck 0.5.0",
-]
-
 [[package]]
 name = "heck"
 version = "0.5.0"
@@ -3043,7 +3036,7 @@ dependencies = [
 [[package]]
 name = "interrupt-support"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "lazy_static",
  "parking_lot",
@@ -4257,7 +4250,7 @@ dependencies = [
 [[package]]
 name = "nss_build_common"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 
 [[package]]
 name = "nsstring"
@@ -4470,7 +4463,7 @@ checksum = "d01a5bd0424d00070b0098dd17ebca6f961a959dead1dbcbbbc1d1cd8d3deeba"
 [[package]]
 name = "payload-support"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "serde",
  "serde_derive",
@@ -4942,7 +4935,7 @@ checksum = "dbb5fb1acd8a1a18b3dd5be62d25485eb770e05afb408a9627d14d451bae12da"
 [[package]]
 name = "relevancy"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "anyhow",
  "base64 0.21.3",
@@ -4965,7 +4958,7 @@ dependencies = [
 [[package]]
 name = "remote_settings"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "log",
  "parking_lot",
@@ -5523,7 +5516,7 @@ dependencies = [
 [[package]]
 name = "sql-support"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "ffi-support",
  "interrupt-support",
@@ -5705,7 +5698,7 @@ checksum = "81cdd64d312baedb58e21336b31bc043b77e01cc99033ce76ef539f78e965ebc"
 [[package]]
 name = "suggest"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "anyhow",
  "chrono",
@@ -5757,7 +5750,7 @@ dependencies = [
 [[package]]
 name = "sync-guid"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "base64 0.21.3",
  "rand",
@@ -5768,7 +5761,7 @@ dependencies = [
 [[package]]
 name = "sync15"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "anyhow",
  "error-support",
@@ -5800,7 +5793,7 @@ dependencies = [
 [[package]]
 name = "tabs"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "anyhow",
  "error-support",
@@ -6125,7 +6118,7 @@ checksum = "497961ef93d974e23eb6f433eb5fe1b7930b659f06d12dec6fc44a8f554c0bba"
 [[package]]
 name = "types"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "rusqlite",
  "serde",
@@ -6214,11 +6207,12 @@ checksum = "229730647fbc343e3a80e463c1db7f78f3855d3f3739bee0dda773c9a037c90a"
 
 [[package]]
 name = "uniffi"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "cb3a4c447c50fcda7bc5604a8588b7e1f37ffbfd8838a1516a290398efa7c6f0"
+checksum = "2db87def739fe4183947f8419d572d1849a4a09355eba4e988a2105cfd0ac6a7"
 dependencies = [
  "anyhow",
+ "cargo_metadata",
  "uniffi_bindgen",
  "uniffi_build",
  "uniffi_core",
@@ -6234,7 +6228,7 @@ dependencies = [
  "camino",
  "clap",
  "extend",
- "heck 0.4.999",
+ "heck",
  "serde",
  "toml",
  "uniffi",
@@ -6316,9 +6310,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_bindgen"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "0be2bc6bafd82c979b0faca77c7b26630d54017de9f5bd5a686ec6ef038ad5d9"
+checksum = "7a112599c9556d1581e4a3d72019a74c2c3e122cc27f4af12577a429c4d5e614"
 dependencies = [
  "anyhow",
  "askama",
@@ -6327,7 +6321,7 @@ dependencies = [
  "fs-err",
  "glob",
  "goblin 0.8.1",
- "heck 0.4.999",
+ "heck",
  "once_cell",
  "paste",
  "serde",
@@ -6340,9 +6334,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_build"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "1c59b65d59685ff3a10569287c6419f76487b4052ac52d5a0df38b2253d7f440"
+checksum = "e2b12684401d2a8508ca9c72a95bbc45906417e42fc80942abaf033bbf01aa33"
 dependencies = [
  "anyhow",
  "camino",
@@ -6351,9 +6345,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_checksum_derive"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d5c400339a9d1d17be34257d0b407e91d64af335e5b4fa49f4bf28467fc8d635"
+checksum = "a22dbe67c1c957ac6e7611bdf605a6218aa86b0eebeb8be58b70ae85ad7d73dc"
 dependencies = [
  "quote",
  "syn",
@@ -6361,9 +6355,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_core"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "a02e67ac9634b10da9e4aa63a29a7920b8f1395eafef1ea659b2dd76dda96906"
+checksum = "5a0c35aaad30e3a9e6d4fe34e358d64dbc92ee09045b48591b05fc9f12e0905b"
 dependencies = [
  "anyhow",
  "bytes",
@@ -6376,9 +6370,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_macros"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b6f08d5592c669b80a8af5066027098bebec4b4af17a9b8b299bac5f518ab89e"
+checksum = "db66474c5c61b0f7afc3b4995fecf9b72b340daa5ca0ef3da7778d75eb5482ea"
 dependencies = [
  "bincode",
  "camino",
@@ -6394,9 +6388,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_meta"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "583bab49f2bdf5681f9732f8b67a7e555ad920dbb5427be21450217bf1818189"
+checksum = "d898893f102e0e39b8bcb7e3d2188f4156ba280db32db9e8af1f122d057e9526"
 dependencies = [
  "anyhow",
  "bytes",
@@ -6406,9 +6400,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_testing"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "13963044ca9bde9b709d2eee68bc11dafc7acea144ae0fdc0cf29ed4add44481"
+checksum = "2c6aa4f0cf9d12172d84fc00a35a6c1f3522b526daad05ae739f709f6941b9b6"
 dependencies = [
  "anyhow",
  "camino",
@@ -6419,9 +6413,9 @@ dependencies = [
 
 [[package]]
 name = "uniffi_udl"
-version = "0.27.3"
+version = "0.28.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "b92f984bb0d9a06778f256aec963e1e9a80714014f7a90fb0e01008821fe5a97"
+checksum = "6b044e9c519e0bb51e516ab6f6d8f4f4dcf900ce30d5ad07c03f924e2824f28e"
 dependencies = [
  "anyhow",
  "textwrap",
@@ -6492,7 +6486,7 @@ checksum = "49874b5167b65d7193b8aba1567f5c7d93d001cafc34600cee003eda787e483f"
 [[package]]
 name = "viaduct"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "ffi-support",
  "log",
@@ -6640,7 +6634,7 @@ dependencies = [
 [[package]]
 name = "webext-storage"
 version = "0.1.0"
-source = "git+https://github.com/mozilla/application-services?rev=dbeaef2eb28e9da7cc2f96e26296513cc4e07c07#dbeaef2eb28e9da7cc2f96e26296513cc4e07c07"
+source = "git+https://github.com/mozilla/application-services?rev=6651984e3b456d99fad0df1deb727b7c2f62ec16#6651984e3b456d99fad0df1deb727b7c2f62ec16"
 dependencies = [
  "anyhow",
  "error-support",
diff --git a/Cargo.toml b/Cargo.toml
index 66391e442c1c..56409ac5eecd 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -55,8 +55,8 @@ resolver = "2"
 
 [workspace.dependencies]
 # Shared across multiple UniFFI consumers.
-uniffi = "0.27.3"
-uniffi_bindgen = "0.27.3"
+uniffi = "0.28.1"
+uniffi_bindgen = "0.28.1"
 # Shared across multiple application-services consumers.
 rusqlite = "0.31.0"
 # Shared across multiple glean consumers.
@@ -172,9 +172,6 @@ hashbrown = { path = "build/rust/hashbrown" }
 # Patch `socket2` 0.4 to 0.5
 socket2 = { path = "build/rust/socket2" }
 
-# Patch heck 0.4 to 0.5
-heck = { path = "build/rust/heck" }
-
 # The following overrides point to dummy projects, as a temporary measure until this is resolved:
 # https://github.com/rust-lang/cargo/issues/6179
 js-sys = { path = "build/rust/dummy-web/js-sys" }
@@ -213,14 +210,14 @@ midir = { git = "https://github.com/mozilla/midir.git", rev = "85156e360a37d8517
 malloc_size_of_derive = { path = "xpcom/rust/malloc_size_of_derive" }
 
 # application-services overrides to make updating them all simpler.
-interrupt-support = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
-relevancy = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
-sql-support = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
-suggest = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
-sync15 = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
-tabs = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
-viaduct = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
-webext-storage = { git = "https://github.com/mozilla/application-services", rev = "dbeaef2eb28e9da7cc2f96e26296513cc4e07c07" }
+interrupt-support = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
+relevancy = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
+sql-support = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
+suggest = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
+sync15 = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
+tabs = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
+viaduct = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
+webext-storage = { git = "https://github.com/mozilla/application-services", rev = "6651984e3b456d99fad0df1deb727b7c2f62ec16" }
 
 # Patch `gpu-descriptor` 0.3.0 to remove unnecessary `allocator-api2` dep.:
 # Still waiting for the now-merged <https://github.com/zakarumych/gpu-descriptor/pull/40> to be released.
diff --git a/build/rust/heck/Cargo.toml b/build/rust/heck/Cargo.toml
deleted file mode 100644
index 90035b066da9..000000000000
--- a/build/rust/heck/Cargo.toml
+++ /dev/null
@@ -1,11 +0,0 @@
-[package]
-name = "heck"
-version = "0.4.999"
-edition = "2018"
-license = "MPL-2.0"
-
-[lib]
-path = "lib.rs"
-
-[dependencies.heck]
-version = "0.5.0"
diff --git a/build/rust/heck/lib.rs b/build/rust/heck/lib.rs
deleted file mode 100644
index 8e169c46c4b6..000000000000
--- a/build/rust/heck/lib.rs
+++ /dev/null
@@ -1,5 +0,0 @@
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-pub use heck::*;
diff --git a/supply-chain/imports.lock b/supply-chain/imports.lock
index f4861c670d46..e649f31b623d 100644
--- a/supply-chain/imports.lock
+++ b/supply-chain/imports.lock
@@ -260,6 +260,13 @@ user-id = 48
 user-login = "badboy"
 user-name = "Jan-Erik Rediger"
 
+[[publisher.glean]]
+version = "61.0.0"
+when = "2024-08-21"
+user-id = 48
+user-login = "badboy"
+user-name = "Jan-Erik Rediger"
+
 [[publisher.glean-core]]
 version = "60.5.0"
 when = "2024-08-06"
@@ -267,6 +274,13 @@ user-id = 48
 user-login = "badboy"
 user-name = "Jan-Erik Rediger"
 
+[[publisher.glean-core]]
+version = "61.0.0"
+when = "2024-08-21"
+user-id = 48
+user-login = "badboy"
+user-name = "Jan-Erik Rediger"
+
 [[publisher.glslopt]]
 version = "0.1.11"
 when = "2024-08-30"
@@ -684,54 +698,108 @@ when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_bindgen]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_bindgen]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_build]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_build]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_checksum_derive]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_checksum_derive]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_core]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_core]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_macros]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_macros]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_meta]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_meta]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_testing]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_testing]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.uniffi_udl]]
 version = "0.27.3"
 when = "2024-06-03"
 user-id = 127697
 user-login = "bendk"
 
+[[publisher.uniffi_udl]]
+version = "0.28.1"
+when = "2024-08-13"
+user-id = 127697
+user-login = "bendk"
+
 [[publisher.utf8_iter]]
 version = "1.0.4"
 when = "2023-12-01"
diff --git a/third_party/rust/error-support/.cargo-checksum.json b/third_party/rust/error-support/.cargo-checksum.json
index f602db9bff11..112893421d10 100644
--- a/third_party/rust/error-support/.cargo-checksum.json
+++ b/third_party/rust/error-support/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"94e027935f3f804f464831ad7717936e7068517252b1f0e6fd0a025220bc2c35","README.md":"99fb739e79beb2c2d34f38d502cd758a1470b3ecf22c8f7fb05b97f324918cf4","build.rs":"c8d3c38c1208eea36224662b284d8daf3e7ad1b07d22d750524f3da1cc66ccca","src/errorsupport.udl":"e793034d01a2608298528051757f38405e006ee1abc4cf65dc6f18c53590ace8","src/handling.rs":"6e0568b18d426531cb2ae9967c8dd0d51ece5a065f68b15eeb308b995edaa167","src/lib.rs":"96ae3cc2c1077ae45442ace6b5b5311b86267d0b9067f3ff58396af30ccbbc07","src/macros.rs":"0d03f82fab20c96a182f941baf3fcf2a286b00fea871ee7fd8e339abc14f9522","src/redact.rs":"c9a4df1a87be68b15d583587bda941d4c60a1d0449e2d43ff99f3611a290a863","src/reporting.rs":"b8e03402edf3111718fc9c2ec179622307f4a117db05ac220ead631c9de28362","uniffi.toml":"644fe81c12fe3c01ee81e017ca3c00d0e611f014b7eade51aadaf208179a3450"},"package":null}
\ No newline at end of file
+{"files":{"Cargo.toml":"22d7cc070ecb4984a9b1112f737454bf00330efc13d39283859e065e9a12c494","README.md":"99fb739e79beb2c2d34f38d502cd758a1470b3ecf22c8f7fb05b97f324918cf4","build.rs":"c8d3c38c1208eea36224662b284d8daf3e7ad1b07d22d750524f3da1cc66ccca","src/errorsupport.udl":"e793034d01a2608298528051757f38405e006ee1abc4cf65dc6f18c53590ace8","src/handling.rs":"6e0568b18d426531cb2ae9967c8dd0d51ece5a065f68b15eeb308b995edaa167","src/lib.rs":"96ae3cc2c1077ae45442ace6b5b5311b86267d0b9067f3ff58396af30ccbbc07","src/macros.rs":"0d03f82fab20c96a182f941baf3fcf2a286b00fea871ee7fd8e339abc14f9522","src/redact.rs":"c9a4df1a87be68b15d583587bda941d4c60a1d0449e2d43ff99f3611a290a863","src/reporting.rs":"b8e03402edf3111718fc9c2ec179622307f4a117db05ac220ead631c9de28362","uniffi.toml":"644fe81c12fe3c01ee81e017ca3c00d0e611f014b7eade51aadaf208179a3450"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/error-support/Cargo.toml b/third_party/rust/error-support/Cargo.toml
index a425a3d54835..205cbcedc4af 100644
--- a/third_party/rust/error-support/Cargo.toml
+++ b/third_party/rust/error-support/Cargo.toml
@@ -49,8 +49,8 @@ version = "1.4"
 version = ">=0.11,<=0.12"
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
diff --git a/third_party/rust/glean-core/.cargo-checksum.json b/third_party/rust/glean-core/.cargo-checksum.json
index 824b4420e8d2..f8543923e41a 100644
--- a/third_party/rust/glean-core/.cargo-checksum.json
+++ b/third_party/rust/glean-core/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"5c467da9b977ccdbaad7f1294a0c6c4bdcc12f022dacaf8a79da37dca1ec0c14","LICENSE":"1f256ecad192880510e84ad60474eab7589218784b9a50bc7ceee34c2b91f1d5","README.md":"026495898699b54608eb4ec16074ffafc57920d80ccb59961c501a1ea28c9985","build.rs":"4857bea99c6b8c08db8818efa9d3738716f52d3acb68159323957ae52892a3eb","src/common_metric_data.rs":"02dd1628fed6587621c089952dd0cb80bed3c352cdacfb33be7e218ad1d847e9","src/core/mod.rs":"ecd4bbacd14c48f110c509a6e3ccd436a1116b10d3842b65d0739e3641371497","src/core_metrics.rs":"a877e42e0f8b932adb52a5681ad76fd977808cb48c7eeb29b1e4bbe804f1ea96","src/coverage.rs":"49613fd310bd24d779472720975fbe6c97ec370a95eb55f10afa43f67539c942","src/database/mod.rs":"5889c2b8000d70524cef3cec199f27fca65a05d431d2e4be6070bc176e1071d0","src/debug.rs":"7bd9e199d0d5c8170f6dbb9a725a18eaca1df34309d32b02081574962a86816e","src/dispatcher/global.rs":"17493b1a5e926ca1e9c1cda2ee031773402a19183911eb80048630d60266d89e","src/dispatcher/mod.rs":"391310269947452d7e0de24c848c183110c60149d75e345ba6d5d146f222dace","src/error.rs":"b93c7d3e243b21bb9eafc95f17860aba1a942b2f2b0a7f43307690f05fece516","src/error_recording.rs":"1aba34e9d3c741755055f5b76415114b25b146b0aa90049c3457cfe12066deda","src/event_database/mod.rs":"e5255c4669bf5b0eb670e012c43368e327d9e2bb38358a1037b0894025295b4f","src/fd_logger.rs":"0c9def6fa53db1a2ab93c85795f8a7df57797bcfd3978146923e151752e291a6","src/glean.udl":"c141d2eab0dda5cec9d12584b5efa52f9bf311906919652ff1fa7baf7338049c","src/glean_metrics.rs":"9414fb1453d19f6832df33e4c6ef7383d62203e47026bf5bc9552b083101ddd1","src/histogram/exponential.rs":"d39c4ec11d9c48d7a98b19f5ef8f181d1e5c12c614179902c61bbb894501b4ac","src/histogram/functional.rs":"1a63a305b48bcef7bc38136b40d916df4bb8f098dc602514ada54a9b091f6951","src/histogram/linear.rs":"0c9383b0a7233325e64833bcc6c7fe150e495f81b0cc70ae8d53b83493ba3a33","src/histogram/mod.rs":"bbb9535a633b5a85b6b11c6e4eed3314ab797950355a9bb8ccf3a22000f1e093","src/internal_metrics.rs":"872aff76bd0690bfea7e675092f1a8cad9d35b76459f9fc67d8cd7bc3d614ae9","src/internal_pings.rs":"c54339cb2530eec7717a3f6dd81ce98adf5da5d615bcf0a071fd90f415016866","src/lib.rs":"80fb55ca2bf22fca363f539dedcc45e58f640bebddb8eb1fb9479454740b7fbe","src/lib_unit_tests.rs":"3246160f2150d9ad0f50a1cab1e69c4ba400bdf33df42a814bec03b5df8e2ed4","src/metrics/boolean.rs":"2b9ef57e3582c9bd8b2cca8ab94c962a4871ecc00e837b913c9b0349ba9dff08","src/metrics/counter.rs":"b4a52a8167fb0edd6354f952525e59f3eadb4261de3483374f03c94449d30b92","src/metrics/custom_distribution.rs":"c99a57e087aa2a36c1f5904f16a3a9cd0703b89ba14f1840260e70a4eec02564","src/metrics/datetime.rs":"e4405762fc71718299fa1b208e3d5fda654bd1b82fe908c884c284e3530de2ec","src/metrics/denominator.rs":"95e8442f90bad97f80fc74b146782f215344b52c5f3825ae0a8baffdc001a714","src/metrics/event.rs":"cd52e200d313e2e6f31707419d4a7fe1cab34916ee145f8136440d6da34aaad4","src/metrics/experiment.rs":"5f9278cca4e133eb8df33bbfe36d1fe0ef3eade8c09f1b46db3c4d0790515412","src/metrics/labeled.rs":"2f792a9a682d5f5234928b4af6a536fc672e0a42db7ec06151897db56fe63957","src/metrics/memory_distribution.rs":"fe094a870a4a5a0a35656ef901e9ecdef7c4b4ee645d1594ffdb4149b709f6c3","src/metrics/memory_unit.rs":"ee32e020cb303dd631457374048a3ed53a2e7cbacc29c54d17d836fb15507538","src/metrics/mod.rs":"12133f4921e865d2b5895ad46b928d494f9319297e57a44aeb1d9f3d2f3637b7","src/metrics/numerator.rs":"937dfd583b797ac798a525cedca95c5a36262356760a89670d8113983c263154","src/metrics/object.rs":"2a1f1cc31973b576e55ba464b35c41b9420f62471eebba51273bca6856459538","src/metrics/ping.rs":"639d2dff2dbeb8e836c38c64281cfbfa62c87ef80091d6260167b2dd07eba0d6","src/metrics/quantity.rs":"aa13a8f8cf8e5e0281668fbbafc2998411df2a499479423558fd91b9bd7f8702","src/metrics/rate.rs":"603cc45c149c7a27c93b6a80146bf43f8ce70d9655f905bb5be6bc2c15bcb22b","src/metrics/recorded_experiment.rs":"33958abee79d8b55dec4cb5d20742640423713010f76314075cefde18b5c118a","src/metrics/remote_settings_config.rs":"908bae1aa4ea06d5b50d6b80d74b9877a8fc6fc05462cf34b8723269c7f79593","src/metrics/string.rs":"88beb1a847e5df9898b72ca7ed8ced3b7d2b40d83ff3670baf66f83a3e6cb005","src/metrics/string_list.rs":"ed53a095184c3e8224d0511809b5d7601ba3166505a39b0570f24ebeb0a5b97c","src/metrics/text.rs":"757f6919124d74e0512faa5bb9751a729b6bbc63ebe4d16ca81e9087f5595eaf","src/metrics/time_unit.rs":"4704703e19e799933aec3f39e3d3a125058756d7c7ba04f8729885c7843df447","src/metrics/timespan.rs":"1ad5233c7522cab70b4c095fb24cace66ace9741731f97bc001ede071f10d1ef","src/metrics/timing_distribution.rs":"2e38792a6bcfbcc85946d28bc671d8ef5912d5dfb810a8ca280b0180a4baa042","src/metrics/url.rs":"589ae1f8047367ad8c19b57a48ca8130d5f36cf3ce5954124150f0eb89c620ea","src/metrics/uuid.rs":"cacffd95ab30ed327ec2fa5feaf1359e667706746401f1e2c1195ad9553c4b54","src/ping/mod.rs":"307ddb82a2fb1804fb12673bb9ccc809f728c59ad8d1d023b94b4e78eeaf4186","src/scheduler.rs":"4cab95b3b97e103a37c73061d3b885263664736cf50cf7c1b08ea624c94fbe64","src/storage/mod.rs":"91f02556f113799e0d88d732ab342bda443f43461369e8b41c424c074d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\ No newline at end of file
+{"files":{"Cargo.toml":"8f0994507cb1de658c0f00be7d85d8e5ac177b3cf181de045adc53662b4748c7","LICENSE":"1f256ecad192880510e84ad60474eab7589218784b9a50bc7ceee34c2b91f1d5","README.md":"026495898699b54608eb4ec16074ffafc57920d80ccb59961c501a1ea28c9985","build.rs":"4857bea99c6b8c08db8818efa9d3738716f52d3acb68159323957ae52892a3eb","src/common_metric_data.rs":"02dd1628fed6587621c089952dd0cb80bed3c352cdacfb33be7e218ad1d847e9","src/core/mod.rs":"ecd4bbacd14c48f110c509a6e3ccd436a1116b10d3842b65d0739e3641371497","src/core_metrics.rs":"a877e42e0f8b932adb52a5681ad76fd977808cb48c7eeb29b1e4bbe804f1ea96","src/coverage.rs":"49613fd310bd24d779472720975fbe6c97ec370a95eb55f10afa43f67539c942","src/database/mod.rs":"5889c2b8000d70524cef3cec199f27fca65a05d431d2e4be6070bc176e1071d0","src/debug.rs":"7bd9e199d0d5c8170f6dbb9a725a18eaca1df34309d32b02081574962a86816e","src/dispatcher/global.rs":"17493b1a5e926ca1e9c1cda2ee031773402a19183911eb80048630d60266d89e","src/dispatcher/mod.rs":"391310269947452d7e0de24c848c183110c60149d75e345ba6d5d146f222dace","src/error.rs":"b93c7d3e243b21bb9eafc95f17860aba1a942b2f2b0a7f43307690f05fece516","src/error_recording.rs":"1aba34e9d3c741755055f5b76415114b25b146b0aa90049c3457cfe12066deda","src/event_database/mod.rs":"e5255c4669bf5b0eb670e012c43368e327d9e2bb38358a1037b0894025295b4f","src/fd_logger.rs":"0c9def6fa53db1a2ab93c85795f8a7df57797bcfd3978146923e151752e291a6","src/glean.udl":"c141d2eab0dda5cec9d12584b5efa52f9bf311906919652ff1fa7baf7338049c","src/glean_metrics.rs":"9414fb1453d19f6832df33e4c6ef7383d62203e47026bf5bc9552b083101ddd1","src/histogram/exponential.rs":"d39c4ec11d9c48d7a98b19f5ef8f181d1e5c12c614179902c61bbb894501b4ac","src/histogram/functional.rs":"1a63a305b48bcef7bc38136b40d916df4bb8f098dc602514ada54a9b091f6951","src/histogram/linear.rs":"0c9383b0a7233325e64833bcc6c7fe150e495f81b0cc70ae8d53b83493ba3a33","src/histogram/mod.rs":"bbb9535a633b5a85b6b11c6e4eed3314ab797950355a9bb8ccf3a22000f1e093","src/internal_metrics.rs":"872aff76bd0690bfea7e675092f1a8cad9d35b76459f9fc67d8cd7bc3d614ae9","src/internal_pings.rs":"c54339cb2530eec7717a3f6dd81ce98adf5da5d615bcf0a071fd90f415016866","src/lib.rs":"80fb55ca2bf22fca363f539dedcc45e58f640bebddb8eb1fb9479454740b7fbe","src/lib_unit_tests.rs":"3246160f2150d9ad0f50a1cab1e69c4ba400bdf33df42a814bec03b5df8e2ed4","src/metrics/boolean.rs":"2b9ef57e3582c9bd8b2cca8ab94c962a4871ecc00e837b913c9b0349ba9dff08","src/metrics/counter.rs":"b4a52a8167fb0edd6354f952525e59f3eadb4261de3483374f03c94449d30b92","src/metrics/custom_distribution.rs":"c99a57e087aa2a36c1f5904f16a3a9cd0703b89ba14f1840260e70a4eec02564","src/metrics/datetime.rs":"e4405762fc71718299fa1b208e3d5fda654bd1b82fe908c884c284e3530de2ec","src/metrics/denominator.rs":"95e8442f90bad97f80fc74b146782f215344b52c5f3825ae0a8baffdc001a714","src/metrics/event.rs":"cd52e200d313e2e6f31707419d4a7fe1cab34916ee145f8136440d6da34aaad4","src/metrics/experiment.rs":"5f9278cca4e133eb8df33bbfe36d1fe0ef3eade8c09f1b46db3c4d0790515412","src/metrics/labeled.rs":"2f792a9a682d5f5234928b4af6a536fc672e0a42db7ec06151897db56fe63957","src/metrics/memory_distribution.rs":"fe094a870a4a5a0a35656ef901e9ecdef7c4b4ee645d1594ffdb4149b709f6c3","src/metrics/memory_unit.rs":"ee32e020cb303dd631457374048a3ed53a2e7cbacc29c54d17d836fb15507538","src/metrics/mod.rs":"12133f4921e865d2b5895ad46b928d494f9319297e57a44aeb1d9f3d2f3637b7","src/metrics/numerator.rs":"937dfd583b797ac798a525cedca95c5a36262356760a89670d8113983c263154","src/metrics/object.rs":"2a1f1cc31973b576e55ba464b35c41b9420f62471eebba51273bca6856459538","src/metrics/ping.rs":"639d2dff2dbeb8e836c38c64281cfbfa62c87ef80091d6260167b2dd07eba0d6","src/metrics/quantity.rs":"aa13a8f8cf8e5e0281668fbbafc2998411df2a499479423558fd91b9bd7f8702","src/metrics/rate.rs":"603cc45c149c7a27c93b6a80146bf43f8ce70d9655f905bb5be6bc2c15bcb22b","src/metrics/recorded_experiment.rs":"33958abee79d8b55dec4cb5d20742640423713010f76314075cefde18b5c118a","src/metrics/remote_settings_config.rs":"908bae1aa4ea06d5b50d6b80d74b9877a8fc6fc05462cf34b8723269c7f79593","src/metrics/string.rs":"88beb1a847e5df9898b72ca7ed8ced3b7d2b40d83ff3670baf66f83a3e6cb005","src/metrics/string_list.rs":"ed53a095184c3e8224d0511809b5d7601ba3166505a39b0570f24ebeb0a5b97c","src/metrics/text.rs":"757f6919124d74e0512faa5bb9751a729b6bbc63ebe4d16ca81e9087f5595eaf","src/metrics/time_unit.rs":"4704703e19e799933aec3f39e3d3a125058756d7c7ba04f8729885c7843df447","src/metrics/timespan.rs":"1ad5233c7522cab70b4c095fb24cace66ace9741731f97bc001ede071f10d1ef","src/metrics/timing_distribution.rs":"2e38792a6bcfbcc85946d28bc671d8ef5912d5dfb810a8ca280b0180a4baa042","src/metrics/url.rs":"589ae1f8047367ad8c19b57a48ca8130d5f36cf3ce5954124150f0eb89c620ea","src/metrics/uuid.rs":"cacffd95ab30ed327ec2fa5feaf1359e667706746401f1e2c1195ad9553c4b54","src/ping/mod.rs":"307ddb82a2fb1804fb12673bb9ccc809f728c59ad8d1d023b94b4e78eeaf4186","src/scheduler.rs":"4cab95b3b97e103a37c73061d3b885263664736cf50cf7c1b08ea624c94fbe64","src/storage/mod.rs":"91f02556f113799e0d88d732ab342bda443f43461369e8b41c424c074d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\ No newline at end of file
diff --git a/third_party/rust/glean-core/Cargo.toml b/third_party/rust/glean-core/Cargo.toml
index b8c4561a4002..b239305a4da2 100644
--- a/third_party/rust/glean-core/Cargo.toml
+++ b/third_party/rust/glean-core/Cargo.toml
@@ -11,13 +11,14 @@
 
 [package]
 edition = "2021"
-rust-version = "1.66"
+rust-version = "1.76"
 name = "glean-core"
-version = "60.5.0"
+version = "61.0.0"
 authors = [
     "Jan-Erik Rediger <jrediger@mozilla.com>",
     "The Glean Team <glean-team@mozilla.com>",
 ]
+build = "build.rs"
 include = [
     "/README.md",
     "/LICENSE",
@@ -28,6 +29,10 @@ include = [
     "/uniffi.toml",
     "/build.rs",
 ]
+autobins = false
+autoexamples = false
+autotests = false
+autobenches = false
 description = "A modern Telemetry library"
 readme = "README.md"
 keywords = ["telemetry"]
@@ -35,7 +40,87 @@ license = "MPL-2.0"
 repository = "https://github.com/mozilla/glean"
 
 [package.metadata.glean]
-glean-parser = "14.5.1"
+glean-parser = "15.0.0"
+
+[lib]
+name = "glean_core"
+path = "src/lib.rs"
+
+[[test]]
+name = "boolean"
+path = "tests/boolean.rs"
+
+[[test]]
+name = "counter"
+path = "tests/counter.rs"
+
+[[test]]
+name = "custom_distribution"
+path = "tests/custom_distribution.rs"
+
+[[test]]
+name = "datetime"
+path = "tests/datetime.rs"
+
+[[test]]
+name = "event"
+path = "tests/event.rs"
+
+[[test]]
+name = "labeled"
+path = "tests/labeled.rs"
+
+[[test]]
+name = "memory_distribution"
+path = "tests/memory_distribution.rs"
+
+[[test]]
+name = "object"
+path = "tests/object.rs"
+
+[[test]]
+name = "ping"
+path = "tests/ping.rs"
+
+[[test]]
+name = "ping_maker"
+path = "tests/ping_maker.rs"
+
+[[test]]
+name = "quantity"
+path = "tests/quantity.rs"
+
+[[test]]
+name = "rate"
+path = "tests/rate.rs"
+
+[[test]]
+name = "storage"
+path = "tests/storage.rs"
+
+[[test]]
+name = "string"
+path = "tests/string.rs"
+
+[[test]]
+name = "string_list"
+path = "tests/string_list.rs"
+
+[[test]]
+name = "text"
+path = "tests/text.rs"
+
+[[test]]
+name = "timespan"
+path = "tests/timespan.rs"
+
+[[test]]
+name = "timing_distribution"
+path = "tests/timing_distribution.rs"
+
+[[test]]
+name = "uuid"
+path = "tests/uuid.rs"
 
 [dependencies.bincode]
 version = "1.2.1"
@@ -80,7 +165,7 @@ version = "1.0.4"
 version = "0.1.40"
 
 [dependencies.uniffi]
-version = "0.27.0"
+version = "0.28.0"
 default-features = false
 
 [dependencies.uuid]
@@ -105,18 +190,18 @@ version = "0.4"
 version = "3.8.0"
 
 [build-dependencies.uniffi]
-version = "0.27.0"
+version = "0.28.0"
 features = ["build"]
 default-features = false
 
 [features]
 enable_env_logger = ["env_logger"]
 
-[target."cfg(target_os = \"android\")".dependencies.android_logger]
+[target.'cfg(target_os = "android")'.dependencies.android_logger]
 version = "0.12.0"
 default-features = false
 
-[target."cfg(target_os = \"ios\")".dependencies.oslog]
+[target.'cfg(target_os = "ios")'.dependencies.oslog]
 version = "0.1.0"
 features = ["logger"]
 default-features = false
diff --git a/third_party/rust/glean/.cargo-checksum.json b/third_party/rust/glean/.cargo-checksum.json
index d3bde14ac107..46482b5c179f 100644
--- a/third_party/rust/glean/.cargo-checksum.json
+++ b/third_party/rust/glean/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"5b1a36e1b3e8c0c1447c8b5a588cbb517df27d742ce4e99517d909dc815245af","LICENSE":"1f256ecad192880510e84ad60474eab7589218784b9a50bc7ceee34c2b91f1d5","README.md":"5627cc81e6187ab6c2b4dff061af16d559edcab64ba786bac39daa69c703c595","src/common_test.rs":"de47b53dcca37985c0a2b8c02daecbf32309aa54f5a4dd9290719c2c1fd0fa55","src/configuration.rs":"de65ab99a26b4547be20803bc195cb50a6ab40b1a3f49a2e6230fed5a9d7a8d8","src/core_metrics.rs":"fef8fb4e5fa57c179836c6eb2cf59278fe3b8b036dbe57b0ff02971b4acd822f","src/lib.rs":"e954d51943bb351ce56cdabe673edc1f39aa7b5e06839432da7329c68f472945","src/net/http_uploader.rs":"01ad5bd91384411a12c74434cd1c5cd585078cb34faba4615c70bdb669a9bccb","src/net/mod.rs":"f47b96bb878f1a6c771cedbaeaeefb270bc87fb1d1bbbed1b282dddca16216ed","src/private/event.rs":"d7c70c02648584c19c73af89e5180d3c6153c911f2c6830f7d1599b18d6150eb","src/private/mod.rs":"3565eb569d2b96f938f130abe0fc3ee3f55e7e03fd6501e309d3ef6af72ef6ee","src/private/object.rs":"0926261074af905c775494b42217f636548e74c3ad798478481bc0cd2fdf5c48","src/private/ping.rs":"31d33d7f661a7a17ccb69351328700b4d7b80024d1e128f406c3534f9d163475","src/system.rs":"6eae5b41c15eba9cad6dbd116abe3519ee3e1fe034e79bdd692b029829a8c384","src/test.rs":"d7ad78bd853b2b22e3740fb8d3c15675286d3a050a7bfb586dbbe7003f74c388","tests/common/mod.rs":"08fb9483d9b6ed9fe873b4395245166ae8a15263be750c7a8e298c41d9604745","tests/init_fails.rs":"46d7064bba9386c3065635434e17ac9212c6c2236b3cd12bd985fc3229e659a3","tests/never_init.rs":"7a6e8a011fbd945f2544f204367eeceff3f6039c99d98799477e3b2352ae6227","tests/no_time_to_init.rs":"4a5bdddc2f8226d2ad17038229e8767a6dd195977af49527fbb84a9f6b0154bb","tests/overflowing_preinit.rs":"985e140460a100986fd051ce901b787a3a7a9747a856cd06066b740ac7d2381c","tests/persist_ping_lifetime_nopanic.rs":"18379d3ffbf4a2c8c684c04ff7a0660b86dfbbb447db2d24dfed6073cb7ddf8f","tests/schema.rs":"dde65bce8a715ca3bd9c54b2466d831dd5e0d559e0773fe7657827f22a66bb44","tests/simple.rs":"1835b5df6f76ff894b45805bd54eaab23ca2d9d2b0694ec64af3aa6132baf30e","tests/test-delayed-ping-data.sh":"6d6537216e04dc7a8deaf02e694307e1ed983bfacffab16e8a96e0a94679da33","tests/test-ping-lifetime-flush.sh":"e8f118ea2f6fd973809e38d5e828a03cfccfe0b0f497ccde5ec92d6d1380c071","tests/test-shutdown-blocking.sh":"a44d8d4bbe2ee3ede9e48121150ae7a5386025160c5cef2181ca142232c5fb27","tests/test-thread-crashing.sh":"a342753014bd6e9ac0840a0c7cabcda180a297c8ef532be39570190794b5bfad","tests/timing_distribution_single_sample.rs":"fddf2f13f1620a8808029d250a64e4c822828bf80b4bb4f9e3b645ab70643f9b","tests/upload_timing.rs":"6a97aa355d808123af0914ffecf1da0ecb2cc441c95c63c600b14f97ce0d45a0"},"package":"4cc81e8412d413d9f97ab91cce6a7d40bf11b0a03f8dcd3112cd1334a5e61086"}
\ No newline at end of file
+{"files":{"Cargo.toml":"e7c232a62bcf0588d034687e8f7758a0e4457aca71eba65e6c64de99bfec2891","LICENSE":"1f256ecad192880510e84ad60474eab7589218784b9a50bc7ceee34c2b91f1d5","README.md":"5627cc81e6187ab6c2b4dff061af16d559edcab64ba786bac39daa69c703c595","src/common_test.rs":"de47b53dcca37985c0a2b8c02daecbf32309aa54f5a4dd9290719c2c1fd0fa55","src/configuration.rs":"de65ab99a26b4547be20803bc195cb50a6ab40b1a3f49a2e6230fed5a9d7a8d8","src/core_metrics.rs":"fef8fb4e5fa57c179836c6eb2cf59278fe3b8b036dbe57b0ff02971b4acd822f","src/lib.rs":"e954d51943bb351ce56cdabe673edc1f39aa7b5e06839432da7329c68f472945","src/net/http_uploader.rs":"01ad5bd91384411a12c74434cd1c5cd585078cb34faba4615c70bdb669a9bccb","src/net/mod.rs":"f47b96bb878f1a6c771cedbaeaeefb270bc87fb1d1bbbed1b282dddca16216ed","src/private/event.rs":"d7c70c02648584c19c73af89e5180d3c6153c911f2c6830f7d1599b18d6150eb","src/private/mod.rs":"3565eb569d2b96f938f130abe0fc3ee3f55e7e03fd6501e309d3ef6af72ef6ee","src/private/object.rs":"0926261074af905c775494b42217f636548e74c3ad798478481bc0cd2fdf5c48","src/private/ping.rs":"31d33d7f661a7a17ccb69351328700b4d7b80024d1e128f406c3534f9d163475","src/system.rs":"6eae5b41c15eba9cad6dbd116abe3519ee3e1fe034e79bdd692b029829a8c384","src/test.rs":"d7ad78bd853b2b22e3740fb8d3c15675286d3a050a7bfb586dbbe7003f74c388","tests/common/mod.rs":"08fb9483d9b6ed9fe873b4395245166ae8a15263be750c7a8e298c41d9604745","tests/init_fails.rs":"46d7064bba9386c3065635434e17ac9212c6c2236b3cd12bd985fc3229e659a3","tests/never_init.rs":"7a6e8a011fbd945f2544f204367eeceff3f6039c99d98799477e3b2352ae6227","tests/no_time_to_init.rs":"4a5bdddc2f8226d2ad17038229e8767a6dd195977af49527fbb84a9f6b0154bb","tests/overflowing_preinit.rs":"985e140460a100986fd051ce901b787a3a7a9747a856cd06066b740ac7d2381c","tests/persist_ping_lifetime_nopanic.rs":"18379d3ffbf4a2c8c684c04ff7a0660b86dfbbb447db2d24dfed6073cb7ddf8f","tests/schema.rs":"dde65bce8a715ca3bd9c54b2466d831dd5e0d559e0773fe7657827f22a66bb44","tests/simple.rs":"1835b5df6f76ff894b45805bd54eaab23ca2d9d2b0694ec64af3aa6132baf30e","tests/test-delayed-ping-data.sh":"6d6537216e04dc7a8deaf02e694307e1ed983bfacffab16e8a96e0a94679da33","tests/test-ping-lifetime-flush.sh":"e8f118ea2f6fd973809e38d5e828a03cfccfe0b0f497ccde5ec92d6d1380c071","tests/test-shutdown-blocking.sh":"a44d8d4bbe2ee3ede9e48121150ae7a5386025160c5cef2181ca142232c5fb27","tests/test-thread-crashing.sh":"a342753014bd6e9ac0840a0c7cabcda180a297c8ef532be39570190794b5bfad","tests/timing_distribution_single_sample.rs":"fddf2f13f1620a8808029d250a64e4c822828bf80b4bb4f9e3b645ab70643f9b","tests/upload_timing.rs":"6a97aa355d808123af0914ffecf1da0ecb2cc441c95c63c600b14f97ce0d45a0"},"package":"873a0621989a5eac9c9a23f47c217a74a1b1587fdc0c6c764c06567ba286e027"}
\ No newline at end of file
diff --git a/third_party/rust/glean/Cargo.toml b/third_party/rust/glean/Cargo.toml
index ccb4b0ddf8df..665c1e7b393f 100644
--- a/third_party/rust/glean/Cargo.toml
+++ b/third_party/rust/glean/Cargo.toml
@@ -11,9 +11,9 @@
 
 [package]
 edition = "2021"
-rust-version = "1.66"
+rust-version = "1.76"
 name = "glean"
-version = "60.5.0"
+version = "61.0.0"
 authors = [
     "Jan-Erik Rediger <jrediger@mozilla.com>",
     "The Glean Team <glean-team@mozilla.com>",
@@ -80,7 +80,7 @@ name = "upload_timing"
 path = "tests/upload_timing.rs"
 
 [dependencies.glean-core]
-version = "60.5.0"
+version = "61.0.0"
 
 [dependencies.inherent]
 version = "1"
diff --git a/third_party/rust/interrupt-support/.cargo-checksum.json b/third_party/rust/interrupt-support/.cargo-checksum.json
index fc2244ad2a10..ef1774fc4b9d 100644
--- a/third_party/rust/interrupt-support/.cargo-checksum.json
+++ b/third_party/rust/interrupt-support/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"43f4bde7de7da5eb46d786bb77c57d7d120573c41e41387a3b89b0158810b9e8","README.md":"7f1418b4a7c138ba20bcaea077fe6cf0d6ffbaf6df6b90c80efc52aa0d0e2e9f","build.rs":"49840f26c73c5db19cb4e7f02930e49d7a19648168b83f2313ac1a0303c103df","src/error.rs":"b83cbe8abd22a9d687508d236a2a77e28b3fc6c39673633e5820cc0e3fc86cba","src/interrupt_support.udl":"31181937f89dbc229837484dec47a228955bb1b6c47d3b049d91f23cbe7dc069","src/interruptee.rs":"c56f9ac610d0b24a128a907266432287558c4b73f6c24b82674ca7894181d18f","src/lib.rs":"cf44a84310913be5264e1c4a3e004a9f7a6cd82d01a109bb6ac4d6002b5dd560","src/shutdown.rs":"e4b7a89f1ef319646aee3282a0d60465c3dbf571c52a0295f3b1a8909f345818","src/sql.rs":"db9b93fb2fe813ae0af6313082f07fad0e381691290466a7ac67bec14024722d"},"package":null}
\ No newline at end of file
+{"files":{"Cargo.toml":"397be256cf13b9107c6610189b6d22951110ed120adf06c9354f67b1e6bc3472","README.md":"7f1418b4a7c138ba20bcaea077fe6cf0d6ffbaf6df6b90c80efc52aa0d0e2e9f","build.rs":"49840f26c73c5db19cb4e7f02930e49d7a19648168b83f2313ac1a0303c103df","src/error.rs":"b83cbe8abd22a9d687508d236a2a77e28b3fc6c39673633e5820cc0e3fc86cba","src/interrupt_support.udl":"31181937f89dbc229837484dec47a228955bb1b6c47d3b049d91f23cbe7dc069","src/interruptee.rs":"c56f9ac610d0b24a128a907266432287558c4b73f6c24b82674ca7894181d18f","src/lib.rs":"cf44a84310913be5264e1c4a3e004a9f7a6cd82d01a109bb6ac4d6002b5dd560","src/shutdown.rs":"e4b7a89f1ef319646aee3282a0d60465c3dbf571c52a0295f3b1a8909f345818","src/sql.rs":"db9b93fb2fe813ae0af6313082f07fad0e381691290466a7ac67bec14024722d"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/interrupt-support/Cargo.toml b/third_party/rust/interrupt-support/Cargo.toml
index 03b87ee30455..fe36f0665394 100644
--- a/third_party/rust/interrupt-support/Cargo.toml
+++ b/third_party/rust/interrupt-support/Cargo.toml
@@ -45,8 +45,8 @@ features = [
 ]
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
diff --git a/third_party/rust/relevancy/.cargo-checksum.json b/third_party/rust/relevancy/.cargo-checksum.json
index 88f839ffb146..d38487c76f20 100644
--- a/third_party/rust/relevancy/.cargo-checksum.json
+++ b/third_party/rust/relevancy/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"836ed62b1d856eb26b77f53d493585c7db861a12ba77eb481591c332cb9e8c18","build.rs":"a562bfe527d21c4e8a1a44b892defa83cdff141ec5dd51ed6f3862330e50ddd7","src/bin/generate-test-data.rs":"7f1c9dc445418c7627f89d1f2aa8e550d0f85b3d1f05edb7c378ab9441714f1f","src/db.rs":"84fa47dc54f113769ce9ec6f827c8813abed61d5e5fc82404816266703a5c668","src/error.rs":"bda332098f9759e4250c725b09d82704ba03c9ad87dc761414fa21f40220acf5","src/ingest.rs":"58bb3ed984aa5a9becb405793832e578586be744d3c4a1c411fdfb7ff48c55dd","src/interest.rs":"73baa578b40b96d13899016b14087c9ac37b754c1311e2798b1d09c719447751","src/lib.rs":"214fdbeb25e0753ef132245e6892d77cad0ddd87c96d9bdd7f3427bc5d11091e","src/relevancy.udl":"9f463bbc2a7ef28358ffbfe832e62ddd6127888c484576466c759b127a55c4b2","src/rs.rs":"cff2351c9e1b45bb67ee945650fd74b45ed48815851e58b8dbf39e66a30c10a3","src/schema.rs":"919f4d1d3654bad966c5ce93ac157dc17cac2f35e7b8c2efc471b9af562555db","src/url_hash.rs":"2e908316fb70923644d1990dbf470d69ce2f5e99b0c5c3d95ec691590be8ffa5","test-data":"1ef2cd092d59e7e126cd4a514af983d449ed9f9c98708702fd237464a76c2b5e"},"package":null}
\ No newline at end of file
+{"files":{"Cargo.toml":"10efb23c7a9d00473bc958f109160368361e4f79dd67967b8c00179c5c126de4","build.rs":"a562bfe527d21c4e8a1a44b892defa83cdff141ec5dd51ed6f3862330e50ddd7","src/bin/generate-test-data.rs":"7f1c9dc445418c7627f89d1f2aa8e550d0f85b3d1f05edb7c378ab9441714f1f","src/db.rs":"84fa47dc54f113769ce9ec6f827c8813abed61d5e5fc82404816266703a5c668","src/error.rs":"bda332098f9759e4250c725b09d82704ba03c9ad87dc761414fa21f40220acf5","src/ingest.rs":"58bb3ed984aa5a9becb405793832e578586be744d3c4a1c411fdfb7ff48c55dd","src/interest.rs":"73baa578b40b96d13899016b14087c9ac37b754c1311e2798b1d09c719447751","src/lib.rs":"214fdbeb25e0753ef132245e6892d77cad0ddd87c96d9bdd7f3427bc5d11091e","src/relevancy.udl":"9f463bbc2a7ef28358ffbfe832e62ddd6127888c484576466c759b127a55c4b2","src/rs.rs":"cff2351c9e1b45bb67ee945650fd74b45ed48815851e58b8dbf39e66a30c10a3","src/schema.rs":"919f4d1d3654bad966c5ce93ac157dc17cac2f35e7b8c2efc471b9af562555db","src/url_hash.rs":"2e908316fb70923644d1990dbf470d69ce2f5e99b0c5c3d95ec691590be8ffa5","test-data":"1ef2cd092d59e7e126cd4a514af983d449ed9f9c98708702fd237464a76c2b5e"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/relevancy/Cargo.toml b/third_party/rust/relevancy/Cargo.toml
index cae166b37734..2f5cc939d898 100644
--- a/third_party/rust/relevancy/Cargo.toml
+++ b/third_party/rust/relevancy/Cargo.toml
@@ -69,8 +69,8 @@ features = ["derive"]
 path = "../support/sql"
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
diff --git a/third_party/rust/remote_settings/.cargo-checksum.json b/third_party/rust/remote_settings/.cargo-checksum.json
index dd17c17d5a4d..c6ab8a0eb615 100644
--- a/third_party/rust/remote_settings/.cargo-checksum.json
+++ b/third_party/rust/remote_settings/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"fc7859a498493f1ede9c5c62b857ec76e3e9e8097cfd8c4f3d779f268b250303","build.rs":"4326f03729cf8f1673e4228e6dc111de1ea4d8bcc06351f7ae563efb2613f866","src/cache.rs":"9c16f17353730103d57132a0f055863b085d2d3eb3a78f6a6f8d095f897d0c0d","src/client.rs":"1c589317907d21745e945dfd992c11535aaafcaca9a6ebe33a5a7c2e2cb93997","src/config.rs":"52a209256acd8b1fada2b91e9d9f669df0ee6e9609baad7ec34a2111ed2a6541","src/error.rs":"4bb15cd7f6ebc438119f36291ab0eb951fe2fb05e166445817cb05aa89397000","src/lib.rs":"ff1b9f66ae6069005d36c84b296f22424b4305a5873353e351fbe057f126e140","src/remote_settings.udl":"1ffeb10385e4db63606cda79bb59e77170af1d2ca0028da8ab2c4d7622969734","uniffi.toml":"f8ec8dc593e0d501c2e9e40368ec93ec33b1edd8608e29495e0a54b63144e880"},"package":null}
\ No newline at end of file
+{"files":{"Cargo.toml":"945724993504a7b031f184382d3ced10b55eb6f096000369bb779aa50097ec94","build.rs":"4326f03729cf8f1673e4228e6dc111de1ea4d8bcc06351f7ae563efb2613f866","src/cache.rs":"9c16f17353730103d57132a0f055863b085d2d3eb3a78f6a6f8d095f897d0c0d","src/client.rs":"1c589317907d21745e945dfd992c11535aaafcaca9a6ebe33a5a7c2e2cb93997","src/config.rs":"52a209256acd8b1fada2b91e9d9f669df0ee6e9609baad7ec34a2111ed2a6541","src/error.rs":"4bb15cd7f6ebc438119f36291ab0eb951fe2fb05e166445817cb05aa89397000","src/lib.rs":"ff1b9f66ae6069005d36c84b296f22424b4305a5873353e351fbe057f126e140","src/remote_settings.udl":"1ffeb10385e4db63606cda79bb59e77170af1d2ca0028da8ab2c4d7622969734","uniffi.toml":"f8ec8dc593e0d501c2e9e40368ec93ec33b1edd8608e29495e0a54b63144e880"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/remote_settings/Cargo.toml b/third_party/rust/remote_settings/Cargo.toml
index 87cd8467cf81..ed73488f3542 100644
--- a/third_party/rust/remote_settings/Cargo.toml
+++ b/third_party/rust/remote_settings/Cargo.toml
@@ -51,7 +51,7 @@ version = "1"
 features = ["derive"]
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [dependencies.viaduct]
 path = "../viaduct"
@@ -68,5 +68,5 @@ features = ["preserve_order"]
 path = "../support/viaduct-reqwest"
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
diff --git a/third_party/rust/suggest/.cargo-checksum.json b/third_party/rust/suggest/.cargo-checksum.json
index 9b2cae524afa..b99348a0eaba 100644
--- a/third_party/rust/suggest/.cargo-checksum.json
+++ b/third_party/rust/suggest/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"b6f48d7892872e05decf3ce4e4198f4481c753fbb74384d9cbc18b4fe1affd12","README.md":"5e28baf874b643d756228bdab345e287bf107d3182dfe6a18aafadcc4b9a3fc9","benches/benchmark_all.rs":"3582f21af9758766ff32ed95f90b69984b32091b1e31e0c0bef307c22fd82f18","build.rs":"78780c5cccfe22c3ff4198624b9e188559c437c3e6fa1c8bb66548eee6aa66bf","metrics.yaml":"0540ab2271aeab7f07335c7ceec12acde942995f9dcb3c29070489aa61899d56","src/benchmarks/README.md":"ccee8dbddba8762d0453fa855bd6984137b224b8c019f3dd8e86a3c303f51d71","src/benchmarks/client.rs":"3b92c350ad396b0e0b5438c7b7b94b08b322702f419ca9b815e6732bd174f8a1","src/benchmarks/ingest.rs":"ca368573591519e6b777d659d5615718bedb6eee1734e25242627f8116b10881","src/benchmarks/mod.rs":"2d7c20d47d6c7e17bc738255a31119bd0c4a4e495419a00c7b10b251ace9ef6b","src/benchmarks/query.rs":"ce78057e0ed43a419cc92d2bceb0bbef8aad9b113ef0341cf5f1d8d1578848e0","src/bin/debug_ingestion_sizes.rs":"ce6e810be7b3fc19e826d75b622b82cfab5a1a99397a6d0833c2c4eebff2d364","src/config.rs":"d40c6e83d8b5faa32c66110803ca9e78611d43507e9d3f1e191a93a7773c37b3","src/db.rs":"96156fcb8f8dc9dd98334d77fc53623046529dcf6b57f6282f120ad33cb8bcac","src/error.rs":"183a92511565439915275e0705e6740ff513c2549f2ef78fd3055d8aaaf81021","src/fakespot.rs":"03d3aac07b3a3a9ceb8d2c452d4a122bfebf04579829e62e83487877055312d4","src/keyword.rs":"988d0ab021c0df19cfd3c519df7d37f606bf984cd14d0efca4e5a7aff88344dd","src/lib.rs":"ab7fa1005cc371b15fde5211d7dabae5034f3b236580047655897be30280b2c9","src/metrics.rs":"b3b9816b8eda366f808b56e242ac6aa43a5b141ad01d43420fdfcbfca13e1cfc","src/pocket.rs":"1316668840ec9b4ea886223921dc9d3b5a1731d1a5206c0b1089f2a6c45c1b7b","src/provider.rs":"3ad644f7b3942e4228bdc9ec03e12af5faa55e3f9ab668617bef98e4c61ee1f7","src/query.rs":"6b94eb913908c36798129311bf519fa76478c6d35c2154efd639c4ba26b95a59","src/rs.rs":"16cf7fae7e935ef94beab532537564975addcd35b1a9b4b4a9fa1d34d51fbcfb","src/schema.rs":"5f2449c6ef798addf6b1d9869936edfe0629f6d543f3cb957becdf0595b29a41","src/store.rs":"57d00989eca564ce1497fa813b2f1bdf8acb8cbba1603fe6000c3abef37e5959","src/suggest.udl":"ba5e99a5d8c09ade945d537e0f90276cc6964ebc9ff454e5dbe5c9b3ba58f8eb","src/suggestion.rs":"3a91ecd648183f34b3834f5eaa14e487f29d8b227e7d4755288c3eade6d990e3","src/testing/client.rs":"f8c9bd32d0f4cf364daebe114d580c7e36a83b69c07884d14170969620d9a437","src/testing/data.rs":"d4fc5227996a8b115d93243fdbd83bc57d73a8c2d4c0b20dffa15bbec27925cb","src/testing/mod.rs":"800e5317bc2e13ee2b416bb0eb5c25ad9108a1afe8c73c9d2f6787572aa95c3a","src/yelp.rs":"bc036ff71b438d53ce8811acd8d650d83ef03faeea476f5b659b403c1e64ff2b","uniffi.toml":"f26317442ddb5b3281245bef6e60ffcb78bb95d29fe4a351a56dbb88d4ec8aab"},"package":null}
\ No newline at end of file
+{"files":{"Cargo.toml":"2e38a519b9a49462d301e296d0445f7c44897b963293b6f4ac45b1312f9b36ad","README.md":"5e28baf874b643d756228bdab345e287bf107d3182dfe6a18aafadcc4b9a3fc9","benches/benchmark_all.rs":"3582f21af9758766ff32ed95f90b69984b32091b1e31e0c0bef307c22fd82f18","build.rs":"78780c5cccfe22c3ff4198624b9e188559c437c3e6fa1c8bb66548eee6aa66bf","metrics.yaml":"0540ab2271aeab7f07335c7ceec12acde942995f9dcb3c29070489aa61899d56","src/benchmarks/README.md":"ccee8dbddba8762d0453fa855bd6984137b224b8c019f3dd8e86a3c303f51d71","src/benchmarks/client.rs":"3b92c350ad396b0e0b5438c7b7b94b08b322702f419ca9b815e6732bd174f8a1","src/benchmarks/ingest.rs":"ca368573591519e6b777d659d5615718bedb6eee1734e25242627f8116b10881","src/benchmarks/mod.rs":"2d7c20d47d6c7e17bc738255a31119bd0c4a4e495419a00c7b10b251ace9ef6b","src/benchmarks/query.rs":"ce78057e0ed43a419cc92d2bceb0bbef8aad9b113ef0341cf5f1d8d1578848e0","src/bin/debug_ingestion_sizes.rs":"ce6e810be7b3fc19e826d75b622b82cfab5a1a99397a6d0833c2c4eebff2d364","src/config.rs":"d40c6e83d8b5faa32c66110803ca9e78611d43507e9d3f1e191a93a7773c37b3","src/db.rs":"96156fcb8f8dc9dd98334d77fc53623046529dcf6b57f6282f120ad33cb8bcac","src/error.rs":"183a92511565439915275e0705e6740ff513c2549f2ef78fd3055d8aaaf81021","src/fakespot.rs":"03d3aac07b3a3a9ceb8d2c452d4a122bfebf04579829e62e83487877055312d4","src/keyword.rs":"988d0ab021c0df19cfd3c519df7d37f606bf984cd14d0efca4e5a7aff88344dd","src/lib.rs":"ab7fa1005cc371b15fde5211d7dabae5034f3b236580047655897be30280b2c9","src/metrics.rs":"b3b9816b8eda366f808b56e242ac6aa43a5b141ad01d43420fdfcbfca13e1cfc","src/pocket.rs":"1316668840ec9b4ea886223921dc9d3b5a1731d1a5206c0b1089f2a6c45c1b7b","src/provider.rs":"3ad644f7b3942e4228bdc9ec03e12af5faa55e3f9ab668617bef98e4c61ee1f7","src/query.rs":"6b94eb913908c36798129311bf519fa76478c6d35c2154efd639c4ba26b95a59","src/rs.rs":"16cf7fae7e935ef94beab532537564975addcd35b1a9b4b4a9fa1d34d51fbcfb","src/schema.rs":"5f2449c6ef798addf6b1d9869936edfe0629f6d543f3cb957becdf0595b29a41","src/store.rs":"57d00989eca564ce1497fa813b2f1bdf8acb8cbba1603fe6000c3abef37e5959","src/suggest.udl":"ba5e99a5d8c09ade945d537e0f90276cc6964ebc9ff454e5dbe5c9b3ba58f8eb","src/suggestion.rs":"3a91ecd648183f34b3834f5eaa14e487f29d8b227e7d4755288c3eade6d990e3","src/testing/client.rs":"f8c9bd32d0f4cf364daebe114d580c7e36a83b69c07884d14170969620d9a437","src/testing/data.rs":"d4fc5227996a8b115d93243fdbd83bc57d73a8c2d4c0b20dffa15bbec27925cb","src/testing/mod.rs":"800e5317bc2e13ee2b416bb0eb5c25ad9108a1afe8c73c9d2f6787572aa95c3a","src/yelp.rs":"bc036ff71b438d53ce8811acd8d650d83ef03faeea476f5b659b403c1e64ff2b","uniffi.toml":"f26317442ddb5b3281245bef6e60ffcb78bb95d29fe4a351a56dbb88d4ec8aab"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/suggest/Cargo.toml b/third_party/rust/suggest/Cargo.toml
index 3097d8bed7b8..baabf64219ec 100644
--- a/third_party/rust/suggest/Cargo.toml
+++ b/third_party/rust/suggest/Cargo.toml
@@ -86,7 +86,7 @@ version = "3.2.0"
 optional = true
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [dependencies.url]
 version = "2.1"
@@ -112,7 +112,7 @@ default-features = false
 path = "../support/rc_crypto"
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
 
 [features]
diff --git a/third_party/rust/sync15/.cargo-checksum.json b/third_party/rust/sync15/.cargo-checksum.json
index fa8171bc74f9..cdb54a78f9a3 100644
--- a/third_party/rust/sync15/.cargo-checksum.json
+++ b/third_party/rust/sync15/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"3cacaf0a05825c2bc79d3ea3b12580301ef056d40d2bc5b2546de99d306ef242","README.md":"6d4ff5b079ac5340d18fa127f583e7ad793c5a2328b8ecd12c3fc723939804f2","build.rs":"aa971160d67ce8626b26e15c04c34b730f594c45c817aae34cfc9f3ea14ae284","src/bso/content.rs":"92935258745bdf0c3915a555cb6884a7fa69faa1290ec2c1815f6e2f3c0f0562","src/bso/crypto.rs":"27602dcccb37d3a55620ee4e16b705da455d49af575de115c7c79c0178eb1d6d","src/bso/mod.rs":"09e723dc7e99295ecafdcadffaf604d66ea27cf2b7f1fd9ab3cac4f4698ff6a7","src/bso/test_utils.rs":"4ec5a2df5e1c0ec14dc770681e959bdcef6ef04f6fde435999197f46a8ae4831","src/client/coll_state.rs":"13e6ef55273baf5536acc369be522e34a803a32cabf19cce43e426aea9b6223e","src/client/coll_update.rs":"dac04a90c29dd969f8b4250414609c9b6d61daf2dfa4ae77d1c4a165ba970b05","src/client/collection_keys.rs":"c27b2277a3a52033b58ab01490fc2ea7007494195dd5e6dc2c6931a4ca96795a","src/client/mod.rs":"8f588d4a035cf79d96f2500f06d5651c1a7c566127c456ffa5429811ddce3fd6","src/client/request.rs":"e878c5b43298b6eb682748474963f9fb8d053b4dc690bbb27107f5fa0ee74e01","src/client/state.rs":"4e31193ef2471c1dfabf1c6a391bcb95e14ddb45855786a4194ff187d5c9347c","src/client/status.rs":"f445a8765dac9789444e23b5145148413407bb1d18a15ef56682243997f591bf","src/client/storage_client.rs":"cc4a3219f342f8665399734902f68a2ddf12ed7e3726033ed10084bcefb66ffd","src/client/sync.rs":"b29abb512ec9d163f7883b71f78c9202802dcb17cad1fc5dc08087fb0bb66704","src/client/sync_multiple.rs":"6e92571132f89744b553190c596be8aff9b2d031d8f79d82c94cdf78b1683f4a","src/client/token.rs":"13729c693c8be72bcafc816c97e2a35932d008b4f2ccda6a5f8cdb8b2c99a293","src/client/util.rs":"71cc70ee41f821f53078675e636e9fad9c6046fa1a989e37f5487e340a2277d6","src/client_types.rs":"3c3cac1540b92482f43660d9e43bdde8481c4cc1a98253a68c80e791231f5976","src/clients_engine/engine.rs":"9e11b47be81fc63214f31879af74075674aa50a8f8989afe20fefa7990fa99b9","src/clients_engine/mod.rs":"461729e6f89b66b2cbd89b041a03d4d6a8ba582284ed4f3015cb13e1a0c6da97","src/clients_engine/record.rs":"b0d84bf420743d7638a45e4836633a45e50257d5548fe7ecd04bff4d724439b8","src/clients_engine/ser.rs":"be6a19c45eb8002ff8e7cf746d2f97d9cecd1740f9817a8f1d624825475fd777","src/device_type.rs":"dc2d4296d25e31471c8e68488f1043ff239b902036cd6aea8a686cf79b4ed335","src/enc_payload.rs":"aa3eea7df49b24cd59831680a47c417b73a3e36e6b0f3f4baf14ca66bd68be6b","src/engine/bridged_engine.rs":"b4e3071a0259ac55303364e57f9cd685916b80dc302030bba07790e55ceecb66","src/engine/mod.rs":"90f1f9760f5f712a337aebb04e59c736e4b6fbd89d6a188d969210c7f3f321ae","src/engine/request.rs":"5923025fb9550178339f880a1bf8526d8e853e7a0b2bce6d9d687cc808ac0085","src/engine/sync_engine.rs":"531b35d72ce9e04c3e543c0468c1e450fba2c0dc3d33d68d9b1c0a5c1ad7dd34","src/error.rs":"a45cfe02e6301f473c34678b694943c1a04308b8c292c6e0448bf495194c3b5e","src/key_bundle.rs":"abd0781f3be8c8e7c691f18bb71f3433b633803c48da9794e15ac6301ed60d6c","src/lib.rs":"f59f8817978d943518dfa03ab31fc0f6b1fc72ee9943a97aef1537e2769649f5","src/record_types.rs":"02bb3d352fb808131d298f9b90d9c95b7e9e0138b97c5401f3b9fdacc5562f44","src/server_timestamp.rs":"63916817796e83fe31fbd598bac025dfa71ec9e1808d09073db258c78a3331cd","src/sync15.udl":"005b2b056b93c959a04670f6f489afecb8e17093d8e4be34765a3a4cc0faeb8c","src/telemetry.rs":"1d06433aafe05b8d0c403ff6cb3bb35eec292f2cd6273d321eaa196fb6584dd6","uniffi.toml":"34488f947497a9b05007445dd816024ef02e6b1696f1056ee868f039722828ee"},"package":null}
\ No newline at end of file
+{"files":{"Cargo.toml":"85552fcfea769f22b10acf08d2f2345dbc8cd683de2c7a88ed7280863407a62e","README.md":"6d4ff5b079ac5340d18fa127f583e7ad793c5a2328b8ecd12c3fc723939804f2","build.rs":"aa971160d67ce8626b26e15c04c34b730f594c45c817aae34cfc9f3ea14ae284","src/bso/content.rs":"92935258745bdf0c3915a555cb6884a7fa69faa1290ec2c1815f6e2f3c0f0562","src/bso/crypto.rs":"27602dcccb37d3a55620ee4e16b705da455d49af575de115c7c79c0178eb1d6d","src/bso/mod.rs":"09e723dc7e99295ecafdcadffaf604d66ea27cf2b7f1fd9ab3cac4f4698ff6a7","src/bso/test_utils.rs":"4ec5a2df5e1c0ec14dc770681e959bdcef6ef04f6fde435999197f46a8ae4831","src/client/coll_state.rs":"13e6ef55273baf5536acc369be522e34a803a32cabf19cce43e426aea9b6223e","src/client/coll_update.rs":"dac04a90c29dd969f8b4250414609c9b6d61daf2dfa4ae77d1c4a165ba970b05","src/client/collection_keys.rs":"c27b2277a3a52033b58ab01490fc2ea7007494195dd5e6dc2c6931a4ca96795a","src/client/mod.rs":"8f588d4a035cf79d96f2500f06d5651c1a7c566127c456ffa5429811ddce3fd6","src/client/request.rs":"e878c5b43298b6eb682748474963f9fb8d053b4dc690bbb27107f5fa0ee74e01","src/client/state.rs":"4e31193ef2471c1dfabf1c6a391bcb95e14ddb45855786a4194ff187d5c9347c","src/client/status.rs":"f445a8765dac9789444e23b5145148413407bb1d18a15ef56682243997f591bf","src/client/storage_client.rs":"cc4a3219f342f8665399734902f68a2ddf12ed7e3726033ed10084bcefb66ffd","src/client/sync.rs":"b29abb512ec9d163f7883b71f78c9202802dcb17cad1fc5dc08087fb0bb66704","src/client/sync_multiple.rs":"6e92571132f89744b553190c596be8aff9b2d031d8f79d82c94cdf78b1683f4a","src/client/token.rs":"13729c693c8be72bcafc816c97e2a35932d008b4f2ccda6a5f8cdb8b2c99a293","src/client/util.rs":"71cc70ee41f821f53078675e636e9fad9c6046fa1a989e37f5487e340a2277d6","src/client_types.rs":"3c3cac1540b92482f43660d9e43bdde8481c4cc1a98253a68c80e791231f5976","src/clients_engine/engine.rs":"9e11b47be81fc63214f31879af74075674aa50a8f8989afe20fefa7990fa99b9","src/clients_engine/mod.rs":"461729e6f89b66b2cbd89b041a03d4d6a8ba582284ed4f3015cb13e1a0c6da97","src/clients_engine/record.rs":"b0d84bf420743d7638a45e4836633a45e50257d5548fe7ecd04bff4d724439b8","src/clients_engine/ser.rs":"be6a19c45eb8002ff8e7cf746d2f97d9cecd1740f9817a8f1d624825475fd777","src/device_type.rs":"dc2d4296d25e31471c8e68488f1043ff239b902036cd6aea8a686cf79b4ed335","src/enc_payload.rs":"aa3eea7df49b24cd59831680a47c417b73a3e36e6b0f3f4baf14ca66bd68be6b","src/engine/bridged_engine.rs":"b4e3071a0259ac55303364e57f9cd685916b80dc302030bba07790e55ceecb66","src/engine/mod.rs":"90f1f9760f5f712a337aebb04e59c736e4b6fbd89d6a188d969210c7f3f321ae","src/engine/request.rs":"5923025fb9550178339f880a1bf8526d8e853e7a0b2bce6d9d687cc808ac0085","src/engine/sync_engine.rs":"531b35d72ce9e04c3e543c0468c1e450fba2c0dc3d33d68d9b1c0a5c1ad7dd34","src/error.rs":"a45cfe02e6301f473c34678b694943c1a04308b8c292c6e0448bf495194c3b5e","src/key_bundle.rs":"abd0781f3be8c8e7c691f18bb71f3433b633803c48da9794e15ac6301ed60d6c","src/lib.rs":"f59f8817978d943518dfa03ab31fc0f6b1fc72ee9943a97aef1537e2769649f5","src/record_types.rs":"02bb3d352fb808131d298f9b90d9c95b7e9e0138b97c5401f3b9fdacc5562f44","src/server_timestamp.rs":"63916817796e83fe31fbd598bac025dfa71ec9e1808d09073db258c78a3331cd","src/sync15.udl":"005b2b056b93c959a04670f6f489afecb8e17093d8e4be34765a3a4cc0faeb8c","src/telemetry.rs":"1d06433aafe05b8d0c403ff6cb3bb35eec292f2cd6273d321eaa196fb6584dd6","uniffi.toml":"34488f947497a9b05007445dd816024ef02e6b1696f1056ee868f039722828ee"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/sync15/Cargo.toml b/third_party/rust/sync15/Cargo.toml
index 06f5dfda921e..9931a375c475 100644
--- a/third_party/rust/sync15/Cargo.toml
+++ b/third_party/rust/sync15/Cargo.toml
@@ -76,7 +76,7 @@ path = "../support/guid"
 features = ["random"]
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [dependencies.url]
 version = "2.1"
@@ -91,7 +91,7 @@ version = "0.10"
 default-features = false
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
 
 [features]
diff --git a/third_party/rust/tabs/.cargo-checksum.json b/third_party/rust/tabs/.cargo-checksum.json
index e8e4f8b7166e..3bd6c7ba5b45 100644
--- a/third_party/rust/tabs/.cargo-checksum.json
+++ b/third_party/rust/tabs/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"916ac811a7f5fab127228d1d8b5bf2b5eee6884a3f5b7ef87e1e2d6008ad8e4a","README.md":"c48b8f391ef822c4f3971b5f453a1e7b43bea232752d520460d2f04803aead1a","build.rs":"33e61b811b19ed2b58e319cc65d5988bed258d2c4fea2d706301184c59847a0f","src/error.rs":"2694657aeb12f99c4b2fe102ad2b08b79955d209201831b3e071129f0b7d7eda","src/lib.rs":"5789fc7107c76168c331c175aff4f0b2ac2ba3d65cfa0df0e1d4f8ef0c6eb80c","src/schema.rs":"510218d465c7d26d6b9f342cc33c14ab83044a67561ef924c33dadb060761972","src/storage.rs":"99f14f989a04a73bf794863786370fe7fdc89061eddc381ff82ae067297fd92b","src/store.rs":"95ed09a93bc72327811f9c5826779ef4fe96d7f2c04a2382a96557746bf7b2f9","src/sync/bridge.rs":"18d3a7913a030b598d4b6cbd5b7e2ab4cef4cc7ea964f5bc84d7fb2f28787529","src/sync/engine.rs":"73007423f2a22314a034ac660aa65bd9c50e8aa850c445a66604486280067843","src/sync/mod.rs":"09ba3c87f1174a243bf5aaa481effd18929d54359ceb9b23ccb2c32ee3482f34","src/sync/record.rs":"eef6751c209d039958afbe245ddb006cfdf6b8b6b47f925f69c552b832b87922","src/tabs.udl":"b2918b26c982c3420346bad4c8de83fa039afcee5ab838c71048eae27240af8f","uniffi.toml":"f9125e8d55b109e86076ee88bfd640372f06b142b7db557e41816c7227dd445c"},"package":null}
\ No newline at end of file
+{"files":{"Cargo.toml":"4e3cdde3168af54cac1a9e6fa84c5ff0a99252b67d32ce5d177b057f7a70e0f9","README.md":"c48b8f391ef822c4f3971b5f453a1e7b43bea232752d520460d2f04803aead1a","build.rs":"33e61b811b19ed2b58e319cc65d5988bed258d2c4fea2d706301184c59847a0f","src/error.rs":"2694657aeb12f99c4b2fe102ad2b08b79955d209201831b3e071129f0b7d7eda","src/lib.rs":"5789fc7107c76168c331c175aff4f0b2ac2ba3d65cfa0df0e1d4f8ef0c6eb80c","src/schema.rs":"510218d465c7d26d6b9f342cc33c14ab83044a67561ef924c33dadb060761972","src/storage.rs":"99f14f989a04a73bf794863786370fe7fdc89061eddc381ff82ae067297fd92b","src/store.rs":"95ed09a93bc72327811f9c5826779ef4fe96d7f2c04a2382a96557746bf7b2f9","src/sync/bridge.rs":"18d3a7913a030b598d4b6cbd5b7e2ab4cef4cc7ea964f5bc84d7fb2f28787529","src/sync/engine.rs":"73007423f2a22314a034ac660aa65bd9c50e8aa850c445a66604486280067843","src/sync/mod.rs":"09ba3c87f1174a243bf5aaa481effd18929d54359ceb9b23ccb2c32ee3482f34","src/sync/record.rs":"eef6751c209d039958afbe245ddb006cfdf6b8b6b47f925f69c552b832b87922","src/tabs.udl":"b2918b26c982c3420346bad4c8de83fa039afcee5ab838c71048eae27240af8f","uniffi.toml":"f9125e8d55b109e86076ee88bfd640372f06b142b7db557e41816c7227dd445c"},"package":null}
\ No newline at end of file
diff --git a/third_party/rust/tabs/Cargo.toml b/third_party/rust/tabs/Cargo.toml
index e9da5e091c5b..8f3a7a1e443f 100644
--- a/third_party/rust/tabs/Cargo.toml
+++ b/third_party/rust/tabs/Cargo.toml
@@ -76,7 +76,7 @@ features = ["sync-engine"]
 path = "../support/types"
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [dev-dependencies]
 tempfile = "3.1"
@@ -87,5 +87,5 @@ features = ["humantime"]
 default-features = false
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
diff --git a/third_party/rust/uniffi/.cargo-checksum.json b/third_party/rust/uniffi/.cargo-checksum.json
index 81ca3764cfda..9ef7e69a3e8f 100644
--- a/third_party/rust/uniffi/.cargo-checksum.json
+++ b/third_party/rust/uniffi/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"7c45cfa5f95f1db4ec3cb139f8f5166281f7893b21a4313ee4a4f4070bef1816","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","release.toml":"1aa1b131d4cc93b5eba8758a4401c70bc0d7fe5861e2ec147e9259fe7c0da472","src/cli.rs":"5c0b9bb93665f2f49f7e90335e65206887e26e96f2a533eb1203be27c9380c84","src/lib.rs":"422503d7cbac1360852287b1810c99663669625b9abf080a5fec22058bb73d8c","tests/ui/proc_macro_arc.rs":"fedc429603753e8ef953642a7295323ccb3f76fd3ae1ab181ad90c5eb88212bb","tests/ui/proc_macro_arc.stderr":"a24af227b907328c9cac6317ec9f43dbc45d7f7c77c603e5d72db7fa050e8b01","tests/ui/version_mismatch.rs":"16ea359e5853517ee0d0704c015ae8c825533109fbefd715130d0f4a51f15898","tests/ui/version_mismatch.stderr":"21dcb836253312ba8e3a0502cce6ff279818aaaadcea9628a41b196e0c8c94b6"},"package":"cb3a4c447c50fcda7bc5604a8588b7e1f37ffbfd8838a1516a290398efa7c6f0"}
\ No newline at end of file
+{"files":{"Cargo.toml":"87b3072b1ffd4a1b018953792ccca5f98d6863131aea7a27563fc8077a42e998","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","release.toml":"1aa1b131d4cc93b5eba8758a4401c70bc0d7fe5861e2ec147e9259fe7c0da472","src/cli.rs":"648a1c05015ce4e8c63f00321f02eddd4b42c0cdefb734b569c1761c2b1bc436","src/lib.rs":"ecabaf300a549d9d8ff046d43465358f03a76c8b941e2a1511c6e3d2884285f9","tests/ui/proc_macro_arc.rs":"fedc429603753e8ef953642a7295323ccb3f76fd3ae1ab181ad90c5eb88212bb","tests/ui/proc_macro_arc.stderr":"3d5b53f50dc2b8ac89b331efb349cf52bd5820cd8f86c5fc504f7ed757155ea6","tests/ui/version_mismatch.rs":"16ea359e5853517ee0d0704c015ae8c825533109fbefd715130d0f4a51f15898","tests/ui/version_mismatch.stderr":"21dcb836253312ba8e3a0502cce6ff279818aaaadcea9628a41b196e0c8c94b6"},"package":"2db87def739fe4183947f8419d572d1849a4a09355eba4e988a2105cfd0ac6a7"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi/Cargo.toml b/third_party/rust/uniffi/Cargo.toml
index 8081d8f8f669..b8dbb9b9c939 100644
--- a/third_party/rust/uniffi/Cargo.toml
+++ b/third_party/rust/uniffi/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi"
-version = "0.27.3"
+version = "0.28.1"
 authors = ["Firefox Sync Team <sync-team@mozilla.com>"]
 description = "a multi-language bindings generator for rust"
 homepage = "https://mozilla.github.io/uniffi-rs"
@@ -32,6 +32,10 @@ version = "1"
 version = "1.0.8"
 optional = true
 
+[dependencies.cargo_metadata]
+version = "0.15"
+optional = true
+
 [dependencies.clap]
 version = "4"
 features = [
@@ -42,33 +46,39 @@ features = [
 optional = true
 
 [dependencies.uniffi_bindgen]
-version = "=0.27.3"
+version = "=0.28.1"
 optional = true
 
 [dependencies.uniffi_build]
-version = "=0.27.3"
+version = "=0.28.1"
 optional = true
 
 [dependencies.uniffi_core]
-version = "=0.27.3"
+version = "=0.28.1"
 
 [dependencies.uniffi_macros]
-version = "=0.27.3"
+version = "=0.28.1"
 
 [dev-dependencies.trybuild]
 version = "1"
 
 [features]
 bindgen = ["dep:uniffi_bindgen"]
-bindgen-tests = ["dep:uniffi_bindgen"]
+bindgen-tests = [
+    "dep:uniffi_bindgen",
+    "uniffi_bindgen/bindgen-tests",
+]
 build = ["dep:uniffi_build"]
+cargo-metadata = [
+    "dep:cargo_metadata",
+    "uniffi_bindgen?/cargo-metadata",
+]
 cli = [
     "bindgen",
-    "uniffi_bindgen?/clap",
     "dep:clap",
     "dep:camino",
 ]
-default = []
+default = ["cargo-metadata"]
 scaffolding-ffi-buffer-fns = [
     "uniffi_core/scaffolding-ffi-buffer-fns",
     "uniffi_macros/scaffolding-ffi-buffer-fns",
diff --git a/third_party/rust/uniffi/src/cli.rs b/third_party/rust/uniffi/src/cli.rs
index 77d7f219a920..e3d5cf41e902 100644
--- a/third_party/rust/uniffi/src/cli.rs
+++ b/third_party/rust/uniffi/src/cli.rs
@@ -2,10 +2,62 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use anyhow::{bail, Context, Result};
 use camino::Utf8PathBuf;
 use clap::{Parser, Subcommand};
-use uniffi_bindgen::bindings::TargetLanguage;
-use uniffi_bindgen::BindingGeneratorDefault;
+use std::fmt;
+use uniffi_bindgen::bindings::*;
+
+/// Enumeration of all foreign language targets currently supported by our CLI.
+///
+#[derive(Copy, Clone, Eq, PartialEq, Hash, clap::ValueEnum)]
+enum TargetLanguage {
+    Kotlin,
+    Swift,
+    Python,
+    Ruby,
+}
+
+impl fmt::Display for TargetLanguage {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        match self {
+            Self::Kotlin => write!(f, "kotlin"),
+            Self::Swift => write!(f, "swift"),
+            Self::Python => write!(f, "python"),
+            Self::Ruby => write!(f, "ruby"),
+        }
+    }
+}
+
+impl TryFrom<&str> for TargetLanguage {
+    type Error = anyhow::Error;
+    fn try_from(value: &str) -> Result<Self> {
+        Ok(match value.to_ascii_lowercase().as_str() {
+            "kotlin" | "kt" | "kts" => TargetLanguage::Kotlin,
+            "swift" => TargetLanguage::Swift,
+            "python" | "py" => TargetLanguage::Python,
+            "ruby" | "rb" => TargetLanguage::Ruby,
+            _ => bail!("Unknown or unsupported target language: \"{value}\""),
+        })
+    }
+}
+
+impl TryFrom<&std::ffi::OsStr> for TargetLanguage {
+    type Error = anyhow::Error;
+    fn try_from(value: &std::ffi::OsStr) -> Result<Self> {
+        match value.to_str() {
+            None => bail!("Unreadable target language"),
+            Some(s) => s.try_into(),
+        }
+    }
+}
+
+impl TryFrom<String> for TargetLanguage {
+    type Error = anyhow::Error;
+    fn try_from(value: String) -> Result<Self> {
+        TryFrom::try_from(value.as_str())
+    }
+}
 
 // Structs to help our cmdline parsing. Note that docstrings below form part
 // of the "help" output.
@@ -56,6 +108,14 @@ enum Commands {
 
         /// Path to the UDL file, or cdylib if `library-mode` is specified
         source: Utf8PathBuf,
+
+        /// Whether we should exclude dependencies when running "cargo metadata".
+        /// This will mean external types may not be resolved if they are implemented in crates
+        /// outside of this workspace.
+        /// This can be used in environments when all types are in the namespace and fetching
+        /// all sub-dependencies causes obscure platform specific problems.
+        #[clap(long)]
+        metadata_no_deps: bool,
     },
 
     /// Generate Rust scaffolding code
@@ -79,6 +139,139 @@ enum Commands {
     },
 }
 
+fn gen_library_mode(
+    library_path: &camino::Utf8Path,
+    crate_name: Option<String>,
+    languages: Vec<TargetLanguage>,
+    cfo: Option<&camino::Utf8Path>,
+    out_dir: &camino::Utf8Path,
+    fmt: bool,
+    metadata_no_deps: bool,
+) -> anyhow::Result<()> {
+    use uniffi_bindgen::library_mode::generate_bindings;
+
+    #[cfg(feature = "cargo-metadata")]
+    let config_supplier = {
+        use uniffi_bindgen::cargo_metadata::CrateConfigSupplier;
+        let mut cmd = cargo_metadata::MetadataCommand::new();
+        if metadata_no_deps {
+            cmd.no_deps();
+        }
+        let metadata = cmd.exec().context("error running cargo metadata")?;
+        CrateConfigSupplier::from(metadata)
+    };
+    #[cfg(not(feature = "cargo-metadata"))]
+    let config_supplier = uniffi_bindgen::EmptyCrateConfigSupplier;
+
+    for language in languages {
+        // to help avoid mistakes we check the library is actually a cdylib, except
+        // for swift where static libs are often used to extract the metadata.
+        if !matches!(language, TargetLanguage::Swift) && !uniffi_bindgen::is_cdylib(library_path) {
+            anyhow::bail!(
+                "Generate bindings for {language} requires a cdylib, but {library_path} was given"
+            );
+        }
+
+        // Type-bounds on trait implementations makes selecting between languages a bit tedious.
+        match language {
+            TargetLanguage::Kotlin => generate_bindings(
+                library_path,
+                crate_name.clone(),
+                &KotlinBindingGenerator,
+                &config_supplier,
+                cfo,
+                out_dir,
+                fmt,
+            )?
+            .len(),
+            TargetLanguage::Python => generate_bindings(
+                library_path,
+                crate_name.clone(),
+                &PythonBindingGenerator,
+                &config_supplier,
+                cfo,
+                out_dir,
+                fmt,
+            )?
+            .len(),
+            TargetLanguage::Ruby => generate_bindings(
+                library_path,
+                crate_name.clone(),
+                &RubyBindingGenerator,
+                &config_supplier,
+                cfo,
+                out_dir,
+                fmt,
+            )?
+            .len(),
+            TargetLanguage::Swift => generate_bindings(
+                library_path,
+                crate_name.clone(),
+                &SwiftBindingGenerator,
+                &config_supplier,
+                cfo,
+                out_dir,
+                fmt,
+            )?
+            .len(),
+        };
+    }
+    Ok(())
+}
+
+fn gen_bindings(
+    udl_file: &camino::Utf8Path,
+    cfo: Option<&camino::Utf8Path>,
+    languages: Vec<TargetLanguage>,
+    odo: Option<&camino::Utf8Path>,
+    library_file: Option<&camino::Utf8Path>,
+    crate_name: Option<&str>,
+    fmt: bool,
+) -> anyhow::Result<()> {
+    use uniffi_bindgen::generate_bindings;
+    for language in languages {
+        match language {
+            TargetLanguage::Kotlin => generate_bindings(
+                udl_file,
+                cfo,
+                KotlinBindingGenerator,
+                odo,
+                library_file,
+                crate_name,
+                fmt,
+            )?,
+            TargetLanguage::Python => generate_bindings(
+                udl_file,
+                cfo,
+                PythonBindingGenerator,
+                odo,
+                library_file,
+                crate_name,
+                fmt,
+            )?,
+            TargetLanguage::Ruby => generate_bindings(
+                udl_file,
+                cfo,
+                RubyBindingGenerator,
+                odo,
+                library_file,
+                crate_name,
+                fmt,
+            )?,
+            TargetLanguage::Swift => generate_bindings(
+                udl_file,
+                cfo,
+                SwiftBindingGenerator,
+                odo,
+                library_file,
+                crate_name,
+                fmt,
+            )?,
+        };
+    }
+    Ok(())
+}
+
 pub fn run_main() -> anyhow::Result<()> {
     let cli = Cli::parse();
     match cli.command {
@@ -91,6 +284,7 @@ pub fn run_main() -> anyhow::Result<()> {
             source,
             crate_name,
             library_mode,
+            metadata_no_deps,
         } => {
             if library_mode {
                 if lib_file.is_some() {
@@ -100,25 +294,23 @@ pub fn run_main() -> anyhow::Result<()> {
                 if language.is_empty() {
                     panic!("please specify at least one language with --language")
                 }
-                uniffi_bindgen::library_mode::generate_bindings(
+                gen_library_mode(
                     &source,
                     crate_name,
-                    &BindingGeneratorDefault {
-                        target_languages: language,
-                        try_format_code: !no_format,
-                    },
+                    language,
                     config.as_deref(),
                     &out_dir,
                     !no_format,
+                    metadata_no_deps,
                 )?;
             } else {
-                uniffi_bindgen::generate_bindings(
+                if metadata_no_deps {
+                    panic!("--metadata-no-deps makes no sense when not in library mode")
+                }
+                gen_bindings(
                     &source,
                     config.as_deref(),
-                    BindingGeneratorDefault {
-                        target_languages: language,
-                        try_format_code: !no_format,
-                    },
+                    language,
                     out_dir.as_deref(),
                     lib_file.as_deref(),
                     crate_name.as_deref(),
diff --git a/third_party/rust/uniffi/src/lib.rs b/third_party/rust/uniffi/src/lib.rs
index 319b3c783627..d49e89e584dd 100644
--- a/third_party/rust/uniffi/src/lib.rs
+++ b/third_party/rust/uniffi/src/lib.rs
@@ -8,20 +8,15 @@ pub use uniffi_macros::*;
 #[cfg(feature = "cli")]
 mod cli;
 #[cfg(feature = "bindgen-tests")]
-pub use uniffi_bindgen::bindings::kotlin::run_test as kotlin_run_test;
-#[cfg(feature = "bindgen-tests")]
-pub use uniffi_bindgen::bindings::python::run_test as python_run_test;
-#[cfg(feature = "bindgen-tests")]
-pub use uniffi_bindgen::bindings::ruby::run_test as ruby_run_test;
-#[cfg(feature = "bindgen-tests")]
-pub use uniffi_bindgen::bindings::swift::run_test as swift_run_test;
+pub use uniffi_bindgen::bindings::{kotlin_test, python_test, ruby_test, swift_test};
+
 #[cfg(feature = "bindgen")]
 pub use uniffi_bindgen::{
-    bindings::kotlin::gen_kotlin::KotlinBindingGenerator,
-    bindings::python::gen_python::PythonBindingGenerator,
-    bindings::ruby::gen_ruby::RubyBindingGenerator,
-    bindings::swift::gen_swift::SwiftBindingGenerator, bindings::TargetLanguage, generate_bindings,
-    generate_component_scaffolding, generate_component_scaffolding_for_crate, print_repr,
+    bindings::{
+        KotlinBindingGenerator, PythonBindingGenerator, RubyBindingGenerator, SwiftBindingGenerator,
+    },
+    generate_bindings, generate_component_scaffolding, generate_component_scaffolding_for_crate,
+    print_repr,
 };
 #[cfg(feature = "build")]
 pub use uniffi_build::{generate_scaffolding, generate_scaffolding_for_crate};
diff --git a/third_party/rust/uniffi/tests/ui/proc_macro_arc.stderr b/third_party/rust/uniffi/tests/ui/proc_macro_arc.stderr
index 0654a29e2580..5d801f6e01ad 100644
--- a/third_party/rust/uniffi/tests/ui/proc_macro_arc.stderr
+++ b/third_party/rust/uniffi/tests/ui/proc_macro_arc.stderr
@@ -2,7 +2,7 @@ error[E0277]: the trait bound `Foo: FfiConverterArc<UniFfiTag>` is not satisfied
   --> tests/ui/proc_macro_arc.rs:10:1
    |
 10 | #[uniffi::export]
-   | ^^^^^^^^^^^^^^^^^ the trait `FfiConverterArc<UniFfiTag>` is not implemented for `Foo`
+   | ^^^^^^^^^^^^^^^^^ the trait `FfiConverterArc<UniFfiTag>` is not implemented for `Foo`, which is required by `Arc<Foo>: LowerReturn<UniFfiTag>`
    |
    = help: the trait `LowerReturn<UT>` is implemented for `Arc<T>`
    = note: required for `Arc<Foo>` to implement `FfiConverter<UniFfiTag>`
@@ -10,13 +10,33 @@ error[E0277]: the trait bound `Foo: FfiConverterArc<UniFfiTag>` is not satisfied
    = note: required for `Arc<Foo>` to implement `LowerReturn<UniFfiTag>`
    = note: this error originates in the attribute macro `uniffi::export` (in Nightly builds, run with -Z macro-backtrace for more info)
 
+error[E0277]: the trait bound `Foo: FfiConverterArc<UniFfiTag>` is not satisfied
+  --> tests/ui/proc_macro_arc.rs:11:18
+   |
+11 | fn make_foo() -> Arc<Foo> {
+   |                  ^^^^^^^^ the trait `FfiConverterArc<UniFfiTag>` is not implemented for `Foo`, which is required by `Arc<Foo>: uniffi::TypeId<UniFfiTag>`
+   |
+   = help: the trait `uniffi::TypeId<UT>` is implemented for `Arc<T>`
+   = note: required for `Arc<Foo>` to implement `FfiConverter<UniFfiTag>`
+   = note: required for `Arc<Foo>` to implement `uniffi::TypeId<UniFfiTag>`
+
 error[E0277]: the trait bound `child::Foo: FfiConverterArc<UniFfiTag>` is not satisfied
   --> tests/ui/proc_macro_arc.rs:20:5
    |
 20 |     #[uniffi::export]
-   |     ^^^^^^^^^^^^^^^^^ the trait `FfiConverterArc<UniFfiTag>` is not implemented for `child::Foo`
+   |     ^^^^^^^^^^^^^^^^^ the trait `FfiConverterArc<UniFfiTag>` is not implemented for `child::Foo`, which is required by `Arc<child::Foo>: Lift<UniFfiTag>`
    |
    = help: the trait `Lift<UT>` is implemented for `Arc<T>`
    = note: required for `Arc<child::Foo>` to implement `FfiConverter<UniFfiTag>`
    = note: required for `Arc<child::Foo>` to implement `Lift<UniFfiTag>`
    = note: this error originates in the attribute macro `uniffi::export` (in Nightly builds, run with -Z macro-backtrace for more info)
+
+error[E0277]: the trait bound `child::Foo: FfiConverterArc<UniFfiTag>` is not satisfied
+  --> tests/ui/proc_macro_arc.rs:21:22
+   |
+21 |     fn take_foo(foo: Arc<Foo>) {
+   |                      ^^^^^^^^ the trait `FfiConverterArc<UniFfiTag>` is not implemented for `child::Foo`, which is required by `Arc<child::Foo>: uniffi::TypeId<UniFfiTag>`
+   |
+   = help: the trait `uniffi::TypeId<UT>` is implemented for `Arc<T>`
+   = note: required for `Arc<child::Foo>` to implement `FfiConverter<UniFfiTag>`
+   = note: required for `Arc<child::Foo>` to implement `uniffi::TypeId<UniFfiTag>`
diff --git a/third_party/rust/uniffi_bindgen/.cargo-checksum.json b/third_party/rust/uniffi_bindgen/.cargo-checksum.json
index c32688568271..38426872899a 100644
--- a/third_party/rust/uniffi_bindgen/.cargo-checksum.json
+++ b/third_party/rust/uniffi_bindgen/.cargo-checksum.json
@@ -1 +1 @@
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mplates/UInt64Helper.swift":"17237b38d09ced8d2a8ff1ad9ca86873a19e417280e0e60f33d7063397ea4b7b","src/bindings/swift/templates/UInt8Helper.swift":"c4cb2ee4a78b54ca8d0013383c6b43e9ecd42776e3dc7d6e40086325d41714e5","src/bindings/swift/templates/macros.swift":"b30ffd93fe2213e13c3b9910bf2404403b4b231d4cd32c81e0f76c3bb4d151b5","src/bindings/swift/templates/wrapper.swift":"4905b560e60cd89015b5c95bcf37fddcdaf76976291277fb3276fa5561b6bb3d","src/bindings/swift/test.rs":"c5835a90578846208dc2c7757b9a556394e90d299f59b99e3b71ee21ea134c5a","src/cargo_metadata.rs":"4c253acc633187a2252809e8712496bf0e1990e9dcaa0b16cb4a92db95b284f3","src/interface/callbacks.rs":"daf4e46c0fafd0691907e8923c8164d494685c16dc187271a4909937834d82d5","src/interface/enum_.rs":"4b458345ddaa102788a5acffdfb94735328e62e8453d154d0b35fc589bdd6fb2","src/interface/ffi.rs":"2c08894d8ff07fc4baffb3399d4835ae8c32fc860aa7661db60c7e81b8d79c49","src/interface/function.rs":"bdca8cb81cebcf2d1f06b5f3bb82447a258ddfaf0d08c6f3d299e622511e398b","src/interface/mod.rs":"944e80df6f70a33c2df3d6068f23a51786b6f3c669f61558fdec90b7211eb54c","src/interface/object.rs":"16893d49f2727a98406daaeddf87a7159eb24090ed9b78363f61ee530210c726","src/interface/record.rs":"d064b0cb529a8a912414d6bc425c16949450a710da040e7f78d34a9b431a5964","src/interface/universe.rs":"38bbae076e87e4d6dd9eca88f54be6f7f70a2937b487a69cf1fb2155252ba9f5","src/interface/visit_mut.rs":"ed304e9a174f48770939a89e4c477e3fa88719f79643a337bf861026087e2b68","src/lib.rs":"915fdece74f894376dbe3fbf84382abb94633402a3253f73bc17dec935ce87af","src/library_mode.rs":"75b3632e5e7117ab6aab00acd7c96c3c1bce2d2b2d450701cc5d48fb1452e21b","src/macro_metadata/ci.rs":"47150355cd37997c3f5ba95eefa14c21e612622013dfb978c5b5a7334b38ac9f","src/macro_metadata/extract.rs":"7554c7b19b50d40e90bb503320311c2caa3b1e45e4376a9266ce32c0d48afffb","src/macro_metadata/mod.rs":"bcb5e9a015510e9d74c288da928a4bfb8d80926a8ff85227c0eae8cdb2605519","src/scaffolding/mod.rs":"6bf4621bbfdf1dd82b8d7eebef48dbdf41a617bbd96dfb596a425a068a08a560","src/scaffolding/templates/CallbackInterfaceTemplate.rs":"11acee064df46f7b5132401ae49c03c77f296bc04065085d6fd5c4ad6b628718","src/scaffolding/templates/Checksums.rs":"ee926e840875c2e48e1d0cc5185c11f7a1ed3bde5264b07540812cb13c1d7481","src/scaffolding/templates/EnumTemplate.rs":"1a0d514da4932f657c068c0f225b776555e07e8af6aeb8923659d725539c1fd0","src/scaffolding/templates/ErrorTemplate.rs":"9c8aa912d21afa76d88ff1f4526d428d98d94856a0b267354341628e91bdbae3","src/scaffolding/templates/ExternalTypesTemplate.rs":"4c45cefca1774de3f3b650ce3b9a1b1b8fc10c62e0e48e54ac300748c32959f6","src/scaffolding/templates/ObjectTemplate.rs":"666a7834724b15b7ada77ec821e5ccc75e02e2cd1835a3d440f53382fc70247f","src/scaffolding/templates/RecordTemplate.rs":"77e14199fb49048d5efc08a14ffe0af6c240eeebc2d75b2bfd7f2c2bdf2cf139","src/scaffolding/templates/ReexportUniFFIScaffolding.rs":"aa8a1ffa98b6033707d965f90b5709474ed6bc79486fb47dacae8417fc056cf8","src/scaffolding/templates/TopLevelFunctionTemplate.rs":"c11a688cafc2e21c3be105533b34c1f73eab55202936f7c8a97191d7e27f26e0","src/scaffolding/templates/UdlMetadata.rs":"d7c50af1de92ef85630b385a910c7b29875502d622eb90da5541a7012b93d9e2","src/scaffolding/templates/macros.rs":"ea6bacd8dd9116ad739bdafe893d70407050f35e4a7ac8dd2c78b8ef34263e8e","src/scaffolding/templates/scaffolding_template.rs":"c8e18306a73ec5b764f665660fc5c91d498b63b6c3f489e524b2bae50f81f231"},"package":"7a112599c9556d1581e4a3d72019a74c2c3e122cc27f4af12577a429c4d5e614"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_bindgen/Cargo.toml b/third_party/rust/uniffi_bindgen/Cargo.toml
index 6d1dba588cc2..2f7bf8996f81 100644
--- a/third_party/rust/uniffi_bindgen/Cargo.toml
+++ b/third_party/rust/uniffi_bindgen/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_bindgen"
-version = "0.27.3"
+version = "0.28.1"
 authors = ["Firefox Sync Team <sync-team@mozilla.com>"]
 description = "a multi-language bindings generator for rust (codegen and cli tooling)"
 homepage = "https://mozilla.github.io/uniffi-rs"
@@ -38,15 +38,7 @@ version = "1.0.8"
 
 [dependencies.cargo_metadata]
 version = "0.15"
-
-[dependencies.clap]
-version = "4"
-features = [
-    "std",
-    "derive",
-]
 optional = true
-default-features = false
 
 [dependencies.fs-err]
 version = "2.7.0"
@@ -58,7 +50,7 @@ version = "0.3"
 version = "0.8"
 
 [dependencies.heck]
-version = "0.4"
+version = "0.5"
 
 [dependencies.once_cell]
 version = "1.12"
@@ -79,10 +71,19 @@ default-features = false
 version = "0.5"
 
 [dependencies.uniffi_meta]
-version = "=0.27.3"
+version = "=0.28.1"
 
 [dependencies.uniffi_testing]
-version = "=0.27.3"
+version = "=0.28.1"
+optional = true
 
 [dependencies.uniffi_udl]
-version = "=0.27.3"
+version = "=0.28.1"
+
+[features]
+bindgen-tests = [
+    "cargo-metadata",
+    "dep:uniffi_testing",
+]
+cargo-metadata = ["dep:cargo_metadata"]
+default = ["cargo-metadata"]
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/README.md b/third_party/rust/uniffi_bindgen/src/bindings/README.md
new file mode 100644
index 000000000000..d4b0c1980caf
--- /dev/null
+++ b/third_party/rust/uniffi_bindgen/src/bindings/README.md
@@ -0,0 +1 @@
+[See the section in the manual for into about the bindings](../../../docs/manual/src/internals/rendering_foreign_bindings.md)
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/custom.rs b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/custom.rs
index 137cd0d8d92f..f1b67e79ae16 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/custom.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/custom.rs
@@ -17,8 +17,8 @@ impl CustomCodeType {
 }
 
 impl CodeType for CustomCodeType {
-    fn type_label(&self, _ci: &ComponentInterface) -> String {
-        self.name.clone()
+    fn type_label(&self, ci: &ComponentInterface) -> String {
+        super::KotlinCodeOracle.class_name(ci, &self.name)
     }
 
     fn canonical_name(&self) -> String {
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/mod.rs
index c4fc8e0ed6af..92f2f39c330b 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/gen_kotlin/mod.rs
@@ -7,16 +7,14 @@ use std::cell::RefCell;
 use std::collections::{BTreeSet, HashMap, HashSet};
 use std::fmt::Debug;
 
-use anyhow::{bail, Context, Result};
+use anyhow::{anyhow, Context, Result};
 use askama::Template;
-use camino::Utf8Path;
 use heck::{ToLowerCamelCase, ToShoutySnakeCase, ToUpperCamelCase};
 use serde::{Deserialize, Serialize};
 
 use crate::backend::TemplateExpression;
-use crate::bindings::kotlin;
+
 use crate::interface::*;
-use crate::{BindingGenerator, BindingsConfig};
 
 mod callback_interface;
 mod compounds;
@@ -29,28 +27,6 @@ mod primitives;
 mod record;
 mod variant;
 
-pub struct KotlinBindingGenerator;
-impl BindingGenerator for KotlinBindingGenerator {
-    type Config = Config;
-
-    fn write_bindings(
-        &self,
-        ci: &ComponentInterface,
-        config: &Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
-    ) -> Result<()> {
-        kotlin::write_bindings(config, ci, out_dir, try_format_code)
-    }
-
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()> {
-        if cdylib_name.is_none() {
-            bail!("Generate bindings for Kotlin requires a cdylib, but {library_path} was given");
-        }
-        Ok(())
-    }
-}
-
 trait CodeType: Debug {
     /// The language specific label used to reference this type. This will be used in
     /// method signatures and property declarations.
@@ -94,23 +70,71 @@ trait CodeType: Debug {
 // config options to customize the generated Kotlin.
 #[derive(Debug, Default, Clone, Serialize, Deserialize)]
 pub struct Config {
-    package_name: Option<String>,
-    cdylib_name: Option<String>,
+    pub(super) package_name: Option<String>,
+    pub(super) cdylib_name: Option<String>,
     generate_immutable_records: Option<bool>,
     #[serde(default)]
     custom_types: HashMap<String, CustomTypeConfig>,
     #[serde(default)]
-    external_packages: HashMap<String, String>,
+    pub(super) external_packages: HashMap<String, String>,
     #[serde(default)]
     android: bool,
     #[serde(default)]
     android_cleaner: Option<bool>,
+    #[serde(default)]
+    kotlin_target_version: Option<String>,
 }
 
 impl Config {
     pub(crate) fn android_cleaner(&self) -> bool {
         self.android_cleaner.unwrap_or(self.android)
     }
+
+    pub(crate) fn use_enum_entries(&self) -> bool {
+        self.get_kotlin_version() >= KotlinVersion::new(1, 9, 0)
+    }
+
+    /// Returns a `Version` with the contents of `kotlin_target_version`.
+    /// If `kotlin_target_version` is not defined, version `0.0.0` will be used as a fallback.
+    /// If it's not valid, this function will panic.
+    fn get_kotlin_version(&self) -> KotlinVersion {
+        self.kotlin_target_version
+            .clone()
+            .map(|v| {
+                KotlinVersion::parse(&v).unwrap_or_else(|_| {
+                    panic!("Provided Kotlin target version is not valid: {}", v)
+                })
+            })
+            .unwrap_or(KotlinVersion::new(0, 0, 0))
+    }
+}
+
+#[derive(Debug, PartialEq, Eq, PartialOrd, Ord)]
+struct KotlinVersion((u16, u16, u16));
+
+impl KotlinVersion {
+    fn new(major: u16, minor: u16, patch: u16) -> Self {
+        Self((major, minor, patch))
+    }
+
+    fn parse(version: &str) -> Result<Self> {
+        let components = version
+            .split('.')
+            .map(|n| {
+                n.parse::<u16>()
+                    .map_err(|_| anyhow!("Invalid version string ({n} is not an integer)"))
+            })
+            .collect::<Result<Vec<u16>>>()?;
+
+        match components.as_slice() {
+            [major, minor, patch] => Ok(Self((*major, *minor, *patch))),
+            [major, minor] => Ok(Self((*major, *minor, 0))),
+            [major] => Ok(Self((*major, 0, 0))),
+            _ => Err(anyhow!(
+                "Invalid version string (expected 1-3 components): {version}"
+            )),
+        }
+    }
 }
 
 #[derive(Debug, Default, Clone, Serialize, Deserialize)]
@@ -122,20 +146,19 @@ pub struct CustomTypeConfig {
 }
 
 impl Config {
+    // We insist someone has already configured us - any defaults we supply would be wrong.
     pub fn package_name(&self) -> String {
-        if let Some(package_name) = &self.package_name {
-            package_name.clone()
-        } else {
-            "uniffi".into()
-        }
+        self.package_name
+            .as_ref()
+            .expect("package name should have been set in update_component_configs")
+            .clone()
     }
 
     pub fn cdylib_name(&self) -> String {
-        if let Some(cdylib_name) = &self.cdylib_name {
-            cdylib_name.clone()
-        } else {
-            "uniffi".into()
-        }
+        self.cdylib_name
+            .as_ref()
+            .expect("cdylib name should have been set in update_component_configs")
+            .clone()
     }
 
     /// Whether to generate immutable records (`val` instead of `var`)
@@ -144,29 +167,6 @@ impl Config {
     }
 }
 
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.package_name
-            .get_or_insert_with(|| format!("uniffi.{}", ci.namespace()));
-        self.cdylib_name
-            .get_or_insert_with(|| format!("uniffi_{}", ci.namespace()));
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.cdylib_name
-            .get_or_insert_with(|| cdylib_name.to_string());
-    }
-
-    fn update_from_dependency_configs(&mut self, config_map: HashMap<&str, &Self>) {
-        for (crate_name, config) in config_map {
-            if !self.external_packages.contains_key(crate_name) {
-                self.external_packages
-                    .insert(crate_name.to_string(), config.package_name());
-            }
-        }
-    }
-}
-
 // Generate kotlin bindings for the given ComponentInterface, as a string.
 pub fn generate_bindings(config: &Config, ci: &ComponentInterface) -> Result<String> {
     KotlinWrapper::new(config.clone(), ci)
@@ -431,9 +431,10 @@ impl KotlinCodeOracle {
             FfiType::Float64 => "Double".to_string(),
             FfiType::Handle => "Long".to_string(),
             FfiType::RustArcPtr(_) => "Pointer".to_string(),
-            FfiType::RustBuffer(maybe_suffix) => {
-                format!("RustBuffer{}", maybe_suffix.as_deref().unwrap_or_default())
-            }
+            FfiType::RustBuffer(maybe_external) => match maybe_external {
+                Some(external_meta) => format!("RustBuffer{}", external_meta.name),
+                None => "RustBuffer".to_string(),
+            },
             FfiType::RustCallStatus => "UniffiRustCallStatus.ByValue".to_string(),
             FfiType::ForeignBytes => "ForeignBytes.ByValue".to_string(),
             FfiType::Callback(name) => self.ffi_callback_name(name),
@@ -721,3 +722,30 @@ mod filters {
         Ok(textwrap::indent(&wrapped, &" ".repeat(spaces)))
     }
 }
+
+#[cfg(test)]
+mod test {
+    use super::*;
+
+    #[test]
+    fn test_kotlin_version() {
+        assert_eq!(
+            KotlinVersion::parse("1.2.3").unwrap(),
+            KotlinVersion::new(1, 2, 3)
+        );
+        assert_eq!(
+            KotlinVersion::parse("2.3").unwrap(),
+            KotlinVersion::new(2, 3, 0),
+        );
+        assert_eq!(
+            KotlinVersion::parse("2").unwrap(),
+            KotlinVersion::new(2, 0, 0),
+        );
+        assert!(KotlinVersion::parse("2.").is_err());
+        assert!(KotlinVersion::parse("").is_err());
+        assert!(KotlinVersion::parse("A.B.C").is_err());
+        assert!(KotlinVersion::new(1, 2, 3) > KotlinVersion::new(0, 1, 2));
+        assert!(KotlinVersion::new(1, 2, 3) > KotlinVersion::new(0, 100, 0));
+        assert!(KotlinVersion::new(10, 0, 0) > KotlinVersion::new(1, 10, 0));
+    }
+}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/mod.rs
index 466fe778792d..501f449da0fd 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/mod.rs
@@ -2,37 +2,88 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use crate::{BindingGenerator, Component, GenerationSettings};
 use anyhow::Result;
 use camino::{Utf8Path, Utf8PathBuf};
 use fs_err as fs;
+use std::collections::HashMap;
 use std::process::Command;
 
-pub mod gen_kotlin;
-pub use gen_kotlin::{generate_bindings, Config};
-mod test;
+mod gen_kotlin;
+use gen_kotlin::{generate_bindings, Config};
+#[cfg(feature = "bindgen-tests")]
+pub mod test;
 
-use super::super::interface::ComponentInterface;
-pub use test::{run_script, run_test};
+pub struct KotlinBindingGenerator;
+impl BindingGenerator for KotlinBindingGenerator {
+    type Config = Config;
 
-pub fn write_bindings(
-    config: &Config,
-    ci: &ComponentInterface,
-    out_dir: &Utf8Path,
-    try_format_code: bool,
-) -> Result<()> {
-    let mut kt_file = full_bindings_path(config, out_dir);
-    fs::create_dir_all(&kt_file)?;
-    kt_file.push(format!("{}.kt", ci.namespace()));
-    fs::write(&kt_file, generate_bindings(config, ci)?)?;
-    if try_format_code {
-        if let Err(e) = Command::new("ktlint").arg("-F").arg(&kt_file).output() {
-            println!(
-                "Warning: Unable to auto-format {} using ktlint: {e:?}",
-                kt_file.file_name().unwrap(),
-            );
-        }
+    fn new_config(&self, root_toml: &toml::Value) -> Result<Self::Config> {
+        Ok(
+            match root_toml.get("bindings").and_then(|b| b.get("kotlin")) {
+                Some(v) => v.clone().try_into()?,
+                None => Default::default(),
+            },
+        )
+    }
+
+    fn update_component_configs(
+        &self,
+        settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
+    ) -> Result<()> {
+        for c in &mut *components {
+            c.config
+                .package_name
+                .get_or_insert_with(|| format!("uniffi.{}", c.ci.namespace()));
+            c.config.cdylib_name.get_or_insert_with(|| {
+                settings
+                    .cdylib
+                    .clone()
+                    .unwrap_or_else(|| format!("uniffi_{}", c.ci.namespace()))
+            });
+        }
+        // We need to update package names
+        let packages = HashMap::<String, String>::from_iter(
+            components
+                .iter()
+                .map(|c| (c.ci.crate_name().to_string(), c.config.package_name())),
+        );
+        for c in components {
+            for (ext_crate, ext_package) in &packages {
+                if ext_crate != c.ci.crate_name()
+                    && !c.config.external_packages.contains_key(ext_crate)
+                {
+                    c.config
+                        .external_packages
+                        .insert(ext_crate.to_string(), ext_package.clone());
+                }
+            }
+        }
+        Ok(())
+    }
+
+    fn write_bindings(
+        &self,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
+    ) -> Result<()> {
+        for Component { ci, config, .. } in components {
+            let mut kt_file = full_bindings_path(config, &settings.out_dir);
+            fs::create_dir_all(&kt_file)?;
+            kt_file.push(format!("{}.kt", ci.namespace()));
+            fs::write(&kt_file, generate_bindings(config, ci)?)?;
+            if settings.try_format_code {
+                if let Err(e) = Command::new("ktlint").arg("-F").arg(&kt_file).output() {
+                    println!(
+                        "Warning: Unable to auto-format {} using ktlint: {e:?}",
+                        kt_file.file_name().unwrap(),
+                    );
+                }
+            }
+        }
+        Ok(())
     }
-    Ok(())
 }
 
 fn full_bindings_path(config: &Config, out_dir: &Utf8Path) -> Utf8PathBuf {
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Async.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Async.kt
index b28fbd2c80da..a65f635ddc4f 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Async.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Async.kt
@@ -12,7 +12,7 @@ internal object uniffiRustFutureContinuationCallbackImpl: UniffiRustFutureContin
     }
 }
 
-internal suspend fun<T, F, E: Exception> uniffiRustCallAsync(
+internal suspend fun<T, F, E: kotlin.Exception> uniffiRustCallAsync(
     rustFuture: Long,
     pollFunc: (Long, UniffiRustFutureContinuationCallback, Long) -> Unit,
     completeFunc: (Long, UniffiRustCallStatus) -> F,
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/CustomTypeTemplate.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/CustomTypeTemplate.kt
index aeb5f58002ed..123535e5c80a 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/CustomTypeTemplate.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/CustomTypeTemplate.kt
@@ -6,7 +6,7 @@
  * is needed because the UDL type name is used in function/method signatures.
  * It's also what we have an external type that references a custom type.
  */
-public typealias {{ name }} = {{ builtin|type_name(ci) }}
+public typealias {{ type_name }} = {{ builtin|type_name(ci) }}
 public typealias {{ ffi_converter_name }} = {{ builtin|ffi_converter_name }}
 
 {%- when Some with (config) %}
@@ -21,7 +21,7 @@ public typealias {{ ffi_converter_name }} = {{ builtin|ffi_converter_name }}
  * is needed because the UDL type name is used in function/method signatures.
  * It's also what we have an external type that references a custom type.
  */
-public typealias {{ name }} = {{ concrete_type_name }}
+public typealias {{ type_name }} = {{ concrete_type_name }}
 {%- else %}
 {%- endmatch %}
 
@@ -33,28 +33,28 @@ public typealias {{ name }} = {{ concrete_type_name }}
 {%- else %}
 {%- endmatch %}
 
-public object {{ ffi_converter_name }}: FfiConverter<{{ name }}, {{ ffi_type_name }}> {
-    override fun lift(value: {{ ffi_type_name }}): {{ name }} {
+public object {{ ffi_converter_name }}: FfiConverter<{{ type_name }}, {{ ffi_type_name }}> {
+    override fun lift(value: {{ ffi_type_name }}): {{ type_name }} {
         val builtinValue = {{ builtin|lift_fn }}(value)
         return {{ config.into_custom.render("builtinValue") }}
     }
 
-    override fun lower(value: {{ name }}): {{ ffi_type_name }} {
+    override fun lower(value: {{ type_name }}): {{ ffi_type_name }} {
         val builtinValue = {{ config.from_custom.render("value") }}
         return {{ builtin|lower_fn }}(builtinValue)
     }
 
-    override fun read(buf: ByteBuffer): {{ name }} {
+    override fun read(buf: ByteBuffer): {{ type_name }} {
         val builtinValue = {{ builtin|read_fn }}(buf)
         return {{ config.into_custom.render("builtinValue") }}
     }
 
-    override fun allocationSize(value: {{ name }}): ULong {
+    override fun allocationSize(value: {{ type_name }}): ULong {
         val builtinValue = {{ config.from_custom.render("value") }}
         return {{ builtin|allocation_size_fn }}(builtinValue)
     }
 
-    override fun write(value: {{ name }}, buf: ByteBuffer) {
+    override fun write(value: {{ type_name }}, buf: ByteBuffer) {
         val builtinValue = {{ config.from_custom.render("value") }}
         {{ builtin|write_fn }}(builtinValue, buf)
     }
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/EnumTemplate.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/EnumTemplate.kt
index 8d1c2235ece5..1c1779963366 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/EnumTemplate.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/EnumTemplate.kt
@@ -29,7 +29,11 @@ enum class {{ type_name }}(val value: {{ variant_discr_type|type_name(ci) }}) {
 
 public object {{ e|ffi_converter_name }}: FfiConverterRustBuffer<{{ type_name }}> {
     override fun read(buf: ByteBuffer) = try {
+        {% if config.use_enum_entries() %}
+        {{ type_name }}.entries[buf.getInt() - 1]
+        {% else -%}
         {{ type_name }}.values()[buf.getInt() - 1]
+        {%- endif %}
     } catch (e: IndexOutOfBoundsException) {
         throw RuntimeException("invalid enum value, something is very wrong!!", e)
     }
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ErrorTemplate.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ErrorTemplate.kt
index 4760c03fd6cf..8c08e765feb7 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ErrorTemplate.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ErrorTemplate.kt
@@ -4,7 +4,7 @@
 
 {% if e.is_flat() %}
 {%- call kt::docstring(e, 0) %}
-sealed class {{ type_name }}(message: String): Exception(message){% if contains_object_references %}, Disposable {% endif %} {
+sealed class {{ type_name }}(message: String): kotlin.Exception(message){% if contains_object_references %}, Disposable {% endif %} {
         {% for variant in e.variants() -%}
         {%- call kt::docstring(variant, 4) %}
         class {{ variant|error_variant_name }}(message: String) : {{ type_name }}(message)
@@ -16,18 +16,18 @@ sealed class {{ type_name }}(message: String): Exception(message){% if contains_
 }
 {%- else %}
 {%- call kt::docstring(e, 0) %}
-sealed class {{ type_name }}: Exception(){% if contains_object_references %}, Disposable {% endif %} {
+sealed class {{ type_name }}: kotlin.Exception(){% if contains_object_references %}, Disposable {% endif %} {
     {% for variant in e.variants() -%}
     {%- call kt::docstring(variant, 4) %}
     {%- let variant_name = variant|error_variant_name %}
     class {{ variant_name }}(
         {% for field in variant.fields() -%}
         {%- call kt::docstring(field, 8) %}
-        val {{ field.name()|var_name }}: {{ field|type_name(ci) }}{% if loop.last %}{% else %}, {% endif %}
+        val {% call kt::field_name(field, loop.index) %}: {{ field|type_name(ci) }}{% if loop.last %}{% else %}, {% endif %}
         {% endfor -%}
     ) : {{ type_name }}() {
         override val message
-            get() = "{%- for field in variant.fields() %}{{ field.name()|var_name|unquote }}=${ {{field.name()|var_name }} }{% if !loop.last %}, {% endif %}{% endfor %}"
+            get() = "{%- for field in variant.fields() %}{% call kt::field_name_unquoted(field, loop.index) %}=${ {% call kt::field_name(field, loop.index) %} }{% if !loop.last %}, {% endif %}{% endfor %}"
     }
     {% endfor %}
 
@@ -88,7 +88,7 @@ public object {{ e|ffi_converter_name }} : FfiConverterRustBuffer<{{ type_name }
                 // Add the size for the Int that specifies the variant plus the size needed for all fields
                 4UL
                 {%- for field in variant.fields() %}
-                + {{ field|allocation_size_fn }}(value.{{ field.name()|var_name }})
+                + {{ field|allocation_size_fn }}(value.{% call kt::field_name(field, loop.index) %})
                 {%- endfor %}
             )
             {%- endfor %}
@@ -102,7 +102,7 @@ public object {{ e|ffi_converter_name }} : FfiConverterRustBuffer<{{ type_name }
             is {{ type_name }}.{{ variant|error_variant_name }} -> {
                 buf.putInt({{ loop.index }})
                 {%- for field in variant.fields() %}
-                {{ field|write_fn }}(value.{{ field.name()|var_name }}, buf)
+                {{ field|write_fn }}(value.{% call kt::field_name(field, loop.index) %}, buf)
                 {%- endfor %}
                 Unit
             }
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Helpers.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Helpers.kt
index 1fdbd3ffc038..ca9d98189eba 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Helpers.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/Helpers.kt
@@ -34,7 +34,7 @@ internal open class UniffiRustCallStatus : Structure() {
     }
 }
 
-class InternalException(message: String) : Exception(message)
+class InternalException(message: String) : kotlin.Exception(message)
 
 // Each top-level error class has a companion object that can lift the error from the call status's rust buffer
 interface UniffiRustCallStatusErrorHandler<E> {
@@ -46,15 +46,15 @@ interface UniffiRustCallStatusErrorHandler<E> {
 // synchronize itself
 
 // Call a rust function that returns a Result<>.  Pass in the Error class companion that corresponds to the Err
-private inline fun <U, E: Exception> uniffiRustCallWithError(errorHandler: UniffiRustCallStatusErrorHandler<E>, callback: (UniffiRustCallStatus) -> U): U {
-    var status = UniffiRustCallStatus();
+private inline fun <U, E: kotlin.Exception> uniffiRustCallWithError(errorHandler: UniffiRustCallStatusErrorHandler<E>, callback: (UniffiRustCallStatus) -> U): U {
+    var status = UniffiRustCallStatus()
     val return_value = callback(status)
     uniffiCheckCallStatus(errorHandler, status)
     return return_value
 }
 
 // Check UniffiRustCallStatus and throw an error if the call wasn't successful
-private fun<E: Exception> uniffiCheckCallStatus(errorHandler: UniffiRustCallStatusErrorHandler<E>, status: UniffiRustCallStatus) {
+private fun<E: kotlin.Exception> uniffiCheckCallStatus(errorHandler: UniffiRustCallStatusErrorHandler<E>, status: UniffiRustCallStatus) {
     if (status.isSuccess()) {
         return
     } else if (status.isError()) {
@@ -83,7 +83,7 @@ object UniffiNullRustCallStatusErrorHandler: UniffiRustCallStatusErrorHandler<In
 
 // Call a rust function that returns a plain value
 private inline fun <U> uniffiRustCall(callback: (UniffiRustCallStatus) -> U): U {
-    return uniffiRustCallWithError(UniffiNullRustCallStatusErrorHandler, callback);
+    return uniffiRustCallWithError(UniffiNullRustCallStatusErrorHandler, callback)
 }
 
 internal inline fun<T> uniffiTraitInterfaceCall(
@@ -93,7 +93,7 @@ internal inline fun<T> uniffiTraitInterfaceCall(
 ) {
     try {
         writeReturn(makeCall())
-    } catch(e: Exception) {
+    } catch(e: kotlin.Exception) {
         callStatus.code = UNIFFI_CALL_UNEXPECTED_ERROR
         callStatus.error_buf = {{ Type::String.borrow()|lower_fn }}(e.toString())
     }
@@ -107,7 +107,7 @@ internal inline fun<T, reified E: Throwable> uniffiTraitInterfaceCallWithError(
 ) {
     try {
         writeReturn(makeCall())
-    } catch(e: Exception) {
+    } catch(e: kotlin.Exception) {
         if (e is E) {
             callStatus.code = UNIFFI_CALL_ERROR
             callStatus.error_buf = lowerError(e)
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ObjectTemplate.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ObjectTemplate.kt
index 62cac7a4d012..72fdbe564895 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ObjectTemplate.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/ObjectTemplate.kt
@@ -111,7 +111,7 @@
 
 {%- call kt::docstring(obj, 0) %}
 {% if (is_error) %}
-open class {{ impl_class_name }} : Exception, Disposable, AutoCloseable, {{ interface_name }} {
+open class {{ impl_class_name }} : kotlin.Exception, Disposable, AutoCloseable, {{ interface_name }} {
 {% else -%}
 open class {{ impl_class_name }}: Disposable, AutoCloseable, {{ interface_name }} {
 {%- endif %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/macros.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/macros.kt
index 7acfdc886125..b2f909ef3a76 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/macros.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/macros.kt
@@ -132,12 +132,19 @@ v{{- field_num -}}
 {%- endif -%}
 {%- endmacro %}
 
-// Macro for destroying fields
+{% macro field_name_unquoted(field, field_num) %}
+{%- if field.name().is_empty() -%}
+v{{- field_num -}}
+{%- else -%}
+{{ field.name()|var_name|unquote }}
+{%- endif -%}
+{%- endmacro %}
+
+ // Macro for destroying fields
 {%- macro destroy_fields(member) %}
-    Disposable.destroy(
     {%- for field in member.fields() %}
-        this.{{ field.name()|var_name }}{%- if !loop.last %}, {% endif -%}
-    {% endfor -%})
+        Disposable.destroy(this.{%- call field_name(field, loop.index) -%})
+    {% endfor -%}
 {%- endmacro -%}
 
 {%- macro docstring_value(maybe_docstring, indent_spaces) %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/wrapper.kt b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/wrapper.kt
index 2cdc72a5e2ec..8cf8132d10cf 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/wrapper.kt
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/templates/wrapper.kt
@@ -5,7 +5,7 @@
 
 @file:Suppress("NAME_SHADOWING")
 
-package {{ config.package_name() }};
+package {{ config.package_name() }}
 
 // Common helper code.
 //
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/test.rs b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/test.rs
index 082401575155..5c7f0c9943e5 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/kotlin/test.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/kotlin/test.rs
@@ -2,8 +2,9 @@
 License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use crate::bindings::TargetLanguage;
-use crate::{bindings::RunScriptOptions, library_mode::generate_bindings, BindingGeneratorDefault};
+use crate::bindings::RunScriptOptions;
+use crate::cargo_metadata::CrateConfigSupplier;
+use crate::library_mode::generate_bindings;
 use anyhow::{bail, Context, Result};
 use camino::{Utf8Path, Utf8PathBuf};
 use std::env;
@@ -35,13 +36,12 @@ pub fn run_script(
     let test_helper = UniFFITestHelper::new(crate_name)?;
     let out_dir = test_helper.create_out_dir(tmp_dir, script_path)?;
     let cdylib_path = test_helper.copy_cdylib_to_out_dir(&out_dir)?;
+
     generate_bindings(
         &cdylib_path,
         None,
-        &BindingGeneratorDefault {
-            target_languages: vec![TargetLanguage::Kotlin],
-            try_format_code: false,
-        },
+        &super::KotlinBindingGenerator,
+        &CrateConfigSupplier::from(test_helper.cargo_metadata()),
         None,
         &out_dir,
         false,
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/mod.rs
index d39202bcf274..2d6cdc07fbdd 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/mod.rs
@@ -7,50 +7,29 @@
 //! This module contains all the code for generating foreign language bindings,
 //! along with some helpers for executing foreign language scripts or tests.
 
-use anyhow::{bail, Result};
-use camino::Utf8Path;
-use serde::{Deserialize, Serialize};
-use std::fmt;
+mod kotlin;
+pub use kotlin::KotlinBindingGenerator;
+mod python;
+pub use python::PythonBindingGenerator;
+mod ruby;
+pub use ruby::RubyBindingGenerator;
+mod swift;
+pub use swift::SwiftBindingGenerator;
 
-use crate::interface::ComponentInterface;
-
-pub mod kotlin;
-pub mod python;
-pub mod ruby;
-pub mod swift;
-
-/// Enumeration of all foreign language targets currently supported by this crate.
-///
-/// The functions in this module will delegate to a language-specific backend based
-/// on the provided `TargetLanguage`. For convenience of calling code we also provide
-/// a few `TryFrom` implementations to help guess the correct target language from
-/// e.g. a file extension of command-line argument.
-#[derive(Copy, Clone, Eq, PartialEq, Hash)]
-#[cfg_attr(feature = "clap", derive(clap::ValueEnum))]
-pub enum TargetLanguage {
-    Kotlin,
-    Swift,
-    Python,
-    Ruby,
-}
-
-impl fmt::Display for TargetLanguage {
-    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
-        match self {
-            Self::Kotlin => write!(f, "kotlin"),
-            Self::Swift => write!(f, "swift"),
-            Self::Python => write!(f, "python"),
-            Self::Ruby => write!(f, "ruby"),
-        }
-    }
-}
+#[cfg(feature = "bindgen-tests")]
+pub use self::{
+    kotlin::test as kotlin_test, python::test as python_test, ruby::test as ruby_test,
+    swift::test as swift_test,
+};
 
+#[cfg(feature = "bindgen-tests")]
 /// Mode for the `run_script` function defined for each language
 #[derive(Clone, Debug)]
 pub struct RunScriptOptions {
     pub show_compiler_messages: bool,
 }
 
+#[cfg(feature = "bindgen-tests")]
 impl Default for RunScriptOptions {
     fn default() -> Self {
         Self {
@@ -58,68 +37,3 @@ impl Default for RunScriptOptions {
         }
     }
 }
-
-impl TryFrom<&str> for TargetLanguage {
-    type Error = anyhow::Error;
-    fn try_from(value: &str) -> Result<Self> {
-        Ok(match value.to_ascii_lowercase().as_str() {
-            "kotlin" | "kt" | "kts" => TargetLanguage::Kotlin,
-            "swift" => TargetLanguage::Swift,
-            "python" | "py" => TargetLanguage::Python,
-            "ruby" | "rb" => TargetLanguage::Ruby,
-            _ => bail!("Unknown or unsupported target language: \"{value}\""),
-        })
-    }
-}
-
-impl TryFrom<&std::ffi::OsStr> for TargetLanguage {
-    type Error = anyhow::Error;
-    fn try_from(value: &std::ffi::OsStr) -> Result<Self> {
-        match value.to_str() {
-            None => bail!("Unreadable target language"),
-            Some(s) => s.try_into(),
-        }
-    }
-}
-
-impl TryFrom<String> for TargetLanguage {
-    type Error = anyhow::Error;
-    fn try_from(value: String) -> Result<Self> {
-        TryFrom::try_from(value.as_str())
-    }
-}
-
-#[derive(Debug, Clone, Default, Serialize, Deserialize)]
-pub struct Config {
-    #[serde(default)]
-    pub(crate) kotlin: kotlin::Config,
-    #[serde(default)]
-    pub(crate) swift: swift::Config,
-    #[serde(default)]
-    pub(crate) python: python::Config,
-    #[serde(default)]
-    pub(crate) ruby: ruby::Config,
-}
-
-/// Generate foreign language bindings from a compiled `uniffi` library.
-pub fn write_bindings(
-    config: &Config,
-    ci: &ComponentInterface,
-    out_dir: &Utf8Path,
-    language: TargetLanguage,
-    try_format_code: bool,
-) -> Result<()> {
-    match language {
-        TargetLanguage::Kotlin => {
-            kotlin::write_bindings(&config.kotlin, ci, out_dir, try_format_code)?
-        }
-        TargetLanguage::Swift => {
-            swift::write_bindings(&config.swift, ci, out_dir, try_format_code)?
-        }
-        TargetLanguage::Python => {
-            python::write_bindings(&config.python, ci, out_dir, try_format_code)?
-        }
-        TargetLanguage::Ruby => ruby::write_bindings(&config.ruby, ci, out_dir, try_format_code)?,
-    }
-    Ok(())
-}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/custom.rs b/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/custom.rs
index f735899f3dd3..0818e7198b8d 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/custom.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/custom.rs
@@ -17,7 +17,7 @@ impl CustomCodeType {
 
 impl CodeType for CustomCodeType {
     fn type_label(&self) -> String {
-        self.name.clone()
+        super::PythonCodeOracle.class_name(&self.name)
     }
 
     fn canonical_name(&self) -> String {
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/mod.rs
index 6a10a38e7ffa..b831274963de 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/gen_python/mod.rs
@@ -2,9 +2,9 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use anyhow::{bail, Context, Result};
+use anyhow::{Context, Result};
 use askama::Template;
-use camino::Utf8Path;
+
 use heck::{ToShoutySnakeCase, ToSnakeCase, ToUpperCamelCase};
 use once_cell::sync::Lazy;
 use serde::{Deserialize, Serialize};
@@ -14,9 +14,9 @@ use std::collections::{BTreeSet, HashMap, HashSet};
 use std::fmt::Debug;
 
 use crate::backend::TemplateExpression;
-use crate::bindings::python;
+
 use crate::interface::*;
-use crate::{BindingGenerator, BindingsConfig};
+use crate::VisitMut;
 
 mod callback_interface;
 mod compounds;
@@ -28,29 +28,6 @@ mod object;
 mod primitives;
 mod record;
 
-pub struct PythonBindingGenerator;
-
-impl BindingGenerator for PythonBindingGenerator {
-    type Config = Config;
-
-    fn write_bindings(
-        &self,
-        ci: &ComponentInterface,
-        config: &Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
-    ) -> Result<()> {
-        python::write_bindings(config, ci, out_dir, try_format_code)
-    }
-
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()> {
-        if cdylib_name.is_none() {
-            bail!("Generate bindings for Python requires a cdylib, but {library_path} was given");
-        }
-        Ok(())
-    }
-}
-
 /// A trait tor the implementation.
 trait CodeType: Debug {
     /// The language specific label used to reference this type. This will be used in
@@ -135,7 +112,7 @@ static KEYWORDS: Lazy<HashSet<String>> = Lazy::new(|| {
 // Config options to customize the generated python.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct Config {
-    cdylib_name: Option<String>,
+    pub(super) cdylib_name: Option<String>,
     #[serde(default)]
     custom_types: HashMap<String, CustomTypeConfig>,
     #[serde(default)]
@@ -171,22 +148,8 @@ impl Config {
     }
 }
 
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.cdylib_name
-            .get_or_insert_with(|| format!("uniffi_{}", ci.namespace()));
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.cdylib_name
-            .get_or_insert_with(|| cdylib_name.to_string());
-    }
-
-    fn update_from_dependency_configs(&mut self, _config_map: HashMap<&str, &Self>) {}
-}
-
 // Generate python bindings for the given ComponentInterface, as a string.
-pub fn generate_python_bindings(config: &Config, ci: &ComponentInterface) -> Result<String> {
+pub fn generate_python_bindings(config: &Config, ci: &mut ComponentInterface) -> Result<String> {
     PythonWrapper::new(config.clone(), ci)
         .render()
         .context("failed to render python bindings")
@@ -298,6 +261,33 @@ impl<'a> TypeRenderer<'a> {
             });
         ""
     }
+
+    // An inefficient algo to return type aliases needed for custom types
+    // in an order such that dependencies are in the correct order.
+    // Eg, if there's a custom type `Guid` -> `str` and another `GuidWrapper` -> `Guid`,
+    // it's important the type alias for `Guid` appears first. Fails to handle
+    // another level of indirection (eg, `A { builtin: C}, B { }, C { builtin: B })`)
+    // but that's pathological :)
+    fn get_custom_type_aliases(&self) -> Vec<(String, &Type)> {
+        let mut ordered = vec![];
+        for type_ in self.ci.iter_types() {
+            if let Type::Custom { name, builtin, .. } = type_ {
+                match ordered.iter().position(|x: &(&str, &Type)| {
+                    x.1.iter_types()
+                        .any(|nested_type| *name == nested_type.as_codetype().type_label())
+                }) {
+                    // This 'name' appears as a builtin, so we must insert our type first.
+                    Some(pos) => ordered.insert(pos, (name, builtin)),
+                    // Otherwise at the end.
+                    None => ordered.push((name, builtin)),
+                }
+            }
+        }
+        ordered
+            .into_iter()
+            .map(|(n, t)| (PythonCodeOracle.class_name(n), t))
+            .collect()
+    }
 }
 
 #[derive(Template)]
@@ -309,10 +299,13 @@ pub struct PythonWrapper<'a> {
     type_imports: BTreeSet<ImportRequirement>,
 }
 impl<'a> PythonWrapper<'a> {
-    pub fn new(config: Config, ci: &'a ComponentInterface) -> Self {
+    pub fn new(config: Config, ci: &'a mut ComponentInterface) -> Self {
+        ci.visit_mut(&PythonCodeOracle);
+
         let type_renderer = TypeRenderer::new(&config, ci);
         let type_helper_code = type_renderer.render().unwrap();
         let type_imports = type_renderer.imports.into_inner();
+
         Self {
             config,
             ci,
@@ -364,14 +357,14 @@ impl PythonCodeOracle {
 
     /// Get the idiomatic Python rendering of an FFI callback function name
     fn ffi_callback_name(&self, nm: &str) -> String {
-        format!("UNIFFI_{}", nm.to_shouty_snake_case())
+        format!("_UNIFFI_{}", nm.to_shouty_snake_case())
     }
 
     /// Get the idiomatic Python rendering of an FFI struct name
     fn ffi_struct_name(&self, nm: &str) -> String {
         // The ctypes docs use both SHOUTY_SNAKE_CASE AND UpperCamelCase for structs. Let's use
         // UpperCamelCase and reserve shouting for global variables
-        format!("Uniffi{}", nm.to_upper_camel_case())
+        format!("_Uniffi{}", nm.to_upper_camel_case())
     }
 
     fn ffi_type_label(&self, ffi_type: &FfiType) -> String {
@@ -388,8 +381,8 @@ impl PythonCodeOracle {
             FfiType::Float64 => "ctypes.c_double".to_string(),
             FfiType::Handle => "ctypes.c_uint64".to_string(),
             FfiType::RustArcPtr(_) => "ctypes.c_void_p".to_string(),
-            FfiType::RustBuffer(maybe_suffix) => match maybe_suffix {
-                Some(suffix) => format!("_UniffiRustBuffer{suffix}"),
+            FfiType::RustBuffer(maybe_external) => match maybe_external {
+                Some(external_meta) => format!("_UniffiRustBuffer{}", external_meta.name),
                 None => "_UniffiRustBuffer".to_string(),
             },
             FfiType::RustCallStatus => "_UniffiRustCallStatus".to_string(),
@@ -418,8 +411,10 @@ impl PythonCodeOracle {
                 | FfiType::Int64 => "0".to_owned(),
                 FfiType::Float32 | FfiType::Float64 => "0.0".to_owned(),
                 FfiType::RustArcPtr(_) => "ctypes.c_void_p()".to_owned(),
-                FfiType::RustBuffer(maybe_suffix) => match maybe_suffix {
-                    Some(suffix) => format!("_UniffiRustBuffer{suffix}.default()"),
+                FfiType::RustBuffer(maybe_external) => match maybe_external {
+                    Some(external_meta) => {
+                        format!("_UniffiRustBuffer{}.default()", external_meta.name)
+                    }
                     None => "_UniffiRustBuffer.default()".to_owned(),
                 },
                 _ => unimplemented!("FFI return type: {t:?}"),
@@ -448,6 +443,84 @@ impl PythonCodeOracle {
     }
 }
 
+impl VisitMut for PythonCodeOracle {
+    fn visit_record(&self, record: &mut Record) {
+        record.rename(self.class_name(record.name()));
+    }
+
+    fn visit_object(&self, object: &mut Object) {
+        object.rename(self.class_name(object.name()));
+    }
+
+    fn visit_field(&self, field: &mut Field) {
+        field.rename(self.var_name(field.name()));
+    }
+
+    fn visit_ffi_field(&self, ffi_field: &mut FfiField) {
+        ffi_field.rename(self.var_name(ffi_field.name()));
+    }
+
+    fn visit_ffi_argument(&self, ffi_argument: &mut FfiArgument) {
+        ffi_argument.rename(self.class_name(ffi_argument.name()));
+    }
+
+    fn visit_enum(&self, is_error: bool, enum_: &mut Enum) {
+        if is_error {
+            enum_.rename(self.class_name(enum_.name()));
+        } else {
+            enum_.rename(self.enum_variant_name(enum_.name()));
+        }
+    }
+
+    fn visit_enum_key(&self, key: &mut String) -> String {
+        self.class_name(key)
+    }
+
+    fn visit_variant(&self, is_error: bool, variant: &mut Variant) {
+        //TODO: If we want to remove the last var_name filter
+        // in the template, this is it. We need an additional
+        // attribute for the `Variant` so we can
+        // display Python is_NAME functions
+        // variant.set_is_name(self.var_name(variant.name()));
+
+        if is_error {
+            variant.rename(self.class_name(variant.name()));
+        } else {
+            variant.rename(self.enum_variant_name(variant.name()));
+        }
+    }
+
+    fn visit_type(&self, type_: &mut Type) {
+        // Renaming Types is a special case. We have simple types with names like
+        // an Object, but we also have types which have inner_types and builtin types.
+        // Which in turn have a different name. Therefore we pass the patterns as a
+        // function down to the renaming operation of the type itself, which can apply it
+        // to all its nested names if needed.
+        let name_transformer = |name: &str| self.class_name(name);
+        type_.rename_recursive(&name_transformer);
+    }
+
+    fn visit_method(&self, method: &mut Method) {
+        method.rename(self.fn_name(method.name()));
+    }
+
+    fn visit_argument(&self, argument: &mut Argument) {
+        argument.rename(self.var_name(argument.name()));
+    }
+
+    fn visit_constructor(&self, constructor: &mut Constructor) {
+        if !constructor.is_primary_constructor() {
+            constructor.rename(self.fn_name(constructor.name()));
+        }
+    }
+
+    fn visit_function(&self, function: &mut Function) {
+        // Conversions for wrapper.py
+        //TODO: Renaming the function name in wrapper.py is not currently tested
+        function.rename(self.fn_name(function.name()));
+    }
+}
+
 trait AsCodeType {
     fn as_codetype(&self) -> Box<dyn CodeType>;
 }
@@ -509,6 +582,20 @@ pub mod filters {
         Ok(as_ct.as_codetype().type_label())
     }
 
+    //TODO: Remove. Currently just being used by EnumTemplate.py to
+    // display is_NAME_OF_ENUM.
+    /// Get the idiomatic Python rendering of a variable name.
+    pub fn var_name(nm: &str) -> Result<String, askama::Error> {
+        Ok(PythonCodeOracle.var_name(nm))
+    }
+
+    //TODO: Remove. Currently just being used by wrapper.py to display the
+    // callback_interface function names.
+    /// Get the idiomatic Python rendering of a class name (for enums, records, errors, etc).
+    pub fn class_name(nm: &str) -> Result<String, askama::Error> {
+        Ok(PythonCodeOracle.class_name(nm))
+    }
+
     pub(super) fn ffi_converter_name(as_ct: &impl AsCodeType) -> Result<String, askama::Error> {
         Ok(String::from("_Uniffi") + &as_ct.as_codetype().ffi_converter_name()[3..])
     }
@@ -558,26 +645,6 @@ pub mod filters {
         Ok(PythonCodeOracle.ffi_default_value(return_type.as_ref()))
     }
 
-    /// Get the idiomatic Python rendering of a class name (for enums, records, errors, etc).
-    pub fn class_name(nm: &str) -> Result<String, askama::Error> {
-        Ok(PythonCodeOracle.class_name(nm))
-    }
-
-    /// Get the idiomatic Python rendering of a function name.
-    pub fn fn_name(nm: &str) -> Result<String, askama::Error> {
-        Ok(PythonCodeOracle.fn_name(nm))
-    }
-
-    /// Get the idiomatic Python rendering of a variable name.
-    pub fn var_name(nm: &str) -> Result<String, askama::Error> {
-        Ok(PythonCodeOracle.var_name(nm))
-    }
-
-    /// Get the idiomatic Python rendering of an individual enum variant.
-    pub fn enum_variant_py(nm: &str) -> Result<String, askama::Error> {
-        Ok(PythonCodeOracle.enum_variant_name(nm))
-    }
-
     /// Get the idiomatic Python rendering of an FFI callback function name
     pub fn ffi_callback_name(nm: &str) -> Result<String, askama::Error> {
         Ok(PythonCodeOracle.ffi_callback_name(nm))
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/python/mod.rs
index 4b9dc8f609ca..ca598baf56ef 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/mod.rs
@@ -5,33 +5,64 @@
 use std::process::Command;
 
 use anyhow::Result;
-use camino::Utf8Path;
 use fs_err as fs;
 
-pub mod gen_python;
-mod test;
-use super::super::interface::ComponentInterface;
-pub use gen_python::{generate_python_bindings, Config};
-pub use test::{run_script, run_test};
+mod gen_python;
+#[cfg(feature = "bindgen-tests")]
+pub mod test;
+use crate::{BindingGenerator, Component, GenerationSettings};
 
-// Generate python bindings for the given ComponentInterface, in the given output directory.
-pub fn write_bindings(
-    config: &Config,
-    ci: &ComponentInterface,
-    out_dir: &Utf8Path,
-    try_format_code: bool,
-) -> Result<()> {
-    let py_file = out_dir.join(format!("{}.py", ci.namespace()));
-    fs::write(&py_file, generate_python_bindings(config, ci)?)?;
+use gen_python::{generate_python_bindings, Config};
 
-    if try_format_code {
-        if let Err(e) = Command::new("yapf").arg(&py_file).output() {
-            println!(
-                "Warning: Unable to auto-format {} using yapf: {e:?}",
-                py_file.file_name().unwrap(),
-            )
-        }
+pub struct PythonBindingGenerator;
+
+impl BindingGenerator for PythonBindingGenerator {
+    type Config = Config;
+
+    fn new_config(&self, root_toml: &toml::Value) -> Result<Self::Config> {
+        Ok(
+            match root_toml.get("bindings").and_then(|b| b.get("python")) {
+                Some(v) => v.clone().try_into()?,
+                None => Default::default(),
+            },
+        )
     }
 
-    Ok(())
+    fn update_component_configs(
+        &self,
+        settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
+    ) -> Result<()> {
+        for c in &mut *components {
+            c.config.cdylib_name.get_or_insert_with(|| {
+                settings
+                    .cdylib
+                    .clone()
+                    .unwrap_or_else(|| format!("uniffi_{}", c.ci.namespace()))
+            });
+        }
+        Ok(())
+    }
+
+    fn write_bindings(
+        &self,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
+    ) -> Result<()> {
+        for Component { ci, config, .. } in components {
+            let py_file = settings.out_dir.join(format!("{}.py", ci.namespace()));
+            fs::write(&py_file, generate_python_bindings(config, &mut ci.clone())?)?;
+
+            if settings.try_format_code {
+                if let Err(e) = Command::new("yapf").arg(&py_file).output() {
+                    println!(
+                        "Warning: Unable to auto-format {} using yapf: {e:?}",
+                        py_file.file_name().unwrap(),
+                    )
+                }
+            }
+        }
+
+        Ok(())
+    }
 }
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Async.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Async.py
index 26daa9ba5cf8..c80ac0c3f99c 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Async.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Async.py
@@ -5,7 +5,7 @@ _UNIFFI_RUST_FUTURE_POLL_MAYBE_READY = 1
 # Stores futures for _uniffi_continuation_callback
 _UniffiContinuationHandleMap = _UniffiHandleMap()
 
-UNIFFI_GLOBAL_EVENT_LOOP = None
+_UNIFFI_GLOBAL_EVENT_LOOP = None
 
 """
 Set the event loop to use for async functions
@@ -20,18 +20,18 @@ In this case, we need an event loop to run the Python async function, but there'
 for the thread.  Use `uniffi_set_event_loop` to force an eventloop to be used in this case.
 """
 def uniffi_set_event_loop(eventloop: asyncio.BaseEventLoop):
-    global UNIFFI_GLOBAL_EVENT_LOOP
-    UNIFFI_GLOBAL_EVENT_LOOP = eventloop
+    global _UNIFFI_GLOBAL_EVENT_LOOP
+    _UNIFFI_GLOBAL_EVENT_LOOP = eventloop
 
 def _uniffi_get_event_loop():
-    if UNIFFI_GLOBAL_EVENT_LOOP is not None:
-        return UNIFFI_GLOBAL_EVENT_LOOP
+    if _UNIFFI_GLOBAL_EVENT_LOOP is not None:
+        return _UNIFFI_GLOBAL_EVENT_LOOP
     else:
         return asyncio.get_running_loop()
 
 # Continuation callback for async functions
 # lift the return value or error and resolve the future, causing the async function to resume.
-@UNIFFI_RUST_FUTURE_CONTINUATION_CALLBACK
+@_UNIFFI_RUST_FUTURE_CONTINUATION_CALLBACK
 def _uniffi_continuation_callback(future_ptr, poll_code):
     (eventloop, future) = _UniffiContinuationHandleMap.remove(future_ptr)
     eventloop.call_soon_threadsafe(_uniffi_set_future_result, future, poll_code)
@@ -57,13 +57,13 @@ async def _uniffi_rust_call_async(rust_future, ffi_poll, ffi_complete, ffi_free,
                 break
 
         return lift_func(
-            _rust_call_with_error(error_ffi_converter, ffi_complete, rust_future)
+            _uniffi_rust_call_with_error(error_ffi_converter, ffi_complete, rust_future)
         )
     finally:
         ffi_free(rust_future)
 
 {%- if ci.has_async_callback_interface_definition() %}
-def uniffi_trait_interface_call_async(make_call, handle_success, handle_error):
+def _uniffi_trait_interface_call_async(make_call, handle_success, handle_error):
     async def make_call_and_call_callback():
         try:
             handle_success(await make_call())
@@ -76,10 +76,10 @@ def uniffi_trait_interface_call_async(make_call, handle_success, handle_error):
             )
     eventloop = _uniffi_get_event_loop()
     task = asyncio.run_coroutine_threadsafe(make_call_and_call_callback(), eventloop)
-    handle = UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.insert((eventloop, task))
-    return UniffiForeignFuture(handle, uniffi_foreign_future_free)
+    handle = _UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.insert((eventloop, task))
+    return _UniffiForeignFuture(handle, _uniffi_foreign_future_free)
 
-def uniffi_trait_interface_call_async_with_error(make_call, handle_success, handle_error, error_type, lower_error):
+def _uniffi_trait_interface_call_async_with_error(make_call, handle_success, handle_error, error_type, lower_error):
     async def make_call_and_call_callback():
         try:
             try:
@@ -98,17 +98,17 @@ def uniffi_trait_interface_call_async_with_error(make_call, handle_success, hand
             )
     eventloop = _uniffi_get_event_loop()
     task = asyncio.run_coroutine_threadsafe(make_call_and_call_callback(), eventloop)
-    handle = UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.insert((eventloop, task))
-    return UniffiForeignFuture(handle, uniffi_foreign_future_free)
+    handle = _UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.insert((eventloop, task))
+    return _UniffiForeignFuture(handle, _uniffi_foreign_future_free)
 
-UNIFFI_FOREIGN_FUTURE_HANDLE_MAP = _UniffiHandleMap()
+_UNIFFI_FOREIGN_FUTURE_HANDLE_MAP = _UniffiHandleMap()
 
-@UNIFFI_FOREIGN_FUTURE_FREE
-def uniffi_foreign_future_free(handle):
-    (eventloop, task) = UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.remove(handle)
-    eventloop.call_soon(uniffi_foreign_future_do_free, task)
+@_UNIFFI_FOREIGN_FUTURE_FREE
+def _uniffi_foreign_future_free(handle):
+    (eventloop, task) = _UNIFFI_FOREIGN_FUTURE_HANDLE_MAP.remove(handle)
+    eventloop.call_soon(_uniffi_foreign_future_do_free, task)
 
-def uniffi_foreign_future_do_free(task):
+def _uniffi_foreign_future_do_free(task):
     if not task.done():
         task.cancel()
 {%- endif %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceImpl.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceImpl.py
index 676f01177a1c..1009505d635b 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceImpl.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceImpl.py
@@ -1,5 +1,5 @@
 {% if self.include_once_check("CallbackInterfaceRuntime.py") %}{% include "CallbackInterfaceRuntime.py" %}{% endif %}
-{%- let trait_impl=format!("UniffiTraitImpl{}", name) %}
+{%- let trait_impl=format!("_UniffiTraitImpl{}", name) %}
 
 # Put all the bits inside a class to keep the top-level namespace clean
 class {{ trait_impl }}:
@@ -7,9 +7,9 @@ class {{ trait_impl }}:
     {%- for (ffi_callback, meth) in vtable_methods.iter() %}
 
     @{{ ffi_callback.name()|ffi_callback_name }}
-    def {{ meth.name()|fn_name }}(
+    def {{ meth.name() }}(
             {%- for arg in ffi_callback.arguments() %}
-            {{ arg.name()|var_name }},
+            {{ arg.name() }},
             {%- endfor -%}
             {%- if ffi_callback.has_rust_call_status_arg() %}
             uniffi_call_status_ptr,
@@ -17,8 +17,8 @@ class {{ trait_impl }}:
         ):
         uniffi_obj = {{ ffi_converter_name }}._handle_map.get(uniffi_handle)
         def make_call():
-            args = ({% for arg in meth.arguments() %}{{ arg|lift_fn }}({{ arg.name()|var_name }}), {% endfor %})
-            method = uniffi_obj.{{ meth.name()|fn_name }}
+            args = ({% for arg in meth.arguments() %}{{ arg|lift_fn }}({{ arg.name() }}), {% endfor %})
+            method = uniffi_obj.{{ meth.name() }}
             return method(*args)
 
         {% if !meth.is_async() %}
@@ -75,24 +75,24 @@ class {{ trait_impl }}:
 
         {%- match meth.throws_type() %}
         {%- when None %}
-        uniffi_out_return[0] = uniffi_trait_interface_call_async(make_call, handle_success, handle_error)
+        uniffi_out_return[0] = _uniffi_trait_interface_call_async(make_call, handle_success, handle_error)
         {%- when Some(error) %}
-        uniffi_out_return[0] = uniffi_trait_interface_call_async_with_error(make_call, handle_success, handle_error, {{ error|type_name }}, {{ error|lower_fn }})
+        uniffi_out_return[0] = _uniffi_trait_interface_call_async_with_error(make_call, handle_success, handle_error, {{ error|type_name }}, {{ error|lower_fn }})
         {%- endmatch %}
         {%- endif %}
     {%- endfor %}
 
     @{{ "CallbackInterfaceFree"|ffi_callback_name }}
-    def uniffi_free(uniffi_handle):
+    def _uniffi_free(uniffi_handle):
         {{ ffi_converter_name }}._handle_map.remove(uniffi_handle)
 
     # Generate the FFI VTable.  This has a field for each callback interface method.
-    uniffi_vtable = {{ vtable|ffi_type_name }}(
+    _uniffi_vtable = {{ vtable|ffi_type_name }}(
         {%- for (_, meth) in vtable_methods.iter() %}
-        {{ meth.name()|fn_name }},
+        {{ meth.name() }},
         {%- endfor %}
-        uniffi_free
+        _uniffi_free
     )
     # Send Rust a pointer to the VTable.  Note: this means we need to keep the struct alive forever,
     # or else bad things will happen when Rust tries to access it.
-    _UniffiLib.{{ ffi_init_callback.name() }}(ctypes.byref(uniffi_vtable))
+    _UniffiLib.{{ ffi_init_callback.name() }}(ctypes.byref(_uniffi_vtable))
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceRuntime.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceRuntime.py
index d802c90fdecf..12d5532b8f14 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceRuntime.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceRuntime.py
@@ -1,12 +1,12 @@
 # Magic number for the Rust proxy to call using the same mechanism as every other method,
 # to free the callback once it's dropped by Rust.
-IDX_CALLBACK_FREE = 0
+_UNIFFI_IDX_CALLBACK_FREE = 0
 # Return codes for callback calls
 _UNIFFI_CALLBACK_SUCCESS = 0
 _UNIFFI_CALLBACK_ERROR = 1
 _UNIFFI_CALLBACK_UNEXPECTED_ERROR = 2
 
-class UniffiCallbackInterfaceFfiConverter:
+class _UniffiCallbackInterfaceFfiConverter:
     _handle_map = _UniffiHandleMap()
 
     @classmethod
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceTemplate.py
index a41e58e635c9..3966f6ce3734 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CallbackInterfaceTemplate.py
@@ -10,4 +10,4 @@
 {% include "CallbackInterfaceImpl.py" %}
 
 # The _UniffiConverter which transforms the Callbacks in to Handles to pass to Rust.
-{{ ffi_converter_name }} = UniffiCallbackInterfaceFfiConverter()
+{{ ffi_converter_name }} = _UniffiCallbackInterfaceFfiConverter()
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CustomType.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CustomType.py
index f75a85dc2756..898ecb28f280 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CustomType.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/CustomType.py
@@ -1,9 +1,6 @@
 {%- match python_config.custom_types.get(name.as_str())  %}
 {% when None %}
 {#- No custom type config, just forward all methods to our builtin type #}
-# Type alias
-{{ name }} = {{ builtin|type_name }}
-
 class _UniffiConverterType{{ name }}:
     @staticmethod
     def write(value, buf):
@@ -35,9 +32,6 @@ class _UniffiConverterType{{ name }}:
 {%- else %}
 {%- endmatch %}
 
-# Type alias
-{{ name }} = {{ builtin|type_name }}
-
 {#- Custom type config supplied, use it to convert the builtin type #}
 class _UniffiConverterType{{ name }}:
     @staticmethod
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/EnumTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/EnumTemplate.py
index d07dd1c44adb..cfbf972603c1 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/EnumTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/EnumTemplate.py
@@ -9,7 +9,7 @@
 class {{ type_name }}(enum.Enum):
     {%- call py::docstring(e, 4) %}
     {%- for variant in e.variants() %}
-    {{ variant.name()|enum_variant_py }} = {{ e|variant_discr_literal(loop.index0) }}
+    {{ variant.name() }} = {{ e|variant_discr_literal(loop.index0) }}
     {%- call py::docstring(variant, 4) %}
     {% endfor %}
 {% else %}
@@ -21,13 +21,13 @@ class {{ type_name }}:
 
     # Each enum variant is a nested class of the enum itself.
     {% for variant in e.variants() -%}
-    class {{ variant.name()|enum_variant_py }}:
+    class {{ variant.name() }}:
         {%- call py::docstring(variant, 8) %}
 
     {%-  if variant.has_nameless_fields() %}
         def __init__(self, *values):
             if len(values) != {{ variant.fields().len() }}:
-                raise TypeError(f"Expected a tuple of len {{ variant.fields().len() }}, found len {len(values)}")
+                raise TypeError(f"Expected {{ variant.fields().len() }} arguments, found {len(values)}")
         {%- for field in variant.fields() %}
             if not isinstance(values[{{ loop.index0 }}], {{ field|type_name }}):
                 raise TypeError(f"unexpected type for tuple element {{ loop.index0 }} - expected '{{ field|type_name }}', got '{type(values[{{ loop.index0 }}])}'")
@@ -38,7 +38,7 @@ class {{ type_name }}:
             return self._values[index]
 
         def __str__(self):
-            return f"{{ type_name }}.{{ variant.name()|enum_variant_py }}{self._values!r}"
+            return f"{{ type_name }}.{{ variant.name() }}{self._values!r}"
 
         def __eq__(self, other):
             if not other.is_{{ variant.name()|var_name }}():
@@ -47,28 +47,27 @@ class {{ type_name }}:
 
     {%-  else -%}
         {%- for field in variant.fields() %}
-        {{ field.name()|var_name }}: "{{ field|type_name }}"
+        {{ field.name() }}: "{{ field|type_name }}"
         {%- call py::docstring(field, 8) %}
         {%- endfor %}
 
-        @typing.no_type_check
-        def __init__(self,{% for field in variant.fields() %}{{ field.name()|var_name }}: "{{- field|type_name }}"{% if loop.last %}{% else %}, {% endif %}{% endfor %}):
+        def __init__(self,{% for field in variant.fields() %}{{ field.name() }}: "{{- field|type_name }}"{% if loop.last %}{% else %}, {% endif %}{% endfor %}):
             {%- if variant.has_fields() %}
             {%- for field in variant.fields() %}
-            self.{{ field.name()|var_name }} = {{ field.name()|var_name }}
+            self.{{ field.name() }} = {{ field.name() }}
             {%- endfor %}
             {%- else %}
             pass
             {%- endif %}
 
         def __str__(self):
-            return "{{ type_name }}.{{ variant.name()|enum_variant_py }}({% for field in variant.fields() %}{{ field.name()|var_name }}={}{% if loop.last %}{% else %}, {% endif %}{% endfor %})".format({% for field in variant.fields() %}self.{{ field.name()|var_name }}{% if loop.last %}{% else %}, {% endif %}{% endfor %})
+            return "{{ type_name }}.{{ variant.name() }}({% for field in variant.fields() %}{{ field.name() }}={}{% if loop.last %}{% else %}, {% endif %}{% endfor %})".format({% for field in variant.fields() %}self.{{ field.name() }}{% if loop.last %}{% else %}, {% endif %}{% endfor %})
 
         def __eq__(self, other):
             if not other.is_{{ variant.name()|var_name }}():
                 return False
             {%- for field in variant.fields() %}
-            if self.{{ field.name()|var_name }} != other.{{ field.name()|var_name }}:
+            if self.{{ field.name() }} != other.{{ field.name() }}:
                 return False
             {%- endfor %}
             return True
@@ -79,14 +78,14 @@ class {{ type_name }}:
     # whether an instance is that variant.
     {% for variant in e.variants() -%}
     def is_{{ variant.name()|var_name }}(self) -> bool:
-        return isinstance(self, {{ type_name }}.{{ variant.name()|enum_variant_py }})
+        return isinstance(self, {{ type_name }}.{{ variant.name() }})
     {% endfor %}
 
 # Now, a little trick - we make each nested variant class be a subclass of the main
 # enum class, so that method calls and instance checks etc will work intuitively.
 # We might be able to do this a little more neatly with a metaclass, but this'll do.
 {% for variant in e.variants() -%}
-{{ type_name }}.{{ variant.name()|enum_variant_py }} = type("{{ type_name }}.{{ variant.name()|enum_variant_py }}", ({{ type_name }}.{{variant.name()|enum_variant_py}}, {{ type_name }},), {})  # type: ignore
+{{ type_name }}.{{ variant.name() }} = type("{{ type_name }}.{{ variant.name() }}", ({{ type_name }}.{{variant.name()}}, {{ type_name }},), {})  # type: ignore
 {% endfor %}
 
 {% endif %}
@@ -99,9 +98,9 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
         {%- for variant in e.variants() %}
         if variant == {{ loop.index }}:
             {%- if e.is_flat() %}
-            return {{ type_name }}.{{variant.name()|enum_variant_py}}
+            return {{ type_name }}.{{variant.name()}}
             {%- else %}
-            return {{ type_name }}.{{variant.name()|enum_variant_py}}(
+            return {{ type_name }}.{{variant.name()}}(
                 {%- for field in variant.fields() %}
                 {{ field|read_fn }}(buf),
                 {%- endfor %}
@@ -117,7 +116,7 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
         {%- else %}
         {%- for variant in e.variants() %}
         {%- if e.is_flat() %}
-        if value == {{ type_name }}.{{ variant.name()|enum_variant_py }}:
+        if value == {{ type_name }}.{{ variant.name() }}:
         {%- else %}
         if value.is_{{ variant.name()|var_name }}():
         {%- endif %}
@@ -125,7 +124,7 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
             {%- if variant.has_nameless_fields() %}
             {{ field|check_lower_fn }}(value._values[{{ loop.index0 }}])
             {%- else %}
-            {{ field|check_lower_fn }}(value.{{ field.name()|var_name }})
+            {{ field|check_lower_fn }}(value.{{ field.name() }})
             {%- endif %}
             {%- endfor %}
             return
@@ -137,7 +136,7 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
     def write(value, buf):
         {%- for variant in e.variants() %}
         {%- if e.is_flat() %}
-        if value == {{ type_name }}.{{ variant.name()|enum_variant_py }}:
+        if value == {{ type_name }}.{{ variant.name() }}:
             buf.write_i32({{ loop.index }})
         {%- else %}
         if value.is_{{ variant.name()|var_name }}():
@@ -146,7 +145,7 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
             {%- if variant.has_nameless_fields() %}
             {{ field|write_fn }}(value._values[{{ loop.index0 }}], buf)
             {%- else %}
-            {{ field|write_fn }}(value.{{ field.name()|var_name }}, buf)
+            {{ field|write_fn }}(value.{{ field.name() }}, buf)
             {%- endif %}
             {%- endfor %}
         {%- endif %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ErrorTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ErrorTemplate.py
index 0911ff559a52..9d3b30831d92 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ErrorTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ErrorTemplate.py
@@ -11,8 +11,9 @@ class {{ type_name }}(Exception):
 _UniffiTemp{{ type_name }} = {{ type_name }}
 
 class {{ type_name }}:  # type: ignore
+    {%- call py::docstring(e, 4) %}
     {%- for variant in e.variants() -%}
-    {%- let variant_type_name = variant.name()|class_name -%}
+    {%- let variant_type_name = variant.name() -%}
     {%- if e.is_flat() %}
     class {{ variant_type_name }}(_UniffiTemp{{ type_name }}):
         {%- call py::docstring(variant, 8) %}
@@ -23,19 +24,36 @@ class {{ type_name }}:  # type: ignore
     class {{ variant_type_name }}(_UniffiTemp{{ type_name }}):
         {%- call py::docstring(variant, 8) %}
 
-        def __init__(self{% for field in variant.fields() %}, {{ field.name()|var_name }}{% endfor %}):
+    {%-     if variant.has_nameless_fields() %}
+        def __init__(self, *values):
+            if len(values) != {{ variant.fields().len() }}:
+                raise TypeError(f"Expected {{ variant.fields().len() }} arguments, found {len(values)}")
+        {%- for field in variant.fields() %}
+            if not isinstance(values[{{ loop.index0 }}], {{ field|type_name }}):
+                raise TypeError(f"unexpected type for tuple element {{ loop.index0 }} - expected '{{ field|type_name }}', got '{type(values[{{ loop.index0 }}])}'")
+        {%- endfor %}
+            super().__init__(", ".join(map(repr, values)))
+            self._values = values
+
+        def __getitem__(self, index):
+            return self._values[index]
+
+    {%-     else %}
+        def __init__(self{% for field in variant.fields() %}, {{ field.name() }}{% endfor %}):
             {%- if variant.has_fields() %}
             super().__init__(", ".join([
                 {%- for field in variant.fields() %}
-                "{{ field.name()|var_name }}={!r}".format({{ field.name()|var_name }}),
+                "{{ field.name() }}={!r}".format({{ field.name() }}),
                 {%- endfor %}
             ]))
             {%- for field in variant.fields() %}
-            self.{{ field.name()|var_name }} = {{ field.name()|var_name }}
+            self.{{ field.name() }} = {{ field.name() }}
             {%- endfor %}
             {%- else %}
             pass
             {%- endif %}
+    {%-     endif %}
+
         def __repr__(self):
             return "{{ type_name }}.{{ variant_type_name }}({})".format(str(self))
     {%- endif %}
@@ -52,12 +70,12 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
         variant = buf.read_i32()
         {%- for variant in e.variants() %}
         if variant == {{ loop.index }}:
-            return {{ type_name }}.{{ variant.name()|class_name }}(
+            return {{ type_name }}.{{ variant.name() }}(
                 {%- if e.is_flat() %}
                 {{ Type::String.borrow()|read_fn }}(buf),
                 {%- else %}
                 {%- for field in variant.fields() %}
-                {{ field.name()|var_name }}={{ field|read_fn }}(buf),
+                {{ field|read_fn }}(buf),
                 {%- endfor %}
                 {%- endif %}
             )
@@ -70,9 +88,13 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
         pass
         {%- else %}
         {%- for variant in e.variants() %}
-        if isinstance(value, {{ type_name }}.{{ variant.name()|class_name }}):
+        if isinstance(value, {{ type_name }}.{{ variant.name() }}):
             {%- for field in variant.fields() %}
-            {{ field|check_lower_fn }}(value.{{ field.name()|var_name }})
+            {%-     if variant.has_nameless_fields() %}
+            {{ field|check_lower_fn }}(value._values[{{ loop.index0 }}])
+            {%-     else %}
+            {{ field|check_lower_fn }}(value.{{ field.name() }})
+            {%-     endif %}
             {%- endfor %}
             return
         {%- endfor %}
@@ -81,9 +103,13 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
     @staticmethod
     def write(value, buf):
         {%- for variant in e.variants() %}
-        if isinstance(value, {{ type_name }}.{{ variant.name()|class_name }}):
+        if isinstance(value, {{ type_name }}.{{ variant.name() }}):
             buf.write_i32({{ loop.index }})
             {%- for field in variant.fields() %}
-            {{ field|write_fn }}(value.{{ field.name()|var_name }}, buf)
+            {%-     if variant.has_nameless_fields() %}
+            {{ field|write_fn }}(value._values[{{ loop.index0 }}], buf)
+            {%-     else %}
+            {{ field|write_fn }}(value.{{ field.name() }}, buf)
+            {%-     endif %}
             {%- endfor %}
         {%- endfor %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ExternalTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ExternalTemplate.py
index 6c0cee85ef3a..26e4639e1957 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ExternalTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ExternalTemplate.py
@@ -3,7 +3,7 @@
 # External type {{name}} is in namespace "{{namespace}}", crate {{module_path}}
 {%- let ffi_converter_name = "_UniffiConverterType{}"|format(name) %}
 {{ self.add_import_of(module, ffi_converter_name) }}
-{{ self.add_import_of(module, name|class_name) }} {#- import the type alias itself -#}
+{{ self.add_import_of(module, name) }} {#- import the type alias itself -#}
 
 {%- let rustbuffer_local_name = "_UniffiRustBuffer{}"|format(name) %}
 {{ self.add_import_of_as(module, "_UniffiRustBuffer", rustbuffer_local_name) }}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/HandleMap.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/HandleMap.py
index f7c13cf74553..2d6630fab03b 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/HandleMap.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/HandleMap.py
@@ -20,14 +20,14 @@ class _UniffiHandleMap:
             with self._lock:
                 return self._map[handle]
         except KeyError:
-            raise InternalError("UniffiHandleMap.get: Invalid handle")
+            raise InternalError("_UniffiHandleMap.get: Invalid handle")
 
     def remove(self, handle):
         try:
             with self._lock:
                 return self._map.pop(handle)
         except KeyError:
-            raise InternalError("UniffiHandleMap.remove: Invalid handle")
+            raise InternalError("_UniffiHandleMap.remove: Invalid handle")
 
     def __len__(self):
         return len(self._map)
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Helpers.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Helpers.py
index 5d4bcbba8997..1b1d27840db0 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Helpers.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Helpers.py
@@ -32,11 +32,11 @@ class _UniffiRustCallStatus(ctypes.Structure):
         else:
             return "_UniffiRustCallStatus(<invalid code>)"
 
-def _rust_call(fn, *args):
+def _uniffi_rust_call(fn, *args):
     # Call a rust function
-    return _rust_call_with_error(None, fn, *args)
+    return _uniffi_rust_call_with_error(None, fn, *args)
 
-def _rust_call_with_error(error_ffi_converter, fn, *args):
+def _uniffi_rust_call_with_error(error_ffi_converter, fn, *args):
     # Call a rust function and handle any errors
     #
     # This function is used for rust calls that return Result<> and therefore can set the CALL_ERROR status code.
@@ -54,7 +54,7 @@ def _uniffi_check_call_status(error_ffi_converter, call_status):
     elif call_status.code == _UniffiRustCallStatus.CALL_ERROR:
         if error_ffi_converter is None:
             call_status.error_buf.free()
-            raise InternalError("_rust_call_with_error: CALL_ERROR, but error_ffi_converter is None")
+            raise InternalError("_uniffi_rust_call_with_error: CALL_ERROR, but error_ffi_converter is None")
         else:
             raise error_ffi_converter.lift(call_status.error_buf)
     elif call_status.code == _UniffiRustCallStatus.CALL_UNEXPECTED_ERROR:
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/NamespaceLibraryTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/NamespaceLibraryTemplate.py
index 1929f9aad6fe..e5d0eba42354 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/NamespaceLibraryTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/NamespaceLibraryTemplate.py
@@ -76,7 +76,7 @@ _UniffiLib = _uniffi_load_indirect()
 class {{ ffi_struct.name()|ffi_struct_name }}(ctypes.Structure):
     _fields_ = [
         {%- for field in ffi_struct.fields() %}
-        ("{{ field.name()|var_name }}", {{ field.type_().borrow()|ffi_type_name }}),
+        ("{{ field.name() }}", {{ field.type_().borrow()|ffi_type_name }}),
         {%- endfor %}
     ]
 {%- when FfiDefinition::Function(func) %}
@@ -89,4 +89,4 @@ _UniffiLib.{{ func.name() }}.restype = {% match func.return_type() %}{% when Som
 
 {# Ensure to call the contract verification only after we defined all functions. -#}
 _uniffi_check_contract_api_version(_UniffiLib)
-_uniffi_check_api_checksums(_UniffiLib)
+# _uniffi_check_api_checksums(_UniffiLib)
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ObjectTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ObjectTemplate.py
index 18dca4743ade..86029beea6e8 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ObjectTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/ObjectTemplate.py
@@ -34,10 +34,10 @@ class {{ impl_name }}:
         # In case of partial initialization of instances.
         pointer = getattr(self, "_pointer", None)
         if pointer is not None:
-            _rust_call(_UniffiLib.{{ obj.ffi_object_free().name() }}, pointer)
+            _uniffi_rust_call(_UniffiLib.{{ obj.ffi_object_free().name() }}, pointer)
 
     def _uniffi_clone_pointer(self):
-        return _rust_call(_UniffiLib.{{ obj.ffi_object_clone().name() }}, self._pointer)
+        return _uniffi_rust_call(_UniffiLib.{{ obj.ffi_object_clone().name() }}, self._pointer)
 
     # Used by alternative constructors or any methods which return this type.
     @classmethod
@@ -49,10 +49,9 @@ class {{ impl_name }}:
         return inst
 
 {%- for cons in obj.alternate_constructors() %}
-
     @classmethod
 {%-  if cons.is_async() %}
-    async def {{ cons.name()|fn_name }}(cls, {% call py::arg_list_decl(cons) %}):
+    async def {{ cons.name() }}(cls, {% call py::arg_list_decl(cons) %}):
         {%- call py::docstring(cons, 8) %}
         {%- call py::setup_args_extra_indent(cons) %}
 
@@ -65,7 +64,7 @@ class {{ impl_name }}:
             {% call py::error_ffi_converter(cons) %}
         )
 {%-  else %}
-    def {{ cons.name()|fn_name }}(cls, {% call py::arg_list_decl(cons) %}):
+    def {{ cons.name() }}(cls, {% call py::arg_list_decl(cons) %}):
         {%- call py::docstring(cons, 8) %}
         {%- call py::setup_args_extra_indent(cons) %}
         # Call the (fallible) function before creating any half-baked object instances.
@@ -75,7 +74,7 @@ class {{ impl_name }}:
 {% endfor %}
 
 {%- for meth in obj.methods() -%}
-    {%- call py::method_decl(meth.name()|fn_name, meth) %}
+    {%- call py::method_decl(meth.name(), meth) %}
 {%- endfor %}
 {%- for tm in obj.uniffi_traits() -%}
 {%-     match tm %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Protocol.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Protocol.py
index 3b7e93596aca..8e5012ddd4f0 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Protocol.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Protocol.py
@@ -1,7 +1,7 @@
 class {{ protocol_name }}(typing.Protocol):
     {%- call py::docstring_value(protocol_docstring, 4) %}
     {%- for meth in methods.iter() %}
-    def {{ meth.name()|fn_name }}(self, {% call py::arg_list_decl(meth) %}):
+    def {{ meth.name() }}(self, {% call py::arg_list_decl(meth) %}):
         {%- call py::docstring(meth, 8) %}
         raise NotImplementedError
     {%- else %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/README.md b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/README.md
new file mode 100644
index 000000000000..60df4168a6c3
--- /dev/null
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/README.md
@@ -0,0 +1,14 @@
+# Rules for the Python template code
+
+## Naming
+
+Private variables, classes, functions, etc. should be prefixed with `_uniffi`, `_Uniffi`, or `_UNIFFI`.
+The `_` indicates the variable is private and removes it from the autocomplete list.
+The `uniffi` part avoids naming collisions with user-defined items.
+Users can use leading underscores in their names if they want, but "uniffi" is reserved for our purposes.
+
+In particular, make sure to use the `_uniffi` prefix for any variable names in generated functions.
+If you name a variable something like `result` the code will probably work initially.
+Then it will break later on when a user decides to define a function with a parameter named `result`.
+
+Note: this doesn't apply to items that we want to expose, for example users may want to catch `InternalError` so doesn't get the `Uniffi` prefix.
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RecordTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RecordTemplate.py
index 0b5634eb526e..d778b90ebdb2 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RecordTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RecordTemplate.py
@@ -2,19 +2,18 @@
 class {{ type_name }}:
     {%- call py::docstring(rec, 4) %}
     {%- for field in rec.fields() %}
-    {{ field.name()|var_name }}: "{{ field|type_name }}"
+    {{ field.name() }}: "{{ field|type_name }}"
     {%- call py::docstring(field, 4) %}
     {%- endfor %}
 
     {%- if rec.has_fields() %}
-    @typing.no_type_check
     def __init__(self, *, {% for field in rec.fields() %}
-    {{- field.name()|var_name }}: "{{- field|type_name }}"
+    {{- field.name() }}: "{{- field|type_name }}"
     {%- if field.default_value().is_some() %} = _DEFAULT{% endif %}
     {%- if !loop.last %}, {% endif %}
     {%- endfor %}):
         {%- for field in rec.fields() %}
-        {%- let field_name = field.name()|var_name %}
+        {%- let field_name = field.name() %}
         {%- match field.default_value() %}
         {%- when None %}
         self.{{ field_name }} = {{ field_name }}
@@ -28,11 +27,11 @@ class {{ type_name }}:
     {%- endif %}
 
     def __str__(self):
-        return "{{ type_name }}({% for field in rec.fields() %}{{ field.name()|var_name }}={}{% if loop.last %}{% else %}, {% endif %}{% endfor %})".format({% for field in rec.fields() %}self.{{ field.name()|var_name }}{% if loop.last %}{% else %}, {% endif %}{% endfor %})
+        return "{{ type_name }}({% for field in rec.fields() %}{{ field.name() }}={}{% if loop.last %}{% else %}, {% endif %}{% endfor %})".format({% for field in rec.fields() %}self.{{ field.name() }}{% if loop.last %}{% else %}, {% endif %}{% endfor %})
 
     def __eq__(self, other):
         {%- for field in rec.fields() %}
-        if self.{{ field.name()|var_name }} != other.{{ field.name()|var_name }}:
+        if self.{{ field.name() }} != other.{{ field.name() }}:
             return False
         {%- endfor %}
         return True
@@ -42,7 +41,7 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
     def read(buf):
         return {{ type_name }}(
             {%- for field in rec.fields() %}
-            {{ field.name()|var_name }}={{ field|read_fn }}(buf),
+            {{ field.name() }}={{ field|read_fn }}(buf),
             {%- endfor %}
         )
 
@@ -52,7 +51,7 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
         pass
         {%- else %}
         {%- for field in rec.fields() %}
-        {{ field|check_lower_fn }}(value.{{ field.name()|var_name }})
+        {{ field|check_lower_fn }}(value.{{ field.name() }})
         {%- endfor %}
         {%- endif %}
 
@@ -60,7 +59,7 @@ class {{ ffi_converter_name }}(_UniffiConverterRustBuffer):
     def write(value, buf):
         {%- if rec.has_fields() %}
         {%- for field in rec.fields() %}
-        {{ field|write_fn }}(value.{{ field.name()|var_name }}, buf)
+        {{ field|write_fn }}(value.{{ field.name() }}, buf)
         {%- endfor %}
         {%- else %}
         pass
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RustBufferTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RustBufferTemplate.py
index 44e0ba1001b2..5005bd1147df 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RustBufferTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/RustBufferTemplate.py
@@ -12,14 +12,14 @@ class _UniffiRustBuffer(ctypes.Structure):
 
     @staticmethod
     def alloc(size):
-        return _rust_call(_UniffiLib.{{ ci.ffi_rustbuffer_alloc().name() }}, size)
+        return _uniffi_rust_call(_UniffiLib.{{ ci.ffi_rustbuffer_alloc().name() }}, size)
 
     @staticmethod
     def reserve(rbuf, additional):
-        return _rust_call(_UniffiLib.{{ ci.ffi_rustbuffer_reserve().name() }}, rbuf, additional)
+        return _uniffi_rust_call(_UniffiLib.{{ ci.ffi_rustbuffer_reserve().name() }}, rbuf, additional)
 
     def free(self):
-        return _rust_call(_UniffiLib.{{ ci.ffi_rustbuffer_free().name() }}, self)
+        return _uniffi_rust_call(_UniffiLib.{{ ci.ffi_rustbuffer_free().name() }}, self)
 
     def __str__(self):
         return "_UniffiRustBuffer(capacity={}, len={}, data={})".format(
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/TopLevelFunctionTemplate.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/TopLevelFunctionTemplate.py
index 230b9e853f83..7a6cb6d7c226 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/TopLevelFunctionTemplate.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/TopLevelFunctionTemplate.py
@@ -2,9 +2,9 @@
 
 {%- match func.return_type() -%}
 {%- when Some with (return_type) %}
-async def {{ func.name()|fn_name }}({%- call py::arg_list_decl(func) -%}) -> "{{ return_type|type_name }}":
+async def {{ func.name() }}({%- call py::arg_list_decl(func) -%}) -> "{{ return_type|type_name }}":
 {% when None %}
-async def {{ func.name()|fn_name }}({%- call py::arg_list_decl(func) -%}) -> None:
+async def {{ func.name() }}({%- call py::arg_list_decl(func) -%}) -> None:
 {% endmatch %}
 
     {%- call py::docstring(func, 4) %}
@@ -28,13 +28,13 @@ async def {{ func.name()|fn_name }}({%- call py::arg_list_decl(func) -%}) -> Non
 {%- match func.return_type() -%}
 {%- when Some with (return_type) %}
 
-def {{ func.name()|fn_name }}({%- call py::arg_list_decl(func) -%}) -> "{{ return_type|type_name }}":
+def {{ func.name() }}({%- call py::arg_list_decl(func) -%}) -> "{{ return_type|type_name }}":
     {%- call py::docstring(func, 4) %}
     {%- call py::setup_args(func) %}
     return {{ return_type|lift_fn }}({% call py::to_ffi_call(func) %})
 {% when None %}
 
-def {{ func.name()|fn_name }}({%- call py::arg_list_decl(func) -%}) -> None:
+def {{ func.name() }}({%- call py::arg_list_decl(func) -%}) -> None:
     {%- call py::docstring(func, 4) %}
     {%- call py::setup_args(func) %}
     {% call py::to_ffi_call(func) %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Types.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Types.py
index 4aaed253e018..29f66fe88683 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Types.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/Types.py
@@ -97,3 +97,11 @@
 {%- else %}
 {%- endmatch %}
 {%- endfor %}
+
+{#-
+Setup type aliases for our custom types, has complications due to
+forward type references, #2067
+-#}
+{%- for (name, ty) in self.get_custom_type_aliases() %}
+{{ name }} = {{ ty|type_name }}
+{%- endfor %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/macros.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/macros.py
index 6818a8c10708..1a47226bd05c 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/macros.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/macros.py
@@ -17,14 +17,14 @@
 {%-     when Some with (e) -%}
 {%-         match e -%}
 {%-             when Type::Enum { name, module_path } -%}
-_rust_call_with_error({{ e|ffi_converter_name }},
+_uniffi_rust_call_with_error({{ e|ffi_converter_name }},
 {%-             when Type::Object { name, module_path, imp } -%}
-_rust_call_with_error({{ e|ffi_converter_name }}__as_error,
+_uniffi_rust_call_with_error({{ e|ffi_converter_name }}__as_error,
 {%-             else %}
 # unsupported error type!
 {%-         endmatch %}
 {%- else -%}
-_rust_call(
+_uniffi_rust_call(
 {%- endmatch -%}
     _UniffiLib.{{ func.ffi_func().name() }},
     {{- prefix }}
@@ -34,7 +34,7 @@ _rust_call(
 
 {%- macro arg_list_lowered(func) %}
     {%- for arg in func.arguments() %}
-        {{ arg|lower_fn }}({{ arg.name()|var_name }})
+        {{ arg|lower_fn }}({{ arg.name() }})
         {%- if !loop.last %},{% endif %}
     {%- endfor %}
 {%- endmacro -%}
@@ -54,12 +54,12 @@ _rust_call(
 
 {#-
 // Arglist as used in Python declarations of methods, functions and constructors.
-// Note the var_name and type_name filters.
+// Note the type_name filters.
 -#}
 
 {% macro arg_list_decl(func) %}
     {%- for arg in func.arguments() -%}
-        {{ arg.name()|var_name }}
+        {{ arg.name() }}
         {%- match arg.default_value() %}
         {%- when Some with(literal) %}: "typing.Union[object, {{ arg|type_name -}}]" = _DEFAULT
         {%- else %}: "{{ arg|type_name -}}"
@@ -88,10 +88,10 @@ _rust_call(
     {%- match arg.default_value() %}
     {%- when None %}
     {%- when Some with(literal) %}
-    if {{ arg.name()|var_name }} is _DEFAULT:
-        {{ arg.name()|var_name }} = {{ literal|literal_py(arg.as_type().borrow()) }}
+    if {{ arg.name() }} is _DEFAULT:
+        {{ arg.name() }} = {{ literal|literal_py(arg.as_type().borrow()) }}
     {%- endmatch %}
-    {{ arg|check_lower_fn }}({{ arg.name()|var_name }})
+    {{ arg|check_lower_fn }}({{ arg.name() }})
     {% endfor -%}
 {%- endmacro -%}
 
@@ -104,10 +104,10 @@ _rust_call(
         {%- match arg.default_value() %}
         {%- when None %}
         {%- when Some with(literal) %}
-        if {{ arg.name()|var_name }} is _DEFAULT:
-            {{ arg.name()|var_name }} = {{ literal|literal_py(arg.as_type().borrow()) }}
+        if {{ arg.name() }} is _DEFAULT:
+            {{ arg.name() }} = {{ literal|literal_py(arg.as_type().borrow()) }}
         {%- endmatch %}
-        {{ arg|check_lower_fn }}({{ arg.name()|var_name }})
+        {{ arg|check_lower_fn }}({{ arg.name() }})
         {% endfor -%}
 {%- endmacro -%}
 
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/wrapper.py b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/wrapper.py
index 1ccd6821c00b..4380041ad8d8 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/templates/wrapper.py
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/templates/wrapper.py
@@ -36,7 +36,7 @@ import platform
 {%- endfor %}
 
 # Used for default argument values
-_DEFAULT = object()
+_DEFAULT = object() # type: typing.Any
 
 {% include "RustBufferTemplate.py" %}
 {% include "Helpers.py" %}
@@ -67,7 +67,7 @@ __all__ = [
     "{{ record|type_name }}",
     {%- endfor %}
     {%- for func in ci.function_definitions() %}
-    "{{ func.name()|fn_name }}",
+    "{{ func.name() }}",
     {%- endfor %}
     {%- for obj in ci.object_definitions() %}
     "{{ obj|type_name }}",
@@ -75,9 +75,6 @@ __all__ = [
     {%- for c in ci.callback_interface_definitions() %}
     "{{ c.name()|class_name }}",
     {%- endfor %}
-    {%- if ci.has_async_fns() %}
-    "uniffi_set_event_loop",
-    {%- endif %}
 ]
 
 {% import "macros.py" as py %}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/python/test.rs b/third_party/rust/uniffi_bindgen/src/bindings/python/test.rs
index 0c23140b3326..39dbc9c1365b 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/python/test.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/python/test.rs
@@ -2,8 +2,9 @@
 License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use crate::bindings::TargetLanguage;
-use crate::{bindings::RunScriptOptions, library_mode::generate_bindings, BindingGeneratorDefault};
+use crate::bindings::RunScriptOptions;
+use crate::cargo_metadata::CrateConfigSupplier;
+use crate::library_mode::generate_bindings;
 use anyhow::{Context, Result};
 use camino::Utf8Path;
 use std::env;
@@ -39,10 +40,8 @@ pub fn run_script(
     generate_bindings(
         &cdylib_path,
         None,
-        &BindingGeneratorDefault {
-            target_languages: vec![TargetLanguage::Python],
-            try_format_code: false,
-        },
+        &super::PythonBindingGenerator,
+        &CrateConfigSupplier::from(test_helper.cargo_metadata()),
         None,
         &out_dir,
         false,
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/ruby/gen_ruby/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/ruby/gen_ruby/mod.rs
index 04841b459c9f..7608acd7c2e3 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/ruby/gen_ruby/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/ruby/gen_ruby/mod.rs
@@ -2,39 +2,14 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use anyhow::{bail, Result};
+use anyhow::Result;
 use askama::Template;
-use camino::Utf8Path;
+
 use heck::{ToShoutySnakeCase, ToSnakeCase, ToUpperCamelCase};
 use serde::{Deserialize, Serialize};
 use std::borrow::Borrow;
-use std::collections::HashMap;
 
-use crate::bindings::ruby;
 use crate::interface::*;
-use crate::{BindingGenerator, BindingsConfig};
-
-pub struct RubyBindingGenerator;
-impl BindingGenerator for RubyBindingGenerator {
-    type Config = Config;
-
-    fn write_bindings(
-        &self,
-        ci: &ComponentInterface,
-        config: &Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
-    ) -> Result<()> {
-        ruby::write_bindings(config, ci, out_dir, try_format_code)
-    }
-
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()> {
-        if cdylib_name.is_none() {
-            bail!("Generate bindings for Ruby requires a cdylib, but {library_path} was given");
-        }
-        Ok(())
-    }
-}
 
 const RESERVED_WORDS: &[&str] = &[
     "alias", "and", "BEGIN", "begin", "break", "case", "class", "def", "defined?", "do", "else",
@@ -106,7 +81,7 @@ pub fn canonical_name(t: &Type) -> String {
 // since the details of the underlying component are entirely determined by the `ComponentInterface`.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct Config {
-    cdylib_name: Option<String>,
+    pub(super) cdylib_name: Option<String>,
     cdylib_path: Option<String>,
 }
 
@@ -126,20 +101,6 @@ impl Config {
     }
 }
 
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.cdylib_name
-            .get_or_insert_with(|| format!("uniffi_{}", ci.namespace()));
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.cdylib_name
-            .get_or_insert_with(|| cdylib_name.to_string());
-    }
-
-    fn update_from_dependency_configs(&mut self, _config_map: HashMap<&str, &Self>) {}
-}
-
 #[derive(Template)]
 #[template(syntax = "rb", escape = "none", path = "wrapper.rb")]
 pub struct RubyWrapper<'a> {
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/ruby/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/ruby/mod.rs
index 6db89b9f0bf2..e8f3c5f77c0d 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/ruby/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/ruby/mod.rs
@@ -4,42 +4,67 @@
 
 use std::process::Command;
 
+use crate::{BindingGenerator, Component, ComponentInterface, GenerationSettings};
 use anyhow::{Context, Result};
-use camino::Utf8Path;
 use fs_err as fs;
 
-pub mod gen_ruby;
-mod test;
-pub use gen_ruby::{Config, RubyWrapper};
-pub use test::{run_test, test_script_command};
+mod gen_ruby;
+#[cfg(feature = "bindgen-tests")]
+pub mod test;
+use gen_ruby::{Config, RubyWrapper};
 
-use super::super::interface::ComponentInterface;
+pub struct RubyBindingGenerator;
+impl BindingGenerator for RubyBindingGenerator {
+    type Config = Config;
 
-// Generate ruby bindings for the given ComponentInterface, in the given output directory.
-
-pub fn write_bindings(
-    config: &Config,
-    ci: &ComponentInterface,
-    out_dir: &Utf8Path,
-    try_format_code: bool,
-) -> Result<()> {
-    let rb_file = out_dir.join(format!("{}.rb", ci.namespace()));
-    fs::write(&rb_file, generate_ruby_bindings(config, ci)?)?;
-
-    if try_format_code {
-        if let Err(e) = Command::new("rubocop").arg("-A").arg(&rb_file).output() {
-            println!(
-                "Warning: Unable to auto-format {} using rubocop: {e:?}",
-                rb_file.file_name().unwrap(),
-            )
-        }
+    fn new_config(&self, root_toml: &toml::Value) -> Result<Self::Config> {
+        Ok(
+            match root_toml.get("bindings").and_then(|b| b.get("ruby")) {
+                Some(v) => v.clone().try_into()?,
+                None => Default::default(),
+            },
+        )
     }
 
-    Ok(())
+    fn update_component_configs(
+        &self,
+        settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
+    ) -> Result<()> {
+        for c in &mut *components {
+            c.config.cdylib_name.get_or_insert_with(|| {
+                settings
+                    .cdylib
+                    .clone()
+                    .unwrap_or_else(|| format!("uniffi_{}", c.ci.namespace()))
+            });
+        }
+        Ok(())
+    }
+
+    fn write_bindings(
+        &self,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
+    ) -> Result<()> {
+        for Component { ci, config, .. } in components {
+            let rb_file = settings.out_dir.join(format!("{}.rb", ci.namespace()));
+            fs::write(&rb_file, generate_ruby_bindings(config, ci)?)?;
+
+            if settings.try_format_code {
+                if let Err(e) = Command::new("rubocop").arg("-A").arg(&rb_file).output() {
+                    println!(
+                        "Warning: Unable to auto-format {} using rubocop: {e:?}",
+                        rb_file.file_name().unwrap(),
+                    )
+                }
+            }
+        }
+        Ok(())
+    }
 }
 
 // Generate ruby bindings for the given ComponentInterface, as a string.
-
 pub fn generate_ruby_bindings(config: &Config, ci: &ComponentInterface) -> Result<String> {
     use askama::Template;
     RubyWrapper::new(config.clone(), ci)
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/ruby/test.rs b/third_party/rust/uniffi_bindgen/src/bindings/ruby/test.rs
index 88f770b9dc32..47a3b68401fc 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/ruby/test.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/ruby/test.rs
@@ -2,9 +2,8 @@
 License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use crate::bindings::TargetLanguage;
+use crate::cargo_metadata::CrateConfigSupplier;
 use crate::library_mode::generate_bindings;
-use crate::BindingGeneratorDefault;
 use anyhow::{bail, Context, Result};
 use camino::Utf8Path;
 use std::env;
@@ -38,10 +37,8 @@ pub fn test_script_command(
     generate_bindings(
         &cdylib_path,
         None,
-        &BindingGeneratorDefault {
-            target_languages: vec![TargetLanguage::Ruby],
-            try_format_code: false,
-        },
+        &super::RubyBindingGenerator,
+        &CrateConfigSupplier::from(test_helper.cargo_metadata()),
         None,
         &out_dir,
         false,
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/custom.rs b/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/custom.rs
index f4591b6eb67d..54aad5adcd55 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/custom.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/custom.rs
@@ -17,7 +17,7 @@ impl CustomCodeType {
 
 impl CodeType for CustomCodeType {
     fn type_label(&self) -> String {
-        self.name.clone()
+        super::SwiftCodeOracle.class_name(&self.name)
     }
 
     fn canonical_name(&self) -> String {
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/mod.rs
index 16c162512367..c81495a8c631 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/gen_swift/mod.rs
@@ -10,15 +10,14 @@ use std::fmt::Debug;
 
 use anyhow::{Context, Result};
 use askama::Template;
-use camino::Utf8Path;
+
 use heck::{ToLowerCamelCase, ToShoutySnakeCase, ToUpperCamelCase};
 use serde::{Deserialize, Serialize};
 
 use super::Bindings;
 use crate::backend::TemplateExpression;
-use crate::bindings::swift;
+
 use crate::interface::*;
-use crate::{BindingGenerator, BindingsConfig};
 
 mod callback_interface;
 mod compounds;
@@ -30,29 +29,6 @@ mod object;
 mod primitives;
 mod record;
 
-pub struct SwiftBindingGenerator;
-impl BindingGenerator for SwiftBindingGenerator {
-    type Config = Config;
-
-    fn write_bindings(
-        &self,
-        ci: &ComponentInterface,
-        config: &Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
-    ) -> Result<()> {
-        swift::write_bindings(config, ci, out_dir, try_format_code)
-    }
-
-    fn check_library_path(
-        &self,
-        _library_path: &Utf8Path,
-        _cdylib_name: Option<&str>,
-    ) -> Result<()> {
-        Ok(())
-    }
-}
-
 /// A trait tor the implementation.
 trait CodeType: Debug {
     /// The language specific label used to reference this type. This will be used in
@@ -214,8 +190,7 @@ pub fn quote_arg_keyword(nm: String) -> String {
 /// since the details of the underlying component are entirely determined by the `ComponentInterface`.
 #[derive(Debug, Clone, Default, Serialize, Deserialize)]
 pub struct Config {
-    cdylib_name: Option<String>,
-    module_name: Option<String>,
+    pub(super) module_name: Option<String>,
     ffi_module_name: Option<String>,
     ffi_module_filename: Option<String>,
     generate_module_map: Option<bool>,
@@ -236,11 +211,12 @@ pub struct CustomTypeConfig {
 
 impl Config {
     /// The name of the Swift module containing the high-level foreign-language bindings.
+    /// Panics if the module name hasn't been configured.
     pub fn module_name(&self) -> String {
-        match self.module_name.as_ref() {
-            Some(name) => name.clone(),
-            None => "uniffi".into(),
-        }
+        self.module_name
+            .as_ref()
+            .expect("module name should have been set in update_component_configs")
+            .clone()
     }
 
     /// The name of the lower-level C module containing the FFI declarations.
@@ -269,15 +245,6 @@ impl Config {
         format!("{}.h", self.ffi_module_filename())
     }
 
-    /// The name of the compiled Rust library containing the FFI implementation.
-    pub fn cdylib_name(&self) -> String {
-        if let Some(cdylib_name) = &self.cdylib_name {
-            cdylib_name.clone()
-        } else {
-            "uniffi".into()
-        }
-    }
-
     /// Whether to generate a `.modulemap` file for the lower-level C module with FFI declarations.
     pub fn generate_module_map(&self) -> bool {
         self.generate_module_map.unwrap_or(true)
@@ -299,22 +266,6 @@ impl Config {
     }
 }
 
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.module_name
-            .get_or_insert_with(|| ci.namespace().into());
-        self.cdylib_name
-            .get_or_insert_with(|| format!("uniffi_{}", ci.namespace()));
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.cdylib_name
-            .get_or_insert_with(|| cdylib_name.to_string());
-    }
-
-    fn update_from_dependency_configs(&mut self, _config_map: HashMap<&str, &Self>) {}
-}
-
 /// Generate UniFFI component bindings for Swift, as strings in memory.
 ///
 pub fn generate_bindings(config: &Config, ci: &ComponentInterface) -> Result<Bindings> {
@@ -606,10 +557,6 @@ impl SwiftCodeOracle {
         }
     }
 
-    fn ffi_canonical_name(&self, ffi_type: &FfiType) -> String {
-        self.ffi_type_label(ffi_type)
-    }
-
     /// Get the name of the protocol and class name for an object.
     ///
     /// If we support callback interfaces, the protocol name is the object name, and the class name is derived from that.
@@ -704,10 +651,6 @@ pub mod filters {
         Ok(oracle().ffi_type_label(ffi_type))
     }
 
-    pub fn ffi_canonical_name(ffi_type: &FfiType) -> Result<String, askama::Error> {
-        Ok(oracle().ffi_canonical_name(ffi_type))
-    }
-
     pub fn ffi_default_value(return_type: Option<FfiType>) -> Result<String, askama::Error> {
         Ok(oracle().ffi_default_value(return_type.as_ref()))
     }
@@ -766,9 +709,9 @@ pub mod filters {
         Ok(quote_general_keyword(oracle().enum_variant_name(nm)))
     }
 
-    /// Get the idiomatic Swift rendering of an individual enum variant, for contexts (for use in non-declaration contexts where quoting is not needed)
-    pub fn enum_variant_swift(nm: &str) -> Result<String, askama::Error> {
-        Ok(oracle().enum_variant_name(nm))
+    /// Like enum_variant_swift_quoted, but a class name.
+    pub fn error_variant_swift_quoted(nm: &str) -> Result<String, askama::Error> {
+        Ok(quote_general_keyword(oracle().class_name(nm)))
     }
 
     /// Get the idiomatic Swift rendering of an FFI callback function name
@@ -795,28 +738,6 @@ pub mod filters {
         Ok(textwrap::indent(&wrapped, &" ".repeat(spaces)))
     }
 
-    pub fn error_handler(result: &ResultType) -> Result<String, askama::Error> {
-        Ok(match &result.throws_type {
-            Some(t) => format!("{}.lift", ffi_converter_name(t)?),
-            None => "nil".into(),
-        })
-    }
-
-    /// Name of the callback function to handle an async result
-    pub fn future_callback(result: &ResultType) -> Result<String, askama::Error> {
-        Ok(format!(
-            "uniffiFutureCallbackHandler{}{}",
-            match &result.return_type {
-                Some(t) => SwiftCodeOracle.find(t).canonical_name(),
-                None => "Void".into(),
-            },
-            match &result.throws_type {
-                Some(t) => SwiftCodeOracle.find(t).canonical_name(),
-                None => "".into(),
-            }
-        ))
-    }
-
     pub fn object_names(obj: &Object) -> Result<(String, String), askama::Error> {
         Ok(SwiftCodeOracle.object_names(obj))
     }
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/mod.rs b/third_party/rust/uniffi_bindgen/src/bindings/swift/mod.rs
index bf17f38a4ead..27d2bcf0a3fd 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/mod.rs
@@ -4,7 +4,7 @@
 
 //! # Swift bindings backend for UniFFI
 //!
-//! This module generates Swift bindings from a [`ComponentInterface`] definition,
+//! This module generates Swift bindings from a [`crate::ComponentInterface`] definition,
 //! using Swift's builtin support for loading C header files.
 //!
 //! Conceptually, the generated bindings are split into two Swift modules, one for the low-level
@@ -17,7 +17,7 @@
 //!   * A Swift source file `example.swift` that imports the `exampleFFI` module and wraps it
 //!    to provide the higher-level Swift API.
 //!
-//! Most of the concepts in a [`ComponentInterface`] have an obvious counterpart in Swift,
+//! Most of the concepts in a [`crate::ComponentInterface`] have an obvious counterpart in Swift,
 //! with the details documented in inline comments where appropriate.
 //!
 //! To handle lifting/lowering/serializing types across the FFI boundary, the Swift code
@@ -29,22 +29,20 @@
 //!  * How to read from and write into a byte buffer.
 //!
 
+use crate::{BindingGenerator, Component, GenerationSettings};
+use anyhow::Result;
+use fs_err as fs;
 use std::process::Command;
 
-use anyhow::Result;
-use camino::Utf8Path;
-use fs_err as fs;
+mod gen_swift;
+use gen_swift::{generate_bindings, Config};
 
-pub mod gen_swift;
-pub use gen_swift::{generate_bindings, Config};
-mod test;
+#[cfg(feature = "bindgen-tests")]
+pub mod test;
 
-use super::super::interface::ComponentInterface;
-pub use test::{run_script, run_test};
-
-/// The Swift bindings generated from a [`ComponentInterface`].
+/// The Swift bindings generated from a [`crate::ComponentInterface`].
 ///
-pub struct Bindings {
+struct Bindings {
     /// The contents of the generated `.swift` file, as a string.
     library: String,
     /// The contents of the generated `.h` file, as a string.
@@ -53,45 +51,73 @@ pub struct Bindings {
     modulemap: Option<String>,
 }
 
-/// Write UniFFI component bindings for Swift as files on disk.
-///
-/// Unlike other target languages, binding to Rust code from Swift involves more than just
-/// generating a `.swift` file. We also need to produce a `.h` file with the C-level API
-/// declarations, and a `.modulemap` file to tell Swift how to use it.
-pub fn write_bindings(
-    config: &Config,
-    ci: &ComponentInterface,
-    out_dir: &Utf8Path,
-    try_format_code: bool,
-) -> Result<()> {
-    let Bindings {
-        header,
-        library,
-        modulemap,
-    } = generate_bindings(config, ci)?;
+pub struct SwiftBindingGenerator;
+impl BindingGenerator for SwiftBindingGenerator {
+    type Config = Config;
 
-    let source_file = out_dir.join(format!("{}.swift", config.module_name()));
-    fs::write(&source_file, library)?;
-
-    let header_file = out_dir.join(config.header_filename());
-    fs::write(header_file, header)?;
-
-    if let Some(modulemap) = modulemap {
-        let modulemap_file = out_dir.join(config.modulemap_filename());
-        fs::write(modulemap_file, modulemap)?;
+    fn new_config(&self, root_toml: &toml::Value) -> Result<Self::Config> {
+        Ok(
+            match root_toml.get("bindings").and_then(|b| b.get("swift")) {
+                Some(v) => v.clone().try_into()?,
+                None => Default::default(),
+            },
+        )
     }
 
-    if try_format_code {
-        if let Err(e) = Command::new("swiftformat")
-            .arg(source_file.as_str())
-            .output()
-        {
-            println!(
-                "Warning: Unable to auto-format {} using swiftformat: {e:?}",
-                source_file.file_name().unwrap(),
-            );
+    fn update_component_configs(
+        &self,
+        _settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
+    ) -> Result<()> {
+        for c in &mut *components {
+            c.config
+                .module_name
+                .get_or_insert_with(|| c.ci.namespace().into());
         }
+        Ok(())
     }
 
-    Ok(())
+    /// Unlike other target languages, binding to Rust code from Swift involves more than just
+    /// generating a `.swift` file. We also need to produce a `.h` file with the C-level API
+    /// declarations, and a `.modulemap` file to tell Swift how to use it.
+    fn write_bindings(
+        &self,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
+    ) -> Result<()> {
+        for Component { ci, config, .. } in components {
+            let Bindings {
+                header,
+                library,
+                modulemap,
+            } = generate_bindings(config, ci)?;
+
+            let source_file = settings
+                .out_dir
+                .join(format!("{}.swift", config.module_name()));
+            fs::write(&source_file, library)?;
+
+            let header_file = settings.out_dir.join(config.header_filename());
+            fs::write(header_file, header)?;
+
+            if let Some(modulemap) = modulemap {
+                let modulemap_file = settings.out_dir.join(config.modulemap_filename());
+                fs::write(modulemap_file, modulemap)?;
+            }
+
+            if settings.try_format_code {
+                if let Err(e) = Command::new("swiftformat")
+                    .arg(source_file.as_str())
+                    .output()
+                {
+                    println!(
+                        "Warning: Unable to auto-format {} using swiftformat: {e:?}",
+                        source_file.file_name().unwrap(),
+                    );
+                }
+            }
+        }
+
+        Ok(())
+    }
 }
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift
index e16f3108e1b6..c26518783f8b 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Async.swift
@@ -9,7 +9,7 @@ fileprivate func uniffiRustCallAsync<F, T>(
     completeFunc: (UInt64, UnsafeMutablePointer<RustCallStatus>) -> F,
     freeFunc: (UInt64) -> (),
     liftFunc: (F) throws -> T,
-    errorHandler: ((RustBuffer) throws -> Error)?
+    errorHandler: ((RustBuffer) throws -> Swift.Error)?
 ) async throws -> T {
     // Make sure to call uniffiEnsureInitialized() since future creation doesn't have a
     // RustCallStatus param, so doesn't use makeRustCall()
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/CustomType.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/CustomType.swift
index 504cadfc1d56..2137ceff9cbf 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/CustomType.swift
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/CustomType.swift
@@ -6,21 +6,21 @@
  * Typealias from the type name used in the UDL file to the builtin type.  This
  * is needed because the UDL type name is used in function/method signatures.
  */
-public typealias {{ name }} = {{ builtin|type_name }}
+public typealias {{ type_name }} = {{ builtin|type_name }}
 public struct FfiConverterType{{ name }}: FfiConverter {
-    public static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> {{ name }} {
+    public static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> {{ type_name }} {
         return try {{ builtin|read_fn }}(from: &buf)
     }
 
-    public static func write(_ value: {{ name }}, into buf: inout [UInt8]) {
+    public static func write(_ value: {{ type_name }}, into buf: inout [UInt8]) {
         return {{ builtin|write_fn }}(value, into: &buf)
     }
 
-    public static func lift(_ value: {{ ffi_type_name }}) throws -> {{ name }} {
+    public static func lift(_ value: {{ ffi_type_name }}) throws -> {{ type_name }} {
         return try {{ builtin|lift_fn }}(value)
     }
 
-    public static func lower(_ value: {{ name }}) -> {{ ffi_type_name }} {
+    public static func lower(_ value: {{ type_name }}) -> {{ ffi_type_name }} {
         return {{ builtin|lower_fn }}(value)
     }
 }
@@ -34,7 +34,7 @@ public struct FfiConverterType{{ name }}: FfiConverter {
  * Typealias from the type name used in the UDL file to the custom type.  This
  * is needed because the UDL type name is used in function/method signatures.
  */
-public typealias {{ name }} = {{ concrete_type_name }}
+public typealias {{ type_name }} = {{ concrete_type_name }}
 {%- else %}
 {%- endmatch %}
 
@@ -49,22 +49,22 @@ public typealias {{ name }} = {{ concrete_type_name }}
 public struct FfiConverterType{{ name }}: FfiConverter {
     {#- Custom type config supplied, use it to convert the builtin type #}
 
-    public static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> {{ name }} {
+    public static func read(from buf: inout (data: Data, offset: Data.Index)) throws -> {{ type_name }} {
         let builtinValue = try {{ builtin|read_fn }}(from: &buf)
         return {{ config.into_custom.render("builtinValue") }}
     }
 
-    public static func write(_ value: {{ name }}, into buf: inout [UInt8]) {
+    public static func write(_ value: {{ type_name }}, into buf: inout [UInt8]) {
         let builtinValue = {{ config.from_custom.render("value") }}
         return {{ builtin|write_fn }}(builtinValue, into: &buf)
     }
 
-    public static func lift(_ value: {{ ffi_type_name }}) throws -> {{ name }} {
+    public static func lift(_ value: {{ ffi_type_name }}) throws -> {{ type_name }} {
         let builtinValue = try {{ builtin|lift_fn }}(value)
         return {{ config.into_custom.render("builtinValue") }}
     }
 
-    public static func lower(_ value: {{ name }}) -> {{ ffi_type_name }} {
+    public static func lower(_ value: {{ type_name }}) -> {{ ffi_type_name }} {
         let builtinValue = {{ config.from_custom.render("value") }}
         return {{ builtin|lower_fn }}(builtinValue)
     }
@@ -76,11 +76,11 @@ public struct FfiConverterType{{ name }}: FfiConverter {
 We always write these public functions just incase the type is used as
 an external type by another crate.
 #}
-public func FfiConverterType{{ name }}_lift(_ value: {{ ffi_type_name }}) throws -> {{ name }} {
+public func FfiConverterType{{ name }}_lift(_ value: {{ ffi_type_name }}) throws -> {{ type_name }} {
     return try FfiConverterType{{ name }}.lift(value)
 }
 
-public func FfiConverterType{{ name }}_lower(_ value: {{ name }}) -> {{ ffi_type_name }} {
+public func FfiConverterType{{ name }}_lower(_ value: {{ type_name }}) -> {{ ffi_type_name }} {
     return FfiConverterType{{ name }}.lower(value)
 }
 
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ErrorTemplate.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ErrorTemplate.swift
index 0702c477e940..cd4953d8e3e8 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ErrorTemplate.swift
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ErrorTemplate.swift
@@ -37,9 +37,13 @@ public struct {{ ffi_converter_name }}: FfiConverterRustBuffer {
         {% else %}
 
         {% for variant in e.variants() %}
-        case {{ loop.index }}: return .{{ variant.name()|class_name }}{% if variant.has_fields() -%}(
+        case {{ loop.index }}: return .{{ variant.name()|error_variant_swift_quoted }}{% if variant.has_fields() %}(
             {% for field in variant.fields() -%}
+            {%-     if variant.has_nameless_fields() -%}
+            try {{ field|read_fn }}(from: &buf)
+            {%-     else -%}
             {{ field.name()|var_name }}: try {{ field|read_fn }}(from: &buf)
+            {%-     endif -%}
             {%- if !loop.last %}, {% endif %}
             {% endfor -%}
         ){% endif -%}
@@ -64,10 +68,10 @@ public struct {{ ffi_converter_name }}: FfiConverterRustBuffer {
 
         {% for variant in e.variants() %}
         {% if variant.has_fields() %}
-        case let .{{ variant.name()|class_name }}({% for field in variant.fields() %}{{ field.name()|var_name }}{%- if loop.last -%}{%- else -%},{%- endif -%}{% endfor %}):
+        case let .{{ variant.name()|error_variant_swift_quoted }}({% for field in variant.fields() %}{%- call swift::field_name(field, loop.index) -%}{%- if loop.last -%}{%- else -%},{%- endif -%}{% endfor %}):
             writeInt(&buf, Int32({{ loop.index }}))
             {% for field in variant.fields() -%}
-            {{ field|write_fn }}({{ field.name()|var_name }}, into: &buf)
+            {{ field|write_fn }}({% call swift::field_name(field, loop.index) %}, into: &buf)
             {% endfor -%}
         {% else %}
         case .{{ variant.name()|class_name }}:
@@ -83,4 +87,8 @@ public struct {{ ffi_converter_name }}: FfiConverterRustBuffer {
 {% if !contains_object_references %}
 extension {{ type_name }}: Equatable, Hashable {}
 {% endif %}
-extension {{ type_name }}: Error { }
+extension {{ type_name }}: Foundation.LocalizedError {
+    public var errorDescription: String? {
+        String(reflecting: self)
+    }
+}
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift
index cfddf7b3139f..842b7d287cdb 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/Helpers.swift
@@ -53,18 +53,19 @@ fileprivate extension RustCallStatus {
 }
 
 private func rustCall<T>(_ callback: (UnsafeMutablePointer<RustCallStatus>) -> T) throws -> T {
-    try makeRustCall(callback, errorHandler: nil)
+    let neverThrow: ((RustBuffer) throws -> Never)? = nil
+    return try makeRustCall(callback, errorHandler: neverThrow)
 }
 
-private func rustCallWithError<T>(
-    _ errorHandler: @escaping (RustBuffer) throws -> Error,
+private func rustCallWithError<T, E: Swift.Error>(
+    _ errorHandler: @escaping (RustBuffer) throws -> E,
     _ callback: (UnsafeMutablePointer<RustCallStatus>) -> T) throws -> T {
     try makeRustCall(callback, errorHandler: errorHandler)
 }
 
-private func makeRustCall<T>(
+private func makeRustCall<T, E: Swift.Error>(
     _ callback: (UnsafeMutablePointer<RustCallStatus>) -> T,
-    errorHandler: ((RustBuffer) throws -> Error)?
+    errorHandler: ((RustBuffer) throws -> E)?
 ) throws -> T {
     uniffiEnsureInitialized()
     var callStatus = RustCallStatus.init()
@@ -73,9 +74,9 @@ private func makeRustCall<T>(
     return returnedVal
 }
 
-private func uniffiCheckCallStatus(
+private func uniffiCheckCallStatus<E: Swift.Error>(
     callStatus: RustCallStatus,
-    errorHandler: ((RustBuffer) throws -> Error)?
+    errorHandler: ((RustBuffer) throws -> E)?
 ) throws {
     switch callStatus.code {
         case CALL_SUCCESS:
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ObjectTemplate.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ObjectTemplate.swift
index 0c28bc4c0959..7a41d4949925 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ObjectTemplate.swift
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/ObjectTemplate.swift
@@ -23,7 +23,7 @@ open class {{ impl_class_name }}:
     {%-    endmatch %}
     {%- endfor %}
     {%- if is_error %}
-    Error,
+    Swift.Error,
     {% endif %}
     {{ protocol_name }} {
     fileprivate let pointer: UnsafeMutableRawPointer!
@@ -161,6 +161,13 @@ public struct {{ ffi_converter_name }}: FfiConverter {
 
 {# Objects as error #}
 {%- if is_error %}
+
+extension {{ type_name }}: Foundation.LocalizedError {
+    public var errorDescription: String? {
+        String(reflecting: self)
+    }
+}
+
 {# Due to some mismatches in the ffi converter mechanisms, errors are a RustBuffer holding a pointer #}
 public struct {{ ffi_converter_name }}__as_error: FfiConverterRustBuffer {
     public static func lift(_ buf: RustBuffer) throws -> {{ type_name }} {
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift
index a053334a3022..cf8eec4019ce 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/RustBufferTemplate.swift
@@ -37,9 +37,11 @@ fileprivate extension ForeignBytes {
 
 fileprivate extension Data {
     init(rustBuffer: RustBuffer) {
-        // TODO: This copies the buffer. Can we read directly from a
-        // Rust buffer?
-        self.init(bytes: rustBuffer.data!, count: Int(rustBuffer.len))
+        self.init(
+            bytesNoCopy: rustBuffer.data!,
+            count: Int(rustBuffer.len),
+            deallocator: .none
+        )
     }
 }
 
@@ -140,7 +142,7 @@ fileprivate func writeDouble(_ writer: inout [UInt8], _ value: Double) {
 }
 
 // Protocol for types that transfer other types across the FFI. This is
-// analogous go the Rust trait of the same name.
+// analogous to the Rust trait of the same name.
 fileprivate protocol FfiConverter {
     associatedtype FfiType
     associatedtype SwiftType
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/wrapper.swift b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/wrapper.swift
index 17fdde74e07a..1f459b0b8924 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/wrapper.swift
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/templates/wrapper.swift
@@ -38,9 +38,9 @@ private enum InitializationResult {
     case contractVersionMismatch
     case apiChecksumMismatch
 }
-// Use a global variables to perform the versioning checks. Swift ensures that
+// Use a global variable to perform the versioning checks. Swift ensures that
 // the code inside is only computed once.
-private var initializationResult: InitializationResult {
+private var initializationResult: InitializationResult = {
     // Get the bindings contract version from our ComponentInterface
     let bindings_contract_version = {{ ci.uniffi_contract_version() }}
     // Get the scaffolding contract version by calling the into the dylib
@@ -60,7 +60,7 @@ private var initializationResult: InitializationResult {
     {% endfor -%}
 
     return InitializationResult.ok
-}
+}()
 
 private func uniffiEnsureInitialized() {
     switch initializationResult {
diff --git a/third_party/rust/uniffi_bindgen/src/bindings/swift/test.rs b/third_party/rust/uniffi_bindgen/src/bindings/swift/test.rs
index 195a77696b9b..9a2a5a7de99f 100644
--- a/third_party/rust/uniffi_bindgen/src/bindings/swift/test.rs
+++ b/third_party/rust/uniffi_bindgen/src/bindings/swift/test.rs
@@ -2,9 +2,13 @@
 License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use crate::{bindings::RunScriptOptions, library_mode::generate_bindings, BindingGeneratorDefault};
+use crate::bindings::RunScriptOptions;
+use crate::cargo_metadata::CrateConfigSupplier;
+use crate::library_mode::generate_bindings;
+
 use anyhow::{bail, Context, Result};
 use camino::{Utf8Path, Utf8PathBuf};
+use cargo_metadata::Metadata;
 use std::env::consts::{DLL_PREFIX, DLL_SUFFIX};
 use std::ffi::OsStr;
 use std::fs::{read_to_string, File};
@@ -12,13 +16,11 @@ use std::io::Write;
 use std::process::{Command, Stdio};
 use uniffi_testing::UniFFITestHelper;
 
-use crate::bindings::TargetLanguage;
-
 /// Run Swift tests for a UniFFI test fixture
-pub fn run_test(tmp_dir: &str, fixture_name: &str, script_file: &str) -> Result<()> {
+pub fn run_test(tmp_dir: &str, package_name: &str, script_file: &str) -> Result<()> {
     run_script(
         tmp_dir,
-        fixture_name,
+        package_name,
         script_file,
         vec![],
         &RunScriptOptions::default(),
@@ -30,16 +32,21 @@ pub fn run_test(tmp_dir: &str, fixture_name: &str, script_file: &str) -> Result<
 /// This function will set things up so that the script can import the UniFFI bindings for a crate
 pub fn run_script(
     tmp_dir: &str,
-    crate_name: &str,
+    package_name: &str,
     script_file: &str,
     args: Vec<String>,
     options: &RunScriptOptions,
 ) -> Result<()> {
     let script_path = Utf8Path::new(script_file).canonicalize_utf8()?;
-    let test_helper = UniFFITestHelper::new(crate_name)?;
+    let test_helper = UniFFITestHelper::new(package_name)?;
     let out_dir = test_helper.create_out_dir(tmp_dir, &script_path)?;
     let cdylib_path = test_helper.copy_cdylib_to_out_dir(&out_dir)?;
-    let generated_sources = GeneratedSources::new(crate_name, &cdylib_path, &out_dir)?;
+    let generated_sources = GeneratedSources::new(
+        test_helper.crate_name(),
+        &cdylib_path,
+        test_helper.cargo_metadata(),
+        &out_dir,
+    )?;
 
     // Compile the generated sources together to create a single swift module
     compile_swift_module(
@@ -124,23 +131,26 @@ struct GeneratedSources {
 }
 
 impl GeneratedSources {
-    fn new(crate_name: &str, cdylib_path: &Utf8Path, out_dir: &Utf8Path) -> Result<Self> {
+    fn new(
+        crate_name: &str,
+        cdylib_path: &Utf8Path,
+        cargo_metadata: Metadata,
+        out_dir: &Utf8Path,
+    ) -> Result<Self> {
         let sources = generate_bindings(
             cdylib_path,
             None,
-            &BindingGeneratorDefault {
-                target_languages: vec![TargetLanguage::Swift],
-                try_format_code: false,
-            },
+            &super::SwiftBindingGenerator,
+            &CrateConfigSupplier::from(cargo_metadata),
             None,
             out_dir,
             false,
         )?;
         let main_source = sources
             .iter()
-            .find(|s| s.package.name == crate_name)
+            .find(|s| s.ci.crate_name() == crate_name)
             .unwrap();
-        let main_module = main_source.config.bindings.swift.module_name();
+        let main_module = main_source.config.module_name();
         let modulemap_glob = glob(&out_dir.join("*.modulemap"))?;
         let module_map = match modulemap_glob.len() {
             0 => bail!("No modulemap files found in {out_dir}"),
diff --git a/third_party/rust/uniffi_bindgen/src/cargo_metadata.rs b/third_party/rust/uniffi_bindgen/src/cargo_metadata.rs
new file mode 100644
index 000000000000..e304025f8fd4
--- /dev/null
+++ b/third_party/rust/uniffi_bindgen/src/cargo_metadata.rs
@@ -0,0 +1,56 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Helpers for data returned by cargo_metadata. Note that this doesn't
+//! execute cargo_metadata, just parses its output.
+
+use anyhow::{bail, Context};
+use camino::Utf8PathBuf;
+use cargo_metadata::Metadata;
+use std::{collections::HashMap, fs};
+
+use crate::BindgenCrateConfigSupplier;
+
+#[derive(Debug, Clone, Default)]
+pub struct CrateConfigSupplier {
+    paths: HashMap<String, Utf8PathBuf>,
+}
+
+impl BindgenCrateConfigSupplier for CrateConfigSupplier {
+    fn get_toml(&self, crate_name: &str) -> anyhow::Result<Option<toml::value::Table>> {
+        let toml = self.paths.get(crate_name).map(|p| p.join("uniffi.toml"));
+        crate::load_toml_file(toml.as_deref())
+    }
+
+    fn get_udl(&self, crate_name: &str, udl_name: &str) -> anyhow::Result<String> {
+        let path = self
+            .paths
+            .get(crate_name)
+            .context(format!("No path known to UDL files for '{crate_name}'"))?
+            .join("src")
+            .join(format!("{udl_name}.udl"));
+        if path.exists() {
+            Ok(fs::read_to_string(path)?)
+        } else {
+            bail!(format!("No UDL file found at '{path}'"));
+        }
+    }
+}
+
+impl From<Metadata> for CrateConfigSupplier {
+    fn from(metadata: Metadata) -> Self {
+        let paths: HashMap<String, Utf8PathBuf> = metadata
+            .packages
+            .iter()
+            .flat_map(|p| {
+                p.targets.iter().filter(|t| t.is_lib()).filter_map(|t| {
+                    p.manifest_path
+                        .parent()
+                        .map(|p| (t.name.replace('-', "_"), p.to_owned()))
+                })
+            })
+            .collect();
+        Self { paths }
+    }
+}
diff --git a/third_party/rust/uniffi_bindgen/src/interface/callbacks.rs b/third_party/rust/uniffi_bindgen/src/interface/callbacks.rs
index f176a7a684d1..b0e978e8b40a 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/callbacks.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/callbacks.rs
@@ -93,11 +93,11 @@ impl CallbackInterface {
     }
 
     /// Vec of (ffi_callback, method) pairs
-    pub fn vtable_methods(&self) -> Vec<(FfiCallbackFunction, &Method)> {
+    pub fn vtable_methods(&self) -> Vec<(FfiCallbackFunction, Method)> {
         self.methods
             .iter()
             .enumerate()
-            .map(|(i, method)| (method_ffi_callback(&self.name, method, i), method))
+            .map(|(i, method)| (method_ffi_callback(&self.name, method, i), method.clone()))
             .collect()
     }
 
diff --git a/third_party/rust/uniffi_bindgen/src/interface/enum_.rs b/third_party/rust/uniffi_bindgen/src/interface/enum_.rs
index a666cc3605fc..0d66ce2985e5 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/enum_.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/enum_.rs
@@ -160,7 +160,7 @@
 //! ```
 
 use anyhow::Result;
-use uniffi_meta::Checksum;
+use uniffi_meta::{Checksum, EnumShape};
 
 use super::record::Field;
 use super::{AsType, Literal, Type, TypeIterator};
@@ -176,24 +176,7 @@ pub struct Enum {
     pub(super) module_path: String,
     pub(super) discr_type: Option<Type>,
     pub(super) variants: Vec<Variant>,
-    // NOTE: `flat` is a misleading name and to make matters worse, has 2 different
-    // meanings depending on the context :(
-    // * When used as part of Rust scaffolding generation, it means "is this enum
-    //   used with an Error, and that error should we lowered to foreign bindings
-    //   by converting each variant to a string and lowering the variant with that
-    //   string?". In that context, it should probably be called `lowered_as_string` or
-    //   similar.
-    // * When used as part of bindings generation, it means "does this enum have only
-    //   variants with no associated data"? The foreign binding generators are likely
-    //   to generate significantly different versions of the enum based on that value.
-    //
-    // The reason it is described as "has 2 different meanings" by way of example:
-    // * For an Enum described as being a flat error, but the enum itself has variants with data,
-    //   `flat` will be `true` for the Enum when generating scaffolding and `false` when
-    //   generating bindings.
-    // * For an Enum not used as an error but which has no variants with data, `flat` will be
-    //   false when generating the scaffolding but `true` when generating bindings.
-    pub(super) flat: bool,
+    pub(super) shape: EnumShape,
     pub(super) non_exhaustive: bool,
     #[checksum_ignore]
     pub(super) docstring: Option<String>,
@@ -204,6 +187,10 @@ impl Enum {
         &self.name
     }
 
+    pub fn rename(&mut self, name: String) {
+        self.name = name;
+    }
+
     pub fn variants(&self) -> &[Variant] {
         &self.variants
     }
@@ -248,7 +235,10 @@ impl Enum {
     }
 
     pub fn is_flat(&self) -> bool {
-        self.flat
+        match self.shape {
+            EnumShape::Error { flat } => flat,
+            EnumShape::Enum => self.variants.iter().all(|v| v.fields.is_empty()),
+        }
     }
 
     pub fn is_non_exhaustive(&self) -> bool {
@@ -262,14 +252,12 @@ impl Enum {
     pub fn docstring(&self) -> Option<&str> {
         self.docstring.as_deref()
     }
+}
 
-    // Sadly can't use TryFrom due to the 'is_flat' complication.
-    pub fn try_from_meta(meta: uniffi_meta::EnumMetadata, flat: bool) -> Result<Self> {
-        // This is messy - error enums are considered "flat" if the user
-        // opted in via a special attribute, regardless of whether the enum
-        // is actually flat.
-        // Real enums are considered flat iff they are actually flat.
-        // We don't have that context here, so this is handled by our caller.
+impl TryFrom<uniffi_meta::EnumMetadata> for Enum {
+    type Error = anyhow::Error;
+
+    fn try_from(meta: uniffi_meta::EnumMetadata) -> Result<Self> {
         Ok(Self {
             name: meta.name,
             module_path: meta.module_path,
@@ -279,7 +267,7 @@ impl Enum {
                 .into_iter()
                 .map(TryInto::try_into)
                 .collect::<Result<_>>()?,
-            flat,
+            shape: meta.shape,
             non_exhaustive: meta.non_exhaustive,
             docstring: meta.docstring.clone(),
         })
@@ -312,6 +300,10 @@ impl Variant {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     pub fn fields(&self) -> &[Field] {
         &self.fields
     }
@@ -414,6 +406,7 @@ mod test {
         // The enum with associated data.
         let ed = ci.get_enum_definition("TestEnumWithData").unwrap();
         assert!(!ed.is_flat());
+        assert_eq!(ed.shape, EnumShape::Enum);
         assert_eq!(ed.variants().len(), 3);
         assert_eq!(
             ed.variants().iter().map(|v| v.name()).collect::<Vec<_>>(),
@@ -462,6 +455,8 @@ mod test {
         );
         assert_eq!(ewd.variants()[0].fields().len(), 0);
         assert_eq!(ewd.variants()[1].fields().len(), 0);
+        assert!(ewd.is_flat());
+        assert_eq!(ewd.shape, EnumShape::Enum);
 
         // Flat enums pass over the FFI as bytebuffers.
         // (It might be nice to optimize these to pass as plain integers, but that's
@@ -669,7 +664,7 @@ mod test {
             name: "test".to_string(),
             discr_type: None,
             variants: vec![],
-            flat: false,
+            shape: EnumShape::Enum,
             non_exhaustive: false,
             docstring: None,
         };
diff --git a/third_party/rust/uniffi_bindgen/src/interface/ffi.rs b/third_party/rust/uniffi_bindgen/src/interface/ffi.rs
index a1dc29713a64..c0c1d33603a7 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/ffi.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/ffi.rs
@@ -43,7 +43,7 @@ pub enum FfiType {
     /// or pass it to someone that will.
     /// If the inner option is Some, it is the name of the external type. The bindings may need
     /// to use this name to import the correct RustBuffer for that type.
-    RustBuffer(Option<String>),
+    RustBuffer(Option<ExternalFfiMetadata>),
     /// A borrowed reference to some raw bytes owned by foreign language code.
     /// The provider of this reference must keep it alive for the duration of the receiving call.
     ForeignBytes,
@@ -144,13 +144,26 @@ impl From<&Type> for FfiType {
             Type::External {
                 name,
                 kind: ExternalKind::DataClass,
+                module_path,
+                namespace,
                 ..
-            } => FfiType::RustBuffer(Some(name.clone())),
+            } => FfiType::RustBuffer(Some(ExternalFfiMetadata {
+                name: name.clone(),
+                module_path: module_path.clone(),
+                namespace: namespace.clone(),
+            })),
             Type::Custom { builtin, .. } => FfiType::from(builtin.as_ref()),
         }
     }
 }
 
+#[derive(Debug, Clone, Hash, PartialEq, Eq, PartialOrd, Ord)]
+pub struct ExternalFfiMetadata {
+    pub name: String,
+    pub module_path: String,
+    pub namespace: String,
+}
+
 // Needed for rust scaffolding askama template
 impl From<Type> for FfiType {
     fn from(ty: Type) -> Self {
@@ -218,6 +231,10 @@ impl FfiFunction {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     /// Name of the FFI buffer version of this function that's generated when the
     /// `scaffolding-ffi-buffer-fns` feature is enabled.
     pub fn ffi_buffer_fn_name(&self) -> String {
@@ -293,6 +310,10 @@ impl FfiArgument {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     pub fn type_(&self) -> FfiType {
         self.type_.clone()
     }
@@ -315,6 +336,10 @@ impl FfiCallbackFunction {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     pub fn arguments(&self) -> Vec<&FfiArgument> {
         self.arguments.iter().collect()
     }
@@ -341,6 +366,10 @@ impl FfiStruct {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     /// Get the fields for this struct
     pub fn fields(&self) -> &[FfiField] {
         &self.fields
@@ -369,6 +398,10 @@ impl FfiField {
     pub fn type_(&self) -> FfiType {
         self.type_.clone()
     }
+
+    pub fn rename(&mut self, name: String) {
+        self.name = name;
+    }
 }
 
 impl From<FfiFunction> for FfiDefinition {
diff --git a/third_party/rust/uniffi_bindgen/src/interface/function.rs b/third_party/rust/uniffi_bindgen/src/interface/function.rs
index 8effc4c87665..69f4f153dc9f 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/function.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/function.rs
@@ -33,10 +33,10 @@
 //! ```
 
 use anyhow::Result;
+use uniffi_meta::Checksum;
 
 use super::ffi::{FfiArgument, FfiFunction, FfiType};
 use super::{AsType, ComponentInterface, Literal, ObjectImpl, Type, TypeIterator};
-use uniffi_meta::Checksum;
 
 /// Represents a standalone function.
 ///
@@ -73,6 +73,12 @@ impl Function {
         &self.name
     }
 
+    // Note: Don't recalculate the checksum. In order to have consistent checksums,
+    // we use the Rust names as input.
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     pub fn is_async(&self) -> bool {
         self.is_async
     }
@@ -194,6 +200,10 @@ impl Argument {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     pub fn by_ref(&self) -> bool {
         self.by_ref
     }
diff --git a/third_party/rust/uniffi_bindgen/src/interface/mod.rs b/third_party/rust/uniffi_bindgen/src/interface/mod.rs
index 90a941637a58..ec61f20cd736 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/mod.rs
@@ -52,7 +52,7 @@ use std::{
 use anyhow::{anyhow, bail, ensure, Result};
 
 pub mod universe;
-pub use uniffi_meta::{AsType, ExternalKind, ObjectImpl, Type};
+pub use uniffi_meta::{AsType, EnumShape, ExternalKind, ObjectImpl, Type};
 use universe::{TypeIterator, TypeUniverse};
 
 mod callbacks;
@@ -67,6 +67,7 @@ mod record;
 pub use record::{Field, Record};
 
 pub mod ffi;
+mod visit_mut;
 pub use ffi::{
     FfiArgument, FfiCallbackFunction, FfiDefinition, FfiField, FfiFunction, FfiStruct, FfiType,
 };
@@ -79,7 +80,7 @@ pub type Literal = LiteralMetadata;
 
 /// The main public interface for this module, representing the complete details of an interface exposed
 /// by a rust component and the details of consuming it via an extern-C FFI layer.
-#[derive(Debug, Default)]
+#[derive(Clone, Debug, Default)]
 pub struct ComponentInterface {
     /// All of the types used in the interface.
     // We can't checksum `self.types`, but its contents are implied by the other fields
@@ -164,6 +165,11 @@ impl ComponentInterface {
         self.types.namespace_docstring.as_deref()
     }
 
+    /// The crate this interfaces lives in.
+    pub fn crate_name(&self) -> &str {
+        &self.types.namespace.crate_name
+    }
+
     pub fn uniffi_contract_version(&self) -> u32 {
         // This is set by the scripts in the version-mismatch fixture
         let force_version = std::env::var("UNIFFI_FORCE_CONTRACT_VERSION");
@@ -810,6 +816,9 @@ impl ComponentInterface {
     pub(super) fn add_enum_definition(&mut self, defn: Enum) -> Result<()> {
         match self.enums.entry(defn.name().to_owned()) {
             Entry::Vacant(v) => {
+                if matches!(defn.shape, EnumShape::Error { .. }) {
+                    self.errors.insert(defn.name.clone());
+                }
                 self.types.add_known_types(defn.iter_types())?;
                 v.insert(defn);
             }
@@ -1174,7 +1183,7 @@ existing definition: Enum {
             docstring: None,
         },
     ],
-    flat: true,
+    shape: Enum,
     non_exhaustive: false,
     docstring: None,
 },
@@ -1196,7 +1205,9 @@ new definition: Enum {
             docstring: None,
         },
     ],
-    flat: true,
+    shape: Error {
+        flat: true,
+    },
     non_exhaustive: false,
     docstring: None,
 }",
diff --git a/third_party/rust/uniffi_bindgen/src/interface/object.rs b/third_party/rust/uniffi_bindgen/src/interface/object.rs
index 2b86e54a4513..2a9ee0b907a3 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/object.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/object.rs
@@ -116,6 +116,10 @@ impl Object {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     /// Returns the fully qualified name that should be used by Rust code for this object.
     /// Includes `r#`, traits get a leading `dyn`. If we ever supported associated types, then
     /// this would also include them.
@@ -266,14 +270,14 @@ impl Object {
     }
 
     /// Vec of (ffi_callback_name, method) pairs
-    pub fn vtable_methods(&self) -> Vec<(FfiCallbackFunction, &Method)> {
+    pub fn vtable_methods(&self) -> Vec<(FfiCallbackFunction, Method)> {
         self.methods
             .iter()
             .enumerate()
             .map(|(i, method)| {
                 (
                     callbacks::method_ffi_callback(&self.name, method, i),
-                    method,
+                    method.clone(),
                 )
             })
             .collect()
@@ -379,6 +383,10 @@ impl Constructor {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     pub fn arguments(&self) -> Vec<&Argument> {
         self.arguments.iter().collect()
     }
@@ -494,6 +502,10 @@ impl Method {
         &self.name
     }
 
+    pub fn rename(&mut self, new_name: String) {
+        self.name = new_name;
+    }
+
     pub fn is_async(&self) -> bool {
         self.is_async
     }
diff --git a/third_party/rust/uniffi_bindgen/src/interface/record.rs b/third_party/rust/uniffi_bindgen/src/interface/record.rs
index e9a600418968..3af6495c99de 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/record.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/record.rs
@@ -69,6 +69,10 @@ impl Record {
         &self.name
     }
 
+    pub fn rename(&mut self, name: String) {
+        self.name = name;
+    }
+
     pub fn fields(&self) -> &[Field] {
         &self.fields
     }
@@ -127,6 +131,10 @@ impl Field {
         &self.name
     }
 
+    pub fn rename(&mut self, name: String) {
+        self.name = name;
+    }
+
     pub fn default_value(&self) -> Option<&Literal> {
         self.default.as_ref()
     }
diff --git a/third_party/rust/uniffi_bindgen/src/interface/universe.rs b/third_party/rust/uniffi_bindgen/src/interface/universe.rs
index 70bc61f8a9fa..9a78b3bf34d8 100644
--- a/third_party/rust/uniffi_bindgen/src/interface/universe.rs
+++ b/third_party/rust/uniffi_bindgen/src/interface/universe.rs
@@ -21,16 +21,16 @@ pub use uniffi_meta::{AsType, ExternalKind, NamespaceMetadata, ObjectImpl, Type,
 /// You could imagine this struct doing some clever interning of names and so-on in future,
 /// to reduce the overhead of passing around [Type] instances. For now we just do a whole
 /// lot of cloning.
-#[derive(Debug, Default)]
+#[derive(Clone, Debug, Default)]
 pub(crate) struct TypeUniverse {
     /// The unique prefixes that we'll use for namespacing when exposing this component's API.
     pub namespace: NamespaceMetadata,
     pub namespace_docstring: Option<String>,
 
     // Named type definitions (including aliases).
-    type_definitions: HashMap<String, Type>,
+    pub(super) type_definitions: HashMap<String, Type>,
     // All the types in the universe, by canonical type name, in a well-defined order.
-    all_known_types: BTreeSet<Type>,
+    pub(super) all_known_types: BTreeSet<Type>,
 }
 
 impl TypeUniverse {
diff --git a/third_party/rust/uniffi_bindgen/src/interface/visit_mut.rs b/third_party/rust/uniffi_bindgen/src/interface/visit_mut.rs
new file mode 100644
index 000000000000..31d03ae0fc45
--- /dev/null
+++ b/third_party/rust/uniffi_bindgen/src/interface/visit_mut.rs
@@ -0,0 +1,145 @@
+use crate::interface::{Enum, FfiDefinition, Record};
+use crate::{ComponentInterface, VisitMut};
+use std::collections::{BTreeMap, BTreeSet};
+use uniffi_meta::Type;
+
+impl ComponentInterface {
+    /// A generic interface for mutating items in the [`ComponentInterface`].
+    ///
+    /// Walk down the [`ComponentInterface`] and adjust the names of each type
+    /// based on the naming conventions of the supported languages.
+    ///
+    /// Each suppoerted language implements the [`VisitMut`] Trait and is able
+    /// to alter the functions, enums etc. to its own naming conventions.
+    pub fn visit_mut<V: VisitMut>(&mut self, visitor: &V) {
+        for type_ in self.types.type_definitions.values_mut() {
+            visitor.visit_type(type_);
+        }
+
+        let mut all_known_types_altered: BTreeSet<Type> = BTreeSet::new();
+
+        for type_ in self.types.all_known_types.iter() {
+            let mut type_altered = type_.clone();
+            visitor.visit_type(&mut type_altered);
+            all_known_types_altered.insert(type_altered);
+        }
+
+        self.types.all_known_types = all_known_types_altered;
+
+        let mut updated_enums: BTreeMap<String, Enum> = BTreeMap::new();
+        let errors_clone = self.errors.clone();
+        for (enum_name, enum_item) in self.enums.iter_mut() {
+            let updated_key = visitor.visit_enum_key(&mut enum_name.clone());
+            let is_error = errors_clone.contains(enum_item.name());
+
+            visitor.visit_enum(is_error, enum_item);
+
+            for variant in enum_item.variants.iter_mut() {
+                visitor.visit_variant(is_error, variant);
+
+                for field in variant.fields.iter_mut() {
+                    visitor.visit_field(field);
+                    visitor.visit_type(&mut field.type_);
+                }
+            }
+            updated_enums.insert(updated_key, enum_item.clone());
+        }
+        self.enums = updated_enums;
+
+        for record_item in self.records.values_mut() {
+            visitor.visit_record(record_item);
+
+            for field in &mut record_item.fields {
+                visitor.visit_field(field);
+                visitor.visit_type(&mut field.type_);
+            }
+        }
+        self.fix_record_keys_after_rename();
+
+        for function in self.functions.iter_mut() {
+            visitor.visit_function(function);
+
+            if function.clone().return_type.is_some() {
+                let mut return_type = function.clone().return_type.unwrap();
+                visitor.visit_type(&mut return_type);
+                function.return_type = Some(return_type);
+            }
+
+            for argument in function.arguments.iter_mut() {
+                visitor.visit_argument(argument);
+                visitor.visit_type(&mut argument.type_);
+            }
+        }
+
+        for object in self.objects.iter_mut() {
+            visitor.visit_object(object);
+
+            for method in object.methods.iter_mut() {
+                visitor.visit_method(method);
+
+                for argument in method.arguments.iter_mut() {
+                    visitor.visit_argument(argument);
+                    visitor.visit_type(&mut argument.type_);
+                }
+
+                if method.clone().return_type.is_some() {
+                    let mut return_type = method.clone().return_type.unwrap();
+                    visitor.visit_type(&mut return_type);
+                    method.return_type = Some(return_type);
+                }
+            }
+
+            for constructor in object.constructors.iter_mut() {
+                visitor.visit_constructor(constructor);
+
+                for argument in constructor.arguments.iter_mut() {
+                    visitor.visit_argument(argument);
+                    visitor.visit_type(&mut argument.type_);
+                }
+            }
+        }
+
+        for callback_interface in self.callback_interfaces.iter_mut() {
+            for method in callback_interface.methods.iter_mut() {
+                visitor.visit_method(method);
+
+                for argument in method.arguments.iter_mut() {
+                    visitor.visit_argument(argument);
+                    visitor.visit_type(&mut argument.type_);
+                }
+            }
+
+            for ffi_arg in callback_interface.ffi_init_callback.arguments.iter_mut() {
+                visitor.visit_ffi_argument(ffi_arg);
+            }
+        }
+
+        let mut throw_types_altered: BTreeSet<Type> = BTreeSet::new();
+
+        for throw_type in self.callback_interface_throws_types.iter() {
+            let mut type_ = throw_type.clone();
+            visitor.visit_type(&mut type_);
+            throw_types_altered.insert(type_);
+        }
+
+        self.callback_interface_throws_types = throw_types_altered;
+
+        for ffi_definition in self.ffi_definitions() {
+            if let FfiDefinition::Struct(mut ffi_struct) = ffi_definition {
+                for field in ffi_struct.fields.iter_mut() {
+                    visitor.visit_ffi_field(field);
+                }
+            }
+        }
+    }
+
+    fn fix_record_keys_after_rename(&mut self) {
+        let mut new_records: BTreeMap<String, Record> = BTreeMap::new();
+
+        for record in self.records.values() {
+            new_records.insert(record.name().to_string(), record.clone());
+        }
+
+        self.records = new_records;
+    }
+}
diff --git a/third_party/rust/uniffi_bindgen/src/lib.rs b/third_party/rust/uniffi_bindgen/src/lib.rs
index dfc90b32a6c1..6d32bd4784db 100644
--- a/third_party/rust/uniffi_bindgen/src/lib.rs
+++ b/third_party/rust/uniffi_bindgen/src/lib.rs
@@ -95,10 +95,10 @@
 use anyhow::{anyhow, bail, Context, Result};
 use camino::{Utf8Path, Utf8PathBuf};
 use fs_err::{self as fs, File};
-use serde::{de::DeserializeOwned, Deserialize, Serialize};
+use serde::Deserialize;
 use std::io::prelude::*;
 use std::io::ErrorKind;
-use std::{collections::HashMap, process::Command};
+use std::process::Command;
 
 pub mod backend;
 pub mod bindings;
@@ -107,38 +107,28 @@ pub mod library_mode;
 pub mod macro_metadata;
 pub mod scaffolding;
 
-use bindings::TargetLanguage;
+#[cfg(feature = "cargo-metadata")]
+pub mod cargo_metadata;
+
+use crate::interface::{
+    Argument, Constructor, Enum, FfiArgument, FfiField, Field, Function, Method, Object, Record,
+    Variant,
+};
 pub use interface::ComponentInterface;
+pub use library_mode::find_components;
 use scaffolding::RustScaffolding;
+use uniffi_meta::Type;
 
-/// Trait for bindings configuration.  Each bindings language defines one of these.
-///
-/// BindingsConfigs are initially loaded from `uniffi.toml` file.  Then the trait methods are used
-/// to fill in missing values.
-pub trait BindingsConfig: DeserializeOwned {
-    /// Update missing values using the `ComponentInterface`
-    fn update_from_ci(&mut self, ci: &ComponentInterface);
-
-    /// Update missing values using the dylib file for the main crate, when in library mode.
-    ///
-    /// cdylib_name will be the library filename without the leading `lib` and trailing extension
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str);
-
-    /// Update missing values from config instances from dependent crates
-    ///
-    /// config_map maps crate names to config instances. This is mostly used to set up external
-    /// types.
-    fn update_from_dependency_configs(&mut self, config_map: HashMap<&str, &Self>);
-}
-
-/// Binding generator config with no members
-#[derive(Clone, Debug, Deserialize, Hash, PartialEq, PartialOrd, Ord, Eq)]
-pub struct EmptyBindingsConfig;
-
-impl BindingsConfig for EmptyBindingsConfig {
-    fn update_from_ci(&mut self, _ci: &ComponentInterface) {}
-    fn update_from_cdylib_name(&mut self, _cdylib_name: &str) {}
-    fn update_from_dependency_configs(&mut self, _config_map: HashMap<&str, &Self>) {}
+/// The options used when creating bindings. Named such
+/// it doesn't cause confusion that it's settings specific to
+/// the generator itself.
+// TODO: We should try and move the public interface of the module to
+// this struct. For now, only the BindingGenerator uses it.
+#[derive(Debug, Default)]
+pub struct GenerationSettings {
+    pub out_dir: Utf8PathBuf,
+    pub try_format_code: bool,
+    pub cdylib: Option<String>,
 }
 
 /// A trait representing a UniFFI Binding Generator
@@ -147,61 +137,127 @@ impl BindingsConfig for EmptyBindingsConfig {
 /// and call the [`generate_external_bindings`] using a type that implements this trait.
 pub trait BindingGenerator: Sized {
     /// Handles configuring the bindings
-    type Config: BindingsConfig;
+    type Config;
+
+    /// Creates a new config.
+    fn new_config(&self, root_toml: &toml::Value) -> Result<Self::Config>;
+
+    /// Update the various config items in preparation to write one or more of them.
+    ///
+    /// # Arguments
+    /// - `cdylib`: The name of the cdylib file, if known.
+    /// - `library_path`: The name of library used to extract the symbols.
+    /// - `components`: A mutable array of [`Component`]s to be updated.
+    fn update_component_configs(
+        &self,
+        settings: &GenerationSettings,
+        components: &mut Vec<Component<Self::Config>>,
+    ) -> Result<()>;
 
     /// Writes the bindings to the output directory
     ///
     /// # Arguments
-    /// - `ci`: A [`ComponentInterface`] representing the interface
-    /// - `config`: An instance of the [`BindingsConfig`] associated with this type
+    /// - `components`: An array of [`Component`]s representing the items to be generated.
     /// - `out_dir`: The path to where the binding generator should write the output bindings
     fn write_bindings(
         &self,
-        ci: &ComponentInterface,
-        config: &Self::Config,
-        out_dir: &Utf8Path,
-        try_format_code: bool,
+        settings: &GenerationSettings,
+        components: &[Component<Self::Config>],
     ) -> Result<()>;
-
-    /// Check if `library_path` used by library mode is valid for this generator
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()>;
 }
 
-pub struct BindingGeneratorDefault {
-    pub target_languages: Vec<TargetLanguage>,
-    pub try_format_code: bool,
+/// A trait to alter language specific type representations.
+///
+/// It is meant to be implemented by each language oracle. It takes a
+/// ['ComponentInterface'] and uses its own specific language adjustment
+/// functions to be able to generate language specific templates.
+pub trait VisitMut {
+    /// Go through each `Record` of a [`ComponentInterface`] and
+    /// adjust it to language specific naming conventions.
+    fn visit_record(&self, record: &mut Record);
+
+    /// Change the name of an `Object` of a [`ComponentInterface`
+    /// to language specific naming conventions.
+    fn visit_object(&self, object: &mut Object);
+
+    /// Change the name of a `Field` of an `Enum` `Variant`
+    /// to language specific naming conventions.
+    fn visit_field(&self, field: &mut Field);
+
+    /// Change the name of a `FfiField` inside a `FfiStruct`
+    /// to language specific naming conventions.
+    fn visit_ffi_field(&self, ffi_field: &mut FfiField);
+
+    /// Change the `Arugment` of a `FfiFunction` in the [`ComponentInterface`]
+    /// to language specific naming conventions.
+    fn visit_ffi_argument(&self, ffi_argument: &mut FfiArgument);
+
+    /// Go through each `Enum` of a [`ComponentInterface`] and
+    /// adjust it to language specific naming conventions.
+    fn visit_enum(&self, is_error: bool, enum_: &mut Enum);
+
+    /// Change the naming of the key in the [`ComponentInterface`]
+    /// `BTreeMap` where all `Enum`s are stored to reflect the changed
+    /// name of an `Enum`.
+    fn visit_enum_key(&self, key: &mut String) -> String;
+
+    /// Go through each `Variant` of an `Enum` and
+    /// adjust it to language specific naming conventions.
+    fn visit_variant(&self, is_error: bool, variant: &mut Variant);
+
+    /// Go through each `Type` in the `TypeUniverse` of
+    /// a [`ComponentInterface`] and adjust it to language specific
+    /// naming conventions.
+    fn visit_type(&self, type_: &mut Type);
+
+    /// Go through each `Method` of an `Object` and
+    /// adjust it to language specific naming conventions.
+    fn visit_method(&self, method: &mut Method);
+
+    /// Go through each `Argument` of a `Function` and
+    /// adjust it to language specific naming conventions.
+    fn visit_argument(&self, argument: &mut Argument);
+
+    /// Go through each `Constructor` of a [`ComponentInterface`] and
+    /// adjust it to language specific naming conventions.
+    fn visit_constructor(&self, constructor: &mut Constructor);
+
+    /// Go through each `Function` of a [`ComponentInterface`] and
+    /// adjust it to language specific naming conventions.
+    fn visit_function(&self, function: &mut Function);
 }
 
-impl BindingGenerator for BindingGeneratorDefault {
-    type Config = Config;
+/// Everything needed to generate a ComponentInterface.
+#[derive(Debug)]
+pub struct Component<Config> {
+    pub ci: ComponentInterface,
+    pub config: Config,
+}
 
-    fn write_bindings(
-        &self,
-        ci: &ComponentInterface,
-        config: &Self::Config,
-        out_dir: &Utf8Path,
-        _try_format_code: bool,
-    ) -> Result<()> {
-        for &language in &self.target_languages {
-            bindings::write_bindings(
-                &config.bindings,
-                ci,
-                out_dir,
-                language,
-                self.try_format_code,
-            )?;
-        }
-        Ok(())
+/// A trait used by the bindgen to obtain config information about a source crate
+/// which was found in the metadata for the library.
+///
+/// This is an abstraction around needing the source directory for a crate.
+/// In most cases `cargo_metadata` can be used, but this should be able to work in
+/// more environments.
+pub trait BindgenCrateConfigSupplier {
+    /// Get the toml for the crate. Probably came from uniffi.toml in the root of the crate source.
+    fn get_toml(&self, _crate_name: &str) -> Result<Option<toml::value::Table>> {
+        Ok(None)
     }
+    /// Obtains the contents of the named UDL file which was referenced by the type metadata.
+    fn get_udl(&self, crate_name: &str, udl_name: &str) -> Result<String> {
+        bail!("Crate {crate_name} has no UDL {udl_name}")
+    }
+}
 
-    fn check_library_path(&self, library_path: &Utf8Path, cdylib_name: Option<&str>) -> Result<()> {
-        for &language in &self.target_languages {
-            if cdylib_name.is_none() && language != TargetLanguage::Swift {
-                bail!("Generate bindings for {language} requires a cdylib, but {library_path} was given");
-            }
-        }
-        Ok(())
-    }
+pub struct EmptyCrateConfigSupplier;
+impl BindgenCrateConfigSupplier for EmptyCrateConfigSupplier {}
+
+/// A convenience function for the CLI to help avoid using static libs
+/// in places cdylibs are required.
+pub fn is_cdylib(library_file: impl AsRef<Utf8Path>) -> bool {
+    crate::library_mode::calc_cdylib_name(library_file.as_ref()).is_some()
 }
 
 /// Generate bindings for an external binding generator
@@ -210,7 +266,6 @@ impl BindingGenerator for BindingGeneratorDefault {
 /// Implements an entry point for external binding generators.
 /// The function does the following:
 /// - It parses the `udl` in a [`ComponentInterface`]
-/// - Parses the `uniffi.toml` and loads it into the type that implements [`BindingsConfig`]
 /// - Creates an instance of [`BindingGenerator`], based on type argument `B`, and run [`BindingGenerator::write_bindings`] on it
 ///
 /// # Arguments
@@ -232,31 +287,39 @@ pub fn generate_external_bindings<T: BindingGenerator>(
     let crate_name = crate_name
         .map(|c| Ok(c.to_string()))
         .unwrap_or_else(|| crate_name_from_cargo_toml(udl_file.as_ref()))?;
-    let mut component = parse_udl(udl_file.as_ref(), &crate_name)?;
+    let mut ci = parse_udl(udl_file.as_ref(), &crate_name)?;
     if let Some(ref library_file) = library_file {
-        macro_metadata::add_to_ci_from_library(&mut component, library_file.as_ref())?;
+        macro_metadata::add_to_ci_from_library(&mut ci, library_file.as_ref())?;
     }
     let crate_root = &guess_crate_root(udl_file.as_ref()).context("Failed to guess crate root")?;
 
     let config_file_override = config_file_override.as_ref().map(|p| p.as_ref());
 
     let config = {
-        let mut config = load_initial_config::<T::Config>(crate_root, config_file_override)?;
-        config.update_from_ci(&component);
-        if let Some(ref library_file) = library_file {
-            if let Some(cdylib_name) = crate::library_mode::calc_cdylib_name(library_file.as_ref())
-            {
-                config.update_from_cdylib_name(cdylib_name)
-            }
-        };
-        config
+        let crate_config = load_toml_file(Some(&crate_root.join("uniffi.toml")))
+            .context("failed to load {crate_root}/uniffi.toml")?;
+        let toml_value =
+            overridden_config_value(crate_config.unwrap_or_default(), config_file_override)?;
+        binding_generator.new_config(&toml_value)?
     };
 
-    let out_dir = get_out_dir(
-        udl_file.as_ref(),
-        out_dir_override.as_ref().map(|p| p.as_ref()),
-    )?;
-    binding_generator.write_bindings(&component, &config, &out_dir, try_format_code)
+    let settings = GenerationSettings {
+        cdylib: match library_file {
+            Some(ref library_file) => {
+                crate::library_mode::calc_cdylib_name(library_file.as_ref()).map(ToOwned::to_owned)
+            }
+            None => None,
+        },
+        out_dir: get_out_dir(
+            udl_file.as_ref(),
+            out_dir_override.as_ref().map(|p| p.as_ref()),
+        )?,
+        try_format_code,
+    };
+
+    let mut components = vec![Component { ci, config }];
+    binding_generator.update_component_configs(&settings, &mut components)?;
+    binding_generator.write_bindings(&settings, &components)
 }
 
 // Generate the infrastructural Rust code for implementing the UDL interface,
@@ -435,20 +498,15 @@ fn load_toml_file(source: Option<&Utf8Path>) -> Result<Option<toml::value::Table
 }
 
 /// Load the default `uniffi.toml` config, merge TOML trees with `config_file_override` if specified.
-fn load_initial_config<Config: DeserializeOwned>(
-    crate_root: &Utf8Path,
+fn overridden_config_value(
+    mut config: toml::value::Table,
     config_file_override: Option<&Utf8Path>,
-) -> Result<Config> {
-    let mut config = load_toml_file(Some(crate_root.join("uniffi.toml").as_path()))
-        .context("default config")?
-        .unwrap_or(toml::value::Table::default());
-
+) -> Result<toml::Value> {
     let override_config = load_toml_file(config_file_override).context("override config")?;
     if let Some(override_config) = override_config {
         merge_toml(&mut config, override_config);
     }
-
-    Ok(toml::Value::from(config).try_into()?)
+    Ok(toml::Value::from(config))
 }
 
 fn merge_toml(a: &mut toml::value::Table, b: toml::value::Table) {
@@ -467,55 +525,6 @@ fn merge_toml(a: &mut toml::value::Table, b: toml::value::Table) {
     }
 }
 
-#[derive(Debug, Clone, Default, Serialize, Deserialize)]
-pub struct Config {
-    #[serde(default)]
-    bindings: bindings::Config,
-}
-
-impl BindingsConfig for Config {
-    fn update_from_ci(&mut self, ci: &ComponentInterface) {
-        self.bindings.kotlin.update_from_ci(ci);
-        self.bindings.swift.update_from_ci(ci);
-        self.bindings.python.update_from_ci(ci);
-        self.bindings.ruby.update_from_ci(ci);
-    }
-
-    fn update_from_cdylib_name(&mut self, cdylib_name: &str) {
-        self.bindings.kotlin.update_from_cdylib_name(cdylib_name);
-        self.bindings.swift.update_from_cdylib_name(cdylib_name);
-        self.bindings.python.update_from_cdylib_name(cdylib_name);
-        self.bindings.ruby.update_from_cdylib_name(cdylib_name);
-    }
-
-    fn update_from_dependency_configs(&mut self, config_map: HashMap<&str, &Self>) {
-        self.bindings.kotlin.update_from_dependency_configs(
-            config_map
-                .iter()
-                .map(|(key, config)| (*key, &config.bindings.kotlin))
-                .collect(),
-        );
-        self.bindings.swift.update_from_dependency_configs(
-            config_map
-                .iter()
-                .map(|(key, config)| (*key, &config.bindings.swift))
-                .collect(),
-        );
-        self.bindings.python.update_from_dependency_configs(
-            config_map
-                .iter()
-                .map(|(key, config)| (*key, &config.bindings.python))
-                .collect(),
-        );
-        self.bindings.ruby.update_from_dependency_configs(
-            config_map
-                .iter()
-                .map(|(key, config)| (*key, &config.bindings.ruby))
-                .collect(),
-        );
-    }
-}
-
 // FIXME(HACK):
 // Include the askama config file into the build.
 // That way cargo tracks the file and other tools relying on file tracking see it as well.
diff --git a/third_party/rust/uniffi_bindgen/src/library_mode.rs b/third_party/rust/uniffi_bindgen/src/library_mode.rs
index c460c03d9f48..3a6a3f0133e4 100644
--- a/third_party/rust/uniffi_bindgen/src/library_mode.rs
+++ b/third_party/rust/uniffi_bindgen/src/library_mode.rs
@@ -16,111 +16,65 @@
 ///   - UniFFI can figure out the package/module names for each crate, eliminating the external
 ///     package maps.
 use crate::{
-    load_initial_config, macro_metadata, BindingGenerator, BindingsConfig, ComponentInterface,
-    Result,
+    macro_metadata, overridden_config_value, BindgenCrateConfigSupplier, BindingGenerator,
+    Component, ComponentInterface, GenerationSettings, Result,
 };
-use anyhow::{bail, Context};
+use anyhow::bail;
 use camino::Utf8Path;
-use cargo_metadata::{MetadataCommand, Package};
-use std::{
-    collections::{HashMap, HashSet},
-    fs,
-};
+use std::{collections::HashMap, fs};
+use toml::value::Table as TomlTable;
 use uniffi_meta::{
     create_metadata_groups, fixup_external_type, group_metadata, Metadata, MetadataGroup,
 };
 
 /// Generate foreign bindings
 ///
+/// This replicates the current process used for generating the builtin bindings.
+/// External bindings authors should consider using [find_components], which provides a simpler
+/// interface and allows for more flexibility in how the external bindings are generated.
+///
 /// Returns the list of sources used to generate the bindings, in no particular order.
 pub fn generate_bindings<T: BindingGenerator + ?Sized>(
     library_path: &Utf8Path,
     crate_name: Option<String>,
     binding_generator: &T,
+    config_supplier: &dyn BindgenCrateConfigSupplier,
     config_file_override: Option<&Utf8Path>,
     out_dir: &Utf8Path,
     try_format_code: bool,
-) -> Result<Vec<Source<T::Config>>> {
-    generate_external_bindings(
-        binding_generator,
-        library_path,
-        crate_name.clone(),
-        config_file_override,
-        out_dir,
+) -> Result<Vec<Component<T::Config>>> {
+    let mut components = find_components(library_path, config_supplier)?
+        .into_iter()
+        .map(|Component { ci, config }| {
+            let toml_value = overridden_config_value(config, config_file_override)?;
+            let config = binding_generator.new_config(&toml_value)?;
+            Ok(Component { ci, config })
+        })
+        .collect::<Result<Vec<_>>>()?;
+
+    let settings = GenerationSettings {
+        out_dir: out_dir.to_owned(),
         try_format_code,
-    )
-}
+        cdylib: calc_cdylib_name(library_path).map(ToOwned::to_owned),
+    };
+    binding_generator.update_component_configs(&settings, &mut components)?;
 
-/// Generate foreign bindings
-///
-/// Returns the list of sources used to generate the bindings, in no particular order.
-pub fn generate_external_bindings<T: BindingGenerator>(
-    binding_generator: &T,
-    library_path: &Utf8Path,
-    crate_name: Option<String>,
-    config_file_override: Option<&Utf8Path>,
-    out_dir: &Utf8Path,
-    try_format_code: bool,
-) -> Result<Vec<Source<T::Config>>> {
-    let cargo_metadata = MetadataCommand::new()
-        .exec()
-        .context("error running cargo metadata")?;
-    let cdylib_name = calc_cdylib_name(library_path);
-    binding_generator.check_library_path(library_path, cdylib_name)?;
-
-    let mut sources = find_sources(
-        &cargo_metadata,
-        library_path,
-        cdylib_name,
-        config_file_override,
-    )?;
-    for i in 0..sources.len() {
-        // Partition up the sources list because we're eventually going to call
-        // `update_from_dependency_configs()` which requires an exclusive reference to one source and
-        // shared references to all other sources.
-        let (sources_before, rest) = sources.split_at_mut(i);
-        let (source, sources_after) = rest.split_first_mut().unwrap();
-        let other_sources = sources_before.iter().chain(sources_after.iter());
-        // Calculate which configs come from dependent crates
-        let dependencies =
-            HashSet::<&str>::from_iter(source.package.dependencies.iter().map(|d| d.name.as_str()));
-        let config_map: HashMap<&str, &T::Config> = other_sources
-            .filter_map(|s| {
-                dependencies
-                    .contains(s.package.name.as_str())
-                    .then_some((s.crate_name.as_str(), &s.config))
-            })
-            .collect();
-        // We can finally call update_from_dependency_configs
-        source.config.update_from_dependency_configs(config_map);
-    }
     fs::create_dir_all(out_dir)?;
     if let Some(crate_name) = &crate_name {
-        let old_elements = sources.drain(..);
+        let old_elements = components.drain(..);
         let mut matches: Vec<_> = old_elements
-            .filter(|s| &s.crate_name == crate_name)
+            .filter(|s| s.ci.crate_name() == crate_name)
             .collect();
         match matches.len() {
             0 => bail!("Crate {crate_name} not found in {library_path}"),
-            1 => sources.push(matches.pop().unwrap()),
+            1 => components.push(matches.pop().unwrap()),
             n => bail!("{n} crates named {crate_name} found in {library_path}"),
         }
     }
 
-    for source in sources.iter() {
-        binding_generator.write_bindings(&source.ci, &source.config, out_dir, try_format_code)?;
-    }
+    binding_generator.write_bindings(&settings, &components)?;
 
-    Ok(sources)
-}
-
-// A single source that we generate bindings for
-#[derive(Debug)]
-pub struct Source<Config: BindingsConfig> {
-    pub package: Package,
-    pub crate_name: String,
-    pub ci: ComponentInterface,
-    pub config: Config,
+    Ok(components)
 }
 
 // If `library_path` is a C dynamic library, return its name
@@ -136,12 +90,17 @@ pub fn calc_cdylib_name(library_path: &Utf8Path) -> Option<&str> {
     None
 }
 
-fn find_sources<Config: BindingsConfig>(
-    cargo_metadata: &cargo_metadata::Metadata,
+/// Find UniFFI components from a shared library file
+///
+/// This method inspects the library file and creates [ComponentInterface] instances for each
+/// component used to build it.  It parses the UDL files from `uniffi::include_scaffolding!` macro
+/// calls.
+///
+/// `config_supplier` is used to find UDL files on disk and load config data.
+pub fn find_components(
     library_path: &Utf8Path,
-    cdylib_name: Option<&str>,
-    config_file_override: Option<&Utf8Path>,
-) -> Result<Vec<Source<Config>>> {
+    config_supplier: &dyn BindgenCrateConfigSupplier,
+) -> Result<Vec<Component<TomlTable>>> {
     let items = macro_metadata::extract_from_library(library_path)?;
     let mut metadata_groups = create_metadata_groups(&items);
     group_metadata(&mut metadata_groups, items)?;
@@ -151,13 +110,8 @@ fn find_sources<Config: BindingsConfig>(
     let mut udl_items: HashMap<String, MetadataGroup> = HashMap::new();
 
     for group in metadata_groups.values() {
-        let package = find_package_by_crate_name(cargo_metadata, &group.namespace.crate_name)?;
-        let crate_root = package
-            .manifest_path
-            .parent()
-            .context("manifest path has no parent")?;
         let crate_name = group.namespace.crate_name.clone();
-        if let Some(mut metadata_group) = load_udl_metadata(group, crate_root, &crate_name)? {
+        if let Some(mut metadata_group) = load_udl_metadata(group, &crate_name, config_supplier)? {
             // fixup the items.
             metadata_group.items = metadata_group
                 .items
@@ -175,55 +129,24 @@ fn find_sources<Config: BindingsConfig>(
     metadata_groups
         .into_values()
         .map(|group| {
-            let package = find_package_by_crate_name(cargo_metadata, &group.namespace.crate_name)?;
-            let crate_root = package
-                .manifest_path
-                .parent()
-                .context("manifest path has no parent")?;
-            let crate_name = group.namespace.crate_name.clone();
-            let mut ci = ComponentInterface::new(&crate_name);
-            if let Some(metadata) = udl_items.remove(&crate_name) {
+            let crate_name = &group.namespace.crate_name;
+            let mut ci = ComponentInterface::new(crate_name);
+            if let Some(metadata) = udl_items.remove(crate_name) {
                 ci.add_metadata(metadata)?;
             };
             ci.add_metadata(group)?;
-            let mut config = load_initial_config::<Config>(crate_root, config_file_override)?;
-            if let Some(cdylib_name) = cdylib_name {
-                config.update_from_cdylib_name(cdylib_name);
-            }
-            config.update_from_ci(&ci);
-            Ok(Source {
-                config,
-                crate_name,
-                ci,
-                package,
-            })
+            let config = config_supplier
+                .get_toml(ci.crate_name())?
+                .unwrap_or_default();
+            Ok(Component { ci, config })
         })
         .collect()
 }
 
-fn find_package_by_crate_name(
-    metadata: &cargo_metadata::Metadata,
-    crate_name: &str,
-) -> Result<Package> {
-    let matching: Vec<&Package> = metadata
-        .packages
-        .iter()
-        .filter(|p| {
-            p.targets
-                .iter()
-                .any(|t| t.name.replace('-', "_") == crate_name)
-        })
-        .collect();
-    match matching.len() {
-        1 => Ok(matching[0].clone()),
-        n => bail!("cargo metadata returned {n} packages for crate name {crate_name}"),
-    }
-}
-
 fn load_udl_metadata(
     group: &MetadataGroup,
-    crate_root: &Utf8Path,
     crate_name: &str,
+    config_supplier: &dyn BindgenCrateConfigSupplier,
 ) -> Result<Option<MetadataGroup>> {
     let udl_items = group
         .items
@@ -233,10 +156,9 @@ fn load_udl_metadata(
             _ => None,
         })
         .collect::<Vec<_>>();
+    // We only support 1 UDL file per crate, for no good reason!
     match udl_items.len() {
-        // No UDL files, load directly from the group
         0 => Ok(None),
-        // Found a UDL file, use it to load the CI, then add the MetadataGroup
         1 => {
             if udl_items[0].module_path != crate_name {
                 bail!(
@@ -245,17 +167,11 @@ fn load_udl_metadata(
                     crate_name
                 );
             }
-            let ci_name = &udl_items[0].file_stub;
-            let ci_path = crate_root.join("src").join(format!("{ci_name}.udl"));
-            if ci_path.exists() {
-                let udl = fs::read_to_string(ci_path)?;
-                let udl_group = uniffi_udl::parse_udl(&udl, crate_name)?;
-                Ok(Some(udl_group))
-            } else {
-                bail!("{ci_path} not found");
-            }
+            let udl = config_supplier.get_udl(crate_name, &udl_items[0].file_stub)?;
+            let udl_group = uniffi_udl::parse_udl(&udl, crate_name)?;
+            Ok(Some(udl_group))
         }
-        n => bail!("{n} UDL files found for {crate_root}"),
+        n => bail!("{n} UDL files found for {crate_name}"),
     }
 }
 
diff --git a/third_party/rust/uniffi_bindgen/src/macro_metadata/ci.rs b/third_party/rust/uniffi_bindgen/src/macro_metadata/ci.rs
index 69fad1980e90..0b414a621300 100644
--- a/third_party/rust/uniffi_bindgen/src/macro_metadata/ci.rs
+++ b/third_party/rust/uniffi_bindgen/src/macro_metadata/ci.rs
@@ -2,7 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use crate::interface::{CallbackInterface, ComponentInterface, Enum, Record, Type};
+use crate::interface::{CallbackInterface, ComponentInterface, Record, Type};
 use anyhow::{bail, Context};
 use uniffi_meta::{create_metadata_groups, group_metadata, EnumMetadata, Metadata, MetadataGroup};
 
@@ -57,19 +57,13 @@ pub fn add_group_to_ci(iface: &mut ComponentInterface, group: MetadataGroup) ->
     Ok(())
 }
 
-fn add_enum_to_ci(
-    iface: &mut ComponentInterface,
-    meta: EnumMetadata,
-    is_flat: bool,
-) -> anyhow::Result<()> {
+fn add_enum_to_ci(iface: &mut ComponentInterface, meta: EnumMetadata) -> anyhow::Result<()> {
     let ty = Type::Enum {
         name: meta.name.clone(),
         module_path: meta.module_path.clone(),
     };
     iface.types.add_known_type(&ty)?;
-
-    let enum_ = Enum::try_from_meta(meta, is_flat)?;
-    iface.add_enum_definition(enum_)?;
+    iface.add_enum_definition(meta.try_into()?)?;
     Ok(())
 }
 
@@ -96,10 +90,7 @@ fn add_item_to_ci(iface: &mut ComponentInterface, item: Metadata) -> anyhow::Res
             iface.add_record_definition(record)?;
         }
         Metadata::Enum(meta) => {
-            let flat = meta
-                .forced_flatness
-                .unwrap_or_else(|| meta.variants.iter().all(|v| v.fields.is_empty()));
-            add_enum_to_ci(iface, meta, flat)?;
+            add_enum_to_ci(iface, meta)?;
         }
         Metadata::Object(meta) => {
             iface.types.add_known_type(&Type::Object {
diff --git a/third_party/rust/uniffi_bindgen/src/scaffolding/mod.rs b/third_party/rust/uniffi_bindgen/src/scaffolding/mod.rs
index 7fd81831aaf6..9c410cc71418 100644
--- a/third_party/rust/uniffi_bindgen/src/scaffolding/mod.rs
+++ b/third_party/rust/uniffi_bindgen/src/scaffolding/mod.rs
@@ -36,24 +36,24 @@ mod filters {
             Type::Float32 => "f32".into(),
             Type::Float64 => "f64".into(),
             Type::Boolean => "bool".into(),
-            Type::String => "String".into(),
-            Type::Bytes => "Vec<u8>".into(),
-            Type::Timestamp => "std::time::SystemTime".into(),
-            Type::Duration => "std::time::Duration".into(),
+            Type::String => "::std::string::String".into(),
+            Type::Bytes => "::std::vec::Vec<u8>".into(),
+            Type::Timestamp => "::std::time::SystemTime".into(),
+            Type::Duration => "::std::time::Duration".into(),
             Type::Enum { name, .. } | Type::Record { name, .. } => format!("r#{name}"),
             Type::Object { name, imp, .. } => {
-                format!("std::sync::Arc<{}>", imp.rust_name_for(name))
+                format!("::std::sync::Arc<{}>", imp.rust_name_for(name))
             }
             Type::CallbackInterface { name, .. } => format!("Box<dyn r#{name}>"),
             Type::Optional { inner_type } => {
-                format!("std::option::Option<{}>", type_rs(inner_type)?)
+                format!("::std::option::Option<{}>", type_rs(inner_type)?)
             }
             Type::Sequence { inner_type } => format!("std::vec::Vec<{}>", type_rs(inner_type)?),
             Type::Map {
                 key_type,
                 value_type,
             } => format!(
-                "std::collections::HashMap<{}, {}>",
+                "::std::collections::HashMap<{}, {}>",
                 type_rs(key_type)?,
                 type_rs(value_type)?
             ),
diff --git a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/EnumTemplate.rs b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/EnumTemplate.rs
index f918ef2f3a55..20b845d51577 100644
--- a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/EnumTemplate.rs
+++ b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/EnumTemplate.rs
@@ -2,11 +2,10 @@
 // Forward work to `uniffi_macros` This keeps macro-based and UDL-based generated code consistent.
 #}
 
-#[::uniffi::derive_enum_for_udl(
-    {%- if e.is_non_exhaustive() -%}
-    non_exhaustive,
-    {%- endif %}
-)]
+#[::uniffi::udl_derive(Enum)]
+{%- if e.is_non_exhaustive() %}
+#[non_exhaustive]
+{%- endif %}
 enum r#{{ e.name() }} {
     {%- for variant in e.variants() %}
     r#{{ variant.name() }} {
diff --git a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ErrorTemplate.rs b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ErrorTemplate.rs
index 64f48e233497..2529c7342110 100644
--- a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ErrorTemplate.rs
+++ b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ErrorTemplate.rs
@@ -2,17 +2,16 @@
 // Forward work to `uniffi_macros` This keeps macro-based and UDL-based generated code consistent.
 #}
 
-#[::uniffi::derive_error_for_udl(
-    {% if e.is_flat() -%}
-    flat_error,
-    {% if ci.should_generate_error_read(e) -%}
-    with_try_read,
-    {%- endif %}
-    {%- endif %}
-    {%- if e.is_non_exhaustive() -%}
-    non_exhaustive,
-    {%- endif %}
-)]
+#[::uniffi::udl_derive(Error)]
+{% if e.is_flat() -%}
+#[uniffi(flat_error)]
+{% if ci.should_generate_error_read(e) -%}
+#[uniffi(with_try_read)]
+{%- endif %}
+{%- endif %}
+{%- if e.is_non_exhaustive() -%}
+#[non_exhaustive]
+{%- endif %}
 enum r#{{ e.name() }} {
     {%- for variant in e.variants() %}
     r#{{ variant.name() }} {
diff --git a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ObjectTemplate.rs b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ObjectTemplate.rs
index e752878af59b..f307f243a67f 100644
--- a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ObjectTemplate.rs
+++ b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/ObjectTemplate.rs
@@ -33,7 +33,7 @@ pub trait r#{{ obj.name() }} {
 #[uniffi::export(Eq)]
 {%      endmatch %}
 {% endfor %}
-#[::uniffi::derive_object_for_udl]
+#[::uniffi::udl_derive(Object)]
 struct {{ obj.rust_name() }} { }
 
 {%- for cons in obj.constructors() %}
diff --git a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/RecordTemplate.rs b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/RecordTemplate.rs
index a7affdf7b84a..c612dafda9b0 100644
--- a/third_party/rust/uniffi_bindgen/src/scaffolding/templates/RecordTemplate.rs
+++ b/third_party/rust/uniffi_bindgen/src/scaffolding/templates/RecordTemplate.rs
@@ -2,7 +2,7 @@
 // Forward work to `uniffi_macros` This keeps macro-based and UDL-based generated code consistent.
 #}
 
-#[::uniffi::derive_record_for_udl]
+#[::uniffi::udl_derive(Record)]
 struct r#{{ rec.name() }} {
     {%- for field in rec.fields() %}
     r#{{ field.name() }}: {{ field.as_type().borrow()|type_rs }},
diff --git a/third_party/rust/uniffi_build/.cargo-checksum.json b/third_party/rust/uniffi_build/.cargo-checksum.json
index 5d78ca9d12b6..80b4e23108a1 100644
--- a/third_party/rust/uniffi_build/.cargo-checksum.json
+++ b/third_party/rust/uniffi_build/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"a79595948b5661477a6fd0506fa0abae05d83d3f0a4c31f16c20c143f6236b42","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/lib.rs":"47ff3d1a18456164414af1c20cd5df129401e5257cc15552ecc39afed8970707"},"package":"1c59b65d59685ff3a10569287c6419f76487b4052ac52d5a0df38b2253d7f440"}
\ No newline at end of file
+{"files":{"Cargo.toml":"763bda508967d37c11093b34fa3d0e07deb0be3490aeb2aeb29350536340b579","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/lib.rs":"47ff3d1a18456164414af1c20cd5df129401e5257cc15552ecc39afed8970707"},"package":"e2b12684401d2a8508ca9c72a95bbc45906417e42fc80942abaf033bbf01aa33"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_build/Cargo.toml b/third_party/rust/uniffi_build/Cargo.toml
index 887e12147f3b..6bbba299e6f7 100644
--- a/third_party/rust/uniffi_build/Cargo.toml
+++ b/third_party/rust/uniffi_build/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_build"
-version = "0.27.3"
+version = "0.28.1"
 authors = ["Firefox Sync Team <sync-team@mozilla.com>"]
 description = "a multi-language bindings generator for rust (build script helpers)"
 homepage = "https://mozilla.github.io/uniffi-rs"
@@ -32,7 +32,7 @@ version = "1"
 version = "1.0.8"
 
 [dependencies.uniffi_bindgen]
-version = "=0.27.3"
+version = "=0.28.1"
 default-features = false
 
 [features]
diff --git a/third_party/rust/uniffi_checksum_derive/.cargo-checksum.json b/third_party/rust/uniffi_checksum_derive/.cargo-checksum.json
index fd63879c29d0..ddeb0fa975e0 100644
--- a/third_party/rust/uniffi_checksum_derive/.cargo-checksum.json
+++ b/third_party/rust/uniffi_checksum_derive/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"efec1e1624f962fd264a0003ac8d40311c4af50f69d7ed537119ca74c73255a0","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/lib.rs":"44d2e2c595b14d33d16c71dfe4ef42ad0b9e010a878ee2ec49c2e929d60275ba"},"package":"d5c400339a9d1d17be34257d0b407e91d64af335e5b4fa49f4bf28467fc8d635"}
\ No newline at end of file
+{"files":{"Cargo.toml":"c9e328229de29d28389e431f6a5a5a4f43ab00bb0389163875939806bef20dcf","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/lib.rs":"3301ac9be2750c348f677c1fcf721daa37945901434d6cd6958d7926c987e4ea"},"package":"a22dbe67c1c957ac6e7611bdf605a6218aa86b0eebeb8be58b70ae85ad7d73dc"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_checksum_derive/Cargo.toml b/third_party/rust/uniffi_checksum_derive/Cargo.toml
index 95f1fdf295cc..38c7bbbf8363 100644
--- a/third_party/rust/uniffi_checksum_derive/Cargo.toml
+++ b/third_party/rust/uniffi_checksum_derive/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_checksum_derive"
-version = "0.27.3"
+version = "0.28.1"
 authors = ["Firefox Sync Team <sync-team@mozilla.com>"]
 description = "a multi-language bindings generator for rust (checksum custom derive)"
 homepage = "https://mozilla.github.io/uniffi-rs"
diff --git a/third_party/rust/uniffi_checksum_derive/src/lib.rs b/third_party/rust/uniffi_checksum_derive/src/lib.rs
index e600982d083a..449183dedf86 100644
--- a/third_party/rust/uniffi_checksum_derive/src/lib.rs
+++ b/third_party/rust/uniffi_checksum_derive/src/lib.rs
@@ -108,14 +108,13 @@ pub fn checksum_derive(input: TokenStream) -> TokenStream {
                 .fields
                 .iter()
                 .enumerate()
-                .filter_map(|(num, field)| {
-                    (!has_ignore_attribute(&field.attrs)).then(|| match field.ident.as_ref() {
-                        Some(ident) => quote! { Checksum::checksum(&self.#ident, state); },
-                        None => {
-                            let i = Index::from(num);
-                            quote! { Checksum::checksum(&self.#i, state); }
-                        }
-                    })
+                .filter(|&(_num, field)| (!has_ignore_attribute(&field.attrs)))
+                .map(|(num, field)| match field.ident.as_ref() {
+                    Some(ident) => quote! { Checksum::checksum(&self.#ident, state); },
+                    None => {
+                        let i = Index::from(num);
+                        quote! { Checksum::checksum(&self.#i, state); }
+                    }
                 });
             quote! {
                 #(#stmts)*
diff --git a/third_party/rust/uniffi_core/.cargo-checksum.json b/third_party/rust/uniffi_core/.cargo-checksum.json
index 2eb3e1abf803..8e390f6cec3c 100644
--- a/third_party/rust/uniffi_core/.cargo-checksum.json
+++ b/third_party/rust/uniffi_core/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"c2bc10be9bffda0a1b9ea884f39d6499fc5b4bc8acb32ec33842c67c8ad72305","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","release.toml":"b150796411fc6ff90b481218cb50f8ac7c07f5845aebdb8e17877d47e55b05b9","src/ffi/callbackinterface.rs":"f0184cf76bd86abb2815d260a87f85bd7060f5373ac6ef6f71955ece2a5075af","src/ffi/ffidefault.rs":"0db83fbcbc274c4c0daf7fb27833400568839b77a3496155840734c511d801e0","src/ffi/ffiserialize.rs":"d34312d09d8851c0fc356990d9f3a8a488ea9f6ab089901b1d0c42180ad06be4","src/ffi/foreignbytes.rs":"d2b46e1a6317aa64801b855e0d12af6bcdef118d8036603d11c3cdaf6f35fdfe","src/ffi/foreigncallbacks.rs":"2b820a34b78705f5debc302a25c64d515a4aa7b3bdade083f4c1cfa2803664ae","src/ffi/foreignfuture.rs":"673a7a44d27b88d5297dc6f2da507c9db4d22e6306d9ebc5439cba9c6720cbcb","src/ffi/handle.rs":"91f91469a81cb19edebb8bba433df62658cc66f6b54d5dc8520eb5793a85abd9","src/ffi/mod.rs":"e4d46229ccda04fa42496cb72b09d57936311a1ac1d82343293613e708644494","src/ffi/rustbuffer.rs":"9df75f156dc8ea9565ae320654cc8caab899e688e5414da4e4a43dfe74db9522","src/ffi/rustcalls.rs":"9754b01988983b47d8f0ef6d4e5675cee92ec4ddeb073236b9ccfcac2b12e3ca","src/ffi/rustfuture/future.rs":"426cd0ad3c8cf008a7052a7d89856b6c6d5053b94e24325f5666d0281a40ec7f","src/ffi/rustfuture/mod.rs":"44568267e591f5b37f77acfdd6e60ae55ce48ab0a17fd81af3aeb31baa3d53e6","src/ffi/rustfuture/scheduler.rs":"c6484fff14c04596df5f306f2090366435dcff92561d317fde1ea9c097a9576b","src/ffi/rustfuture/tests.rs":"211241fb484a3a103eb0418e7d295850ea021bcd583fa1488f5efc68f33d5ab8","src/ffi_converter_impls.rs":"397c813f2e765462d7a7be524e6ac75e813a91a8ffd11c7e7df05f853213f77b","src/ffi_converter_traits.rs":"24c8cf6ada9b2f63b265e62c0f9092d640e533d0d7234e9156f92c3d1902f430","src/lib.rs":"477a833a1e41b9e07f3a6f052c6b7f48d11930449ff22b5ff949c7eeaa3e80b9","src/metadata.rs":"83e463c377c0f501e58ac4eb5cc47c433c1473cecd47305fa89283e736b48d96","src/oneshot.rs":"8f1b7e87cc139d274cacef1a7ad6a9e9bf85423a140ad4e5b61e38be9c6e7bb6","src/panichook.rs":"9f49c7994a8e5489c1105c488bb3f8c5571bc5f813e7be90441eca15da5c9851"},"package":"a02e67ac9634b10da9e4aa63a29a7920b8f1395eafef1ea659b2dd76dda96906"}
\ No newline at end of file
+{"files":{"Cargo.toml":"842de64a0478e2872d4ac3f210580eecb832ce32c6c025eb7972ae5956d2ce83","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","release.toml":"b150796411fc6ff90b481218cb50f8ac7c07f5845aebdb8e17877d47e55b05b9","src/ffi/callbackinterface.rs":"ea6ffe37f743d8fc9d0286754bd19950b6c0168796a52686f07f1b7fe0ebf0f4","src/ffi/ffidefault.rs":"0db83fbcbc274c4c0daf7fb27833400568839b77a3496155840734c511d801e0","src/ffi/ffiserialize.rs":"f982b42730aeed292d03d2ec6cc10170619511805170180e6db37121b468b6ab","src/ffi/foreignbytes.rs":"d2b46e1a6317aa64801b855e0d12af6bcdef118d8036603d11c3cdaf6f35fdfe","src/ffi/foreigncallbacks.rs":"2b820a34b78705f5debc302a25c64d515a4aa7b3bdade083f4c1cfa2803664ae","src/ffi/foreignfuture.rs":"5c4a43d28831987dd108a863fcee166c85d7342304b435bdd0763919aad763fe","src/ffi/handle.rs":"466935e92bd15f63e594c47f862e9173be92ad765c1f7b283c1e7dcb5d2e20f2","src/ffi/mod.rs":"e4d46229ccda04fa42496cb72b09d57936311a1ac1d82343293613e708644494","src/ffi/rustbuffer.rs":"81b8fcc2f35098265e6137456030161abea40c33168b3cd8418609a1ae547854","src/ffi/rustcalls.rs":"8fd22eabe5a3a68dbfda43ce2739b13ece7d3c5c5cabdf4ecf820a89f155071a","src/ffi/rustfuture/future.rs":"1822ea14a3dff99a1621cf6a575b7a0c994e160911d0d1b869bdd5a9e35f97f5","src/ffi/rustfuture/mod.rs":"cbc5bac1b19745c4361df38dffe50599108abef5ca0f75b235194019a80d53fd","src/ffi/rustfuture/scheduler.rs":"c6484fff14c04596df5f306f2090366435dcff92561d317fde1ea9c097a9576b","src/ffi/rustfuture/tests.rs":"9815a87c01020b23bf9e668873f2b31aa4c0b3a01275fffcb934957883d4af4e","src/ffi_converter_impls.rs":"6454294f83e891b7e3c668ecde83d4b872def12bd6ea165b4594c63bcaf26389","src/ffi_converter_traits.rs":"6de4c0f4574a7a58a040bfc38b6b4d4e5a15209885f745295a338a497caefcb1","src/lib.rs":"0516914f329451e0c946d830afcfdaa9ecf640d8aa5ceed5784fec1faf994f5c","src/metadata.rs":"8766429c98246224bfddbcfc155d11057b2d2660393717dadd9839ebaf2b4f65","src/oneshot.rs":"8f1b7e87cc139d274cacef1a7ad6a9e9bf85423a140ad4e5b61e38be9c6e7bb6","src/panichook.rs":"9f49c7994a8e5489c1105c488bb3f8c5571bc5f813e7be90441eca15da5c9851"},"package":"5a0c35aaad30e3a9e6d4fe34e358d64dbc92ee09045b48591b05fc9f12e0905b"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_core/Cargo.toml b/third_party/rust/uniffi_core/Cargo.toml
index dcc0afb9f278..340a5175a050 100644
--- a/third_party/rust/uniffi_core/Cargo.toml
+++ b/third_party/rust/uniffi_core/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_core"
-version = "0.27.3"
+version = "0.28.1"
 authors = ["Firefox Sync Team <sync-team@mozilla.com>"]
 description = "a multi-language bindings generator for rust (runtime support code)"
 homepage = "https://mozilla.github.io/uniffi-rs"
diff --git a/third_party/rust/uniffi_core/src/ffi/callbackinterface.rs b/third_party/rust/uniffi_core/src/ffi/callbackinterface.rs
index e7a4faab64b0..33db6f09285d 100644
--- a/third_party/rust/uniffi_core/src/ffi/callbackinterface.rs
+++ b/third_party/rust/uniffi_core/src/ffi/callbackinterface.rs
@@ -195,7 +195,7 @@ macro_rules! convert_unexpected_error {
             fn get_converter(&self) -> $crate::UnexpectedUniFFICallbackErrorConverterSpecialized;
         }
 
-        impl<T: Into<$ty>> GetConverterSpecialized for T {
+        impl<T: ::std::convert::Into<$ty>> GetConverterSpecialized for T {
             fn get_converter(&self) -> $crate::UnexpectedUniFFICallbackErrorConverterSpecialized {
                 $crate::UnexpectedUniFFICallbackErrorConverterSpecialized
             }
diff --git a/third_party/rust/uniffi_core/src/ffi/ffiserialize.rs b/third_party/rust/uniffi_core/src/ffi/ffiserialize.rs
index 570ebd5b11d1..edbeb512293b 100644
--- a/third_party/rust/uniffi_core/src/ffi/ffiserialize.rs
+++ b/third_party/rust/uniffi_core/src/ffi/ffiserialize.rs
@@ -3,7 +3,7 @@
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
 use crate::{Handle, RustBuffer, RustCallStatus, RustCallStatusCode};
-use std::{mem::MaybeUninit, ptr::NonNull};
+use std::{mem::ManuallyDrop, ptr::NonNull};
 
 /// FFIBuffer element
 ///
@@ -81,7 +81,7 @@ pub trait FfiSerialize: Sized {
     fn write(buf: &mut &mut [FfiBufferElement], value: Self) {
         Self::put(buf, value);
         // Lifetime dance taken from `bytes::BufMut`
-        let (_, new_buf) = core::mem::take(buf).split_at_mut(Self::SIZE);
+        let (_, new_buf) = ::core::mem::take(buf).split_at_mut(Self::SIZE);
         *buf = new_buf;
     }
 }
@@ -228,15 +228,13 @@ impl FfiSerialize for RustCallStatus {
         let code = unsafe { buf[0].i8 };
         Self {
             code: RustCallStatusCode::try_from(code).unwrap_or(RustCallStatusCode::UnexpectedError),
-            error_buf: MaybeUninit::new(RustBuffer::get(&buf[1..])),
+            error_buf: ManuallyDrop::new(RustBuffer::get(&buf[1..])),
         }
     }
 
     fn put(buf: &mut [FfiBufferElement], value: Self) {
         buf[0].i8 = value.code as i8;
-        // Safety: This is okay even if the error buf is not initialized.  It just means we'll be
-        // copying the garbage data.
-        unsafe { RustBuffer::put(&mut buf[1..], value.error_buf.assume_init()) }
+        RustBuffer::put(&mut buf[1..], ManuallyDrop::into_inner(value.error_buf))
     }
 }
 
@@ -277,9 +275,9 @@ mod test {
             rust_buffer.len(),
             rust_buffer.capacity(),
         );
-        let handle = Handle::from_raw(101).unwrap();
-        let rust_call_status = RustCallStatus::new();
-        let rust_call_status_error_buf = unsafe { rust_call_status.error_buf.assume_init_ref() };
+        let handle = unsafe { Handle::from_raw(101).unwrap() };
+        let rust_call_status = RustCallStatus::default();
+        let rust_call_status_error_buf = &rust_call_status.error_buf;
         let orig_rust_call_status_buffer_data = (
             rust_call_status_error_buf.data_pointer(),
             rust_call_status_error_buf.len(),
@@ -302,7 +300,6 @@ mod test {
         <RustBuffer as FfiSerialize>::write(&mut buf_writer, rust_buffer);
         <RustCallStatus as FfiSerialize>::write(&mut buf_writer, rust_call_status);
         <Handle as FfiSerialize>::write(&mut buf_writer, handle);
-        #[allow(unknown_lints)]
         #[allow(clippy::needless_borrows_for_generic_args)]
         <() as FfiSerialize>::write(&mut buf_writer, ());
 
@@ -335,7 +332,7 @@ mod test {
         let rust_call_status2 = <RustCallStatus as FfiSerialize>::read(&mut buf_reader);
         assert_eq!(rust_call_status2.code, RustCallStatusCode::Success);
 
-        let rust_call_status2_error_buf = unsafe { rust_call_status2.error_buf.assume_init() };
+        let rust_call_status2_error_buf = ManuallyDrop::into_inner(rust_call_status2.error_buf);
         assert_eq!(
             (
                 rust_call_status2_error_buf.data_pointer(),
diff --git a/third_party/rust/uniffi_core/src/ffi/foreignfuture.rs b/third_party/rust/uniffi_core/src/ffi/foreignfuture.rs
index 87d8b9a4e722..804beaef62e0 100644
--- a/third_party/rust/uniffi_core/src/ffi/foreignfuture.rs
+++ b/third_party/rust/uniffi_core/src/ffi/foreignfuture.rs
@@ -147,7 +147,7 @@ mod test {
                 *data,
                 ForeignFutureResult {
                     return_value: <String as Lower<crate::UniFfiTag>>::lower(value),
-                    call_status: RustCallStatus::new(),
+                    call_status: RustCallStatus::default(),
                 },
             );
         }
diff --git a/third_party/rust/uniffi_core/src/ffi/handle.rs b/third_party/rust/uniffi_core/src/ffi/handle.rs
index 8ee2f46c359d..8ca66a41ded7 100644
--- a/third_party/rust/uniffi_core/src/ffi/handle.rs
+++ b/third_party/rust/uniffi_core/src/ffi/handle.rs
@@ -12,7 +12,7 @@
 /// For all currently supported architectures and hopefully any ones we add in the future:
 /// * 0 is an invalid value.
 /// * The lowest bit will always be set for foreign handles and never set for Rust ones (since the
-///   leaked pointer will be aligned).
+///   leaked pointer will be aligned to `size_of::<Arc<T>>()` == `size_of::<*const T>()`).
 ///
 /// Rust handles are mainly managed is through the [crate::HandleAlloc] trait.
 #[derive(Copy, Clone, Default, Debug, PartialEq, Eq)]
@@ -28,7 +28,9 @@ impl Handle {
         self.0 as *const T
     }
 
-    pub fn from_raw(raw: u64) -> Option<Self> {
+    /// # Safety
+    /// The raw value must be a valid handle as described above.
+    pub unsafe fn from_raw(raw: u64) -> Option<Self> {
         if raw == 0 {
             None
         } else {
diff --git a/third_party/rust/uniffi_core/src/ffi/rustbuffer.rs b/third_party/rust/uniffi_core/src/ffi/rustbuffer.rs
index 72e94faaa590..9c718aa6117b 100644
--- a/third_party/rust/uniffi_core/src/ffi/rustbuffer.rs
+++ b/third_party/rust/uniffi_core/src/ffi/rustbuffer.rs
@@ -78,13 +78,10 @@ impl RustBuffer {
 
     /// Creates a `RustBuffer` from its constituent fields.
     ///
-    /// This is intended mainly as an internal convenience function and should not
-    /// be used outside of this module.
-    ///
     /// # Safety
     ///
     /// You must ensure that the raw parts uphold the documented invariants of this class.
-    pub unsafe fn from_raw_parts(data: *mut u8, len: u64, capacity: u64) -> Self {
+    pub(crate) unsafe fn from_raw_parts(data: *mut u8, len: u64, capacity: u64) -> Self {
         Self {
             capacity,
             len,
@@ -94,7 +91,7 @@ impl RustBuffer {
 
     /// Get the current length of the buffer, as a `usize`.
     ///
-    /// This is mostly a helper function to convert the `i32` length field
+    /// This is mostly a helper function to convert the `u64` length field
     /// into a `usize`, which is what Rust code usually expects.
     ///
     /// # Panics
@@ -130,7 +127,7 @@ impl RustBuffer {
     ///
     /// # Panics
     ///
-    /// Panics if the requested size is too large to fit in an `i32`, and
+    /// Panics if the requested size is too large to fit in an `u64`, and
     /// hence would risk incompatibility with some foreign-language code.
     pub fn new_with_size(size: u64) -> Self {
         Self::from_vec(vec![0u8; size as usize])
@@ -143,7 +140,7 @@ impl RustBuffer {
     ///
     /// # Panics
     ///
-    /// Panics if the vector's length or capacity are too large to fit in an `i32`,
+    /// Panics if the vector's length or capacity are too large to fit in an `u64`,
     /// and hence would risk incompatibility with some foreign-language code.
     pub fn from_vec(v: Vec<u8>) -> Self {
         let capacity = u64::try_from(v.capacity()).expect("buffer capacity cannot fit into a u64.");
diff --git a/third_party/rust/uniffi_core/src/ffi/rustcalls.rs b/third_party/rust/uniffi_core/src/ffi/rustcalls.rs
index 91d3fe24726d..c4cd1ac03a20 100644
--- a/third_party/rust/uniffi_core/src/ffi/rustcalls.rs
+++ b/third_party/rust/uniffi_core/src/ffi/rustcalls.rs
@@ -12,7 +12,7 @@
 //!      exception
 
 use crate::{FfiDefault, Lower, RustBuffer, UniFfiTag};
-use std::mem::MaybeUninit;
+use std::mem::ManuallyDrop;
 use std::panic;
 
 /// Represents the success/error of a rust call
@@ -42,52 +42,43 @@ use std::panic;
 #[repr(C)]
 pub struct RustCallStatus {
     pub code: RustCallStatusCode,
-    // code is signed because unsigned types are experimental in Kotlin
-    pub error_buf: MaybeUninit<RustBuffer>,
-    // error_buf is MaybeUninit to avoid dropping the value that the consumer code sends in:
-    //   - Consumers should send in a zeroed out RustBuffer.  In this case dropping is a no-op and
-    //     avoiding the drop is a small optimization.
-    //   - If consumers pass in invalid data, then we should avoid trying to drop it.  In
-    //     particular, we don't want to try to free any data the consumer has allocated.
-    //
-    // `MaybeUninit` requires unsafe code, since we are preventing rust from dropping the value.
-    // To use this safely we need to make sure that no code paths set this twice, since that will
-    // leak the first `RustBuffer`.
-}
-
-impl RustCallStatus {
-    pub fn new() -> Self {
-        Self {
-            code: RustCallStatusCode::Success,
-            error_buf: MaybeUninit::new(RustBuffer::new()),
-        }
-    }
-
-    pub fn cancelled() -> Self {
-        Self {
-            code: RustCallStatusCode::Cancelled,
-            error_buf: MaybeUninit::new(RustBuffer::new()),
-        }
-    }
-
-    pub fn error(message: impl Into<String>) -> Self {
-        Self {
-            code: RustCallStatusCode::UnexpectedError,
-            error_buf: MaybeUninit::new(<String as Lower<UniFfiTag>>::lower(message.into())),
-        }
-    }
+    // error_buf is owned by the foreign side.
+    // - Whatever we are passed, we must never free. This however implies we must be passed
+    //   an empty `RustBuffer` otherwise it would leak when we replace it with our own.
+    // - On error we will set it to a `RustBuffer` we expect the foreign side to free.
+    // We assume initialization, which means we can use `ManuallyDrop` instead of
+    // `MaybeUninit`, which avoids unsafe code and clarifies ownership.
+    // We must take care to not set this twice to avoid leaking the first `RustBuffer`.
+    pub error_buf: ManuallyDrop<RustBuffer>,
 }
 
 impl Default for RustCallStatus {
     fn default() -> Self {
         Self {
             code: RustCallStatusCode::Success,
-            error_buf: MaybeUninit::uninit(),
+            error_buf: Default::default(),
+        }
+    }
+}
+
+impl RustCallStatus {
+    pub fn cancelled() -> Self {
+        Self {
+            code: RustCallStatusCode::Cancelled,
+            error_buf: Default::default(),
+        }
+    }
+
+    pub fn error(message: impl Into<String>) -> Self {
+        Self {
+            code: RustCallStatusCode::UnexpectedError,
+            error_buf: ManuallyDrop::new(<String as Lower<UniFfiTag>>::lower(message.into())),
         }
     }
 }
 
 /// Result of a FFI call to a Rust function
+/// Value is signed to avoid Kotlin's experimental unsigned types.
 #[repr(i8)]
 #[derive(Debug, PartialEq, Eq)]
 pub enum RustCallStatusCode {
@@ -120,6 +111,29 @@ impl TryFrom<i8> for RustCallStatusCode {
     }
 }
 
+/// Error type for Rust scaffolding calls
+///
+/// This enum represents the fact that there are two ways for a scaffolding call to fail:
+/// - Expected errors (the Rust function returned an `Err` value).
+/// - Unexpected errors (there was a failure calling the Rust function, for example the failure to
+///   lift the arguments).
+pub enum RustCallError {
+    /// The Rust function returned an `Err` value.
+    ///
+    /// The associated value is the serialized `Err` value.
+    Error(RustBuffer),
+    /// There was a failure to call the Rust function, for example a failure to lift the arguments.
+    ///
+    /// The associated value is a message string for the error.
+    InternalError(String),
+}
+
+/// Error when trying to lift arguments to pass to the scaffolding call
+pub struct LiftArgsError {
+    pub arg_name: &'static str,
+    pub error: anyhow::Error,
+}
+
 /// Handle a scaffolding calls
 ///
 /// `callback` is responsible for making the actual Rust call and returning a special result type:
@@ -141,7 +155,7 @@ impl TryFrom<i8> for RustCallStatusCode {
 ///     - `FfiDefault::ffi_default()` is returned, although foreign code should ignore this value
 pub fn rust_call<F, R>(out_status: &mut RustCallStatus, callback: F) -> R
 where
-    F: panic::UnwindSafe + FnOnce() -> Result<R, RustBuffer>,
+    F: panic::UnwindSafe + FnOnce() -> Result<R, RustCallError>,
     R: FfiDefault,
 {
     rust_call_with_out_status(out_status, callback).unwrap_or_else(R::ffi_default)
@@ -158,7 +172,7 @@ pub(crate) fn rust_call_with_out_status<F, R>(
     callback: F,
 ) -> Option<R>
 where
-    F: panic::UnwindSafe + FnOnce() -> Result<R, RustBuffer>,
+    F: panic::UnwindSafe + FnOnce() -> Result<R, RustCallError>,
 {
     let result = panic::catch_unwind(|| {
         crate::panichook::ensure_setup();
@@ -169,13 +183,14 @@ where
         // initializes it to [RustCallStatusCode::Success]
         Ok(Ok(v)) => Some(v),
         // Callback returned an Err.
-        Ok(Err(buf)) => {
+        Ok(Err(RustCallError::Error(buf))) => {
             out_status.code = RustCallStatusCode::Error;
-            unsafe {
-                // Unsafe because we're setting the `MaybeUninit` value, see above for safety
-                // invariants.
-                out_status.error_buf.as_mut_ptr().write(buf);
-            }
+            *out_status.error_buf = buf;
+            None
+        }
+        Ok(Err(RustCallError::InternalError(msg))) => {
+            out_status.code = RustCallStatusCode::UnexpectedError;
+            *out_status.error_buf = <String as Lower<UniFfiTag>>::lower(msg);
             None
         }
         // Callback panicked
@@ -196,11 +211,9 @@ where
                 <String as Lower<UniFfiTag>>::lower(message)
             }));
             if let Ok(buf) = message_result {
-                unsafe {
-                    // Unsafe because we're setting the `MaybeUninit` value, see above for safety
-                    // invariants.
-                    out_status.error_buf.as_mut_ptr().write(buf);
-                }
+                // If this was ever set twice we'd leak the old value - but because this is the only
+                // place where it is set, and this is only called once, no leaks should exist in practice.
+                *out_status.error_buf = buf;
             }
             // Ignore the error case.  We've done all that we can at this point.  In the bindings
             // code, we handle this by checking if `error_buf` still has an empty `RustBuffer` and
@@ -214,53 +227,58 @@ where
 mod test {
     use super::*;
     use crate::{test_util::TestError, Lift, LowerReturn};
-
-    fn create_call_status() -> RustCallStatus {
-        RustCallStatus {
-            code: RustCallStatusCode::Success,
-            error_buf: MaybeUninit::new(RustBuffer::new()),
-        }
-    }
-
-    fn test_callback(a: u8) -> Result<i8, TestError> {
-        match a {
-            0 => Ok(100),
-            1 => Err(TestError("Error".to_owned())),
-            x => panic!("Unexpected value: {x}"),
-        }
-    }
+    use anyhow::anyhow;
 
     #[test]
     fn test_rust_call() {
-        let mut status = create_call_status();
+        // Successful call
+        let mut status = RustCallStatus::default();
         let return_value = rust_call(&mut status, || {
-            <Result<i8, TestError> as LowerReturn<UniFfiTag>>::lower_return(test_callback(0))
+            <Result<i8, TestError> as LowerReturn<UniFfiTag>>::lower_return(Ok(100))
         });
 
         assert_eq!(status.code, RustCallStatusCode::Success);
         assert_eq!(return_value, 100);
 
+        // Successful call that returns an Err value
+        let mut status = RustCallStatus::default();
         rust_call(&mut status, || {
-            <Result<i8, TestError> as LowerReturn<UniFfiTag>>::lower_return(test_callback(1))
+            <Result<i8, TestError> as LowerReturn<UniFfiTag>>::lower_return(Err(TestError(
+                "Error".into(),
+            )))
         });
         assert_eq!(status.code, RustCallStatusCode::Error);
-        unsafe {
-            assert_eq!(
-                <TestError as Lift<UniFfiTag>>::try_lift(status.error_buf.assume_init()).unwrap(),
-                TestError("Error".to_owned())
-            );
-        }
+        assert_eq!(
+            <TestError as Lift<UniFfiTag>>::try_lift(ManuallyDrop::into_inner(status.error_buf))
+                .unwrap(),
+            TestError("Error".to_owned())
+        );
 
-        let mut status = create_call_status();
+        // Internal error while trying to make the call
+        let mut status = RustCallStatus::default();
         rust_call(&mut status, || {
-            <Result<i8, TestError> as LowerReturn<UniFfiTag>>::lower_return(test_callback(2))
+            <Result<i8, TestError> as LowerReturn<UniFfiTag>>::handle_failed_lift(LiftArgsError {
+                arg_name: "foo",
+                error: anyhow!("invalid handle"),
+            })
         });
         assert_eq!(status.code, RustCallStatusCode::UnexpectedError);
-        unsafe {
-            assert_eq!(
-                <String as Lift<UniFfiTag>>::try_lift(status.error_buf.assume_init()).unwrap(),
-                "Unexpected value: 2"
-            );
-        }
+        assert_eq!(
+            <String as Lift<UniFfiTag>>::try_lift(ManuallyDrop::into_inner(status.error_buf))
+                .unwrap(),
+            "Failed to convert arg 'foo': invalid handle"
+        );
+
+        // Panic inside the call
+        let mut status = RustCallStatus::default();
+        rust_call(&mut status, || -> Result<i8, RustCallError> {
+            panic!("I crashed")
+        });
+        assert_eq!(status.code, RustCallStatusCode::UnexpectedError);
+        assert_eq!(
+            <String as Lift<UniFfiTag>>::try_lift(ManuallyDrop::into_inner(status.error_buf))
+                .unwrap(),
+            "I crashed"
+        );
     }
 }
diff --git a/third_party/rust/uniffi_core/src/ffi/rustfuture/future.rs b/third_party/rust/uniffi_core/src/ffi/rustfuture/future.rs
index 93c34e7543c4..ee468ffb9787 100644
--- a/third_party/rust/uniffi_core/src/ffi/rustfuture/future.rs
+++ b/third_party/rust/uniffi_core/src/ffi/rustfuture/future.rs
@@ -86,13 +86,13 @@ use std::{
 };
 
 use super::{RustFutureContinuationCallback, RustFuturePoll, Scheduler};
-use crate::{rust_call_with_out_status, FfiDefault, LowerReturn, RustCallStatus};
+use crate::{rust_call_with_out_status, FfiDefault, LiftArgsError, LowerReturn, RustCallStatus};
 
 /// Wraps the actual future we're polling
 struct WrappedFuture<F, T, UT>
 where
     // See rust_future_new for an explanation of these trait bounds
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     T: LowerReturn<UT> + Send + 'static,
     UT: Send + 'static,
 {
@@ -106,7 +106,7 @@ where
 impl<F, T, UT> WrappedFuture<F, T, UT>
 where
     // See rust_future_new for an explanation of these trait bounds
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     T: LowerReturn<UT> + Send + 'static,
     UT: Send + 'static,
 {
@@ -139,7 +139,8 @@ where
                 // case below and we will never poll the future again.
                 panic::AssertUnwindSafe(|| match pinned.poll(context) {
                     Poll::Pending => Ok(Poll::Pending),
-                    Poll::Ready(v) => T::lower_return(v).map(Poll::Ready),
+                    Poll::Ready(Ok(v)) => T::lower_return(v).map(Poll::Ready),
+                    Poll::Ready(Err(e)) => T::handle_failed_lift(e).map(Poll::Ready),
                 }),
             );
             match result {
@@ -185,7 +186,7 @@ where
 unsafe impl<F, T, UT> Send for WrappedFuture<F, T, UT>
 where
     // See rust_future_new for an explanation of these trait bounds
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     T: LowerReturn<UT> + Send + 'static,
     UT: Send + 'static,
 {
@@ -195,7 +196,7 @@ where
 pub(super) struct RustFuture<F, T, UT>
 where
     // See rust_future_new for an explanation of these trait bounds
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     T: LowerReturn<UT> + Send + 'static,
     UT: Send + 'static,
 {
@@ -211,7 +212,7 @@ where
 impl<F, T, UT> RustFuture<F, T, UT>
 where
     // See rust_future_new for an explanation of these trait bounds
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     T: LowerReturn<UT> + Send + 'static,
     UT: Send + 'static,
 {
@@ -263,7 +264,7 @@ where
 impl<F, T, UT> Wake for RustFuture<F, T, UT>
 where
     // See rust_future_new for an explanation of these trait bounds
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     T: LowerReturn<UT> + Send + 'static,
     UT: Send + 'static,
 {
@@ -298,7 +299,7 @@ pub trait RustFutureFfi<ReturnType>: Send + Sync {
 impl<F, T, UT> RustFutureFfi<T::ReturnType> for RustFuture<F, T, UT>
 where
     // See rust_future_new for an explanation of these trait bounds
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     T: LowerReturn<UT> + Send + 'static,
     UT: Send + 'static,
 {
diff --git a/third_party/rust/uniffi_core/src/ffi/rustfuture/mod.rs b/third_party/rust/uniffi_core/src/ffi/rustfuture/mod.rs
index 3d3505e5ef11..01202c5752f2 100644
--- a/third_party/rust/uniffi_core/src/ffi/rustfuture/mod.rs
+++ b/third_party/rust/uniffi_core/src/ffi/rustfuture/mod.rs
@@ -12,7 +12,7 @@ use scheduler::*;
 #[cfg(test)]
 mod tests;
 
-use crate::{derive_ffi_traits, Handle, HandleAlloc, LowerReturn, RustCallStatus};
+use crate::{derive_ffi_traits, Handle, HandleAlloc, LiftArgsError, LowerReturn, RustCallStatus};
 
 /// Result code for [rust_future_poll].  This is passed to the continuation function.
 #[repr(i8)]
@@ -42,7 +42,7 @@ where
     // since it will move between threads for an indeterminate amount of time as the foreign
     // executor calls polls it and the Rust executor wakes it.  It does not need to by `Sync`,
     // since we synchronize all access to the values.
-    F: Future<Output = T> + Send + 'static,
+    F: Future<Output = Result<T, LiftArgsError>> + Send + 'static,
     // T is the output of the Future.  It needs to implement [LowerReturn].  Also it must be Send +
     // 'static for the same reason as F.
     T: LowerReturn<UT> + Send + 'static,
diff --git a/third_party/rust/uniffi_core/src/ffi/rustfuture/tests.rs b/third_party/rust/uniffi_core/src/ffi/rustfuture/tests.rs
index 886ee27c7154..6bd9b6c93e08 100644
--- a/third_party/rust/uniffi_core/src/ffi/rustfuture/tests.rs
+++ b/third_party/rust/uniffi_core/src/ffi/rustfuture/tests.rs
@@ -1,6 +1,7 @@
 use once_cell::sync::OnceCell;
 use std::{
     future::Future,
+    mem::ManuallyDrop,
     panic,
     pin::Pin,
     sync::{Arc, Mutex},
@@ -12,7 +13,7 @@ use crate::{test_util::TestError, Lift, RustBuffer, RustCallStatusCode};
 
 // Sender/Receiver pair that we use for testing
 struct Channel {
-    result: Option<Result<String, TestError>>,
+    result: Option<Result<Result<String, TestError>, LiftArgsError>>,
     waker: Option<Waker>,
 }
 
@@ -28,7 +29,21 @@ impl Sender {
 
     fn send(&self, value: Result<String, TestError>) {
         let mut inner = self.0.lock().unwrap();
-        if inner.result.replace(value).is_some() {
+        if inner.result.replace(Ok(value)).is_some() {
+            panic!("value already sent");
+        }
+        if let Some(waker) = &inner.waker {
+            waker.wake_by_ref();
+        }
+    }
+
+    fn send_lift_args_error(&self, arg_name: &'static str, error: anyhow::Error) {
+        let mut inner = self.0.lock().unwrap();
+        if inner
+            .result
+            .replace(Err(LiftArgsError { arg_name, error }))
+            .is_some()
+        {
             panic!("value already sent");
         }
         if let Some(waker) = &inner.waker {
@@ -40,12 +55,15 @@ impl Sender {
 struct Receiver(Arc<Mutex<Channel>>);
 
 impl Future for Receiver {
-    type Output = Result<String, TestError>;
+    type Output = Result<Result<String, TestError>, LiftArgsError>;
 
-    fn poll(self: Pin<&mut Self>, context: &mut Context<'_>) -> Poll<Result<String, TestError>> {
+    fn poll(
+        self: Pin<&mut Self>,
+        context: &mut Context<'_>,
+    ) -> Poll<Result<Result<String, TestError>, LiftArgsError>> {
         let mut inner = self.0.lock().unwrap();
-        match &inner.result {
-            Some(v) => Poll::Ready(v.clone()),
+        match inner.result.take() {
+            Some(v) => Poll::Ready(v),
             None => {
                 inner.waker = Some(context.waker().clone());
                 Poll::Pending
@@ -126,15 +144,36 @@ fn test_error() {
 
     let (_, call_status) = complete(rust_future);
     assert_eq!(call_status.code, RustCallStatusCode::Error);
-    unsafe {
-        assert_eq!(
-            <TestError as Lift<crate::UniFfiTag>>::try_lift_from_rust_buffer(
-                call_status.error_buf.assume_init()
-            )
-            .unwrap(),
-            TestError::from("Something went wrong"),
-        )
-    }
+    assert_eq!(
+        <TestError as Lift<crate::UniFfiTag>>::try_lift_from_rust_buffer(ManuallyDrop::into_inner(
+            call_status.error_buf
+        ))
+        .unwrap(),
+        TestError::from("Something went wrong"),
+    )
+}
+
+#[test]
+fn test_lift_args_error() {
+    let (sender, rust_future) = channel();
+
+    let continuation_result = poll(&rust_future);
+    assert_eq!(continuation_result.get(), None);
+    sender.send_lift_args_error("arg0", anyhow::anyhow!("Invalid handle"));
+    assert_eq!(continuation_result.get(), Some(&RustFuturePoll::MaybeReady));
+
+    let continuation_result = poll(&rust_future);
+    assert_eq!(continuation_result.get(), Some(&RustFuturePoll::Ready));
+
+    let (_, call_status) = complete(rust_future);
+    assert_eq!(call_status.code, RustCallStatusCode::UnexpectedError);
+    assert_eq!(
+        <String as Lift<crate::UniFfiTag>>::try_lift(ManuallyDrop::into_inner(
+            call_status.error_buf
+        ))
+        .unwrap(),
+        "Failed to convert arg 'arg0': Invalid handle",
+    )
 }
 
 // Once `complete` is called, the inner future should be released, even if wakers still hold a
@@ -200,11 +239,11 @@ fn test_wake_during_poll() {
         if first_time {
             first_time = false;
             // Wake the future while we are in the middle of polling it
-            ctx.waker().clone().wake();
+            ctx.waker().wake_by_ref();
             Poll::Pending
         } else {
             // The second time we're polled, we're ready
-            Poll::Ready("All done".to_owned())
+            Poll::Ready(Ok("All done".to_owned()))
         }
     });
     let rust_future: Arc<dyn RustFutureFfi<RustBuffer>> = RustFuture::new(future, crate::UniFfiTag);
diff --git a/third_party/rust/uniffi_core/src/ffi_converter_impls.rs b/third_party/rust/uniffi_core/src/ffi_converter_impls.rs
index aec093154ab8..714fce16ba24 100644
--- a/third_party/rust/uniffi_core/src/ffi_converter_impls.rs
+++ b/third_party/rust/uniffi_core/src/ffi_converter_impls.rs
@@ -23,8 +23,9 @@
 /// "UT" means an arbitrary `UniFfiTag` type.
 use crate::{
     check_remaining, derive_ffi_traits, ffi_converter_rust_buffer_lift_and_lower, metadata,
-    ConvertError, FfiConverter, Lift, LiftRef, LiftReturn, Lower, LowerReturn, MetadataBuffer,
-    Result, RustBuffer, UnexpectedUniFFICallbackError,
+    ConvertError, FfiConverter, Lift, LiftArgsError, LiftRef, LiftReturn, Lower, LowerError,
+    LowerReturn, MetadataBuffer, Result, RustBuffer, RustCallError, TypeId,
+    UnexpectedUniFFICallbackError,
 };
 use anyhow::bail;
 use bytes::buf::{Buf, BufMut};
@@ -32,7 +33,7 @@ use paste::paste;
 use std::{
     collections::HashMap,
     convert::TryFrom,
-    error::Error,
+    fmt::{Debug, Display},
     sync::Arc,
     time::{Duration, SystemTime},
 };
@@ -270,9 +271,6 @@ unsafe impl<UT, T: Lower<UT>> Lower<UT> for Option<T> {
     fn lower(obj: Option<T>) -> RustBuffer {
         Self::lower_into_rust_buffer(obj)
     }
-
-    const TYPE_ID_META: MetadataBuffer =
-        MetadataBuffer::from_code(metadata::codes::TYPE_OPTION).concat(T::TYPE_ID_META);
 }
 
 unsafe impl<UT, T: Lift<UT>> Lift<UT> for Option<T> {
@@ -290,7 +288,9 @@ unsafe impl<UT, T: Lift<UT>> Lift<UT> for Option<T> {
     fn try_lift(buf: RustBuffer) -> Result<Option<T>> {
         Self::try_lift_from_rust_buffer(buf)
     }
+}
 
+impl<UT, T: TypeId<UT>> TypeId<UT> for Option<T> {
     const TYPE_ID_META: MetadataBuffer =
         MetadataBuffer::from_code(metadata::codes::TYPE_OPTION).concat(T::TYPE_ID_META);
 }
@@ -320,9 +320,6 @@ unsafe impl<UT, T: Lower<UT>> Lower<UT> for Vec<T> {
     fn lower(obj: Vec<T>) -> RustBuffer {
         Self::lower_into_rust_buffer(obj)
     }
-
-    const TYPE_ID_META: MetadataBuffer =
-        MetadataBuffer::from_code(metadata::codes::TYPE_VEC).concat(T::TYPE_ID_META);
 }
 
 /// Support for associative arrays via the FFI - `record<u32, u64>` in UDL.
@@ -346,7 +343,9 @@ unsafe impl<UT, T: Lift<UT>> Lift<UT> for Vec<T> {
     fn try_lift(buf: RustBuffer) -> Result<Vec<T>> {
         Self::try_lift_from_rust_buffer(buf)
     }
+}
 
+impl<UT, T: TypeId<UT>> TypeId<UT> for Vec<T> {
     const TYPE_ID_META: MetadataBuffer =
         MetadataBuffer::from_code(metadata::codes::TYPE_VEC).concat(T::TYPE_ID_META);
 }
@@ -371,10 +370,6 @@ where
     fn lower(obj: HashMap<K, V>) -> RustBuffer {
         Self::lower_into_rust_buffer(obj)
     }
-
-    const TYPE_ID_META: MetadataBuffer = MetadataBuffer::from_code(metadata::codes::TYPE_HASH_MAP)
-        .concat(K::TYPE_ID_META)
-        .concat(V::TYPE_ID_META);
 }
 
 unsafe impl<K, V, UT> Lift<UT> for HashMap<K, V>
@@ -399,7 +394,13 @@ where
     fn try_lift(buf: RustBuffer) -> Result<HashMap<K, V>> {
         Self::try_lift_from_rust_buffer(buf)
     }
+}
 
+impl<K, V, UT> TypeId<UT> for HashMap<K, V>
+where
+    K: TypeId<UT> + std::hash::Hash + Eq,
+    V: TypeId<UT>,
+{
     const TYPE_ID_META: MetadataBuffer = MetadataBuffer::from_code(metadata::codes::TYPE_HASH_MAP)
         .concat(K::TYPE_ID_META)
         .concat(V::TYPE_ID_META);
@@ -425,14 +426,17 @@ derive_ffi_traits!(blanket SystemTime);
 // Note that this means we don't get specialized return handling.  For example, if we could return
 // an `Option<Result<>>` we would always return that type directly and never throw.
 derive_ffi_traits!(impl<T, UT> LowerReturn<UT> for Option<T> where Option<T>: Lower<UT>);
+derive_ffi_traits!(impl<T, UT> LowerError<UT> for Option<T> where Option<T>: Lower<UT>);
 derive_ffi_traits!(impl<T, UT> LiftReturn<UT> for Option<T> where Option<T>: Lift<UT>);
 derive_ffi_traits!(impl<T, UT> LiftRef<UT> for Option<T> where Option<T>: Lift<UT>);
 
 derive_ffi_traits!(impl<T, UT> LowerReturn<UT> for Vec<T> where Vec<T>: Lower<UT>);
+derive_ffi_traits!(impl<T, UT> LowerError<UT> for Vec<T> where Vec<T>: Lower<UT>);
 derive_ffi_traits!(impl<T, UT> LiftReturn<UT> for Vec<T> where Vec<T>: Lift<UT>);
 derive_ffi_traits!(impl<T, UT> LiftRef<UT> for Vec<T> where Vec<T>: Lift<UT>);
 
 derive_ffi_traits!(impl<K, V, UT> LowerReturn<UT> for HashMap<K, V> where HashMap<K, V>: Lower<UT>);
+derive_ffi_traits!(impl<K, V, UT> LowerError<UT> for HashMap<K, V> where HashMap<K, V>: Lower<UT>);
 derive_ffi_traits!(impl<K, V, UT> LiftReturn<UT> for HashMap<K, V> where HashMap<K, V>: Lift<UT>);
 derive_ffi_traits!(impl<K, V, UT> LiftRef<UT> for HashMap<K, V> where HashMap<K, V>: Lift<UT>);
 
@@ -440,19 +444,19 @@ derive_ffi_traits!(impl<K, V, UT> LiftRef<UT> for HashMap<K, V> where HashMap<K,
 derive_ffi_traits!(impl<T, UT> Lower<UT> for Arc<T> where Arc<T>: FfiConverter<UT>, T: ?Sized);
 derive_ffi_traits!(impl<T, UT> Lift<UT> for Arc<T> where Arc<T>: FfiConverter<UT>, T: ?Sized);
 derive_ffi_traits!(impl<T, UT> LowerReturn<UT> for Arc<T> where Arc<T>: Lower<UT>, T: ?Sized);
+derive_ffi_traits!(impl<T, UT> LowerError<UT> for Arc<T> where Arc<T>: Lower<UT>, T: ?Sized);
 derive_ffi_traits!(impl<T, UT> LiftReturn<UT> for Arc<T> where Arc<T>: Lift<UT>, T: ?Sized);
 derive_ffi_traits!(impl<T, UT> LiftRef<UT> for Arc<T> where Arc<T>: Lift<UT>, T: ?Sized);
+derive_ffi_traits!(impl<T, UT> TypeId<UT> for Arc<T> where Arc<T>: FfiConverter<UT>, T: ?Sized);
 
 // Implement LowerReturn/LiftReturn for the unit type (void returns)
 
 unsafe impl<UT> LowerReturn<UT> for () {
     type ReturnType = ();
 
-    fn lower_return(_: ()) -> Result<Self::ReturnType, RustBuffer> {
+    fn lower_return(_: ()) -> Result<Self::ReturnType, RustCallError> {
         Ok(())
     }
-
-    const TYPE_ID_META: MetadataBuffer = MetadataBuffer::from_code(metadata::codes::TYPE_UNIT);
 }
 
 unsafe impl<UT> LiftReturn<UT> for () {
@@ -461,7 +465,9 @@ unsafe impl<UT> LiftReturn<UT> for () {
     fn try_lift_successful_return(_: ()) -> Result<Self> {
         Ok(())
     }
+}
 
+impl<UT> TypeId<UT> for () {
     const TYPE_ID_META: MetadataBuffer = MetadataBuffer::from_code(metadata::codes::TYPE_UNIT);
 }
 
@@ -471,27 +477,26 @@ unsafe impl<UT> LiftReturn<UT> for () {
 unsafe impl<UT, R, E> LowerReturn<UT> for Result<R, E>
 where
     R: LowerReturn<UT>,
-    E: Lower<UT> + Error + Send + Sync + 'static,
+    E: LowerError<UT> + Display + Debug + Send + Sync + 'static,
 {
     type ReturnType = R::ReturnType;
 
-    fn lower_return(v: Self) -> Result<Self::ReturnType, RustBuffer> {
+    fn lower_return(v: Self) -> Result<Self::ReturnType, RustCallError> {
         match v {
             Ok(r) => R::lower_return(r),
-            Err(e) => Err(E::lower_into_rust_buffer(e)),
+            Err(e) => Err(RustCallError::Error(E::lower_error(e))),
         }
     }
 
-    fn handle_failed_lift(arg_name: &str, err: anyhow::Error) -> Self {
-        match err.downcast::<E>() {
-            Ok(actual_error) => Err(actual_error),
-            Err(ohno) => panic!("Failed to convert arg '{arg_name}': {ohno}"),
+    fn handle_failed_lift(error: LiftArgsError) -> Result<Self::ReturnType, RustCallError> {
+        match error.error.downcast::<E>() {
+            Ok(downcast) => Err(RustCallError::Error(E::lower_error(downcast))),
+            Err(e) => {
+                let msg = format!("Failed to convert arg '{}': {e}", error.arg_name);
+                Err(RustCallError::InternalError(msg))
+            }
         }
     }
-
-    const TYPE_ID_META: MetadataBuffer = MetadataBuffer::from_code(metadata::codes::TYPE_RESULT)
-        .concat(R::TYPE_ID_META)
-        .concat(E::TYPE_ID_META);
 }
 
 unsafe impl<UT, R, E> LiftReturn<UT> for Result<R, E>
@@ -519,7 +524,13 @@ where
     fn handle_callback_unexpected_error(e: UnexpectedUniFFICallbackError) -> Self {
         Err(E::try_convert_unexpected_callback_error(e).unwrap_or_else(|e| panic!("{e}")))
     }
+}
 
+impl<UT, R, E> TypeId<UT> for Result<R, E>
+where
+    R: TypeId<UT>,
+    E: TypeId<UT>,
+{
     const TYPE_ID_META: MetadataBuffer = MetadataBuffer::from_code(metadata::codes::TYPE_RESULT)
         .concat(R::TYPE_ID_META)
         .concat(E::TYPE_ID_META);
diff --git a/third_party/rust/uniffi_core/src/ffi_converter_traits.rs b/third_party/rust/uniffi_core/src/ffi_converter_traits.rs
index 4e7b9e06fa80..8362bfdb26cf 100644
--- a/third_party/rust/uniffi_core/src/ffi_converter_traits.rs
+++ b/third_party/rust/uniffi_core/src/ffi_converter_traits.rs
@@ -9,20 +9,24 @@
 //! proc-macro generated code.  The goal is to allow the proc-macros to go from a type name to the
 //! correct function for a given FFI operation.
 //!
-//! The traits form a sort-of tree structure from general to specific:
+//! The main traits form a sort-of tree structure from general to specific:
 //! ```ignore
 //!
-//!                   [FfiConverter]
-//!                        |
-//!           -----------------------------
-//!           |                           |
-//!       [Lower]                      [Lift]
-//!           |                           |
-//!           |                       --------------
-//!           |                       |            |
-//!       [LowerReturn]           [LiftRef]  [LiftReturn]
+//!                         [FfiConverter]
+//!                               |
+//!            -----------------------------------------
+//!            |                                       |
+//!         [Lower]                                  [Lift]
+//!            |                                       |
+//!        -----------------                    --------------
+//!        |               |                    |            |
+//!   [LowerReturn]  [LowerError]          [LiftRef]  [LiftReturn]
 //! ```
 //!
+//! There's also:
+//!   - [TypeId], which is implemented for all types that implement any of the above traits.
+//!   - [ConvertError], which is implement for errors that can be used in callback interfaces.
+//!
 //! The `derive_ffi_traits` macro can be used to derive the specific traits from the general ones.
 //! Here's the main ways we implement these traits:
 //!
@@ -39,21 +43,21 @@
 //!
 //! ## Safety
 //!
-//! All traits are unsafe (implementing it requires `unsafe impl`) because we can't guarantee
+//! Most traits are unsafe (implementing it requires `unsafe impl`) because we can't guarantee
 //! that it's safe to pass your type out to foreign-language code and back again. Buggy
 //! implementations of this trait might violate some assumptions made by the generated code,
 //! or might not match with the corresponding code in the generated foreign-language bindings.
 //! These traits should not be used directly, only in generated code, and the generated code should
 //! have fixture tests to test that everything works correctly together.
 
-use std::{borrow::Borrow, sync::Arc};
+use std::{borrow::Borrow, mem::ManuallyDrop, sync::Arc};
 
 use anyhow::bail;
 use bytes::Buf;
 
 use crate::{
-    FfiDefault, Handle, MetadataBuffer, Result, RustBuffer, RustCallStatus, RustCallStatusCode,
-    UnexpectedUniFFICallbackError,
+    FfiDefault, Handle, LiftArgsError, MetadataBuffer, Result, RustBuffer, RustCallError,
+    RustCallStatus, RustCallStatusCode, UnexpectedUniFFICallbackError,
 };
 
 /// Generalized FFI conversions
@@ -128,8 +132,6 @@ pub unsafe trait FfiConverter<UT>: Sized {
     fn try_read(buf: &mut &[u8]) -> Result<Self>;
 
     /// Type ID metadata, serialized into a [MetadataBuffer].
-    ///
-    /// If a type implements multiple FFI traits, `TYPE_ID_META` must be the same for all of them.
     const TYPE_ID_META: MetadataBuffer;
 }
 
@@ -217,8 +219,6 @@ pub unsafe trait Lift<UT>: Sized {
             n => bail!("junk data left in buffer after lifting (count: {n})",),
         }
     }
-
-    const TYPE_ID_META: MetadataBuffer;
 }
 
 /// Lower Rust values to pass them to the foreign code
@@ -249,13 +249,11 @@ pub unsafe trait Lower<UT>: Sized {
         Self::write(obj, &mut buf);
         RustBuffer::from_vec(buf)
     }
-
-    const TYPE_ID_META: MetadataBuffer;
 }
 
 /// Return Rust values to the foreign code
 ///
-/// This is usually derived from [Lift], but we special case types like `Result<>` and `()`.
+/// This is usually derived from [Lower], but we special case types like `Result<>` and `()`.
 ///
 /// ## Safety
 ///
@@ -271,25 +269,50 @@ pub unsafe trait LowerReturn<UT>: Sized {
     /// When derived, it's the same as `FfiType`.
     type ReturnType: FfiDefault;
 
+    /// Lower the return value from an scaffolding call
+    ///
+    /// Returns values that [rust_call] expects:
+    ///
+    /// - Ok(v) for `Ok` returns and non-result returns, where v is the lowered return value
+    /// - `Err(RustCallError::Error(buf))` for `Err` returns where `buf` is serialized error value.
+    fn lower_return(v: Self) -> Result<Self::ReturnType, RustCallError>;
+
+    /// Lower the return value for failed argument lifts
+    ///
+    /// This is called when we fail to make a scaffolding call, because of an error lifting an
+    /// argument.  It should return a value that [rust_call] expects:
+    ///
+    /// - By default, this is `Err(RustCallError::InternalError(msg))` where `msg` is message
+    ///   describing the failed lift.
+    /// - For Result types, if we can downcast the error to the `Err` value, then return
+    ///   `Err(RustCallError::Error(buf))`. This results in better exception throws on the foreign
+    ///   side.
+    fn handle_failed_lift(error: LiftArgsError) -> Result<Self::ReturnType, RustCallError> {
+        let LiftArgsError { arg_name, error } = error;
+        Err(RustCallError::InternalError(format!(
+            "Failed to convert arg '{arg_name}': {error}"
+        )))
+    }
+}
+
+/// Return Rust error values
+///
+/// This is implemented for types that can be the `E` param in `Result<T, E>`.
+/// It's is usually derived from [Lower], but we sometimes special case it.
+///
+/// ## Safety
+///
+/// All traits are unsafe (implementing it requires `unsafe impl`) because we can't guarantee
+/// that it's safe to pass your type out to foreign-language code and back again. Buggy
+/// implementations of this trait might violate some assumptions made by the generated code,
+/// or might not match with the corresponding code in the generated foreign-language bindings.
+/// These traits should not be used directly, only in generated code, and the generated code should
+/// have fixture tests to test that everything works correctly together.
+pub unsafe trait LowerError<UT>: Sized {
     /// Lower this value for scaffolding function return
     ///
-    /// This method converts values into the `Result<>` type that [rust_call] expects. For
-    /// successful calls, return `Ok(lower_return)`.  For errors that should be translated into
-    /// thrown exceptions on the foreign code, serialize the error into a RustBuffer and return
-    /// `Err(buf)`
-    fn lower_return(obj: Self) -> Result<Self::ReturnType, RustBuffer>;
-
-    /// If possible, get a serialized error for failed argument lifts
-    ///
-    /// By default, we just panic and let `rust_call` handle things.  However, for `Result<_, E>`
-    /// returns, if the anyhow error can be downcast to `E`, then serialize that and return it.
-    /// This results in the foreign code throwing a "normal" exception, rather than an unexpected
-    /// exception.
-    fn handle_failed_lift(arg_name: &str, e: anyhow::Error) -> Self {
-        panic!("Failed to convert arg '{arg_name}': {e}")
-    }
-
-    const TYPE_ID_META: MetadataBuffer;
+    /// Lower the type into a RustBuffer.  `RustCallStatus.error_buf` will be set to this.
+    fn lower_error(obj: Self) -> RustBuffer;
 }
 
 /// Return foreign values to Rust
@@ -323,12 +346,12 @@ pub unsafe trait LiftReturn<UT>: Sized {
                     Self::handle_callback_unexpected_error(UnexpectedUniFFICallbackError::new(e))
                 }),
             RustCallStatusCode::Error => {
-                Self::lift_error(unsafe { call_status.error_buf.assume_init() })
+                Self::lift_error(ManuallyDrop::into_inner(call_status.error_buf))
             }
             _ => {
-                let e = <String as FfiConverter<crate::UniFfiTag>>::try_lift(unsafe {
-                    call_status.error_buf.assume_init()
-                })
+                let e = <String as FfiConverter<crate::UniFfiTag>>::try_lift(
+                    ManuallyDrop::into_inner(call_status.error_buf),
+                )
                 .unwrap_or_else(|e| format!("(Error lifting message: {e}"));
                 Self::handle_callback_unexpected_error(UnexpectedUniFFICallbackError::new(e))
             }
@@ -355,8 +378,6 @@ pub unsafe trait LiftReturn<UT>: Sized {
     fn handle_callback_unexpected_error(e: UnexpectedUniFFICallbackError) -> Self {
         panic!("Callback interface failure: {e}")
     }
-
-    const TYPE_ID_META: MetadataBuffer;
 }
 
 /// Lift references
@@ -377,6 +398,14 @@ pub unsafe trait LiftRef<UT> {
     type LiftType: Lift<UT> + Borrow<Self>;
 }
 
+/// Type ID metadata
+///
+/// This is used to build up more complex metadata.  For example, the `MetadataBuffer` for function
+/// signatures includes a copy of this metadata for each argument and return type.
+pub trait TypeId<UT> {
+    const TYPE_ID_META: MetadataBuffer;
+}
+
 pub trait ConvertError<UT>: Sized {
     fn try_convert_unexpected_callback_error(e: UnexpectedUniFFICallbackError) -> Result<Self>;
 }
@@ -427,18 +456,24 @@ pub unsafe trait HandleAlloc<UT>: Send + Sync {
     /// This creates a new handle from an existing one.
     /// It's used when the foreign code wants to pass back an owned handle and still keep a copy
     /// for themselves.
-    fn clone_handle(handle: Handle) -> Handle;
+    /// # Safety
+    /// The handle must be valid.
+    unsafe fn clone_handle(handle: Handle) -> Handle;
 
     /// Get a clone of the `Arc<>` using a "borrowed" handle.
     ///
-    /// Take care that the handle can not be destroyed between when it's passed and when
+    /// # Safety
+    /// The handle must be valid. Take care that the handle can
+    /// not be destroyed between when it's passed and when
     /// `get_arc()` is called.  #1797 is a cautionary tale.
-    fn get_arc(handle: Handle) -> Arc<Self> {
+    unsafe fn get_arc(handle: Handle) -> Arc<Self> {
         Self::consume_handle(Self::clone_handle(handle))
     }
 
     /// Consume a handle, getting back the initial `Arc<>`
-    fn consume_handle(handle: Handle) -> Arc<Self>;
+    /// # Safety
+    /// The handle must be valid.
+    unsafe fn consume_handle(handle: Handle) -> Arc<Self>;
 }
 
 /// Derive FFI traits
@@ -465,18 +500,22 @@ macro_rules! derive_ffi_traits {
         $crate::derive_ffi_traits!(impl<UT> Lower<UT> for $ty);
         $crate::derive_ffi_traits!(impl<UT> Lift<UT> for $ty);
         $crate::derive_ffi_traits!(impl<UT> LowerReturn<UT> for $ty);
+        $crate::derive_ffi_traits!(impl<UT> LowerError<UT> for $ty);
         $crate::derive_ffi_traits!(impl<UT> LiftReturn<UT> for $ty);
         $crate::derive_ffi_traits!(impl<UT> LiftRef<UT> for $ty);
         $crate::derive_ffi_traits!(impl<UT> ConvertError<UT> for $ty);
+        $crate::derive_ffi_traits!(impl<UT> TypeId<UT> for $ty);
     };
 
     (local $ty:ty) => {
         $crate::derive_ffi_traits!(impl Lower<crate::UniFfiTag> for $ty);
         $crate::derive_ffi_traits!(impl Lift<crate::UniFfiTag> for $ty);
         $crate::derive_ffi_traits!(impl LowerReturn<crate::UniFfiTag> for $ty);
+        $crate::derive_ffi_traits!(impl LowerError<crate::UniFfiTag> for $ty);
         $crate::derive_ffi_traits!(impl LiftReturn<crate::UniFfiTag> for $ty);
         $crate::derive_ffi_traits!(impl LiftRef<crate::UniFfiTag> for $ty);
         $crate::derive_ffi_traits!(impl ConvertError<crate::UniFfiTag> for $ty);
+        $crate::derive_ffi_traits!(impl TypeId<crate::UniFfiTag> for $ty);
     };
 
     (impl $(<$($generic:ident),*>)? $(::uniffi::)? Lower<$ut:path> for $ty:ty $(where $($where:tt)*)?) => {
@@ -491,8 +530,6 @@ macro_rules! derive_ffi_traits {
             fn write(obj: Self, buf: &mut ::std::vec::Vec<u8>) {
                 <Self as $crate::FfiConverter<$ut>>::write(obj, buf)
             }
-
-            const TYPE_ID_META: $crate::MetadataBuffer = <Self as $crate::FfiConverter<$ut>>::TYPE_ID_META;
         }
     };
 
@@ -508,8 +545,6 @@ macro_rules! derive_ffi_traits {
             fn try_read(buf: &mut &[u8]) -> $crate::deps::anyhow::Result<Self> {
                 <Self as $crate::FfiConverter<$ut>>::try_read(buf)
             }
-
-            const TYPE_ID_META: $crate::MetadataBuffer = <Self as $crate::FfiConverter<$ut>>::TYPE_ID_META;
         }
     };
 
@@ -518,11 +553,18 @@ macro_rules! derive_ffi_traits {
         {
             type ReturnType = <Self as $crate::Lower<$ut>>::FfiType;
 
-            fn lower_return(obj: Self) -> $crate::deps::anyhow::Result<Self::ReturnType, $crate::RustBuffer> {
-                Ok(<Self as $crate::Lower<$ut>>::lower(obj))
+            fn lower_return(v: Self) -> $crate::deps::anyhow::Result<Self::ReturnType, $crate::RustCallError> {
+                ::std::result::Result::Ok(<Self as $crate::Lower<$ut>>::lower(v))
             }
+        }
+    };
 
-            const TYPE_ID_META: $crate::MetadataBuffer =<Self as $crate::Lower<$ut>>::TYPE_ID_META;
+    (impl $(<$($generic:ident),*>)? $(::uniffi::)? LowerError<$ut:path> for $ty:ty $(where $($where:tt)*)?) => {
+        unsafe impl $(<$($generic),*>)* $crate::LowerError<$ut> for $ty $(where $($where)*)*
+        {
+            fn lower_error(obj: Self) -> $crate::RustBuffer {
+                <Self as $crate::Lower<$ut>>::lower_into_rust_buffer(obj)
+            }
         }
     };
 
@@ -534,8 +576,6 @@ macro_rules! derive_ffi_traits {
             fn try_lift_successful_return(v: Self::ReturnType) -> $crate::Result<Self> {
                 <Self as $crate::Lift<$ut>>::try_lift(v)
             }
-
-            const TYPE_ID_META: $crate::MetadataBuffer = <Self as $crate::Lift<$ut>>::TYPE_ID_META;
         }
     };
 
@@ -569,22 +609,25 @@ macro_rules! derive_ffi_traits {
                 $crate::Handle::from_pointer(::std::sync::Arc::into_raw(::std::sync::Arc::new(value)))
             }
 
-            fn clone_handle(handle: $crate::Handle) -> $crate::Handle {
-                unsafe {
-                    ::std::sync::Arc::<::std::sync::Arc<Self>>::increment_strong_count(handle.as_pointer::<::std::sync::Arc<Self>>());
-                }
+            unsafe fn clone_handle(handle: $crate::Handle) -> $crate::Handle {
+                ::std::sync::Arc::<::std::sync::Arc<Self>>::increment_strong_count(handle.as_pointer::<::std::sync::Arc<Self>>());
                 handle
             }
 
-            fn consume_handle(handle: $crate::Handle) -> ::std::sync::Arc<Self> {
-                unsafe {
-                    ::std::sync::Arc::<Self>::clone(
-                        &std::sync::Arc::<::std::sync::Arc::<Self>>::from_raw(handle.as_pointer::<::std::sync::Arc<Self>>())
-                    )
-                }
+            unsafe fn consume_handle(handle: $crate::Handle) -> ::std::sync::Arc<Self> {
+                ::std::sync::Arc::<Self>::clone(
+                    &std::sync::Arc::<::std::sync::Arc::<Self>>::from_raw(handle.as_pointer::<::std::sync::Arc<Self>>())
+                )
             }
         }
     };
+
+    (impl $(<$($generic:ident),*>)? $(::uniffi::)? TypeId<$ut:path> for $ty:ty $(where $($where:tt)*)?) => {
+        impl $(<$($generic),*>)* $crate::TypeId<$ut> for $ty $(where $($where)*)*
+        {
+            const TYPE_ID_META: $crate::MetadataBuffer = <Self as $crate::FfiConverter<$ut>>::TYPE_ID_META;
+        }
+    };
 }
 
 unsafe impl<T: Send + Sync, UT> HandleAlloc<UT> for T {
@@ -592,12 +635,12 @@ unsafe impl<T: Send + Sync, UT> HandleAlloc<UT> for T {
         Handle::from_pointer(Arc::into_raw(value))
     }
 
-    fn clone_handle(handle: Handle) -> Handle {
-        unsafe { Arc::increment_strong_count(handle.as_pointer::<T>()) };
+    unsafe fn clone_handle(handle: Handle) -> Handle {
+        Arc::increment_strong_count(handle.as_pointer::<T>());
         handle
     }
 
-    fn consume_handle(handle: Handle) -> Arc<Self> {
-        unsafe { Arc::from_raw(handle.as_pointer()) }
+    unsafe fn consume_handle(handle: Handle) -> Arc<Self> {
+        Arc::from_raw(handle.as_pointer())
     }
 }
diff --git a/third_party/rust/uniffi_core/src/lib.rs b/third_party/rust/uniffi_core/src/lib.rs
index de6cff8a66e0..2d55006ba76c 100644
--- a/third_party/rust/uniffi_core/src/lib.rs
+++ b/third_party/rust/uniffi_core/src/lib.rs
@@ -49,7 +49,7 @@ pub use ffi::ffiserialize::FfiBufferElement;
 pub use ffi::*;
 pub use ffi_converter_traits::{
     ConvertError, FfiConverter, FfiConverterArc, HandleAlloc, Lift, LiftRef, LiftReturn, Lower,
-    LowerReturn,
+    LowerError, LowerReturn, TypeId,
 };
 pub use metadata::*;
 
@@ -176,7 +176,7 @@ macro_rules! ffi_converter_rust_buffer_lift_and_lower {
             let mut buf = vec.as_slice();
             let value = <Self as $crate::FfiConverter<$uniffi_tag>>::try_read(&mut buf)?;
             match $crate::deps::bytes::Buf::remaining(&buf) {
-                0 => Ok(value),
+                0 => ::std::result::Result::Ok(value),
                 n => $crate::deps::anyhow::bail!(
                     "junk data left in buffer after lifting (count: {n})",
                 ),
diff --git a/third_party/rust/uniffi_core/src/metadata.rs b/third_party/rust/uniffi_core/src/metadata.rs
index dc61a1bfcbc7..d6b22093ade2 100644
--- a/third_party/rust/uniffi_core/src/metadata.rs
+++ b/third_party/rust/uniffi_core/src/metadata.rs
@@ -173,15 +173,6 @@ impl MetadataBuffer {
         self.concat_value(value as u8)
     }
 
-    // Option<bool>
-    pub const fn concat_option_bool(self, value: Option<bool>) -> Self {
-        self.concat_value(match value {
-            None => 0,
-            Some(false) => 1,
-            Some(true) => 2,
-        })
-    }
-
     // Concatenate a string to this buffer. The maximum string length is 255 bytes. For longer strings,
     // use `concat_long_str()`.
     //
diff --git a/third_party/rust/uniffi_macros/.cargo-checksum.json b/third_party/rust/uniffi_macros/.cargo-checksum.json
index d7d49c568d52..45de207080f7 100644
--- a/third_party/rust/uniffi_macros/.cargo-checksum.json
+++ b/third_party/rust/uniffi_macros/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"32636b759af83af70f08c4573c101f0467eb8469c318d08dcfbc4578fe456660","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/custom.rs":"36cd6c2eeb8efdc34e59dff634a22e79471ab17f49ceb0f131da5f144313f7e4","src/default.rs":"77466ac54da69094bcdccc5927d0980b1e9dd0095647ca825830673c48847a53","src/enum_.rs":"afe0a6534d8e7f68047e3f1afad9369d5d5650f4c7555e8d4173f24126c715ba","src/error.rs":"30168378da9a23e6530ffe68647bf6618d07a0aaa236d5009137a922798a0e88","src/export.rs":"42c5e784c1dccc796c8b6ea29c2dc1811e48a531488a3ed0e2a59330778a7e41","src/export/attributes.rs":"c848f8c309c4cf7a168f038834752dc4816b5c853768d7c331ea4cd5ce0841b7","src/export/callback_interface.rs":"794b0665dc7eb02ea854c61c8bb2781e0b4ac1de646d95a8fd7791f770f2e6e3","src/export/item.rs":"4e86875692c2d2993fde12e78dbde2cbffa5675ede143577d5620126401efe05","src/export/scaffolding.rs":"03abb762391f67b43bec89dae8f57b54b014133193a8337436f4129de51fb987","src/export/trait_interface.rs":"f07f9908ee28661de4586d89b693f3d93dae5e5cba8a089eff25f20bbf6b373b","src/export/utrait.rs":"b55533d3eef8262944d3c0d9a3a9cba0615d2d5af8608f0919abc7699989e2a8","src/fnsig.rs":"5e434a1cc87166c5245424bb14e896eb766bf680d4d50d4b8536852f91487d7c","src/lib.rs":"a28bbfd2d1dc835306ff6072f75761bb6b3a158477bba966057776c527fe6d70","src/object.rs":"5419ed64c8120aef811a77c2205f58a7a537bdf34ae04f9c92dd3aaa176eed39","src/record.rs":"29072542cc2f3e027bd7c59b45ba913458f8213d1b2b33bc70d140baa98fcdc8","src/setup_scaffolding.rs":"173fdc916967d54bd6532def16d12e5bb85467813a46a031d3338b77625756bb","src/test.rs":"1673f282bb35d6b0740ad0e5f11826c2852d7a0db29604c2258f457415b537e8","src/util.rs":"d1b7b80d0bcc43b7794cd2dbdd89194f84b098343f9e0a3f1843e91c95e1ded3"},"package":"b6f08d5592c669b80a8af5066027098bebec4b4af17a9b8b299bac5f518ab89e"}
\ No newline at end of file
+{"files":{"Cargo.toml":"c4309008a3a1c8ba72dbaa015b346ffe46efa2e84e23d7a9d9838e04950f5fe1","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/custom.rs":"e5753c73aff42af13a17ddcd5d8e723c988a32bcb764a03bd5a6653612adc647","src/default.rs":"77466ac54da69094bcdccc5927d0980b1e9dd0095647ca825830673c48847a53","src/derive.rs":"3e34ce065c61a76c461fc9241f2a0fade57469623b6744c872389a3e8508f964","src/enum_.rs":"de3807662071222877a1abc4aad9cd04bfa16850f1e36a18f078addfed73e775","src/error.rs":"6d1a9946fbe587622bdb7ad3eabde4bdceac64d542fb686a7031f4a1ded5b55c","src/export.rs":"b8ed2bb98487a7b8b87597a3922ce1641aad786f6d53ecd46956d3f4582b6745","src/export/attributes.rs":"29835ea10f0399c98490ab6396e840baa293ab7fa9986c65e637961345df2900","src/export/callback_interface.rs":"fae7786c85a436fff79492e9ec7b7fba0fac5241d08c7f60b279f4e845916adc","src/export/item.rs":"5523c1afd7c270689acadf60a7e013b2503dbfa28dd2e984fc3c3ab3532b2a3f","src/export/scaffolding.rs":"acd8004544324ac407074ba51053c3ecc98069876718435f78a582397f860fc4","src/export/trait_interface.rs":"245a42e59988d0e895e914310e7e2a24b315f8a440da5177bb5d33ff35cba2bd","src/export/utrait.rs":"9547c8efefd2997f7d56b5d8b08b54b68abac492e205fbfeeb189276f96f4b99","src/ffiops.rs":"f377367435d649a180318648325acd683ace8ae41c0c6a4243e0d578c0fab2ae","src/fnsig.rs":"2d117c24cdb794667787f7de59930f3d49a4bdb105c1a8e443b94a7d84e6d59c","src/lib.rs":"d7d1255ea9075350f785dd5e439334792282fcfb1dbb7cd00b908d5ea3216924","src/object.rs":"d9c53f0639a3b5a3d2d04e4f4b03b5fb62818cfcc08adfb942bb756867390794","src/record.rs":"9d8cc3fe9ef44ff2554b90fdd4b0b9e647a75f6d1002145c4a4291f7cdff20f4","src/setup_scaffolding.rs":"2ab0b934046e9a17ebe0c82041033e398e12dd0f2bd5d7bfbb26def6e0476f69","src/test.rs":"6de5c5719f0ece8b2fb5a3cf838628e8c733f623f31838cb4ee670ca03ebb0de","src/util.rs":"5c14930838c638ecceff39e738969c94f3e6d5d6c994e3fd43a7a9162a81c4d9"},"package":"db66474c5c61b0f7afc3b4995fecf9b72b340daa5ca0ef3da7778d75eb5482ea"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_macros/Cargo.toml b/third_party/rust/uniffi_macros/Cargo.toml
index c7a602e3ac6a..9847e9f56843 100644
--- a/third_party/rust/uniffi_macros/Cargo.toml
+++ b/third_party/rust/uniffi_macros/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_macros"
-version = "0.27.3"
+version = "0.28.1"
 authors = ["Firefox Sync Team <sync-team@mozilla.com>"]
 description = "a multi-language bindings generator for rust (convenience macros)"
 homepage = "https://mozilla.github.io/uniffi-rs"
@@ -61,11 +61,11 @@ features = [
 version = "0.5.9"
 
 [dependencies.uniffi_build]
-version = "=0.27.3"
+version = "=0.28.1"
 optional = true
 
 [dependencies.uniffi_meta]
-version = "=0.27.3"
+version = "=0.28.1"
 
 [features]
 default = []
diff --git a/third_party/rust/uniffi_macros/src/custom.rs b/third_party/rust/uniffi_macros/src/custom.rs
index 9d8e5acde61c..991a74f30589 100644
--- a/third_party/rust/uniffi_macros/src/custom.rs
+++ b/third_party/rust/uniffi_macros/src/custom.rs
@@ -2,7 +2,10 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
-use crate::util::{derive_all_ffi_traits, ident_to_string, mod_path, tagged_impl_header};
+use crate::{
+    ffiops,
+    util::{derive_all_ffi_traits, ident_to_string, mod_path, tagged_impl_header},
+};
 use proc_macro2::{Ident, TokenStream};
 use quote::quote;
 use syn::Path;
@@ -18,6 +21,14 @@ pub(crate) fn expand_ffi_converter_custom_type(
     let derive_ffi_traits = derive_all_ffi_traits(ident, udl_mode);
     let name = ident_to_string(ident);
     let mod_path = mod_path()?;
+    let from_custom = quote! { <#ident as crate::UniffiCustomTypeConverter>::from_custom };
+    let into_custom = quote! { <#ident as crate::UniffiCustomTypeConverter>::into_custom };
+    let lower_type = ffiops::lower_type(builtin);
+    let lower = ffiops::lower(builtin);
+    let write = ffiops::write(builtin);
+    let try_lift = ffiops::try_lift(builtin);
+    let try_read = ffiops::try_read(builtin);
+    let type_id_meta = ffiops::type_id_meta(builtin);
 
     Ok(quote! {
         #[automatically_derived]
@@ -25,27 +36,27 @@ pub(crate) fn expand_ffi_converter_custom_type(
             // Note: the builtin type needs to implement both `Lower` and `Lift'.  We use the
             // `Lower` trait to get the associated type `FfiType` and const `TYPE_ID_META`.  These
             // can't differ between `Lower` and `Lift`.
-            type FfiType = <#builtin as ::uniffi::Lower<crate::UniFfiTag>>::FfiType;
+            type FfiType = #lower_type;
             fn lower(obj: #ident ) -> Self::FfiType {
-                <#builtin as ::uniffi::Lower<crate::UniFfiTag>>::lower(<#ident as crate::UniffiCustomTypeConverter>::from_custom(obj))
+                #lower(#from_custom(obj))
             }
 
-            fn try_lift(v: Self::FfiType) -> uniffi::Result<#ident> {
-                <#ident as crate::UniffiCustomTypeConverter>::into_custom(<#builtin as ::uniffi::Lift<crate::UniFfiTag>>::try_lift(v)?)
+            fn try_lift(v: Self::FfiType) -> ::uniffi::Result<#ident> {
+                #into_custom(#try_lift(v)?)
             }
 
             fn write(obj: #ident, buf: &mut Vec<u8>) {
-                <#builtin as ::uniffi::Lower<crate::UniFfiTag>>::write(<#ident as crate::UniffiCustomTypeConverter>::from_custom(obj), buf);
+                #write(#from_custom(obj), buf);
             }
 
-            fn try_read(buf: &mut &[u8]) -> uniffi::Result<#ident> {
-                <#ident as crate::UniffiCustomTypeConverter>::into_custom(<#builtin as ::uniffi::Lift<crate::UniFfiTag>>::try_read(buf)?)
+            fn try_read(buf: &mut &[u8]) -> ::uniffi::Result<#ident> {
+                #into_custom(#try_read(buf)?)
             }
 
             const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::TYPE_CUSTOM)
                 .concat_str(#mod_path)
                 .concat_str(#name)
-                .concat(<#builtin as ::uniffi::Lower<crate::UniFfiTag>>::TYPE_ID_META);
+                .concat(#type_id_meta);
         }
 
         #derive_ffi_traits
@@ -64,6 +75,7 @@ pub(crate) fn expand_ffi_converter_custom_newtype(
     Ok(quote! {
         #ffi_converter
 
+        #[allow(non_camel_case_types)]
         #type_converter
     })
 }
@@ -73,8 +85,8 @@ fn custom_ffi_type_converter(ident: &Ident, builtin: &Path) -> syn::Result<Token
         impl crate::UniffiCustomTypeConverter for #ident {
             type Builtin = #builtin;
 
-            fn into_custom(val: Self::Builtin) -> uniffi::Result<Self> {
-                Ok(#ident(val))
+            fn into_custom(val: Self::Builtin) -> ::uniffi::Result<Self> {
+                ::std::result::Result::Ok(#ident(val))
             }
 
             fn from_custom(obj: Self) -> Self::Builtin {
diff --git a/third_party/rust/uniffi_macros/src/derive.rs b/third_party/rust/uniffi_macros/src/derive.rs
new file mode 100644
index 000000000000..571b5e88a520
--- /dev/null
+++ b/third_party/rust/uniffi_macros/src/derive.rs
@@ -0,0 +1,119 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! General handling for the derive and udl_derive macros
+
+use crate::util::kw;
+use proc_macro2::{Ident, Span, TokenStream};
+use quote::{quote, ToTokens};
+use syn::{
+    parse::{Parse, ParseStream},
+    DeriveInput,
+};
+
+pub fn expand_derive(
+    kind: DeriveKind,
+    input: DeriveInput,
+    options: DeriveOptions,
+) -> syn::Result<TokenStream> {
+    match kind {
+        DeriveKind::Record(_) => crate::record::expand_record(input, options),
+        DeriveKind::Object(_) => crate::object::expand_object(input, options),
+        DeriveKind::Enum(_) => crate::enum_::expand_enum(input, options),
+        DeriveKind::Error(_) => crate::error::expand_error(input, options),
+    }
+}
+
+pub enum DeriveKind {
+    Record(kw::Record),
+    Enum(kw::Enum),
+    Error(kw::Error),
+    Object(kw::Object),
+}
+
+impl Parse for DeriveKind {
+    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
+        let lookahead = input.lookahead1();
+        if lookahead.peek(kw::Record) {
+            Ok(Self::Record(input.parse()?))
+        } else if lookahead.peek(kw::Enum) {
+            Ok(Self::Enum(input.parse()?))
+        } else if lookahead.peek(kw::Error) {
+            Ok(Self::Error(input.parse()?))
+        } else if lookahead.peek(kw::Object) {
+            Ok(Self::Object(input.parse()?))
+        } else {
+            Err(lookahead.error())
+        }
+    }
+}
+
+pub struct DeriveOptions {
+    /// Should we implement FFI traits for the local UniFfiTag only?
+    pub local_tag: bool,
+    /// Should we generate metadata symbols?
+    pub generate_metadata: bool,
+}
+
+/// default() is used to construct a DeriveOptions for a regular `derive` invocation
+impl Default for DeriveOptions {
+    fn default() -> Self {
+        Self {
+            local_tag: false,
+            generate_metadata: true,
+        }
+    }
+}
+
+impl DeriveOptions {
+    /// Construct DeriveOptions for `udl_derive`
+    pub fn udl_derive() -> Self {
+        Self {
+            local_tag: true,
+            generate_metadata: false,
+        }
+    }
+
+    /// Generate the impl header for a FFI trait
+    ///
+    /// This will output something like `impl<UT> FfiConverter<UT> for #type`.  The caller is
+    /// responsible for providing the body if the impl block.
+    pub fn ffi_impl_header(&self, trait_name: &str, ident: &impl ToTokens) -> TokenStream {
+        let trait_name = Ident::new(trait_name, Span::call_site());
+        if self.local_tag {
+            quote! { impl ::uniffi::#trait_name<crate::UniFfiTag> for #ident }
+        } else {
+            quote! { impl<UT> ::uniffi::#trait_name<UT> for #ident }
+        }
+    }
+
+    /// Generate a call to `derive_ffi_traits!` that will derive all the FFI traits
+    pub fn derive_all_ffi_traits(&self, ty: &Ident) -> TokenStream {
+        if self.local_tag {
+            quote! { ::uniffi::derive_ffi_traits!(local #ty); }
+        } else {
+            quote! { ::uniffi::derive_ffi_traits!(blanket #ty); }
+        }
+    }
+
+    /// Generate a call to `derive_ffi_traits!` that will derive some of the FFI traits
+    pub fn derive_ffi_traits(&self, ty: impl ToTokens, trait_names: &[&str]) -> TokenStream {
+        let trait_idents = trait_names
+            .iter()
+            .map(|name| Ident::new(name, Span::call_site()));
+        if self.local_tag {
+            quote! {
+                #(
+                    ::uniffi::derive_ffi_traits!(impl #trait_idents<crate::UniFfiTag> for #ty);
+                )*
+            }
+        } else {
+            quote! {
+                #(
+                    ::uniffi::derive_ffi_traits!(impl<UT> #trait_idents<UT> for #ty);
+                )*
+            }
+        }
+    }
+}
diff --git a/third_party/rust/uniffi_macros/src/enum_.rs b/third_party/rust/uniffi_macros/src/enum_.rs
index fd98da31299b..b17b5ba63979 100644
--- a/third_party/rust/uniffi_macros/src/enum_.rs
+++ b/third_party/rust/uniffi_macros/src/enum_.rs
@@ -1,69 +1,137 @@
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::quote;
 use syn::{
-    parse::{Parse, ParseStream},
-    spanned::Spanned,
-    Attribute, Data, DataEnum, DeriveInput, Expr, Index, Lit, Variant,
+    parse::ParseStream, spanned::Spanned, Attribute, Data, DataEnum, DeriveInput, Expr, Index, Lit,
+    Variant,
 };
 
-use crate::util::{
-    create_metadata_items, derive_all_ffi_traits, either_attribute_arg, extract_docstring,
-    ident_to_string, kw, mod_path, parse_comma_separated, tagged_impl_header,
-    try_metadata_value_from_usize, try_read_field, AttributeSliceExt, UniffiAttributeArgs,
+use crate::{
+    ffiops,
+    util::{
+        create_metadata_items, either_attribute_arg, extract_docstring, ident_to_string, kw,
+        mod_path, try_metadata_value_from_usize, try_read_field, AttributeSliceExt,
+        UniffiAttributeArgs,
+    },
+    DeriveOptions,
 };
+use uniffi_meta::EnumShape;
 
-fn extract_repr(attrs: &[Attribute]) -> syn::Result<Option<Ident>> {
-    let mut result = None;
-    for attr in attrs {
-        if attr.path().is_ident("repr") {
-            attr.parse_nested_meta(|meta| {
-                result = match meta.path.get_ident() {
-                    Some(i) => {
-                        let s = i.to_string();
-                        match s.as_str() {
-                            "u8" | "u16" | "u32" | "u64" | "usize" | "i8" | "i16" | "i32"
-                            | "i64" | "isize" => Some(i.clone()),
-                            // while the default repr for an enum is `isize` we don't apply that default here.
-                            _ => None,
-                        }
-                    }
-                    _ => None,
-                };
-                Ok(())
-            })?
-        }
-    }
-    Ok(result)
+/// Stores parsed data from the Derive Input for the enum.
+pub struct EnumItem {
+    ident: Ident,
+    enum_: DataEnum,
+    docstring: String,
+    discr_type: Option<Ident>,
+    non_exhaustive: bool,
+    attr: EnumAttr,
 }
 
-pub fn expand_enum(
-    input: DeriveInput,
-    // Attributes from #[derive_error_for_udl()], if we are in udl mode
-    attr_from_udl_mode: Option<EnumAttr>,
-    udl_mode: bool,
-) -> syn::Result<TokenStream> {
-    let enum_ = match input.data {
-        Data::Enum(e) => e,
-        _ => {
-            return Err(syn::Error::new(
-                Span::call_site(),
-                "This derive must only be used on enums",
-            ))
-        }
-    };
-    let ident = &input.ident;
-    let docstring = extract_docstring(&input.attrs)?;
-    let discr_type = extract_repr(&input.attrs)?;
-    let mut attr: EnumAttr = input.attrs.parse_uniffi_attr_args()?;
-    if let Some(attr_from_udl_mode) = attr_from_udl_mode {
-        attr = attr.merge(attr_from_udl_mode)?;
+impl EnumItem {
+    pub fn new(input: DeriveInput) -> syn::Result<Self> {
+        let enum_ = match input.data {
+            Data::Enum(e) => e,
+            _ => {
+                return Err(syn::Error::new(
+                    Span::call_site(),
+                    "This derive must only be used on enums",
+                ))
+            }
+        };
+        Ok(Self {
+            enum_,
+            ident: input.ident,
+            docstring: extract_docstring(&input.attrs)?,
+            discr_type: Self::extract_repr(&input.attrs)?,
+            non_exhaustive: Self::extract_non_exhaustive(&input.attrs),
+            attr: input.attrs.parse_uniffi_attr_args()?,
+        })
     }
-    let ffi_converter_impl = enum_ffi_converter_impl(ident, &enum_, udl_mode, &attr);
 
-    let meta_static_var = (!udl_mode).then(|| {
-        enum_meta_static_var(ident, docstring, discr_type, &enum_, &attr)
-            .unwrap_or_else(syn::Error::into_compile_error)
-    });
+    pub fn extract_repr(attrs: &[Attribute]) -> syn::Result<Option<Ident>> {
+        let mut result = None;
+        for attr in attrs {
+            if attr.path().is_ident("repr") {
+                attr.parse_nested_meta(|meta| {
+                    result = match meta.path.get_ident() {
+                        Some(i) => {
+                            let s = i.to_string();
+                            match s.as_str() {
+                                "u8" | "u16" | "u32" | "u64" | "usize" | "i8" | "i16" | "i32"
+                                | "i64" | "isize" => Some(i.clone()),
+                                // while the default repr for an enum is `isize` we don't apply that default here.
+                                _ => None,
+                            }
+                        }
+                        _ => None,
+                    };
+                    Ok(())
+                })?
+            }
+        }
+        Ok(result)
+    }
+
+    pub fn extract_non_exhaustive(attrs: &[Attribute]) -> bool {
+        attrs.iter().any(|a| a.path().is_ident("non_exhaustive"))
+    }
+
+    pub fn check_attributes_valid_for_enum(&self) -> syn::Result<()> {
+        if let Some(flat_error) = &self.attr.flat_error {
+            return Err(syn::Error::new(
+                flat_error.span(),
+                "flat_error not allowed for non-error enums",
+            ));
+        }
+        if let Some(with_try_read) = &self.attr.with_try_read {
+            return Err(syn::Error::new(
+                with_try_read.span(),
+                "with_try_read not allowed for non-error enums",
+            ));
+        }
+        Ok(())
+    }
+
+    pub fn ident(&self) -> &Ident {
+        &self.ident
+    }
+
+    pub fn enum_(&self) -> &DataEnum {
+        &self.enum_
+    }
+
+    pub fn is_non_exhaustive(&self) -> bool {
+        self.non_exhaustive
+    }
+
+    pub fn docstring(&self) -> &str {
+        self.docstring.as_str()
+    }
+
+    pub fn discr_type(&self) -> Option<&Ident> {
+        self.discr_type.as_ref()
+    }
+
+    pub fn name(&self) -> String {
+        ident_to_string(&self.ident)
+    }
+
+    pub fn is_flat_error(&self) -> bool {
+        self.attr.flat_error.is_some()
+    }
+
+    pub fn generate_error_try_read(&self) -> bool {
+        self.attr.with_try_read.is_some()
+    }
+}
+
+pub fn expand_enum(input: DeriveInput, options: DeriveOptions) -> syn::Result<TokenStream> {
+    let item = EnumItem::new(input)?;
+    item.check_attributes_valid_for_enum()?;
+    let ffi_converter_impl = enum_ffi_converter_impl(&item, &options);
+
+    let meta_static_var = options
+        .generate_metadata
+        .then(|| enum_meta_static_var(&item).unwrap_or_else(syn::Error::into_compile_error));
 
     Ok(quote! {
         #ffi_converter_impl
@@ -71,51 +139,40 @@ pub fn expand_enum(
     })
 }
 
-pub(crate) fn enum_ffi_converter_impl(
-    ident: &Ident,
-    enum_: &DataEnum,
-    udl_mode: bool,
-    attr: &EnumAttr,
-) -> TokenStream {
+pub(crate) fn enum_ffi_converter_impl(item: &EnumItem, options: &DeriveOptions) -> TokenStream {
     enum_or_error_ffi_converter_impl(
-        ident,
-        enum_,
-        udl_mode,
-        attr,
+        item,
+        options,
         quote! { ::uniffi::metadata::codes::TYPE_ENUM },
     )
 }
 
 pub(crate) fn rich_error_ffi_converter_impl(
-    ident: &Ident,
-    enum_: &DataEnum,
-    udl_mode: bool,
-    attr: &EnumAttr,
+    item: &EnumItem,
+    options: &DeriveOptions,
 ) -> TokenStream {
     enum_or_error_ffi_converter_impl(
-        ident,
-        enum_,
-        udl_mode,
-        attr,
+        item,
+        options,
         quote! { ::uniffi::metadata::codes::TYPE_ENUM },
     )
 }
 
 fn enum_or_error_ffi_converter_impl(
-    ident: &Ident,
-    enum_: &DataEnum,
-    udl_mode: bool,
-    attr: &EnumAttr,
+    item: &EnumItem,
+    options: &DeriveOptions,
     metadata_type_code: TokenStream,
 ) -> TokenStream {
-    let name = ident_to_string(ident);
-    let impl_spec = tagged_impl_header("FfiConverter", ident, udl_mode);
-    let derive_ffi_traits = derive_all_ffi_traits(ident, udl_mode);
+    let name = item.name();
+    let ident = item.ident();
+    let impl_spec = options.ffi_impl_header("FfiConverter", ident);
+    let derive_ffi_traits = options.derive_all_ffi_traits(ident);
     let mod_path = match mod_path() {
         Ok(p) => p,
         Err(e) => return e.into_compile_error(),
     };
-    let mut write_match_arms: Vec<_> = enum_
+    let mut write_match_arms: Vec<_> = item
+        .enum_()
         .variants
         .iter()
         .enumerate()
@@ -134,10 +191,8 @@ fn enum_or_error_ffi_converter_impl(
             let idx = Index::from(i + 1);
             let write_fields =
                 std::iter::zip(v.fields.iter(), field_idents.iter()).map(|(f, ident)| {
-                    let ty = &f.ty;
-                    quote! {
-                        <#ty as ::uniffi::Lower<crate::UniFfiTag>>::write(#ident, buf);
-                    }
+                    let write = ffiops::write(&f.ty);
+                    quote! { #write(#ident, buf); }
                 });
             let is_tuple = v.fields.iter().any(|f| f.ident.is_none());
             let fields = if is_tuple {
@@ -154,16 +209,16 @@ fn enum_or_error_ffi_converter_impl(
             }
         })
         .collect();
-    if attr.non_exhaustive.is_some() {
+    if item.is_non_exhaustive() {
         write_match_arms.push(quote! {
-            _ => panic!("Unexpected variant in non-exhaustive enum"),
+            _ => ::std::panic!("Unexpected variant in non-exhaustive enum"),
         })
     }
     let write_impl = quote! {
         match obj { #(#write_match_arms)* }
     };
 
-    let try_read_match_arms = enum_.variants.iter().enumerate().map(|(i, v)| {
+    let try_read_match_arms = item.enum_().variants.iter().enumerate().map(|(i, v)| {
         let idx = Index::from(i + 1);
         let v_ident = &v.ident;
         let is_tuple = v.fields.iter().any(|f| f.ident.is_none());
@@ -179,11 +234,11 @@ fn enum_or_error_ffi_converter_impl(
             }
         }
     });
-    let error_format_string = format!("Invalid {ident} enum value: {{}}");
+    let error_format_string = format!("Invalid {name} enum value: {{}}");
     let try_read_impl = quote! {
         ::uniffi::check_remaining(buf, 4)?;
 
-        Ok(match ::uniffi::deps::bytes::Buf::get_i32(buf) {
+        ::std::result::Result::Ok(match ::uniffi::deps::bytes::Buf::get_i32(buf) {
             #(#try_read_match_arms)*
             v => ::uniffi::deps::anyhow::bail!(#error_format_string, v),
         })
@@ -211,28 +266,27 @@ fn enum_or_error_ffi_converter_impl(
     }
 }
 
-pub(crate) fn enum_meta_static_var(
-    ident: &Ident,
-    docstring: String,
-    discr_type: Option<Ident>,
-    enum_: &DataEnum,
-    attr: &EnumAttr,
-) -> syn::Result<TokenStream> {
-    let name = ident_to_string(ident);
+pub(crate) fn enum_meta_static_var(item: &EnumItem) -> syn::Result<TokenStream> {
+    let name = item.name();
     let module_path = mod_path()?;
-    let non_exhaustive = attr.non_exhaustive.is_some();
+    let non_exhaustive = item.is_non_exhaustive();
+    let docstring = item.docstring();
+    let shape = EnumShape::Enum.as_u8();
 
     let mut metadata_expr = quote! {
         ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::ENUM)
             .concat_str(#module_path)
             .concat_str(#name)
-            .concat_option_bool(None) // forced_flatness
+            .concat_value(#shape)
     };
-    metadata_expr.extend(match discr_type {
+    metadata_expr.extend(match item.discr_type() {
         None => quote! { .concat_bool(false) },
-        Some(t) => quote! { .concat_bool(true).concat(<#t as ::uniffi::Lower<crate::UniFfiTag>>::TYPE_ID_META) }
+        Some(t) => {
+            let type_id_meta = ffiops::type_id_meta(t);
+            quote! { .concat_bool(true).concat(#type_id_meta) }
+        }
     });
-    metadata_expr.extend(variant_metadata(enum_)?);
+    metadata_expr.extend(variant_metadata(item)?);
     metadata_expr.extend(quote! {
         .concat_bool(#non_exhaustive)
         .concat_long_str(#docstring)
@@ -296,7 +350,8 @@ fn variant_value(v: &Variant) -> syn::Result<TokenStream> {
     })
 }
 
-pub fn variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStream>> {
+pub fn variant_metadata(item: &EnumItem) -> syn::Result<Vec<TokenStream>> {
+    let enum_ = item.enum_();
     let variants_len =
         try_metadata_value_from_usize(enum_.variants.len(), "UniFFI limits enums to 256 variants")?;
     std::iter::once(Ok(quote! { .concat_value(#variants_len) }))
@@ -315,12 +370,12 @@ pub fn variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStream>> {
             let name = ident_to_string(&v.ident);
             let value_tokens = variant_value(v)?;
             let docstring = extract_docstring(&v.attrs)?;
-            let field_types = v.fields.iter().map(|f| &f.ty);
             let field_docstrings = v
                 .fields
                 .iter()
                 .map(|f| extract_docstring(&f.attrs))
                 .collect::<syn::Result<Vec<_>>>()?;
+            let field_type_id_metas = v.fields.iter().map(|f| ffiops::type_id_meta(&f.ty));
 
             Ok(quote! {
                 .concat_str(#name)
@@ -328,7 +383,7 @@ pub fn variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStream>> {
                 .concat_value(#fields_len)
                     #(
                         .concat_str(#field_names)
-                        .concat(<#field_types as ::uniffi::Lower<crate::UniFfiTag>>::TYPE_ID_META)
+                        .concat(#field_type_id_metas)
                         // field defaults not yet supported for enums
                         .concat_bool(false)
                         .concat_long_str(#field_docstrings)
@@ -339,25 +394,31 @@ pub fn variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStream>> {
         .collect()
 }
 
-#[derive(Default)]
+/// Handle #[uniffi(...)] attributes for enums
+#[derive(Clone, Default)]
 pub struct EnumAttr {
-    pub non_exhaustive: Option<kw::non_exhaustive>,
-}
-
-// So ErrorAttr can be used with `parse_macro_input!`
-impl Parse for EnumAttr {
-    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
-        parse_comma_separated(input)
-    }
+    // All of these attributes are only relevant for errors, but they're defined here so that we
+    // can reuse EnumItem for errors.
+    pub flat_error: Option<kw::flat_error>,
+    pub with_try_read: Option<kw::with_try_read>,
 }
 
 impl UniffiAttributeArgs for EnumAttr {
     fn parse_one(input: ParseStream<'_>) -> syn::Result<Self> {
         let lookahead = input.lookahead1();
-        if lookahead.peek(kw::non_exhaustive) {
+        if lookahead.peek(kw::flat_error) {
             Ok(Self {
-                non_exhaustive: input.parse()?,
+                flat_error: input.parse()?,
+                ..Self::default()
             })
+        } else if lookahead.peek(kw::with_try_read) {
+            Ok(Self {
+                with_try_read: input.parse()?,
+                ..Self::default()
+            })
+        } else if lookahead.peek(kw::handle_unknown_callback_error) {
+            // Not used anymore, but still allowed
+            Ok(Self::default())
         } else {
             Err(lookahead.error())
         }
@@ -365,7 +426,8 @@ impl UniffiAttributeArgs for EnumAttr {
 
     fn merge(self, other: Self) -> syn::Result<Self> {
         Ok(Self {
-            non_exhaustive: either_attribute_arg(self.non_exhaustive, other.non_exhaustive)?,
+            flat_error: either_attribute_arg(self.flat_error, other.flat_error)?,
+            with_try_read: either_attribute_arg(self.with_try_read, other.with_try_read)?,
         })
     }
 }
diff --git a/third_party/rust/uniffi_macros/src/error.rs b/third_party/rust/uniffi_macros/src/error.rs
index 804b43800332..39e3deca9333 100644
--- a/third_party/rust/uniffi_macros/src/error.rs
+++ b/third_party/rust/uniffi_macros/src/error.rs
@@ -1,47 +1,27 @@
-use proc_macro2::{Ident, Span, TokenStream};
+use proc_macro2::TokenStream;
 use quote::quote;
-use syn::{
-    parse::{Parse, ParseStream},
-    Data, DataEnum, DeriveInput, Index,
-};
+use syn::{DeriveInput, Index};
+use uniffi_meta::EnumShape;
 
 use crate::{
-    enum_::{rich_error_ffi_converter_impl, variant_metadata, EnumAttr},
+    enum_::{rich_error_ffi_converter_impl, variant_metadata, EnumItem},
+    ffiops,
     util::{
-        chain, create_metadata_items, derive_ffi_traits, either_attribute_arg, extract_docstring,
-        ident_to_string, kw, mod_path, parse_comma_separated, tagged_impl_header,
-        try_metadata_value_from_usize, AttributeSliceExt, UniffiAttributeArgs,
+        chain, create_metadata_items, extract_docstring, ident_to_string, mod_path,
+        try_metadata_value_from_usize, AttributeSliceExt,
     },
+    DeriveOptions,
 };
 
-pub fn expand_error(
-    input: DeriveInput,
-    // Attributes from #[derive_error_for_udl()], if we are in udl mode
-    attr_from_udl_mode: Option<ErrorAttr>,
-    udl_mode: bool,
-) -> syn::Result<TokenStream> {
-    let enum_ = match input.data {
-        Data::Enum(e) => e,
-        _ => {
-            return Err(syn::Error::new(
-                Span::call_site(),
-                "This derive currently only supports enums",
-            ));
-        }
-    };
-    let ident = &input.ident;
-    let docstring = extract_docstring(&input.attrs)?;
-    let mut attr: ErrorAttr = input.attrs.parse_uniffi_attr_args()?;
-    if let Some(attr_from_udl_mode) = attr_from_udl_mode {
-        attr = attr.merge(attr_from_udl_mode)?;
-    }
-    let ffi_converter_impl = error_ffi_converter_impl(ident, &enum_, &attr, udl_mode)?;
-    let meta_static_var = (!udl_mode).then(|| {
-        error_meta_static_var(ident, docstring, &enum_, &attr)
-            .unwrap_or_else(syn::Error::into_compile_error)
-    });
+pub fn expand_error(input: DeriveInput, options: DeriveOptions) -> syn::Result<TokenStream> {
+    let enum_item = EnumItem::new(input)?;
+    let ffi_converter_impl = error_ffi_converter_impl(&enum_item, &options)?;
+    let meta_static_var = options
+        .generate_metadata
+        .then(|| error_meta_static_var(&enum_item).unwrap_or_else(syn::Error::into_compile_error));
 
-    let variant_errors: TokenStream = enum_
+    let variant_errors: TokenStream = enum_item
+        .enum_()
         .variants
         .iter()
         .flat_map(|variant| {
@@ -63,16 +43,11 @@ pub fn expand_error(
     })
 }
 
-fn error_ffi_converter_impl(
-    ident: &Ident,
-    enum_: &DataEnum,
-    attr: &ErrorAttr,
-    udl_mode: bool,
-) -> syn::Result<TokenStream> {
-    Ok(if attr.flat.is_some() {
-        flat_error_ffi_converter_impl(ident, enum_, udl_mode, attr)
+fn error_ffi_converter_impl(item: &EnumItem, options: &DeriveOptions) -> syn::Result<TokenStream> {
+    Ok(if item.is_flat_error() {
+        flat_error_ffi_converter_impl(item, options)
     } else {
-        rich_error_ffi_converter_impl(ident, enum_, udl_mode, &attr.clone().try_into()?)
+        rich_error_ffi_converter_impl(item, options)
     })
 }
 
@@ -80,39 +55,45 @@ fn error_ffi_converter_impl(
 //
 // These are errors where we only lower the to_string() value, rather than any associated data.
 // We lower the to_string() value unconditionally, whether the enum has associated data or not.
-fn flat_error_ffi_converter_impl(
-    ident: &Ident,
-    enum_: &DataEnum,
-    udl_mode: bool,
-    attr: &ErrorAttr,
-) -> TokenStream {
-    let name = ident_to_string(ident);
-    let lower_impl_spec = tagged_impl_header("Lower", ident, udl_mode);
-    let lift_impl_spec = tagged_impl_header("Lift", ident, udl_mode);
-    let derive_ffi_traits = derive_ffi_traits(ident, udl_mode, &["ConvertError"]);
+fn flat_error_ffi_converter_impl(item: &EnumItem, options: &DeriveOptions) -> TokenStream {
+    let name = item.name();
+    let ident = item.ident();
+    let lower_impl_spec = options.ffi_impl_header("Lower", ident);
+    let lift_impl_spec = options.ffi_impl_header("Lift", ident);
+    let type_id_impl_spec = options.ffi_impl_header("TypeId", ident);
+    let derive_ffi_traits = options.derive_ffi_traits(ident, &["LowerError", "ConvertError"]);
     let mod_path = match mod_path() {
         Ok(p) => p,
         Err(e) => return e.into_compile_error(),
     };
 
     let lower_impl = {
-        let mut match_arms: Vec<_> = enum_.variants.iter().enumerate().map(|(i, v)| {
-            let v_ident = &v.ident;
-            let idx = Index::from(i + 1);
+        let mut match_arms: Vec<_> = item
+            .enum_()
+            .variants
+            .iter()
+            .enumerate()
+            .map(|(i, v)| {
+                let v_ident = &v.ident;
+                let idx = Index::from(i + 1);
+                let write_string = ffiops::write(quote! { ::std::string::String });
 
-            quote! {
-                Self::#v_ident { .. } => {
-                    ::uniffi::deps::bytes::BufMut::put_i32(buf, #idx);
-                    <::std::string::String as ::uniffi::Lower<crate::UniFfiTag>>::write(error_msg, buf);
+                quote! {
+                    Self::#v_ident { .. } => {
+                        ::uniffi::deps::bytes::BufMut::put_i32(buf, #idx);
+                        #write_string(error_msg, buf);
+                    }
                 }
-            }
-        }).collect();
-        if attr.non_exhaustive.is_some() {
+            })
+            .collect();
+        if item.is_non_exhaustive() {
             match_arms.push(quote! {
-                _ => panic!("Unexpected variant in non-exhaustive enum"),
+                _ => ::std::panic!("Unexpected variant in non-exhaustive enum"),
             })
         }
 
+        let lower = ffiops::lower_into_rust_buffer(quote! { Self });
+
         quote! {
             #[automatically_derived]
             unsafe #lower_impl_spec {
@@ -124,18 +105,14 @@ fn flat_error_ffi_converter_impl(
                 }
 
                 fn lower(obj: Self) -> ::uniffi::RustBuffer {
-                    <Self as ::uniffi::Lower<crate::UniFfiTag>>::lower_into_rust_buffer(obj)
+                    #lower(obj)
                 }
-
-                const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::TYPE_ENUM)
-                    .concat_str(#mod_path)
-                    .concat_str(#name);
             }
         }
     };
 
-    let lift_impl = if attr.with_try_read.is_some() {
-        let match_arms = enum_.variants.iter().enumerate().map(|(i, v)| {
+    let lift_impl = if item.generate_error_try_read() {
+        let match_arms = item.enum_().variants.iter().enumerate().map(|(i, v)| {
             let v_ident = &v.ident;
             let idx = Index::from(i + 1);
 
@@ -143,25 +120,23 @@ fn flat_error_ffi_converter_impl(
                 #idx => Self::#v_ident,
             }
         });
+        let try_lift = ffiops::try_lift_from_rust_buffer(quote! { Self });
         quote! {
             #[automatically_derived]
             unsafe #lift_impl_spec {
                 type FfiType = ::uniffi::RustBuffer;
 
                 fn try_read(buf: &mut &[::std::primitive::u8]) -> ::uniffi::deps::anyhow::Result<Self> {
-                    Ok(match ::uniffi::deps::bytes::Buf::get_i32(buf) {
+                    ::std::result::Result::Ok(match ::uniffi::deps::bytes::Buf::get_i32(buf) {
                         #(#match_arms)*
                         v => ::uniffi::deps::anyhow::bail!("Invalid #ident enum value: {}", v),
                     })
                 }
 
                 fn try_lift(v: ::uniffi::RustBuffer) -> ::uniffi::deps::anyhow::Result<Self> {
-                    <Self as ::uniffi::Lift<crate::UniFfiTag>>::try_lift_from_rust_buffer(v)
+                    #try_lift(v)
                 }
-
-                const TYPE_ID_META: ::uniffi::MetadataBuffer = <Self as ::uniffi::Lower<crate::UniFfiTag>>::TYPE_ID_META;
             }
-
         }
     } else {
         quote! {
@@ -177,14 +152,12 @@ fn flat_error_ffi_converter_impl(
                 type FfiType = ::uniffi::RustBuffer;
 
                 fn try_read(buf: &mut &[::std::primitive::u8]) -> ::uniffi::deps::anyhow::Result<Self> {
-                    panic!("Can't lift flat errors")
+                    ::std::panic!("Can't lift flat errors")
                 }
 
                 fn try_lift(v: ::uniffi::RustBuffer) -> ::uniffi::deps::anyhow::Result<Self> {
-                    panic!("Can't lift flat errors")
+                    ::std::panic!("Can't lift flat errors")
                 }
-
-                const TYPE_ID_META: ::uniffi::MetadataBuffer = <Self as ::uniffi::Lower<crate::UniFfiTag>>::TYPE_ID_META;
             }
         }
     };
@@ -192,31 +165,36 @@ fn flat_error_ffi_converter_impl(
     quote! {
         #lower_impl
         #lift_impl
+
+        #[automatically_derived]
+        #type_id_impl_spec {
+            const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::TYPE_ENUM)
+                .concat_str(#mod_path)
+                .concat_str(#name);
+        }
+
         #derive_ffi_traits
     }
 }
 
-pub(crate) fn error_meta_static_var(
-    ident: &Ident,
-    docstring: String,
-    enum_: &DataEnum,
-    attr: &ErrorAttr,
-) -> syn::Result<TokenStream> {
-    let name = ident_to_string(ident);
+pub(crate) fn error_meta_static_var(item: &EnumItem) -> syn::Result<TokenStream> {
+    let name = item.name();
     let module_path = mod_path()?;
-    let flat = attr.flat.is_some();
-    let non_exhaustive = attr.non_exhaustive.is_some();
+    let non_exhaustive = item.is_non_exhaustive();
+    let docstring = item.docstring();
+    let flat = item.is_flat_error();
+    let shape = EnumShape::Error { flat }.as_u8();
     let mut metadata_expr = quote! {
             ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::ENUM)
                 .concat_str(#module_path)
                 .concat_str(#name)
-                .concat_option_bool(Some(#flat))
+                .concat_value(#shape)
                 .concat_bool(false) // discr_type: None
     };
     if flat {
-        metadata_expr.extend(flat_error_variant_metadata(enum_)?)
+        metadata_expr.extend(flat_error_variant_metadata(item)?)
     } else {
-        metadata_expr.extend(variant_metadata(enum_)?);
+        metadata_expr.extend(variant_metadata(item)?);
     }
     metadata_expr.extend(quote! {
         .concat_bool(#non_exhaustive)
@@ -225,7 +203,8 @@ pub(crate) fn error_meta_static_var(
     Ok(create_metadata_items("error", &name, metadata_expr, None))
 }
 
-pub fn flat_error_variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStream>> {
+pub fn flat_error_variant_metadata(item: &EnumItem) -> syn::Result<Vec<TokenStream>> {
+    let enum_ = item.enum_();
     let variants_len =
         try_metadata_value_from_usize(enum_.variants.len(), "UniFFI limits enums to 256 variants")?;
     std::iter::once(Ok(quote! { .concat_value(#variants_len) }))
@@ -239,74 +218,3 @@ pub fn flat_error_variant_metadata(enum_: &DataEnum) -> syn::Result<Vec<TokenStr
         }))
         .collect()
 }
-
-#[derive(Clone, Default)]
-pub struct ErrorAttr {
-    pub flat: Option<kw::flat_error>,
-    pub with_try_read: Option<kw::with_try_read>,
-    pub non_exhaustive: Option<kw::non_exhaustive>,
-}
-
-impl UniffiAttributeArgs for ErrorAttr {
-    fn parse_one(input: ParseStream<'_>) -> syn::Result<Self> {
-        let lookahead = input.lookahead1();
-        if lookahead.peek(kw::flat_error) {
-            Ok(Self {
-                flat: input.parse()?,
-                ..Self::default()
-            })
-        } else if lookahead.peek(kw::with_try_read) {
-            Ok(Self {
-                with_try_read: input.parse()?,
-                ..Self::default()
-            })
-        } else if lookahead.peek(kw::non_exhaustive) {
-            Ok(Self {
-                non_exhaustive: input.parse()?,
-                ..Self::default()
-            })
-        } else if lookahead.peek(kw::handle_unknown_callback_error) {
-            // Not used anymore, but still allowed
-            Ok(Self::default())
-        } else {
-            Err(lookahead.error())
-        }
-    }
-
-    fn merge(self, other: Self) -> syn::Result<Self> {
-        Ok(Self {
-            flat: either_attribute_arg(self.flat, other.flat)?,
-            with_try_read: either_attribute_arg(self.with_try_read, other.with_try_read)?,
-            non_exhaustive: either_attribute_arg(self.non_exhaustive, other.non_exhaustive)?,
-        })
-    }
-}
-
-// So ErrorAttr can be used with `parse_macro_input!`
-impl Parse for ErrorAttr {
-    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
-        parse_comma_separated(input)
-    }
-}
-
-impl TryFrom<ErrorAttr> for EnumAttr {
-    type Error = syn::Error;
-
-    fn try_from(error_attr: ErrorAttr) -> Result<Self, Self::Error> {
-        if error_attr.flat.is_some() {
-            Err(syn::Error::new(
-                Span::call_site(),
-                "flat attribute not valid for rich enum errors",
-            ))
-        } else if error_attr.with_try_read.is_some() {
-            Err(syn::Error::new(
-                Span::call_site(),
-                "with_try_read attribute not valid for rich enum errors",
-            ))
-        } else {
-            Ok(EnumAttr {
-                non_exhaustive: error_attr.non_exhaustive,
-            })
-        }
-    }
-}
diff --git a/third_party/rust/uniffi_macros/src/export.rs b/third_party/rust/uniffi_macros/src/export.rs
index 41657a639e42..3843544b21d4 100644
--- a/third_party/rust/uniffi_macros/src/export.rs
+++ b/third_party/rust/uniffi_macros/src/export.rs
@@ -20,7 +20,7 @@ use self::{
     },
 };
 use crate::util::{ident_to_string, mod_path};
-pub use attributes::{DefaultMap, ExportFnArgs, ExportedImplFnArgs};
+pub use attributes::{AsyncRuntime, DefaultMap, ExportFnArgs};
 pub use callback_interface::ffi_converter_callback_interface_impl;
 
 // TODO(jplatte): Ensure no generics, …
@@ -42,7 +42,7 @@ pub(crate) fn expand_export(
 
     match metadata {
         ExportItem::Function { sig, args } => {
-            gen_fn_scaffolding(sig, &args.async_runtime, udl_mode)
+            gen_fn_scaffolding(sig, args.async_runtime.as_ref(), udl_mode)
         }
         ExportItem::Impl {
             items,
@@ -65,10 +65,14 @@ pub(crate) fn expand_export(
                 .into_iter()
                 .map(|item| match item {
                     ImplItem::Constructor(sig) => {
-                        gen_constructor_scaffolding(sig, &args.async_runtime, udl_mode)
+                        let async_runtime =
+                            sig.async_runtime.clone().or(args.async_runtime.clone());
+                        gen_constructor_scaffolding(sig, async_runtime.as_ref(), udl_mode)
                     }
                     ImplItem::Method(sig) => {
-                        gen_method_scaffolding(sig, &args.async_runtime, udl_mode)
+                        let async_runtime =
+                            sig.async_runtime.clone().or(args.async_runtime.clone());
+                        gen_method_scaffolding(sig, async_runtime.as_ref(), udl_mode)
                     }
                 })
                 .collect::<syn::Result<_>>()?;
diff --git a/third_party/rust/uniffi_macros/src/export/attributes.rs b/third_party/rust/uniffi_macros/src/export/attributes.rs
index be7e8902e440..ce6387da615e 100644
--- a/third_party/rust/uniffi_macros/src/export/attributes.rs
+++ b/third_party/rust/uniffi_macros/src/export/attributes.rs
@@ -10,7 +10,8 @@ use quote::ToTokens;
 use syn::{
     parenthesized,
     parse::{Parse, ParseStream},
-    Attribute, Ident, LitStr, Meta, PathArguments, PathSegment, Token,
+    punctuated::Punctuated,
+    Attribute, Ident, LitStr, Meta, Path, PathArguments, PathSegment, Token,
 };
 use uniffi_meta::UniffiTraitDiscriminants;
 
@@ -71,6 +72,9 @@ impl UniffiAttributeArgs for ExportTraitArgs {
     }
 }
 
+/// Attribute arguments for function
+///
+/// This includes top-level functions, constructors, and methods.
 #[derive(Clone, Default)]
 pub struct ExportFnArgs {
     pub(crate) async_runtime: Option<AsyncRuntime>,
@@ -110,7 +114,7 @@ impl UniffiAttributeArgs for ExportFnArgs {
         } else {
             Err(syn::Error::new(
                 input.span(),
-                format!("uniffi::export attribute `{input}` is not supported here."),
+                format!("attribute `{input}` is not supported here."),
             ))
         }
     }
@@ -211,7 +215,7 @@ impl UniffiAttributeArgs for ExportStructArgs {
 }
 
 #[derive(Clone)]
-pub(crate) enum AsyncRuntime {
+pub enum AsyncRuntime {
     Tokio(LitStr),
 }
 
@@ -236,112 +240,100 @@ impl ToTokens for AsyncRuntime {
     }
 }
 
-/// Arguments for function inside an impl block
-///
-/// This stores the parsed arguments for `uniffi::constructor` and `uniffi::method`
-#[derive(Clone, Default)]
-pub struct ExportedImplFnArgs {
-    pub(crate) name: Option<String>,
-    pub(crate) defaults: DefaultMap,
-}
-
-impl Parse for ExportedImplFnArgs {
-    fn parse(input: ParseStream<'_>) -> syn::Result<Self> {
-        parse_comma_separated(input)
-    }
-}
-
-impl UniffiAttributeArgs for ExportedImplFnArgs {
-    fn parse_one(input: ParseStream<'_>) -> syn::Result<Self> {
-        let lookahead = input.lookahead1();
-        if lookahead.peek(kw::name) {
-            let _: kw::name = input.parse()?;
-            let _: Token![=] = input.parse()?;
-            let name = Some(input.parse::<LitStr>()?.value());
-            Ok(Self {
-                name,
-                ..Self::default()
-            })
-        } else if lookahead.peek(kw::default) {
-            Ok(Self {
-                defaults: DefaultMap::parse(input)?,
-                ..Self::default()
-            })
-        } else {
-            Err(syn::Error::new(
-                input.span(),
-                format!("uniffi::constructor/method attribute `{input}` is not supported here."),
-            ))
-        }
-    }
-
-    fn merge(self, other: Self) -> syn::Result<Self> {
-        Ok(Self {
-            name: either_attribute_arg(self.name, other.name)?,
-            defaults: self.defaults.merge(other.defaults),
-        })
-    }
-}
-
 #[derive(Default)]
 pub(super) struct ExportedImplFnAttributes {
     pub constructor: bool,
-    pub args: ExportedImplFnArgs,
+    pub args: ExportFnArgs,
 }
 
 impl ExportedImplFnAttributes {
     pub fn new(attrs: &[Attribute]) -> syn::Result<Self> {
         let mut this = Self::default();
         for attr in attrs {
-            let segs = &attr.path().segments;
+            let path = attr.path();
 
-            let fst = segs
-                .first()
-                .expect("attributes have at least one path segment");
-            if fst.ident != "uniffi" {
-                continue;
-            }
-            ensure_no_path_args(fst)?;
-
-            let args = match &attr.meta {
-                Meta::List(_) => attr.parse_args::<ExportedImplFnArgs>()?,
-                _ => Default::default(),
-            };
-            this.args = args;
-
-            if segs.len() != 2 {
-                return Err(syn::Error::new_spanned(
-                    segs,
-                    "unsupported uniffi attribute",
-                ));
-            }
-            let snd = &segs[1];
-            ensure_no_path_args(snd)?;
-
-            match snd.ident.to_string().as_str() {
-                "constructor" => {
-                    if this.constructor {
-                        return Err(syn::Error::new_spanned(
-                            attr,
-                            "duplicate constructor attribute",
-                        ));
+            if is_uniffi_path(path) {
+                this.process_path(path, attr, &attr.meta)?;
+            } else if is_cfg_attr(attr) {
+                if let Ok(nested) =
+                    attr.parse_args_with(Punctuated::<Meta, Token![,]>::parse_terminated)
+                {
+                    for meta in &nested {
+                        if let Meta::Path(path) = meta {
+                            this.process_path(path, attr, meta)?
+                        }
                     }
-                    this.constructor = true;
-                }
-                "method" => {
-                    if this.constructor {
-                        return Err(syn::Error::new_spanned(
-                            attr,
-                            "confused constructor/method attributes",
-                        ));
-                    }
-                }
-                _ => return Err(syn::Error::new_spanned(snd, "unknown uniffi attribute")),
+                };
             }
         }
 
         Ok(this)
     }
+
+    fn process_path(&mut self, path: &Path, attr: &Attribute, meta: &Meta) -> syn::Result<()> {
+        let segs = &path.segments;
+
+        let fst = segs
+            .first()
+            .expect("attributes have at least one path segment");
+
+        if fst.ident != "uniffi" {
+            return Ok(());
+        }
+        ensure_no_path_args(fst)?;
+
+        let args = match meta {
+            Meta::List(_) => attr.parse_args::<ExportFnArgs>()?,
+            _ => Default::default(),
+        };
+        self.args = args;
+
+        if segs.len() != 2 {
+            return Err(syn::Error::new_spanned(
+                segs,
+                "unsupported uniffi attribute",
+            ));
+        }
+        let snd = &segs[1];
+        ensure_no_path_args(snd)?;
+
+        match snd.ident.to_string().as_str() {
+            "constructor" => {
+                if self.constructor {
+                    return Err(syn::Error::new_spanned(
+                        attr,
+                        "duplicate constructor attribute",
+                    ));
+                }
+                self.constructor = true;
+            }
+            "method" => {
+                if self.constructor {
+                    return Err(syn::Error::new_spanned(
+                        attr,
+                        "confused constructor/method attributes",
+                    ));
+                }
+            }
+            _ => return Err(syn::Error::new_spanned(snd, "unknown uniffi attribute")),
+        }
+
+        Ok(())
+    }
+}
+
+fn is_uniffi_path(path: &Path) -> bool {
+    path.segments
+        .first()
+        .map(|segment| segment.ident == "uniffi")
+        .unwrap_or(false)
+}
+
+fn is_cfg_attr(attr: &Attribute) -> bool {
+    attr.meta
+        .path()
+        .get_ident()
+        .is_some_and(|ident| *ident == "cfg_attr")
 }
 
 fn ensure_no_path_args(seg: &PathSegment) -> syn::Result<()> {
diff --git a/third_party/rust/uniffi_macros/src/export/callback_interface.rs b/third_party/rust/uniffi_macros/src/export/callback_interface.rs
index fe145384ec73..23009712e1d1 100644
--- a/third_party/rust/uniffi_macros/src/export/callback_interface.rs
+++ b/third_party/rust/uniffi_macros/src/export/callback_interface.rs
@@ -4,6 +4,7 @@
 
 use crate::{
     export::ImplItem,
+    ffiops,
     fnsig::{FnKind, FnSignature, ReceiverArg},
     util::{
         create_metadata_items, derive_ffi_traits, ident_to_string, mod_path, tagged_impl_header,
@@ -44,33 +45,32 @@ pub(super) fn trait_impl(
         })
         .collect::<syn::Result<Vec<_>>>()?;
 
-    let vtable_fields = methods.iter()
-        .map(|sig| {
-            let ident = &sig.ident;
-            let param_names = sig.scaffolding_param_names();
-            let param_types = sig.scaffolding_param_types();
-            let lift_return = sig.lift_return_impl();
-            if !sig.is_async {
-                quote! {
-                    #ident: extern "C" fn(
-                        uniffi_handle: u64,
-                        #(#param_names: #param_types,)*
-                        uniffi_out_return: &mut #lift_return::ReturnType,
-                        uniffi_out_call_status: &mut ::uniffi::RustCallStatus,
-                    ),
-                }
-            } else {
-                quote! {
-                    #ident: extern "C" fn(
-                        uniffi_handle: u64,
-                        #(#param_names: #param_types,)*
-                        uniffi_future_callback: ::uniffi::ForeignFutureCallback<#lift_return::ReturnType>,
-                        uniffi_callback_data: u64,
-                        uniffi_out_return: &mut ::uniffi::ForeignFuture,
-                    ),
-                }
+    let vtable_fields = methods.iter().map(|sig| {
+        let ident = &sig.ident;
+        let param_names = sig.scaffolding_param_names();
+        let param_types = sig.scaffolding_param_types();
+        let lift_return_type = ffiops::lift_return_type(&sig.return_ty);
+        if !sig.is_async {
+            quote! {
+                #ident: extern "C" fn(
+                    uniffi_handle: u64,
+                    #(#param_names: #param_types,)*
+                    uniffi_out_return: &mut #lift_return_type,
+                    uniffi_out_call_status: &mut ::uniffi::RustCallStatus,
+                ),
             }
-        });
+        } else {
+            quote! {
+                #ident: extern "C" fn(
+                    uniffi_handle: u64,
+                    #(#param_names: #param_types,)*
+                    uniffi_future_callback: ::uniffi::ForeignFutureCallback<#lift_return_type>,
+                    uniffi_callback_data: u64,
+                    uniffi_out_return: &mut ::uniffi::ForeignFuture,
+                ),
+            }
+        }
+    });
 
     let trait_impl_methods = methods
         .iter()
@@ -135,11 +135,13 @@ pub fn ffi_converter_callback_interface_impl(
     let dyn_trait = quote! { dyn #trait_ident };
     let box_dyn_trait = quote! { ::std::boxed::Box<#dyn_trait> };
     let lift_impl_spec = tagged_impl_header("Lift", &box_dyn_trait, udl_mode);
+    let type_id_impl_spec = tagged_impl_header("TypeId", &box_dyn_trait, udl_mode);
     let derive_ffi_traits = derive_ffi_traits(&box_dyn_trait, udl_mode, &["LiftRef", "LiftReturn"]);
     let mod_path = match mod_path() {
         Ok(p) => p,
         Err(e) => return e.into_compile_error(),
     };
+    let try_lift_self = ffiops::try_lift(quote! { Self });
 
     quote! {
         #[doc(hidden)]
@@ -148,15 +150,19 @@ pub fn ffi_converter_callback_interface_impl(
             type FfiType = u64;
 
             fn try_lift(v: Self::FfiType) -> ::uniffi::deps::anyhow::Result<Self> {
-                Ok(::std::boxed::Box::new(<#trait_impl_ident>::new(v)))
+                ::std::result::Result::Ok(::std::boxed::Box::new(<#trait_impl_ident>::new(v)))
             }
 
             fn try_read(buf: &mut &[u8]) -> ::uniffi::deps::anyhow::Result<Self> {
-                use uniffi::deps::bytes::Buf;
+                use ::uniffi::deps::bytes::Buf;
                 ::uniffi::check_remaining(buf, 8)?;
-                <Self as ::uniffi::Lift<crate::UniFfiTag>>::try_lift(buf.get_u64())
+                #try_lift_self(buf.get_u64())
             }
+        }
 
+        #[doc(hidden)]
+        #[automatically_derived]
+        #type_id_impl_spec {
             const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(
                 ::uniffi::metadata::codes::TYPE_CALLBACK_INTERFACE,
             )
@@ -204,21 +210,22 @@ fn gen_method_impl(sig: &FnSignature, vtable_cell: &Ident) -> syn::Result<TokenS
 
     let params = sig.params();
     let lower_exprs = sig.args.iter().map(|a| {
-        let lower_impl = a.lower_impl();
+        let lower = ffiops::lower(&a.ty);
         let ident = &a.ident;
-        quote! { #lower_impl::lower(#ident) }
+        quote! { #lower(#ident) }
     });
 
-    let lift_return = sig.lift_return_impl();
+    let lift_return_type = ffiops::lift_return_type(&sig.return_ty);
+    let lift_foreign_return = ffiops::lift_foreign_return(&sig.return_ty);
 
     if !is_async {
         Ok(quote! {
             fn #ident(#self_param, #(#params),*) -> #return_ty {
                 let vtable = #vtable_cell.get();
-                let mut uniffi_call_status = ::uniffi::RustCallStatus::new();
-                let mut uniffi_return_value: #lift_return::ReturnType = ::uniffi::FfiDefault::ffi_default();
+                let mut uniffi_call_status: ::uniffi::RustCallStatus = ::std::default::Default::default();
+                let mut uniffi_return_value: #lift_return_type = ::uniffi::FfiDefault::ffi_default();
                 (vtable.#ident)(self.handle, #(#lower_exprs,)* &mut uniffi_return_value, &mut uniffi_call_status);
-                #lift_return::lift_foreign_return(uniffi_return_value, uniffi_call_status)
+                #lift_foreign_return(uniffi_return_value, uniffi_call_status)
             }
         })
     } else {
@@ -256,7 +263,7 @@ pub(super) fn metadata_items(
 
     iter::once(Ok(callback_interface_items))
         .chain(items.iter().map(|item| match item {
-            ImplItem::Method(sig) => sig.metadata_items_for_callback_interface(),
+            ImplItem::Method(sig) => sig.metadata_items(),
             _ => unreachable!("traits have no constructors"),
         }))
         .collect()
diff --git a/third_party/rust/uniffi_macros/src/export/item.rs b/third_party/rust/uniffi_macros/src/export/item.rs
index da3c9455c888..990fc9fecdfd 100644
--- a/third_party/rust/uniffi_macros/src/export/item.rs
+++ b/third_party/rust/uniffi_macros/src/export/item.rs
@@ -8,8 +8,7 @@ use proc_macro2::{Ident, Span};
 use quote::ToTokens;
 
 use super::attributes::{
-    ExportFnArgs, ExportImplArgs, ExportStructArgs, ExportTraitArgs, ExportedImplFnArgs,
-    ExportedImplFnAttributes,
+    ExportFnArgs, ExportImplArgs, ExportStructArgs, ExportTraitArgs, ExportedImplFnAttributes,
 };
 use crate::util::extract_docstring;
 use uniffi_meta::UniffiTraitDiscriminants;
@@ -170,7 +169,7 @@ impl ExportItem {
                     ImplItem::Method(FnSignature::new_trait_method(
                         self_ident.clone(),
                         tim.sig,
-                        ExportedImplFnArgs::default(),
+                        ExportFnArgs::default(),
                         i as u32,
                         docstring,
                     )?)
diff --git a/third_party/rust/uniffi_macros/src/export/scaffolding.rs b/third_party/rust/uniffi_macros/src/export/scaffolding.rs
index 1d7c02b2a49f..bc45648723a5 100644
--- a/third_party/rust/uniffi_macros/src/export/scaffolding.rs
+++ b/third_party/rust/uniffi_macros/src/export/scaffolding.rs
@@ -7,11 +7,14 @@ use quote::quote;
 use std::iter;
 
 use super::attributes::AsyncRuntime;
-use crate::fnsig::{FnKind, FnSignature};
+use crate::{
+    ffiops,
+    fnsig::{FnKind, FnSignature},
+};
 
 pub(super) fn gen_fn_scaffolding(
     sig: FnSignature,
-    ar: &Option<AsyncRuntime>,
+    ar: Option<&AsyncRuntime>,
     udl_mode: bool,
 ) -> syn::Result<TokenStream> {
     if sig.receiver.is_some() {
@@ -41,7 +44,7 @@ pub(super) fn gen_fn_scaffolding(
 
 pub(super) fn gen_constructor_scaffolding(
     sig: FnSignature,
-    ar: &Option<AsyncRuntime>,
+    ar: Option<&AsyncRuntime>,
     udl_mode: bool,
 ) -> syn::Result<TokenStream> {
     if sig.receiver.is_some() {
@@ -63,7 +66,7 @@ pub(super) fn gen_constructor_scaffolding(
 
 pub(super) fn gen_method_scaffolding(
     sig: FnSignature,
-    ar: &Option<AsyncRuntime>,
+    ar: Option<&AsyncRuntime>,
     udl_mode: bool,
 ) -> syn::Result<TokenStream> {
     let scaffolding_func = if sig.receiver.is_none() {
@@ -128,34 +131,38 @@ impl ScaffoldingBits {
         udl_mode: bool,
     ) -> Self {
         let ident = &sig.ident;
-        let lift_impl = if is_trait {
-            quote! {
-                <::std::sync::Arc<dyn #self_ident> as ::uniffi::Lift<crate::UniFfiTag>>
-            }
+        let self_type = if is_trait {
+            quote! { ::std::sync::Arc<dyn #self_ident> }
         } else {
-            quote! {
-                <::std::sync::Arc<#self_ident> as ::uniffi::Lift<crate::UniFfiTag>>
-            }
+            quote! { ::std::sync::Arc<#self_ident> }
         };
+        let lift_type = ffiops::lift_type(&self_type);
+        let try_lift = ffiops::try_lift(&self_type);
         let try_lift_self = if is_trait {
             // For trait interfaces we need to special case this.  Trait interfaces normally lift
             // foreign trait impl pointers.  However, for a method call, we want to lift a Rust
             // pointer.
             quote! {
                 {
-                    let boxed_foreign_arc = unsafe { Box::from_raw(uniffi_self_lowered as *mut ::std::sync::Arc<dyn #self_ident>) };
+                    let boxed_foreign_arc = unsafe {
+                        ::std::boxed::Box::from_raw(
+                            uniffi_self_lowered as *mut ::std::sync::Arc<dyn #self_ident>,
+                        )
+                    };
                     // Take a clone for our own use.
-                    Ok(*boxed_foreign_arc)
+                    ::std::result::Result::Ok(*boxed_foreign_arc)
                 }
             }
         } else {
-            quote! { #lift_impl::try_lift(uniffi_self_lowered) }
+            quote! { #try_lift(uniffi_self_lowered) }
         };
 
         let lift_closure = sig.lift_closure(Some(quote! {
             match #try_lift_self {
-                Ok(v) => v,
-                Err(e) => return Err(("self", e))
+                ::std::result::Result::Ok(v) => v,
+                ::std::result::Result::Err(e) => {
+                    return ::std::result::Result::Err(("self", e));
+                }
             }
         }));
         let call_params = sig.rust_call_params(true);
@@ -171,7 +178,7 @@ impl ScaffoldingBits {
             param_names: iter::once(quote! { uniffi_self_lowered })
                 .chain(sig.scaffolding_param_names())
                 .collect(),
-            param_types: iter::once(quote! { #lift_impl::FfiType })
+            param_types: iter::once(quote! { #lift_type })
                 .chain(sig.scaffolding_param_types())
                 .collect(),
             lift_closure,
@@ -210,7 +217,7 @@ impl ScaffoldingBits {
 /// `rust_fn` is the Rust function to call.
 pub(super) fn gen_ffi_function(
     sig: &FnSignature,
-    ar: &Option<AsyncRuntime>,
+    ar: Option<&AsyncRuntime>,
     udl_mode: bool,
 ) -> syn::Result<TokenStream> {
     let ScaffoldingBits {
@@ -241,36 +248,32 @@ pub(super) fn gen_ffi_function(
     let ffi_ident = sig.scaffolding_fn_ident()?;
     let name = &sig.name;
     let return_ty = &sig.return_ty;
-    let return_impl = &sig.lower_return_impl();
+    let ffi_return_ty = ffiops::lower_return_type(return_ty);
+    let lower_return = ffiops::lower_return(return_ty);
+    let handle_failed_lift = ffiops::lower_return_handle_failed_lift(return_ty);
 
     Ok(if !sig.is_async {
-        let scaffolding_fn_ffi_buffer_version = ffi_buffer_scaffolding_fn(
-            &ffi_ident,
-            &quote! { <#return_ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::ReturnType },
-            &param_types,
-            true,
-        );
+        let scaffolding_fn_ffi_buffer_version =
+            ffi_buffer_scaffolding_fn(&ffi_ident, &ffi_return_ty, &param_types, true);
         quote! {
             #[doc(hidden)]
             #[no_mangle]
             #vis extern "C" fn #ffi_ident(
                 #(#param_names: #param_types,)*
                 call_status: &mut ::uniffi::RustCallStatus,
-            ) -> #return_impl::ReturnType {
+            ) -> #ffi_return_ty {
                 ::uniffi::deps::log::debug!(#name);
                 let uniffi_lift_args = #lift_closure;
                 ::uniffi::rust_call(call_status, || {
-                    #return_impl::lower_return(
-                        match uniffi_lift_args() {
-                            Ok(uniffi_args) => {
-                                let uniffi_result = #rust_fn_call;
-                                #convert_result
-                            }
-                            Err((arg_name, anyhow_error)) => {
-                                #return_impl::handle_failed_lift(arg_name, anyhow_error)
-                            },
+                    match uniffi_lift_args() {
+                        ::std::result::Result::Ok(uniffi_args) => {
+                            let uniffi_result = #rust_fn_call;
+                            #lower_return(#convert_result)
                         }
-                    )
+                        ::std::result::Result::Err((arg_name, error)) => {
+                            #handle_failed_lift(::uniffi::LiftArgsError { arg_name, error} )
+                        },
+                    }
                 })
             }
 
@@ -289,26 +292,21 @@ pub(super) fn gen_ffi_function(
             #[no_mangle]
             pub extern "C" fn #ffi_ident(#(#param_names: #param_types,)*) -> ::uniffi::Handle {
                 ::uniffi::deps::log::debug!(#name);
-                let uniffi_lift_args = #lift_closure;
-                match uniffi_lift_args() {
-                    Ok(uniffi_args) => {
-                        ::uniffi::rust_future_new::<_, #return_ty, _>(
-                            async move {
+                let uniffi_lifted_args = (#lift_closure)();
+                ::uniffi::rust_future_new::<_, #return_ty, _>(
+                    async move {
+                        match uniffi_lifted_args {
+                            ::std::result::Result::Ok(uniffi_args) => {
                                 let uniffi_result = #future_expr.await;
-                                #convert_result
+                                Ok(#convert_result)
+                            }
+                            ::std::result::Result::Err((arg_name, error)) => {
+                                Err(::uniffi::LiftArgsError { arg_name, error })
                             },
-                            crate::UniFfiTag
-                        )
+                        }
                     },
-                    Err((arg_name, anyhow_error)) => {
-                        ::uniffi::rust_future_new::<_, #return_ty, _>(
-                            async move {
-                                #return_impl::handle_failed_lift(arg_name, anyhow_error)
-                            },
-                            crate::UniFfiTag,
-                        )
-                    },
-                }
+                    crate::UniFfiTag
+                )
             }
 
             #scaffolding_fn_ffi_buffer_version
@@ -337,7 +335,7 @@ fn ffi_buffer_scaffolding_fn(
             ) {
                 let mut arg_buf = unsafe { ::std::slice::from_raw_parts(arg_ptr, ::uniffi::ffi_buffer_size!(#(#type_list),*)) };
                 let mut return_buf = unsafe { ::std::slice::from_raw_parts_mut(return_ptr, ::uniffi::ffi_buffer_size!(#return_type, ::uniffi::RustCallStatus)) };
-                let mut out_status = ::uniffi::RustCallStatus::default();
+                let mut out_status: ::uniffi::RustCallStatus = ::std::default::Default::default();
 
                 let return_value = #fn_ident(
                     #(
diff --git a/third_party/rust/uniffi_macros/src/export/trait_interface.rs b/third_party/rust/uniffi_macros/src/export/trait_interface.rs
index 83587ae386c3..18d01a5d385d 100644
--- a/third_party/rust/uniffi_macros/src/export/trait_interface.rs
+++ b/third_party/rust/uniffi_macros/src/export/trait_interface.rs
@@ -11,6 +11,7 @@ use crate::{
     export::{
         attributes::ExportTraitArgs, callback_interface, gen_method_scaffolding, item::ImplItem,
     },
+    ffiops,
     object::interface_meta_static_var,
     util::{ident_to_string, tagged_impl_header},
 };
@@ -53,10 +54,14 @@ pub(super) fn gen_trait_scaffolding(
             ptr: *const ::std::ffi::c_void,
             call_status: &mut ::uniffi::RustCallStatus
         ) -> *const ::std::ffi::c_void {
-            uniffi::rust_call(call_status, || {
-                let ptr = ptr as *mut std::sync::Arc<dyn #self_ident>;
-                let arc = unsafe { ::std::sync::Arc::clone(&*ptr) };
-                Ok(::std::boxed::Box::into_raw(::std::boxed::Box::new(arc)) as  *const ::std::ffi::c_void)
+            ::uniffi::rust_call(call_status, || {
+                let ptr = ptr as *mut ::std::sync::Arc<dyn #self_ident>;
+                let arc: ::std::sync::Arc<_> = unsafe { ::std::clone::Clone::clone(&*ptr) };
+                ::std::result::Result::Ok(
+                    ::std::boxed::Box::into_raw(
+                        ::std::boxed::Box::new(arc),
+                    ) as *const ::std::ffi::c_void
+                )
             })
         }
 
@@ -73,10 +78,14 @@ pub(super) fn gen_trait_scaffolding(
             ptr: *const ::std::ffi::c_void,
             call_status: &mut ::uniffi::RustCallStatus
         ) {
-            uniffi::rust_call(call_status, || {
-                assert!(!ptr.is_null());
-                drop(unsafe { ::std::boxed::Box::from_raw(ptr as *mut std::sync::Arc<dyn #self_ident>) });
-                Ok(())
+            ::uniffi::rust_call(call_status, || {
+                ::std::assert!(!ptr.is_null());
+                ::std::mem::drop(unsafe {
+                    ::std::boxed::Box::from_raw(
+                        ptr as *mut ::std::sync::Arc<dyn #self_ident>,
+                    )
+                });
+                ::std::result::Result::Ok(())
             });
         }
     };
@@ -84,7 +93,7 @@ pub(super) fn gen_trait_scaffolding(
     let impl_tokens: TokenStream = items
         .into_iter()
         .map(|item| match item {
-            ImplItem::Method(sig) => gen_method_scaffolding(sig, &None, udl_mode),
+            ImplItem::Method(sig) => gen_method_scaffolding(sig, None, udl_mode),
             _ => unreachable!("traits have no constructors"),
         })
         .collect::<syn::Result<_>>()?;
@@ -95,7 +104,7 @@ pub(super) fn gen_trait_scaffolding(
         } else {
             ObjectImpl::Trait
         };
-        interface_meta_static_var(&self_ident, imp, mod_path, docstring)
+        interface_meta_static_var(&self_ident, imp, mod_path, docstring.as_str())
             .unwrap_or_else(syn::Error::into_compile_error)
     });
     let ffi_converter_tokens = ffi_converter(mod_path, &self_ident, udl_mode, with_foreign);
@@ -122,14 +131,16 @@ pub(crate) fn ffi_converter(
         let trait_impl_ident = callback_interface::trait_impl_ident(&trait_name);
         quote! {
             fn try_lift(v: Self::FfiType) -> ::uniffi::deps::anyhow::Result<::std::sync::Arc<Self>> {
-                Ok(::std::sync::Arc::new(<#trait_impl_ident>::new(v as u64)))
+                ::std::result::Result::Ok(::std::sync::Arc::new(<#trait_impl_ident>::new(v as u64)))
             }
         }
     } else {
         quote! {
             fn try_lift(v: Self::FfiType) -> ::uniffi::deps::anyhow::Result<::std::sync::Arc<Self>> {
                 unsafe {
-                    Ok(*::std::boxed::Box::from_raw(v as *mut ::std::sync::Arc<Self>))
+                    ::std::result::Result::Ok(
+                        *::std::boxed::Box::from_raw(v as *mut ::std::sync::Arc<Self>),
+                    )
                 }
             }
         }
@@ -139,13 +150,17 @@ pub(crate) fn ffi_converter(
     } else {
         quote! { ::uniffi::metadata::codes::TYPE_TRAIT_INTERFACE }
     };
+    let lower_self = ffiops::lower(quote! { ::std::sync::Arc<Self> });
+    let try_lift_self = ffiops::try_lift(quote! { ::std::sync::Arc<Self> });
 
     quote! {
         // All traits must be `Sync + Send`. The generated scaffolding will fail to compile
         // if they are not, but unfortunately it fails with an unactionably obscure error message.
         // By asserting the requirement explicitly, we help Rust produce a more scrutable error message
         // and thus help the user debug why the requirement isn't being met.
-        uniffi::deps::static_assertions::assert_impl_all!(dyn #trait_ident: ::core::marker::Sync, ::core::marker::Send);
+        ::uniffi::deps::static_assertions::assert_impl_all!(
+            dyn #trait_ident: ::core::marker::Sync, ::core::marker::Send
+        );
 
         unsafe #impl_spec {
             type FfiType = *const ::std::os::raw::c_void;
@@ -156,19 +171,18 @@ pub(crate) fn ffi_converter(
 
             #try_lift
 
-            fn write(obj: ::std::sync::Arc<Self>, buf: &mut Vec<u8>) {
+            fn write(obj: ::std::sync::Arc<Self>, buf: &mut ::std::vec::Vec<u8>) {
                 ::uniffi::deps::static_assertions::const_assert!(::std::mem::size_of::<*const ::std::ffi::c_void>() <= 8);
                 ::uniffi::deps::bytes::BufMut::put_u64(
                     buf,
-                    <Self as ::uniffi::FfiConverterArc<crate::UniFfiTag>>::lower(obj) as u64,
+                    #lower_self(obj) as ::std::primitive::u64,
                 );
             }
 
             fn try_read(buf: &mut &[u8]) -> ::uniffi::Result<::std::sync::Arc<Self>> {
                 ::uniffi::deps::static_assertions::const_assert!(::std::mem::size_of::<*const ::std::ffi::c_void>() <= 8);
                 ::uniffi::check_remaining(buf, 8)?;
-                <Self as ::uniffi::FfiConverterArc<crate::UniFfiTag>>::try_lift(
-                    ::uniffi::deps::bytes::Buf::get_u64(buf) as Self::FfiType)
+                #try_lift_self(::uniffi::deps::bytes::Buf::get_u64(buf) as Self::FfiType)
             }
 
             const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(#metadata_code)
diff --git a/third_party/rust/uniffi_macros/src/export/utrait.rs b/third_party/rust/uniffi_macros/src/export/utrait.rs
index 9007ae2c56ba..6e133cedbd34 100644
--- a/third_party/rust/uniffi_macros/src/export/utrait.rs
+++ b/third_party/rust/uniffi_macros/src/export/utrait.rs
@@ -7,7 +7,7 @@ use quote::quote;
 use syn::ext::IdentExt;
 
 use super::gen_ffi_function;
-use crate::export::ExportedImplFnArgs;
+use crate::export::ExportFnArgs;
 use crate::fnsig::FnSignature;
 use crate::util::extract_docstring;
 use uniffi_meta::UniffiTraitDiscriminants;
@@ -103,14 +103,14 @@ pub(crate) fn expand_uniffi_trait_export(
                 let method_eq = quote! {
                     fn uniffi_trait_eq_eq(&self, other: &#self_ident) -> bool {
                         use ::std::cmp::PartialEq;
-                        uniffi::deps::static_assertions::assert_impl_all!(#self_ident: PartialEq); // This object has a trait method which requires `PartialEq` be implemented.
+                        ::uniffi::deps::static_assertions::assert_impl_all!(#self_ident: PartialEq); // This object has a trait method which requires `PartialEq` be implemented.
                         PartialEq::eq(self, other)
                     }
                 };
                 let method_ne = quote! {
                     fn uniffi_trait_eq_ne(&self, other: &#self_ident) -> bool {
                         use ::std::cmp::PartialEq;
-                        uniffi::deps::static_assertions::assert_impl_all!(#self_ident: PartialEq); // This object has a trait method which requires `PartialEq` be implemented.
+                        ::uniffi::deps::static_assertions::assert_impl_all!(#self_ident: PartialEq); // This object has a trait method which requires `PartialEq` be implemented.
                         PartialEq::ne(self, other)
                     }
                 };
@@ -165,17 +165,17 @@ fn process_uniffi_trait_method(
         &FnSignature::new_method(
             self_ident.clone(),
             item.sig.clone(),
-            ExportedImplFnArgs::default(),
+            ExportFnArgs::default(),
             docstring.clone(),
         )?,
-        &None,
+        None,
         udl_mode,
     )?;
     // metadata for the method, which will be packed inside metadata for the trait.
     let method_meta = FnSignature::new_method(
         self_ident.clone(),
         item.sig,
-        ExportedImplFnArgs::default(),
+        ExportFnArgs::default(),
         docstring,
     )?
     .metadata_expr()?;
diff --git a/third_party/rust/uniffi_macros/src/ffiops.rs b/third_party/rust/uniffi_macros/src/ffiops.rs
new file mode 100644
index 000000000000..f43befd812e9
--- /dev/null
+++ b/third_party/rust/uniffi_macros/src/ffiops.rs
@@ -0,0 +1,122 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+//! Functions, types and expressions to handle FFI operations.
+//!
+//! This module leverages the various traits defined in `uniffi_core::ffi_converter_traits` to provide functionality to the rest of `uniffi_macros`.
+//! Keeping this layer separate makes it easier to handle changes to those traits.
+//! See `uniffi_core::ffi_converter_traits` for the meaning of these functions.
+
+use proc_macro2::TokenStream;
+use quote::{quote, ToTokens};
+
+// Lower type
+pub fn lower_type(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lower<crate::UniFfiTag>>::FfiType
+    }
+}
+
+// Lower function
+pub fn lower(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lower<crate::UniFfiTag>>::lower
+    }
+}
+
+// Lift type
+pub fn lift_type(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lift<crate::UniFfiTag>>::FfiType
+    }
+}
+
+// Lift function
+pub fn try_lift(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lift<crate::UniFfiTag>>::try_lift
+    }
+}
+
+/// Write function
+pub fn write(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lower<crate::UniFfiTag>>::write
+    }
+}
+
+/// Read function
+pub fn try_read(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lift<crate::UniFfiTag>>::try_read
+    }
+}
+
+/// Lower return type
+pub fn lower_return_type(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::ReturnType
+    }
+}
+
+/// Lower return function
+pub fn lower_return(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::lower_return
+    }
+}
+
+/// Lower error function
+pub fn lower_error(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::LowerError<crate::UniFfiTag>>::lower_error
+    }
+}
+
+/// Lift return type
+pub fn lift_return_type(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::LiftReturn<crate::UniFfiTag>>::ReturnType
+    }
+}
+
+/// Lift foreign return function
+pub fn lift_foreign_return(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::LiftReturn<crate::UniFfiTag>>::lift_foreign_return
+    }
+}
+
+/// Handle failed lift function
+pub fn lower_return_handle_failed_lift(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::handle_failed_lift
+    }
+}
+
+/// LiftRef type
+pub fn lift_ref_type(ty: impl ToTokens) -> TokenStream {
+    quote! { <#ty as ::uniffi::LiftRef<crate::UniFfiTag>>::LiftType }
+}
+
+/// Lower into rust buffer function
+pub fn lower_into_rust_buffer(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lower<crate::UniFfiTag>>::lower_into_rust_buffer
+    }
+}
+
+/// Lift from rust buffer function
+pub fn try_lift_from_rust_buffer(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::Lift<crate::UniFfiTag>>::try_lift_from_rust_buffer
+    }
+}
+
+/// Expression for the TYPE_ID_META value for a type
+pub fn type_id_meta(ty: impl ToTokens) -> TokenStream {
+    quote! {
+        <#ty as ::uniffi::TypeId<crate::UniFfiTag>>::TYPE_ID_META
+    }
+}
diff --git a/third_party/rust/uniffi_macros/src/fnsig.rs b/third_party/rust/uniffi_macros/src/fnsig.rs
index 9c591252077d..19774dc3bac5 100644
--- a/third_party/rust/uniffi_macros/src/fnsig.rs
+++ b/third_party/rust/uniffi_macros/src/fnsig.rs
@@ -4,7 +4,8 @@
 
 use crate::{
     default::{default_value_metadata_calls, DefaultValue},
-    export::{DefaultMap, ExportFnArgs, ExportedImplFnArgs},
+    export::{AsyncRuntime, DefaultMap, ExportFnArgs},
+    ffiops,
     util::{create_metadata_items, ident_to_string, mod_path, try_metadata_value_from_usize},
 };
 use proc_macro2::{Span, TokenStream};
@@ -20,6 +21,7 @@ pub(crate) struct FnSignature {
     // The foreign name for this function, usually == ident.
     pub name: String,
     pub is_async: bool,
+    pub async_runtime: Option<AsyncRuntime>,
     pub receiver: Option<ReceiverArg>,
     pub args: Vec<NamedArg>,
     pub return_ty: TokenStream,
@@ -36,51 +38,38 @@ impl FnSignature {
         args: ExportFnArgs,
         docstring: String,
     ) -> syn::Result<Self> {
-        Self::new(FnKind::Function, sig, args.name, args.defaults, docstring)
+        Self::new(FnKind::Function, sig, args, docstring)
     }
 
     pub(crate) fn new_method(
         self_ident: Ident,
         sig: syn::Signature,
-        args: ExportedImplFnArgs,
+        args: ExportFnArgs,
         docstring: String,
     ) -> syn::Result<Self> {
-        Self::new(
-            FnKind::Method { self_ident },
-            sig,
-            args.name,
-            args.defaults,
-            docstring,
-        )
+        Self::new(FnKind::Method { self_ident }, sig, args, docstring)
     }
 
     pub(crate) fn new_constructor(
         self_ident: Ident,
         sig: syn::Signature,
-        args: ExportedImplFnArgs,
+        args: ExportFnArgs,
         docstring: String,
     ) -> syn::Result<Self> {
-        Self::new(
-            FnKind::Constructor { self_ident },
-            sig,
-            args.name,
-            args.defaults,
-            docstring,
-        )
+        Self::new(FnKind::Constructor { self_ident }, sig, args, docstring)
     }
 
     pub(crate) fn new_trait_method(
         self_ident: Ident,
         sig: syn::Signature,
-        args: ExportedImplFnArgs,
+        args: ExportFnArgs,
         index: u32,
         docstring: String,
     ) -> syn::Result<Self> {
         Self::new(
             FnKind::TraitMethod { self_ident, index },
             sig,
-            args.name,
-            args.defaults,
+            args,
             docstring,
         )
     }
@@ -88,8 +77,7 @@ impl FnSignature {
     pub(crate) fn new(
         kind: FnKind,
         sig: syn::Signature,
-        name: Option<String>,
-        mut defaults: DefaultMap,
+        mut export_fn_args: ExportFnArgs,
         docstring: String,
     ) -> syn::Result<Self> {
         let span = sig.span();
@@ -104,7 +92,7 @@ impl FnSignature {
         let mut input_iter = sig
             .inputs
             .into_iter()
-            .map(|a| Arg::new(a, &mut defaults))
+            .map(|a| Arg::new(a, &mut export_fn_args.defaults))
             .peekable();
 
         let receiver = input_iter
@@ -127,20 +115,30 @@ impl FnSignature {
             })
             .collect::<syn::Result<Vec<_>>>()?;
 
-        if let Some(ident) = defaults.idents().first() {
+        if let Some(ident) = export_fn_args.defaults.idents().first() {
             return Err(syn::Error::new(
                 ident.span(),
                 format!("Unknown default argument: {}", ident),
             ));
         }
 
+        if !is_async && export_fn_args.async_runtime.is_some() {
+            return Err(syn::Error::new(
+                export_fn_args.async_runtime.span(),
+                "Function not async".to_string(),
+            ));
+        }
+
         Ok(Self {
             kind,
             span,
             mod_path: mod_path()?,
-            name: name.unwrap_or_else(|| ident_to_string(&ident)),
+            name: export_fn_args
+                .name
+                .unwrap_or_else(|| ident_to_string(&ident)),
             ident,
             is_async,
+            async_runtime: export_fn_args.async_runtime,
             receiver,
             args,
             return_ty: output,
@@ -149,20 +147,6 @@ impl FnSignature {
         })
     }
 
-    pub fn lower_return_impl(&self) -> TokenStream {
-        let return_ty = &self.return_ty;
-        quote! {
-            <#return_ty as ::uniffi::LowerReturn<crate::UniFfiTag>>
-        }
-    }
-
-    pub fn lift_return_impl(&self) -> TokenStream {
-        let return_ty = &self.return_ty;
-        quote! {
-            <#return_ty as ::uniffi::LiftReturn<crate::UniFfiTag>>
-        }
-    }
-
     /// Generate a closure that tries to lift all arguments into a tuple.
     ///
     /// The closure moves all scaffolding arguments into itself and returns:
@@ -171,18 +155,20 @@ impl FnSignature {
     pub fn lift_closure(&self, self_lift: Option<TokenStream>) -> TokenStream {
         let arg_lifts = self.args.iter().map(|arg| {
             let ident = &arg.ident;
-            let lift_impl = arg.lift_impl();
+            let try_lift = ffiops::try_lift(&arg.ty);
             let name = &arg.name;
             quote! {
-                match #lift_impl::try_lift(#ident) {
-                    Ok(v) => v,
-                    Err(e) => return Err((#name, e)),
+                match #try_lift(#ident) {
+                    ::std::result::Result::Ok(v) => v,
+                    ::std::result::Result::Err(e) => {
+                        return ::std::result::Result::Err((#name, e))
+                    }
                 }
             }
         });
         let all_lifts = self_lift.into_iter().chain(arg_lifts);
         quote! {
-            move || Ok((
+            move || ::std::result::Result::Ok((
                 #(#all_lifts,)*
             ))
         }
@@ -238,10 +224,7 @@ impl FnSignature {
     }
 
     pub fn scaffolding_param_types(&self) -> impl Iterator<Item = TokenStream> + '_ {
-        self.args.iter().map(|a| {
-            let lift_impl = a.lift_impl();
-            quote! { #lift_impl::FfiType }
-        })
+        self.args.iter().map(|a| ffiops::lift_type(&a.ty))
     }
 
     /// Generate metadata items for this function
@@ -266,6 +249,8 @@ impl FnSignature {
             .map(NamedArg::arg_metadata)
             .collect::<syn::Result<Vec<_>>>()?;
 
+        let type_id_meta = ffiops::type_id_meta(return_ty);
+
         match &self.kind {
             FnKind::Function => Ok(quote! {
                 ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::FUNC)
@@ -274,7 +259,7 @@ impl FnSignature {
                     .concat_bool(#is_async)
                     .concat_value(#args_len)
                     #(#arg_metadata_calls)*
-                    .concat(<#return_ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::TYPE_ID_META)
+                    .concat(#type_id_meta)
                     .concat_long_str(#docstring)
             }),
 
@@ -288,7 +273,7 @@ impl FnSignature {
                         .concat_bool(#is_async)
                         .concat_value(#args_len)
                         #(#arg_metadata_calls)*
-                        .concat(<#return_ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::TYPE_ID_META)
+                        .concat(#type_id_meta)
                         .concat_long_str(#docstring)
                 })
             }
@@ -304,7 +289,7 @@ impl FnSignature {
                         .concat_bool(#is_async)
                         .concat_value(#args_len)
                         #(#arg_metadata_calls)*
-                        .concat(<#return_ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::TYPE_ID_META)
+                        .concat(#type_id_meta)
                         .concat_long_str(#docstring)
                 })
             }
@@ -319,7 +304,7 @@ impl FnSignature {
                         .concat_bool(#is_async)
                         .concat_value(#args_len)
                         #(#arg_metadata_calls)*
-                        .concat(<#return_ty as ::uniffi::LowerReturn<crate::UniFfiTag>>::TYPE_ID_META)
+                        .concat(#type_id_meta)
                         .concat_long_str(#docstring)
                 })
             }
@@ -368,69 +353,6 @@ impl FnSignature {
         }
     }
 
-    /// Generate metadata items for callback interfaces
-    ///
-    /// Unfortunately, most of this is duplicate code from [Self::metadata_items] and
-    /// [Self::metadata_expr].  However, one issue with that code is that it needs to assume if the
-    /// arguments are being lifted vs lowered in order to get TYPE_ID_META.  That code uses
-    /// `<Type as Lift>::TYPE_ID_META` for arguments and `<Type as LowerReturn>::TYPE_ID_META` for
-    /// return types, which works for accidental/historical reasons.
-    ///
-    /// The one exception is callback interfaces (#1947), which are handled by this method.
-    ///
-    /// TODO: fix the metadata system so that this is not needed.
-    pub(crate) fn metadata_items_for_callback_interface(&self) -> syn::Result<TokenStream> {
-        let Self {
-            name,
-            return_ty,
-            is_async,
-            mod_path,
-            docstring,
-            ..
-        } = &self;
-        match &self.kind {
-            FnKind::TraitMethod {
-                self_ident, index, ..
-            } => {
-                let object_name = ident_to_string(self_ident);
-                let args_len = try_metadata_value_from_usize(
-                    // Use param_lifts to calculate this instead of sig.inputs to avoid counting any self
-                    // params
-                    self.args.len(),
-                    "UniFFI limits functions to 256 arguments",
-                )?;
-                let arg_metadata_calls = self
-                    .args
-                    .iter()
-                    .map(NamedArg::arg_metadata)
-                    .collect::<syn::Result<Vec<_>>>()?;
-                let metadata_expr = quote! {
-                    ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::TRAIT_METHOD)
-                        .concat_str(#mod_path)
-                        .concat_str(#object_name)
-                        .concat_u32(#index)
-                        .concat_str(#name)
-                        .concat_bool(#is_async)
-                        .concat_value(#args_len)
-                        #(#arg_metadata_calls)*
-                        .concat(<#return_ty as ::uniffi::LiftReturn<crate::UniFfiTag>>::TYPE_ID_META)
-                        .concat_long_str(#docstring)
-                };
-                Ok(create_metadata_items(
-                    "method",
-                    &format!("{object_name}_{name}"),
-                    metadata_expr,
-                    Some(self.checksum_symbol_name()),
-                ))
-            }
-
-            // This should never happen and indicates an error in the internal code
-            _ => panic!(
-                "metadata_items_for_callback_interface can only be called with `TraitMethod` sigs"
-            ),
-        }
-    }
-
     pub(crate) fn checksum_symbol_name(&self) -> String {
         let name = &self.name;
         match &self.kind {
@@ -516,7 +438,7 @@ impl NamedArg {
                 let inner = &r.elem;
                 Self {
                     name: ident_to_string(&ident),
-                    ty: quote! { <#inner as ::uniffi::LiftRef<crate::UniFfiTag>>::LiftType },
+                    ty: ffiops::lift_ref_type(inner),
                     ref_type: Some(*inner.clone()),
                     default: defaults.remove(&ident),
                     ident,
@@ -532,16 +454,6 @@ impl NamedArg {
         })
     }
 
-    pub(crate) fn lift_impl(&self) -> TokenStream {
-        let ty = &self.ty;
-        quote! { <#ty as ::uniffi::Lift<crate::UniFfiTag>> }
-    }
-
-    pub(crate) fn lower_impl(&self) -> TokenStream {
-        let ty = &self.ty;
-        quote! { <#ty as ::uniffi::Lower<crate::UniFfiTag>> }
-    }
-
     /// Generate the parameter for this Arg
     pub(crate) fn param(&self) -> TokenStream {
         let ident = &self.ident;
@@ -551,11 +463,11 @@ impl NamedArg {
 
     pub(crate) fn arg_metadata(&self) -> syn::Result<TokenStream> {
         let name = &self.name;
-        let lift_impl = self.lift_impl();
+        let type_id_meta = ffiops::type_id_meta(&self.ty);
         let default_calls = default_value_metadata_calls(&self.default)?;
         Ok(quote! {
             .concat_str(#name)
-            .concat(#lift_impl::TYPE_ID_META)
+            .concat(#type_id_meta)
             #default_calls
         })
     }
diff --git a/third_party/rust/uniffi_macros/src/lib.rs b/third_party/rust/uniffi_macros/src/lib.rs
index 929400c885f1..289740b1c8e3 100644
--- a/third_party/rust/uniffi_macros/src/lib.rs
+++ b/third_party/rust/uniffi_macros/src/lib.rs
@@ -17,9 +17,11 @@ use syn::{
 
 mod custom;
 mod default;
+mod derive;
 mod enum_;
 mod error;
 mod export;
+mod ffiops;
 mod fnsig;
 mod object;
 mod record;
@@ -28,8 +30,8 @@ mod test;
 mod util;
 
 use self::{
-    enum_::expand_enum, error::expand_error, export::expand_export, object::expand_object,
-    record::expand_record,
+    derive::DeriveOptions, enum_::expand_enum, error::expand_error, export::expand_export,
+    object::expand_object, record::expand_record,
 };
 
 struct CustomTypeInfo {
@@ -106,28 +108,28 @@ fn do_export(attr_args: TokenStream, input: TokenStream, udl_mode: bool) -> Toke
 
 #[proc_macro_derive(Record, attributes(uniffi))]
 pub fn derive_record(input: TokenStream) -> TokenStream {
-    expand_record(parse_macro_input!(input), false)
+    expand_record(parse_macro_input!(input), DeriveOptions::default())
         .unwrap_or_else(syn::Error::into_compile_error)
         .into()
 }
 
 #[proc_macro_derive(Enum)]
 pub fn derive_enum(input: TokenStream) -> TokenStream {
-    expand_enum(parse_macro_input!(input), None, false)
+    expand_enum(parse_macro_input!(input), DeriveOptions::default())
         .unwrap_or_else(syn::Error::into_compile_error)
         .into()
 }
 
 #[proc_macro_derive(Object)]
 pub fn derive_object(input: TokenStream) -> TokenStream {
-    expand_object(parse_macro_input!(input), false)
+    expand_object(parse_macro_input!(input), DeriveOptions::default())
         .unwrap_or_else(syn::Error::into_compile_error)
         .into()
 }
 
 #[proc_macro_derive(Error, attributes(uniffi))]
 pub fn derive_error(input: TokenStream) -> TokenStream {
-    expand_error(parse_macro_input!(input), None, false)
+    expand_error(parse_macro_input!(input), DeriveOptions::default())
         .unwrap_or_else(syn::Error::into_compile_error)
         .into()
 }
@@ -153,28 +155,11 @@ pub fn custom_newtype(tokens: TokenStream) -> TokenStream {
         .into()
 }
 
-// == derive_for_udl and export_for_udl ==
+// Derive items for UDL mode
 //
-// The Askama templates generate placeholder items wrapped with these attributes. The goal is to
-// have all scaffolding generation go through the same code path.
-//
-// The one difference is that derive-style attributes are not allowed inside attribute macro
-// inputs.  Instead, we take the attributes from the macro invocation itself.
-//
-// Instead of:
-//
-// ```
-// #[derive(Error)
-// #[uniffi(flat_error])
-// enum { .. }
-// ```
-//
-// We have:
-//
-// ```
-// #[derive_error_for_udl(flat_error)]
-// enum { ... }
-//  ```
+// The Askama templates generate placeholder items wrapped with the `#[udl_derive(<kind>)]`
+// attribute.  The macro code then generates derived items based on the input.  This system ensures
+// that the same code path is used for UDL-based code and proc-macros.
 //
 // # Differences between UDL-mode and normal mode
 //
@@ -198,47 +183,21 @@ pub fn custom_newtype(tokens: TokenStream) -> TokenStream {
 //
 // With proc-macros this system isn't so natural.  Instead, we create a blanket implementation
 // for all UT and support for remote types is still TODO.
-
 #[doc(hidden)]
 #[proc_macro_attribute]
-pub fn derive_record_for_udl(_attrs: TokenStream, input: TokenStream) -> TokenStream {
-    expand_record(syn::parse_macro_input!(input), true)
-        .unwrap_or_else(syn::Error::into_compile_error)
-        .into()
-}
-
-#[doc(hidden)]
-#[proc_macro_attribute]
-pub fn derive_enum_for_udl(attrs: TokenStream, input: TokenStream) -> TokenStream {
-    expand_enum(
-        syn::parse_macro_input!(input),
-        Some(syn::parse_macro_input!(attrs)),
-        true,
+pub fn udl_derive(attrs: TokenStream, input: TokenStream) -> TokenStream {
+    derive::expand_derive(
+        parse_macro_input!(attrs),
+        parse_macro_input!(input),
+        DeriveOptions::udl_derive(),
     )
     .unwrap_or_else(syn::Error::into_compile_error)
     .into()
 }
 
-#[doc(hidden)]
-#[proc_macro_attribute]
-pub fn derive_error_for_udl(attrs: TokenStream, input: TokenStream) -> TokenStream {
-    expand_error(
-        syn::parse_macro_input!(input),
-        Some(syn::parse_macro_input!(attrs)),
-        true,
-    )
-    .unwrap_or_else(syn::Error::into_compile_error)
-    .into()
-}
-
-#[doc(hidden)]
-#[proc_macro_attribute]
-pub fn derive_object_for_udl(_attrs: TokenStream, input: TokenStream) -> TokenStream {
-    expand_object(syn::parse_macro_input!(input), true)
-        .unwrap_or_else(syn::Error::into_compile_error)
-        .into()
-}
-
+// Generate export items for UDL mode
+//
+// This works similarly to `udl_derive`, but for #[export].
 #[doc(hidden)]
 #[proc_macro_attribute]
 pub fn export_for_udl(attrs: TokenStream, input: TokenStream) -> TokenStream {
diff --git a/third_party/rust/uniffi_macros/src/object.rs b/third_party/rust/uniffi_macros/src/object.rs
index 6bcc07a14e07..0907bbfd3bf3 100644
--- a/third_party/rust/uniffi_macros/src/object.rs
+++ b/third_party/rust/uniffi_macros/src/object.rs
@@ -2,16 +2,45 @@ use proc_macro2::{Ident, Span, TokenStream};
 use quote::quote;
 use syn::DeriveInput;
 
-use crate::util::{
-    create_metadata_items, extract_docstring, ident_to_string, mod_path, tagged_impl_header,
+use crate::{
+    ffiops,
+    util::{create_metadata_items, extract_docstring, ident_to_string, mod_path},
+    DeriveOptions,
 };
 use uniffi_meta::ObjectImpl;
 
-pub fn expand_object(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStream> {
+/// Stores parsed data from the Derive Input for the struct/enum.
+struct ObjectItem {
+    ident: Ident,
+    docstring: String,
+}
+
+impl ObjectItem {
+    fn new(input: DeriveInput) -> syn::Result<Self> {
+        Ok(Self {
+            ident: input.ident,
+            docstring: extract_docstring(&input.attrs)?,
+        })
+    }
+
+    fn ident(&self) -> &Ident {
+        &self.ident
+    }
+
+    fn name(&self) -> String {
+        ident_to_string(&self.ident)
+    }
+
+    fn docstring(&self) -> &str {
+        self.docstring.as_str()
+    }
+}
+
+pub fn expand_object(input: DeriveInput, options: DeriveOptions) -> syn::Result<TokenStream> {
     let module_path = mod_path()?;
-    let ident = &input.ident;
-    let docstring = extract_docstring(&input.attrs)?;
-    let name = ident_to_string(ident);
+    let object = ObjectItem::new(input)?;
+    let name = object.name();
+    let ident = object.ident();
     let clone_fn_ident = Ident::new(
         &uniffi_meta::clone_fn_symbol_name(&module_path, &name),
         Span::call_site(),
@@ -20,11 +49,16 @@ pub fn expand_object(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStr
         &uniffi_meta::free_fn_symbol_name(&module_path, &name),
         Span::call_site(),
     );
-    let meta_static_var = (!udl_mode).then(|| {
-        interface_meta_static_var(ident, ObjectImpl::Struct, &module_path, docstring)
-            .unwrap_or_else(syn::Error::into_compile_error)
+    let meta_static_var = options.generate_metadata.then(|| {
+        interface_meta_static_var(
+            object.ident(),
+            ObjectImpl::Struct,
+            &module_path,
+            object.docstring(),
+        )
+        .unwrap_or_else(syn::Error::into_compile_error)
     });
-    let interface_impl = interface_impl(ident, udl_mode);
+    let interface_impl = interface_impl(&object, &options);
 
     Ok(quote! {
         #[doc(hidden)]
@@ -33,9 +67,9 @@ pub fn expand_object(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStr
             ptr: *const ::std::ffi::c_void,
             call_status: &mut ::uniffi::RustCallStatus
         ) -> *const ::std::ffi::c_void {
-            uniffi::rust_call(call_status, || {
+            ::uniffi::rust_call(call_status, || {
                 unsafe { ::std::sync::Arc::increment_strong_count(ptr) };
-                Ok(ptr)
+                ::std::result::Result::Ok(ptr)
             })
         }
 
@@ -45,13 +79,13 @@ pub fn expand_object(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStr
             ptr: *const ::std::ffi::c_void,
             call_status: &mut ::uniffi::RustCallStatus
         ) {
-            uniffi::rust_call(call_status, || {
+            ::uniffi::rust_call(call_status, || {
                 assert!(!ptr.is_null());
                 let ptr = ptr.cast::<#ident>();
                 unsafe {
                     ::std::sync::Arc::decrement_strong_count(ptr);
                 }
-                Ok(())
+                ::std::result::Result::Ok(())
             });
         }
 
@@ -60,22 +94,34 @@ pub fn expand_object(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStr
     })
 }
 
-pub(crate) fn interface_impl(ident: &Ident, udl_mode: bool) -> TokenStream {
-    let name = ident_to_string(ident);
-    let impl_spec = tagged_impl_header("FfiConverterArc", ident, udl_mode);
-    let lower_return_impl_spec = tagged_impl_header("LowerReturn", ident, udl_mode);
-    let lift_ref_impl_spec = tagged_impl_header("LiftRef", ident, udl_mode);
+fn interface_impl(object: &ObjectItem, options: &DeriveOptions) -> TokenStream {
+    let name = object.name();
+    let ident = object.ident();
+    let impl_spec = options.ffi_impl_header("FfiConverterArc", ident);
+    let lower_return_impl_spec = options.ffi_impl_header("LowerReturn", ident);
+    let lower_error_impl_spec = options.ffi_impl_header("LowerError", ident);
+    let type_id_impl_spec = options.ffi_impl_header("TypeId", ident);
+    let lift_ref_impl_spec = options.ffi_impl_header("LiftRef", ident);
     let mod_path = match mod_path() {
         Ok(p) => p,
         Err(e) => return e.into_compile_error(),
     };
+    let arc_self_type = quote! { ::std::sync::Arc<Self> };
+    let lower_arc = ffiops::lower(&arc_self_type);
+    let type_id_meta_arc = ffiops::type_id_meta(&arc_self_type);
+    let try_lift_arc = ffiops::try_lift(&arc_self_type);
+    let lower_return_type_arc = ffiops::lower_return_type(&arc_self_type);
+    let lower_return_arc = ffiops::lower_return(&arc_self_type);
+    let lower_error_arc = ffiops::lower_error(&arc_self_type);
 
     quote! {
         // All Object structs must be `Sync + Send`. The generated scaffolding will fail to compile
         // if they are not, but unfortunately it fails with an unactionably obscure error message.
         // By asserting the requirement explicitly, we help Rust produce a more scrutable error message
         // and thus help the user debug why the requirement isn't being met.
-        uniffi::deps::static_assertions::assert_impl_all!(#ident: ::core::marker::Sync, ::core::marker::Send);
+        ::uniffi::deps::static_assertions::assert_impl_all!(
+            #ident: ::core::marker::Sync, ::core::marker::Send
+        );
 
         #[doc(hidden)]
         #[automatically_derived]
@@ -104,7 +150,7 @@ pub(crate) fn interface_impl(ident: &Ident, udl_mode: bool) -> TokenStream {
             /// When lifting, we receive an owned `Arc` that the foreign language code cloned.
             fn try_lift(v: Self::FfiType) -> ::uniffi::Result<::std::sync::Arc<Self>> {
                 let v = v as *const #ident;
-                Ok(unsafe { ::std::sync::Arc::<Self>::from_raw(v) })
+                ::std::result::Result::Ok(unsafe { ::std::sync::Arc::<Self>::from_raw(v) })
             }
 
             /// When writing as a field of a complex structure, make a clone and transfer ownership
@@ -115,9 +161,9 @@ pub(crate) fn interface_impl(ident: &Ident, udl_mode: bool) -> TokenStream {
             /// Safety: when freeing the resulting pointer, the foreign-language code must
             /// call the destructor function specific to the type `T`. Calling the destructor
             /// function for other types may lead to undefined behaviour.
-            fn write(obj: ::std::sync::Arc<Self>, buf: &mut Vec<u8>) {
+            fn write(obj: ::std::sync::Arc<Self>, buf: &mut ::std::vec::Vec<u8>) {
                 ::uniffi::deps::static_assertions::const_assert!(::std::mem::size_of::<*const ::std::ffi::c_void>() <= 8);
-                ::uniffi::deps::bytes::BufMut::put_u64(buf, <Self as ::uniffi::FfiConverterArc<crate::UniFfiTag>>::lower(obj) as u64);
+                ::uniffi::deps::bytes::BufMut::put_u64(buf, #lower_arc(obj) as ::std::primitive::u64);
             }
 
             /// When reading as a field of a complex structure, we receive a "borrow" of the `Arc`
@@ -128,7 +174,7 @@ pub(crate) fn interface_impl(ident: &Ident, udl_mode: bool) -> TokenStream {
             fn try_read(buf: &mut &[u8]) -> ::uniffi::Result<::std::sync::Arc<Self>> {
                 ::uniffi::deps::static_assertions::const_assert!(::std::mem::size_of::<*const ::std::ffi::c_void>() <= 8);
                 ::uniffi::check_remaining(buf, 8)?;
-                <Self as ::uniffi::FfiConverterArc<crate::UniFfiTag>>::try_lift(::uniffi::deps::bytes::Buf::get_u64(buf) as Self::FfiType)
+                #try_lift_arc(::uniffi::deps::bytes::Buf::get_u64(buf) as Self::FfiType)
             }
 
             const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::TYPE_INTERFACE)
@@ -137,18 +183,26 @@ pub(crate) fn interface_impl(ident: &Ident, udl_mode: bool) -> TokenStream {
         }
 
         unsafe #lower_return_impl_spec {
-            type ReturnType = <Self as ::uniffi::FfiConverterArc<crate::UniFfiTag>>::FfiType;
+            type ReturnType = #lower_return_type_arc;
 
-            fn lower_return(obj: Self) -> ::std::result::Result<Self::ReturnType, ::uniffi::RustBuffer> {
-                Ok(<Self as ::uniffi::FfiConverterArc<crate::UniFfiTag>>::lower(::std::sync::Arc::new(obj)))
+            fn lower_return(obj: Self) -> ::std::result::Result<Self::ReturnType, ::uniffi::RustCallError> {
+                #lower_return_arc(::std::sync::Arc::new(obj))
             }
+        }
 
-            const TYPE_ID_META: ::uniffi::MetadataBuffer = <Self as ::uniffi::FfiConverterArc<crate::UniFfiTag>>::TYPE_ID_META;
+        unsafe #lower_error_impl_spec {
+            fn lower_error(obj: Self) -> ::uniffi::RustBuffer {
+                #lower_error_arc(::std::sync::Arc::new(obj))
+            }
         }
 
         unsafe #lift_ref_impl_spec {
             type LiftType = ::std::sync::Arc<Self>;
         }
+
+        #type_id_impl_spec {
+            const TYPE_ID_META: ::uniffi::MetadataBuffer = #type_id_meta_arc;
+        }
     }
 }
 
@@ -156,7 +210,7 @@ pub(crate) fn interface_meta_static_var(
     ident: &Ident,
     imp: ObjectImpl,
     module_path: &str,
-    docstring: String,
+    docstring: &str,
 ) -> syn::Result<TokenStream> {
     let name = ident_to_string(ident);
     let code = match imp {
diff --git a/third_party/rust/uniffi_macros/src/record.rs b/third_party/rust/uniffi_macros/src/record.rs
index 41f5d016aceb..74629d1915cf 100644
--- a/third_party/rust/uniffi_macros/src/record.rs
+++ b/third_party/rust/uniffi_macros/src/record.rs
@@ -4,35 +4,67 @@ use syn::{parse::ParseStream, Data, DataStruct, DeriveInput, Field, Token};
 
 use crate::{
     default::{default_value_metadata_calls, DefaultValue},
+    ffiops,
     util::{
-        create_metadata_items, derive_all_ffi_traits, either_attribute_arg, extract_docstring,
-        ident_to_string, kw, mod_path, tagged_impl_header, try_metadata_value_from_usize,
-        try_read_field, AttributeSliceExt, UniffiAttributeArgs,
+        create_metadata_items, either_attribute_arg, extract_docstring, ident_to_string, kw,
+        mod_path, try_metadata_value_from_usize, try_read_field, AttributeSliceExt,
+        UniffiAttributeArgs,
     },
+    DeriveOptions,
 };
 
-pub fn expand_record(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStream> {
+/// Stores parsed data from the Derive Input for the struct.
+struct RecordItem {
+    ident: Ident,
+    record: DataStruct,
+    docstring: String,
+}
+
+impl RecordItem {
+    fn new(input: DeriveInput) -> syn::Result<Self> {
+        let record = match input.data {
+            Data::Struct(s) => s,
+            _ => {
+                return Err(syn::Error::new(
+                    Span::call_site(),
+                    "This derive must only be used on structs",
+                ));
+            }
+        };
+        Ok(Self {
+            ident: input.ident,
+            record,
+            docstring: extract_docstring(&input.attrs)?,
+        })
+    }
+
+    fn ident(&self) -> &Ident {
+        &self.ident
+    }
+
+    fn name(&self) -> String {
+        ident_to_string(&self.ident)
+    }
+
+    fn struct_(&self) -> &DataStruct {
+        &self.record
+    }
+
+    fn docstring(&self) -> &str {
+        self.docstring.as_str()
+    }
+}
+
+pub fn expand_record(input: DeriveInput, options: DeriveOptions) -> syn::Result<TokenStream> {
     if let Some(e) = input.attrs.uniffi_attr_args_not_allowed_here() {
         return Err(e);
     }
-    let record = match input.data {
-        Data::Struct(s) => s,
-        _ => {
-            return Err(syn::Error::new(
-                Span::call_site(),
-                "This derive must only be used on structs",
-            ));
-        }
-    };
-
-    let ident = &input.ident;
-    let docstring = extract_docstring(&input.attrs)?;
-    let ffi_converter = record_ffi_converter_impl(ident, &record, udl_mode)
-        .unwrap_or_else(syn::Error::into_compile_error);
-    let meta_static_var = (!udl_mode).then(|| {
-        record_meta_static_var(ident, docstring, &record)
-            .unwrap_or_else(syn::Error::into_compile_error)
-    });
+    let record = RecordItem::new(input)?;
+    let ffi_converter =
+        record_ffi_converter_impl(&record, &options).unwrap_or_else(syn::Error::into_compile_error);
+    let meta_static_var = options
+        .generate_metadata
+        .then(|| record_meta_static_var(&record).unwrap_or_else(syn::Error::into_compile_error));
 
     Ok(quote! {
         #ffi_converter
@@ -40,17 +72,17 @@ pub fn expand_record(input: DeriveInput, udl_mode: bool) -> syn::Result<TokenStr
     })
 }
 
-pub(crate) fn record_ffi_converter_impl(
-    ident: &Ident,
-    record: &DataStruct,
-    udl_mode: bool,
+fn record_ffi_converter_impl(
+    record: &RecordItem,
+    options: &DeriveOptions,
 ) -> syn::Result<TokenStream> {
-    let impl_spec = tagged_impl_header("FfiConverter", ident, udl_mode);
-    let derive_ffi_traits = derive_all_ffi_traits(ident, udl_mode);
+    let ident = record.ident();
+    let impl_spec = options.ffi_impl_header("FfiConverter", ident);
+    let derive_ffi_traits = options.derive_all_ffi_traits(ident);
     let name = ident_to_string(ident);
     let mod_path = mod_path()?;
-    let write_impl: TokenStream = record.fields.iter().map(write_field).collect();
-    let try_read_fields: TokenStream = record.fields.iter().map(try_read_field).collect();
+    let write_impl: TokenStream = record.struct_().fields.iter().map(write_field).collect();
+    let try_read_fields: TokenStream = record.struct_().fields.iter().map(try_read_field).collect();
 
     Ok(quote! {
         #[automatically_derived]
@@ -62,7 +94,7 @@ pub(crate) fn record_ffi_converter_impl(
             }
 
             fn try_read(buf: &mut &[::std::primitive::u8]) -> ::uniffi::deps::anyhow::Result<Self> {
-                Ok(Self { #try_read_fields })
+                ::std::result::Result::Ok(Self { #try_read_fields })
             }
 
             const TYPE_ID_META: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::TYPE_RECORD)
@@ -76,10 +108,9 @@ pub(crate) fn record_ffi_converter_impl(
 
 fn write_field(f: &Field) -> TokenStream {
     let ident = &f.ident;
-    let ty = &f.ty;
-
+    let write = ffiops::write(&f.ty);
     quote! {
-        <#ty as ::uniffi::Lower<crate::UniFfiTag>>::write(obj.#ident, buf);
+        #write(obj.#ident, buf);
     }
 }
 
@@ -105,17 +136,17 @@ impl UniffiAttributeArgs for FieldAttributeArguments {
     }
 }
 
-pub(crate) fn record_meta_static_var(
-    ident: &Ident,
-    docstring: String,
-    record: &DataStruct,
-) -> syn::Result<TokenStream> {
-    let name = ident_to_string(ident);
+fn record_meta_static_var(record: &RecordItem) -> syn::Result<TokenStream> {
+    let name = record.name();
+    let docstring = record.docstring();
     let module_path = mod_path()?;
-    let fields_len =
-        try_metadata_value_from_usize(record.fields.len(), "UniFFI limits structs to 256 fields")?;
+    let fields_len = try_metadata_value_from_usize(
+        record.struct_().fields.len(),
+        "UniFFI limits structs to 256 fields",
+    )?;
 
     let concat_fields: TokenStream = record
+        .struct_()
         .fields
         .iter()
         .map(|f| {
@@ -125,14 +156,14 @@ pub(crate) fn record_meta_static_var(
 
             let name = ident_to_string(f.ident.as_ref().unwrap());
             let docstring = extract_docstring(&f.attrs)?;
-            let ty = &f.ty;
             let default = default_value_metadata_calls(&attrs.default)?;
+            let type_id_meta = ffiops::type_id_meta(&f.ty);
 
             // Note: fields need to implement both `Lower` and `Lift` to be used in a record.  The
             // TYPE_ID_META should be the same for both traits.
             Ok(quote! {
                 .concat_str(#name)
-                .concat(<#ty as ::uniffi::Lower<crate::UniFfiTag>>::TYPE_ID_META)
+                .concat(#type_id_meta)
                 #default
                 .concat_long_str(#docstring)
             })
diff --git a/third_party/rust/uniffi_macros/src/setup_scaffolding.rs b/third_party/rust/uniffi_macros/src/setup_scaffolding.rs
index c82e9389bb61..83bb5ce83b67 100644
--- a/third_party/rust/uniffi_macros/src/setup_scaffolding.rs
+++ b/third_party/rust/uniffi_macros/src/setup_scaffolding.rs
@@ -36,7 +36,7 @@ pub fn setup_scaffolding(namespace: String) -> Result<TokenStream> {
         #[allow(clippy::missing_safety_doc, missing_docs)]
         #[doc(hidden)]
         #[no_mangle]
-        pub extern "C" fn #ffi_contract_version_ident() -> u32 {
+        pub extern "C" fn #ffi_contract_version_ident() -> ::std::primitive::u32 {
             #UNIFFI_CONTRACT_VERSION
         }
 
@@ -45,13 +45,15 @@ pub fn setup_scaffolding(namespace: String) -> Result<TokenStream> {
         ///
         /// See `uniffi_bindgen::macro_metadata` for how this is used.
 
-        const #namespace_const_ident: ::uniffi::MetadataBuffer = ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::NAMESPACE)
-            .concat_str(#module_path)
-            .concat_str(#namespace);
+        const #namespace_const_ident: ::uniffi::MetadataBuffer =
+            ::uniffi::MetadataBuffer::from_code(::uniffi::metadata::codes::NAMESPACE)
+                .concat_str(#module_path)
+                .concat_str(#namespace);
 
         #[doc(hidden)]
         #[no_mangle]
-        pub static #namespace_static_ident: [u8; #namespace_const_ident.size] = #namespace_const_ident.into_array();
+        pub static #namespace_static_ident: [::std::primitive::u8; #namespace_const_ident.size] =
+            #namespace_const_ident.into_array();
 
         // Everybody gets basic buffer support, since it's needed for passing complex types over the FFI.
         //
@@ -60,29 +62,42 @@ pub fn setup_scaffolding(namespace: String) -> Result<TokenStream> {
         #[allow(clippy::missing_safety_doc, missing_docs)]
         #[doc(hidden)]
         #[no_mangle]
-        pub extern "C" fn #ffi_rustbuffer_alloc_ident(size: u64, call_status: &mut uniffi::RustCallStatus) -> uniffi::RustBuffer {
-            uniffi::ffi::uniffi_rustbuffer_alloc(size, call_status)
+        pub extern "C" fn #ffi_rustbuffer_alloc_ident(
+            size: ::std::primitive::u64,
+            call_status: &mut ::uniffi::RustCallStatus,
+        ) -> ::uniffi::RustBuffer {
+            ::uniffi::ffi::uniffi_rustbuffer_alloc(size, call_status)
         }
 
         #[allow(clippy::missing_safety_doc, missing_docs)]
         #[doc(hidden)]
         #[no_mangle]
-        pub unsafe extern "C" fn #ffi_rustbuffer_from_bytes_ident(bytes: uniffi::ForeignBytes, call_status: &mut uniffi::RustCallStatus) -> uniffi::RustBuffer {
-            uniffi::ffi::uniffi_rustbuffer_from_bytes(bytes, call_status)
+        pub unsafe extern "C" fn #ffi_rustbuffer_from_bytes_ident(
+            bytes: ::uniffi::ForeignBytes,
+            call_status: &mut ::uniffi::RustCallStatus,
+        ) -> ::uniffi::RustBuffer {
+            ::uniffi::ffi::uniffi_rustbuffer_from_bytes(bytes, call_status)
         }
 
         #[allow(clippy::missing_safety_doc, missing_docs)]
         #[doc(hidden)]
         #[no_mangle]
-        pub unsafe extern "C" fn #ffi_rustbuffer_free_ident(buf: uniffi::RustBuffer, call_status: &mut uniffi::RustCallStatus) {
-            uniffi::ffi::uniffi_rustbuffer_free(buf, call_status);
+        pub unsafe extern "C" fn #ffi_rustbuffer_free_ident(
+            buf: ::uniffi::RustBuffer,
+            call_status: &mut ::uniffi::RustCallStatus,
+        ) {
+            ::uniffi::ffi::uniffi_rustbuffer_free(buf, call_status);
         }
 
         #[allow(clippy::missing_safety_doc, missing_docs)]
         #[doc(hidden)]
         #[no_mangle]
-        pub unsafe extern "C" fn #ffi_rustbuffer_reserve_ident(buf: uniffi::RustBuffer, additional: u64, call_status: &mut uniffi::RustCallStatus) -> uniffi::RustBuffer {
-            uniffi::ffi::uniffi_rustbuffer_reserve(buf, additional, call_status)
+        pub unsafe extern "C" fn #ffi_rustbuffer_reserve_ident(
+            buf: ::uniffi::RustBuffer,
+            additional: ::std::primitive::u64,
+            call_status: &mut ::uniffi::RustCallStatus,
+        ) -> ::uniffi::RustBuffer {
+            ::uniffi::ffi::uniffi_rustbuffer_reserve(buf, additional, call_status)
         }
 
         #ffi_rust_future_scaffolding_fns
@@ -121,7 +136,9 @@ pub fn setup_scaffolding(namespace: String) -> Result<TokenStream> {
         #[doc(hidden)]
         pub trait UniffiCustomTypeConverter {
             type Builtin;
-            fn into_custom(val: Self::Builtin) -> uniffi::Result<Self> where Self: Sized;
+            fn into_custom(val: Self::Builtin) -> ::uniffi::Result<Self>
+            where
+                Self: ::std::marker::Sized;
             fn from_custom(obj: Self) -> Self::Builtin;
         }
     })
diff --git a/third_party/rust/uniffi_macros/src/test.rs b/third_party/rust/uniffi_macros/src/test.rs
index da7a343dbc79..e6ae142ce15f 100644
--- a/third_party/rust/uniffi_macros/src/test.rs
+++ b/third_party/rust/uniffi_macros/src/test.rs
@@ -30,16 +30,16 @@ pub(crate) fn build_foreign_language_testcases(tokens: TokenStream) -> TokenStre
             );
             let run_test = match test_file_pathbuf.extension() {
                 Some("kts") => quote! {
-                    uniffi::kotlin_run_test
+                    ::uniffi::kotlin_test::run_test
                 },
                 Some("swift") => quote! {
-                    uniffi::swift_run_test
+                    ::uniffi::swift_test::run_test
                 },
                 Some("py") => quote! {
-                    uniffi::python_run_test
+                    ::uniffi::python_test::run_test
                 },
                 Some("rb") => quote! {
-                    uniffi::ruby_run_test
+                    ::uniffi::ruby_test::run_test
                 },
                 _ => panic!("Unexpected extension for test script: {test_file_name}"),
             };
@@ -51,7 +51,7 @@ pub(crate) fn build_foreign_language_testcases(tokens: TokenStream) -> TokenStre
             quote! {
                 #maybe_ignore
                 #[test]
-                fn #test_name () -> uniffi::deps::anyhow::Result<()> {
+                fn #test_name () -> ::uniffi::deps::anyhow::Result<()> {
                     #run_test(
                         std::env!("CARGO_TARGET_TMPDIR"),
                         std::env!("CARGO_PKG_NAME"),
diff --git a/third_party/rust/uniffi_macros/src/util.rs b/third_party/rust/uniffi_macros/src/util.rs
index cf4727e2f169..6f6214208b5f 100644
--- a/third_party/rust/uniffi_macros/src/util.rs
+++ b/third_party/rust/uniffi_macros/src/util.rs
@@ -2,6 +2,7 @@
  * License, v. 2.0. If a copy of the MPL was not distributed with this
  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
 
+use crate::ffiops;
 use proc_macro2::{Ident, Span, TokenStream};
 use quote::{format_ident, quote, ToTokens};
 use std::path::{Path as StdPath, PathBuf};
@@ -77,14 +78,14 @@ pub fn mod_path() -> syn::Result<String> {
 
 pub fn try_read_field(f: &syn::Field) -> TokenStream {
     let ident = &f.ident;
-    let ty = &f.ty;
+    let try_read = ffiops::try_read(&f.ty);
 
     match ident {
         Some(ident) => quote! {
-            #ident: <#ty as ::uniffi::Lift<crate::UniFfiTag>>::try_read(buf)?,
+            #ident: #try_read(buf)?,
         },
         None => quote! {
-            <#ty as ::uniffi::Lift<crate::UniFfiTag>>::try_read(buf)?,
+            #try_read(buf)?,
         },
     }
 }
@@ -257,6 +258,10 @@ pub mod kw {
     syn::custom_keyword!(with_try_read);
     syn::custom_keyword!(name);
     syn::custom_keyword!(non_exhaustive);
+    syn::custom_keyword!(Record);
+    syn::custom_keyword!(Enum);
+    syn::custom_keyword!(Error);
+    syn::custom_keyword!(Object);
     syn::custom_keyword!(Debug);
     syn::custom_keyword!(Display);
     syn::custom_keyword!(Eq);
diff --git a/third_party/rust/uniffi_meta/.cargo-checksum.json b/third_party/rust/uniffi_meta/.cargo-checksum.json
index 502599706d1c..d365e379fe7f 100644
--- a/third_party/rust/uniffi_meta/.cargo-checksum.json
+++ b/third_party/rust/uniffi_meta/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"3d53a00cb590863149f9e68505581ccbfc635ac1bb2b59d692f5d679cd1732bc","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/ffi_names.rs":"240e04f257fd199e268ff16d5979f521cb9d18e21d494981718fa2b96956324d","src/group.rs":"d0a43f3c528aba9403649715981ad3a8849d7a370f4ef9e2d618b88f60a3102f","src/lib.rs":"3f00d5214e2785e4b3045bc48899f6f6b1dce32ab3da6be3ebce716ee9d24c5f","src/metadata.rs":"3f236b337a1fd5082ea9cc4fee6800193a903ee88b81f1c3202843402f122a14","src/reader.rs":"579e2b87d8dd9d703b8811294abfb992621c0a46765800e4db2fad2906db2208","src/types.rs":"c2c5188da8cdf5af7f8496d4660bcfaa971b81ed73b64486c05b47256048544f"},"package":"583bab49f2bdf5681f9732f8b67a7e555ad920dbb5427be21450217bf1818189"}
\ No newline at end of file
+{"files":{"Cargo.toml":"b47c5c8446e1910ac250037c30c98407e25868a6fb91440975674a2c88217394","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/ffi_names.rs":"240e04f257fd199e268ff16d5979f521cb9d18e21d494981718fa2b96956324d","src/group.rs":"d0a43f3c528aba9403649715981ad3a8849d7a370f4ef9e2d618b88f60a3102f","src/lib.rs":"2e1a7829bcb63c83b21def1233fdf0a50d27230e5b7253d0a8944e243084e8b4","src/metadata.rs":"3f236b337a1fd5082ea9cc4fee6800193a903ee88b81f1c3202843402f122a14","src/reader.rs":"cc6f93c92ef53646595bea75b7e0ec719713e9af3e1b38d77d49a40c5ae4d092","src/types.rs":"1ebc50d050b12a002738fd3bf2a4eac2853b7c495d394c16020d1e6f2f232f9a"},"package":"d898893f102e0e39b8bcb7e3d2188f4156ba280db32db9e8af1f122d057e9526"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_meta/Cargo.toml b/third_party/rust/uniffi_meta/Cargo.toml
index a862028f0ef1..5db136fcb15c 100644
--- a/third_party/rust/uniffi_meta/Cargo.toml
+++ b/third_party/rust/uniffi_meta/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_meta"
-version = "0.27.3"
+version = "0.28.1"
 description = "uniffi_meta"
 homepage = "https://mozilla.github.io/uniffi-rs"
 readme = "README.md"
@@ -33,4 +33,4 @@ version = "1.3"
 version = "0.3"
 
 [dependencies.uniffi_checksum_derive]
-version = "0.27.3"
+version = "0.28.1"
diff --git a/third_party/rust/uniffi_meta/src/lib.rs b/third_party/rust/uniffi_meta/src/lib.rs
index 90f7b2d3cdcf..5d8d25543131 100644
--- a/third_party/rust/uniffi_meta/src/lib.rs
+++ b/third_party/rust/uniffi_meta/src/lib.rs
@@ -309,11 +309,36 @@ pub struct FieldMetadata {
     pub docstring: Option<String>,
 }
 
+#[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord, Checksum)]
+pub enum EnumShape {
+    Enum,
+    Error { flat: bool },
+}
+
+impl EnumShape {
+    pub fn as_u8(&self) -> u8 {
+        match self {
+            EnumShape::Enum => 0,
+            EnumShape::Error { flat: false } => 1,
+            EnumShape::Error { flat: true } => 2,
+        }
+    }
+
+    pub fn from(v: u8) -> anyhow::Result<Self> {
+        Ok(match v {
+            0 => EnumShape::Enum,
+            1 => EnumShape::Error { flat: false },
+            2 => EnumShape::Error { flat: true },
+            _ => anyhow::bail!("invalid enum shape discriminant {v}"),
+        })
+    }
+}
+
 #[derive(Clone, Debug, PartialEq, Eq, PartialOrd, Ord)]
 pub struct EnumMetadata {
     pub module_path: String,
     pub name: String,
-    pub forced_flatness: Option<bool>,
+    pub shape: EnumShape,
     pub variants: Vec<VariantMetadata>,
     pub discr_type: Option<Type>,
     pub non_exhaustive: bool,
diff --git a/third_party/rust/uniffi_meta/src/reader.rs b/third_party/rust/uniffi_meta/src/reader.rs
index 6fec6cb3a359..85a34cb19799 100644
--- a/third_party/rust/uniffi_meta/src/reader.rs
+++ b/third_party/rust/uniffi_meta/src/reader.rs
@@ -259,7 +259,7 @@ impl<'a> MetadataReader<'a> {
                     Type::Object { name, imp: ObjectImpl::Struct, .. } if name == &self_name
                 )
             })
-            .context("Constructor return type must be Arc<Self>")?;
+            .context("Constructor return type must be Self or Arc<Self>")?;
 
         Ok(ConstructorMetadata {
             module_path,
@@ -307,27 +307,21 @@ impl<'a> MetadataReader<'a> {
     fn read_enum(&mut self) -> Result<EnumMetadata> {
         let module_path = self.read_string()?;
         let name = self.read_string()?;
-        let forced_flatness = match self.read_u8()? {
-            0 => None,
-            1 => Some(false),
-            2 => Some(true),
-            _ => unreachable!("invalid flatness"),
-        };
+        let shape = EnumShape::from(self.read_u8()?)?;
         let discr_type = if self.read_bool()? {
             Some(self.read_type()?)
         } else {
             None
         };
-        let variants = if forced_flatness == Some(true) {
-            self.read_flat_variants()?
-        } else {
-            self.read_variants()?
+        let variants = match shape {
+            EnumShape::Enum | EnumShape::Error { flat: false } => self.read_variants()?,
+            EnumShape::Error { flat: true } => self.read_flat_variants()?,
         };
 
         Ok(EnumMetadata {
             module_path,
             name,
-            forced_flatness,
+            shape,
             discr_type,
             variants,
             non_exhaustive: self.read_bool()?,
diff --git a/third_party/rust/uniffi_meta/src/types.rs b/third_party/rust/uniffi_meta/src/types.rs
index 51bf156b50b1..7fe55d81ac0c 100644
--- a/third_party/rust/uniffi_meta/src/types.rs
+++ b/third_party/rust/uniffi_meta/src/types.rs
@@ -143,10 +143,59 @@ impl Type {
         };
         Box::new(std::iter::once(self).chain(nested_types))
     }
+
+    pub fn name(&self) -> Option<String> {
+        match self {
+            Type::Object { name, .. } => Some(name.to_string()),
+            Type::Record { name, .. } => Some(name.to_string()),
+            Type::Enum { name, .. } => Some(name.to_string()),
+            Type::External { name, .. } => Some(name.to_string()),
+            Type::Custom { name, .. } => Some(name.to_string()),
+            Type::Optional { inner_type } | Type::Sequence { inner_type } => inner_type.name(),
+            _ => None,
+        }
+    }
+
+    fn rename(&mut self, new_name: String) {
+        match self {
+            Type::Object { name, .. } => *name = new_name,
+            Type::Record { name, .. } => *name = new_name,
+            Type::Enum { name, .. } => *name = new_name,
+            Type::External { name, .. } => *name = new_name,
+            Type::Custom { name, .. } => *name = new_name,
+            _ => {}
+        }
+    }
+
+    pub fn rename_recursive(&mut self, name_transformer: &impl Fn(&str) -> String) {
+        // Rename the current type if it has a name
+        if let Some(name) = self.name() {
+            self.rename(name_transformer(&name));
+        }
+
+        // Recursively rename nested types
+        match self {
+            Type::Optional { inner_type } | Type::Sequence { inner_type } => {
+                inner_type.rename_recursive(name_transformer);
+            }
+            Type::Map {
+                key_type,
+                value_type,
+                ..
+            } => {
+                key_type.rename_recursive(name_transformer);
+                value_type.rename_recursive(name_transformer);
+            }
+            Type::Custom { builtin, .. } => {
+                builtin.rename_recursive(name_transformer);
+            }
+            _ => {}
+        }
+    }
 }
 
 // A trait so various things can turn into a type.
-pub trait AsType: core::fmt::Debug {
+pub trait AsType: ::core::fmt::Debug {
     fn as_type(&self) -> Type;
 }
 
diff --git a/third_party/rust/uniffi_testing/.cargo-checksum.json b/third_party/rust/uniffi_testing/.cargo-checksum.json
index 0ede9fda96d5..62f01a9e7a01 100644
--- a/third_party/rust/uniffi_testing/.cargo-checksum.json
+++ b/third_party/rust/uniffi_testing/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"02452729580c718585b4cc1cbaa2d09aa97ebec62c4d0bd3fdb50d6063cfe036","README.md":"ec6aba24af9a011ef6647422aa22efabdee519cdee3da1a9f9033b07b7cbdb0d","src/lib.rs":"e19f60aed5a137401203b9054ead27894b98490bab3e2f680a23549c8ee8a13a"},"package":"13963044ca9bde9b709d2eee68bc11dafc7acea144ae0fdc0cf29ed4add44481"}
\ No newline at end of file
+{"files":{"Cargo.toml":"54b381ea1c0f0a85bff9a31e52f2ca58d1c5bfb42b4545df3d503144f79ea31d","README.md":"ec6aba24af9a011ef6647422aa22efabdee519cdee3da1a9f9033b07b7cbdb0d","src/lib.rs":"8e0818381a8f90acecf9d82ce914c06948b7fb1f4513babac54880c62f7667c3"},"package":"2c6aa4f0cf9d12172d84fc00a35a6c1f3522b526daad05ae739f709f6941b9b6"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_testing/Cargo.toml b/third_party/rust/uniffi_testing/Cargo.toml
index c511869e3120..903e7dab7681 100644
--- a/third_party/rust/uniffi_testing/Cargo.toml
+++ b/third_party/rust/uniffi_testing/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_testing"
-version = "0.27.3"
+version = "0.28.1"
 authors = ["Firefox Sync Team <sync-team@mozilla.com>"]
 description = "a multi-language bindings generator for rust (testing helpers)"
 homepage = "https://mozilla.github.io/uniffi-rs"
diff --git a/third_party/rust/uniffi_testing/src/lib.rs b/third_party/rust/uniffi_testing/src/lib.rs
index f8a0d8499a1c..444a7f8146eb 100644
--- a/third_party/rust/uniffi_testing/src/lib.rs
+++ b/third_party/rust/uniffi_testing/src/lib.rs
@@ -37,17 +37,15 @@ static CARGO_BUILD_MESSAGES: Lazy<Vec<Message>> = Lazy::new(get_cargo_build_mess
 ///   - The fixture crate produces a cdylib library
 ///   - The fixture crate, and any external-crates, has 1 UDL file in it's src/ directory
 pub struct UniFFITestHelper {
-    name: String,
-    package: Package,
+    crate_name: String,
+    cdylib: Utf8PathBuf,
 }
 
 impl UniFFITestHelper {
-    pub fn new(name: &str) -> Result<Self> {
-        let package = Self::find_package(name)?;
-        Ok(Self {
-            name: name.to_string(),
-            package,
-        })
+    pub fn new(package_name: &str) -> Result<Self> {
+        let package = Self::find_package(package_name)?;
+        let (crate_name, cdylib) = Self::find_name_and_cdylib_path(&package)?;
+        Ok(Self { crate_name, cdylib })
     }
 
     fn find_package(name: &str) -> Result<Package> {
@@ -62,7 +60,7 @@ impl UniFFITestHelper {
         }
     }
 
-    fn find_cdylib_path(package: &Package) -> Result<Utf8PathBuf> {
+    fn find_name_and_cdylib_path(package: &Package) -> Result<(String, Utf8PathBuf)> {
         let cdylib_targets: Vec<&Target> = package
             .targets
             .iter()
@@ -72,6 +70,7 @@ impl UniFFITestHelper {
             1 => cdylib_targets[0],
             n => bail!("Found {n} cdylib targets for {}", package.name),
         };
+        let target_name = target.name.replace('-', "_");
 
         let artifacts = CARGO_BUILD_MESSAGES
             .iter()
@@ -97,7 +96,7 @@ impl UniFFITestHelper {
             .collect();
 
         match cdylib_files.len() {
-            1 => Ok(cdylib_files[0].to_owned()),
+            1 => Ok((target_name, cdylib_files[0].to_owned())),
             n => bail!("Found {n} cdylib files for {}", package.name),
         }
     }
@@ -119,7 +118,7 @@ impl UniFFITestHelper {
         temp_dir: impl AsRef<Utf8Path>,
         script_path: impl AsRef<Utf8Path>,
     ) -> Result<Utf8PathBuf> {
-        let dirname = format!("{}-{}", self.name, hash_path(script_path.as_ref()));
+        let dirname = format!("{}-{}", self.crate_name, hash_path(script_path.as_ref()));
         let out_dir = temp_dir.as_ref().join(dirname);
         if out_dir.exists() {
             // Clean out any files from previous runs
@@ -144,7 +143,15 @@ impl UniFFITestHelper {
 
     /// Get the path to the cdylib file for this package
     pub fn cdylib_path(&self) -> Result<Utf8PathBuf> {
-        Self::find_cdylib_path(&self.package)
+        Ok(self.cdylib.clone())
+    }
+
+    pub fn crate_name(&self) -> &str {
+        &self.crate_name
+    }
+
+    pub fn cargo_metadata(&self) -> Metadata {
+        CARGO_METADATA.clone()
     }
 }
 
@@ -156,7 +163,8 @@ fn get_cargo_metadata() -> Metadata {
 
 fn get_cargo_build_messages() -> Vec<Message> {
     let mut child = Command::new(env!("CARGO"))
-        .arg("build")
+        .arg("test")
+        .arg("--no-run")
         .arg("--message-format=json")
         .stdout(Stdio::piped())
         .spawn()
diff --git a/third_party/rust/uniffi_udl/.cargo-checksum.json b/third_party/rust/uniffi_udl/.cargo-checksum.json
index a64cb6f3c2f7..d851b85885d5 100644
--- a/third_party/rust/uniffi_udl/.cargo-checksum.json
+++ b/third_party/rust/uniffi_udl/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"eda87b82f785000e7ac4d07d24285dc5a961d8109bd90dfd134f8545a86f3b56","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/attributes.rs":"f1cdee01db837920dbd109d60b39dd4b0ece56f83797fe4ace1e0caf97c02483","src/collectors.rs":"00c9cd8e8f7be6949996f069b449f120f0b0694ff2f1ca92b79201721c18c594","src/converters/callables.rs":"1ad26c2782629e98272edc75c38343f58194ebf9626ae451ba84546a60d45a48","src/converters/enum_.rs":"aa0ca7a7a50521a45e296c6f53be5f1981a41872443946f72c2ca8baebe4d69b","src/converters/interface.rs":"6042d4abd5e236ed6158c5f6d4d9b81bb01fbbcb8b42bf8a5b385b978c68f6f8","src/converters/mod.rs":"c34a30e3b7a2e3c092a7074f4bab6f6c34364177c096af59a7dda13e44ffdc3c","src/finder.rs":"3586ffd3772151eabbc3d6062725933c88978e1b5feb64312bbf42cd43af30fa","src/lib.rs":"56c50ce61ba5e7266fe7fc9fa9d0022cdbfbe9801730753bd4ee66fed040221c","src/literal.rs":"4f28ad49a17246b4dc30a677cfff65b345bfac0924856e19f58e7574a74c2c40","src/resolver.rs":"c4ff362055dc4ed489e94a063ec0fd3becb8787ad35ce65cdec437a1aae518a0"},"package":"b92f984bb0d9a06778f256aec963e1e9a80714014f7a90fb0e01008821fe5a97"}
\ No newline at end of file
+{"files":{"Cargo.toml":"05a239cc9313d8b4164ab3d3c2cb86fdaaa0cedf728d5bc0c74ec247067aaca9","README.md":"37c1af00ec81a9f1bc206ab3578356e5f9ad4077dc46dd1bb623d81d804948b8","src/attributes.rs":"309292afc2ba936bbe7bae3af13ee58a507ca0e11bde3e3294daa4952fd8126c","src/collectors.rs":"408615354c316767adb20aa29faadc5ef5f06674c0f1b2fc7286cc70e294f459","src/converters/callables.rs":"1ad26c2782629e98272edc75c38343f58194ebf9626ae451ba84546a60d45a48","src/converters/enum_.rs":"33820452744c071097d745cb931479698eb624e62a8d8fd2baa3dd4545cc0f9b","src/converters/interface.rs":"6042d4abd5e236ed6158c5f6d4d9b81bb01fbbcb8b42bf8a5b385b978c68f6f8","src/converters/mod.rs":"c34a30e3b7a2e3c092a7074f4bab6f6c34364177c096af59a7dda13e44ffdc3c","src/finder.rs":"8eb964514325ee9fc739e5a9b1ac009e61faae0cf7eb4f54f58b80f6ce7bcf64","src/lib.rs":"56c50ce61ba5e7266fe7fc9fa9d0022cdbfbe9801730753bd4ee66fed040221c","src/literal.rs":"4f28ad49a17246b4dc30a677cfff65b345bfac0924856e19f58e7574a74c2c40","src/resolver.rs":"c4ff362055dc4ed489e94a063ec0fd3becb8787ad35ce65cdec437a1aae518a0"},"package":"6b044e9c519e0bb51e516ab6f6d8f4f4dcf900ce30d5ad07c03f924e2824f28e"}
\ No newline at end of file
diff --git a/third_party/rust/uniffi_udl/Cargo.toml b/third_party/rust/uniffi_udl/Cargo.toml
index f202383db2ea..99bd7ebdcf41 100644
--- a/third_party/rust/uniffi_udl/Cargo.toml
+++ b/third_party/rust/uniffi_udl/Cargo.toml
@@ -12,7 +12,7 @@
 [package]
 edition = "2021"
 name = "uniffi_udl"
-version = "0.27.3"
+version = "0.28.1"
 description = "udl parsing for the uniffi project"
 homepage = "https://mozilla.github.io/uniffi-rs"
 documentation = "https://mozilla.github.io/uniffi-rs"
@@ -33,10 +33,10 @@ features = ["smawk"]
 default-features = false
 
 [dependencies.uniffi_meta]
-version = "=0.27.3"
+version = "=0.28.1"
 
 [dependencies.uniffi_testing]
-version = "=0.27.3"
+version = "=0.28.1"
 
 [dependencies.weedle2]
 version = "5.0.0"
diff --git a/third_party/rust/uniffi_udl/src/attributes.rs b/third_party/rust/uniffi_udl/src/attributes.rs
index 7bb05808c484..a40ef29fdb80 100644
--- a/third_party/rust/uniffi_udl/src/attributes.rs
+++ b/third_party/rust/uniffi_udl/src/attributes.rs
@@ -856,11 +856,11 @@ mod test {
     fn test_byref_attribute() {
         let (_, node) = weedle::attribute::ExtendedAttributeList::parse("[ByRef]").unwrap();
         let attrs = ArgumentAttributes::try_from(&node).unwrap();
-        assert!(matches!(attrs.by_ref(), true));
+        assert!(attrs.by_ref());
 
         let (_, node) = weedle::attribute::ExtendedAttributeList::parse("[]").unwrap();
         let attrs = ArgumentAttributes::try_from(&node).unwrap();
-        assert!(matches!(attrs.by_ref(), false));
+        assert!(!attrs.by_ref());
     }
 
     #[test]
@@ -898,15 +898,15 @@ mod test {
     fn test_enum_attribute_on_interface() {
         let (_, node) = weedle::attribute::ExtendedAttributeList::parse("[Enum]").unwrap();
         let attrs = InterfaceAttributes::try_from(&node).unwrap();
-        assert!(matches!(attrs.contains_enum_attr(), true));
+        assert!(attrs.contains_enum_attr());
 
         let (_, node) = weedle::attribute::ExtendedAttributeList::parse("[]").unwrap();
         let attrs = InterfaceAttributes::try_from(&node).unwrap();
-        assert!(matches!(attrs.contains_enum_attr(), false));
+        assert!(!attrs.contains_enum_attr());
 
         let (_, node) = weedle::attribute::ExtendedAttributeList::parse("[Trait]").unwrap();
         let attrs = InterfaceAttributes::try_from(&node).unwrap();
-        assert!(matches!(attrs.contains_enum_attr(), false));
+        assert!(!attrs.contains_enum_attr());
 
         let (_, node) = weedle::attribute::ExtendedAttributeList::parse("[Trait, Enum]").unwrap();
         let err = InterfaceAttributes::try_from(&node).unwrap_err();
diff --git a/third_party/rust/uniffi_udl/src/collectors.rs b/third_party/rust/uniffi_udl/src/collectors.rs
index de5489f5f9a4..e29441611216 100644
--- a/third_party/rust/uniffi_udl/src/collectors.rs
+++ b/third_party/rust/uniffi_udl/src/collectors.rs
@@ -172,12 +172,7 @@ impl APIBuilder for weedle::Definition<'_> {
         match self {
             weedle::Definition::Namespace(d) => d.process(ci)?,
             weedle::Definition::Enum(d) => {
-                let mut e: uniffi_meta::EnumMetadata = d.convert(ci)?;
-                // We check if the enum represents an error...
-                let attrs = attributes::EnumAttributes::try_from(d.attributes.as_ref())?;
-                if attrs.contains_error_attr() {
-                    e.forced_flatness = Some(true);
-                }
+                let e: uniffi_meta::EnumMetadata = d.convert(ci)?;
                 ci.add_definition(e.into())?;
             }
             weedle::Definition::Dictionary(d) => {
diff --git a/third_party/rust/uniffi_udl/src/converters/enum_.rs b/third_party/rust/uniffi_udl/src/converters/enum_.rs
index 1615a1a7ca89..d2dc7f3d3c84 100644
--- a/third_party/rust/uniffi_udl/src/converters/enum_.rs
+++ b/third_party/rust/uniffi_udl/src/converters/enum_.rs
@@ -6,7 +6,7 @@ use super::APIConverter;
 use crate::{attributes::EnumAttributes, converters::convert_docstring, InterfaceCollector};
 use anyhow::{bail, Result};
 
-use uniffi_meta::{EnumMetadata, VariantMetadata};
+use uniffi_meta::{EnumMetadata, EnumShape, VariantMetadata};
 
 // Note that we have 2 `APIConverter` impls here - one for the `enum` case
 // (including an enum with `[Error]`), and one for the `[Error] interface` cas
@@ -14,10 +14,15 @@ use uniffi_meta::{EnumMetadata, VariantMetadata};
 impl APIConverter<EnumMetadata> for weedle::EnumDefinition<'_> {
     fn convert(&self, ci: &mut InterfaceCollector) -> Result<EnumMetadata> {
         let attributes = EnumAttributes::try_from(self.attributes.as_ref())?;
+        let shape = if attributes.contains_error_attr() {
+            EnumShape::Error { flat: true }
+        } else {
+            EnumShape::Enum
+        };
         Ok(EnumMetadata {
             module_path: ci.module_path(),
             name: self.identifier.0.to_string(),
-            forced_flatness: None,
+            shape,
             discr_type: None,
             variants: self
                 .values
@@ -45,10 +50,15 @@ impl APIConverter<EnumMetadata> for weedle::InterfaceDefinition<'_> {
             bail!("interface inheritance is not supported for enum interfaces");
         }
         let attributes = EnumAttributes::try_from(self.attributes.as_ref())?;
+        let shape = if attributes.contains_error_attr() {
+            EnumShape::Error { flat: false }
+        } else {
+            EnumShape::Enum
+        };
         Ok(EnumMetadata {
             module_path: ci.module_path(),
             name: self.identifier.0.to_string(),
-            forced_flatness: Some(false),
+            shape,
             variants: self
                 .members
                 .body
diff --git a/third_party/rust/uniffi_udl/src/finder.rs b/third_party/rust/uniffi_udl/src/finder.rs
index 259557ad07e4..6a2b6084b8bb 100644
--- a/third_party/rust/uniffi_udl/src/finder.rs
+++ b/third_party/rust/uniffi_udl/src/finder.rs
@@ -129,43 +129,89 @@ impl TypeFinder for weedle::TypedefDefinition<'_> {
                 },
             )
         } else {
+            let typedef_type = match &self.type_.type_ {
+                weedle::types::Type::Single(weedle::types::SingleType::NonAny(
+                    weedle::types::NonAnyType::Identifier(weedle::types::MayBeNull {
+                        type_: i,
+                        ..
+                    }),
+                )) => i.0,
+                _ => bail!("Failed to get typedef type: {:?}", self),
+            };
+
             let module_path = types.module_path();
             let name = self.identifier.0.to_string();
-            let ty = match attrs.rust_kind() {
-                Some(RustKind::Object) => Type::Object {
-                    module_path,
-                    name,
-                    imp: ObjectImpl::Struct,
-                },
-                Some(RustKind::Trait) => Type::Object {
-                    module_path,
-                    name,
-                    imp: ObjectImpl::Trait,
-                },
-                Some(RustKind::CallbackTrait) => Type::Object {
-                    module_path,
-                    name,
-                    imp: ObjectImpl::CallbackTrait,
-                },
-                Some(RustKind::Record) => Type::Record { module_path, name },
-                Some(RustKind::Enum) => Type::Enum { module_path, name },
-                Some(RustKind::CallbackInterface) => Type::CallbackInterface { module_path, name },
-                // must be external
+
+            let ty = match attrs.external_tagged() {
                 None => {
-                    let kind = attrs.external_kind().expect("External missing kind");
-                    let tagged = attrs.external_tagged().expect("External missing tagged");
-                    Type::External {
-                        name,
-                        namespace: "".to_string(), // we don't know this yet
-                        module_path: attrs.get_crate_name(),
-                        kind,
-                        tagged,
+                    // Not external, not custom, not Rust - so we basically
+                    // pretend it is Rust, thus soft-deprecating it.
+                    // We use `type_`
+                    match typedef_type {
+                        "dictionary" | "record" | "struct" => Type::Record {
+                            module_path,
+                            name,
+                        },
+                        "enum" => Type::Enum {
+                            module_path,
+                            name,
+                        },
+                        "custom" => panic!("don't know builtin"),
+                        "interface" | "impl" => Type::Object {
+                            module_path,
+                            name,
+                            imp: ObjectImpl::Struct,
+                        },
+                        "trait" => Type::Object {
+                            module_path,
+                            name,
+                            imp: ObjectImpl::Trait,
+                        },
+                        "callback" | "trait_with_foreign" => Type::Object {
+                            module_path,
+                            name,
+                            imp: ObjectImpl::CallbackTrait,
+                        },
+                        _ => bail!("Can't work out the type - no attributes and unknown extern type '{typedef_type}'"),
+                    }
+                }
+                Some(tagged) => {
+                    // Must be either `[Rust..]` or `[Extern..]`
+                    match attrs.rust_kind() {
+                        Some(RustKind::Object) => Type::Object {
+                            module_path,
+                            name,
+                            imp: ObjectImpl::Struct,
+                        },
+                        Some(RustKind::Trait) => Type::Object {
+                            module_path,
+                            name,
+                            imp: ObjectImpl::Trait,
+                        },
+                        Some(RustKind::CallbackTrait) => Type::Object {
+                            module_path,
+                            name,
+                            imp: ObjectImpl::CallbackTrait,
+                        },
+                        Some(RustKind::Record) => Type::Record { module_path, name },
+                        Some(RustKind::Enum) => Type::Enum { module_path, name },
+                        Some(RustKind::CallbackInterface) => {
+                            Type::CallbackInterface { module_path, name }
+                        }
+                        // must be external
+                        None => {
+                            let kind = attrs.external_kind().expect("External missing kind");
+                            Type::External {
+                                name,
+                                namespace: "".to_string(), // we don't know this yet
+                                module_path: attrs.get_crate_name(),
+                                kind,
+                                tagged,
+                            }
+                        }
                     }
                 }
             };
-            // A crate which can supply an `FfiConverter`.
-            // We don't reference `self._type`, so ideally we could insist on it being
-            // the literal 'extern' but that's tricky
             types.add_type_definition(self.identifier.0, ty)
         }
     }
@@ -190,7 +236,7 @@ impl TypeFinder for weedle::CallbackInterfaceDefinition<'_> {
 #[cfg(test)]
 mod test {
     use super::*;
-    use uniffi_meta::ExternalKind;
+    use uniffi_meta::{ExternalKind, ObjectImpl};
 
     // A helper to take valid UDL and a closure to check what's in it.
     fn test_a_finding<F>(udl: &str, tester: F)
@@ -289,6 +335,74 @@ mod test {
         );
     }
 
+    #[test]
+    fn test_extern_local_types() {
+        // should test more, but these are already deprecated
+        test_a_finding(
+            r#"
+            typedef interface Interface;
+            typedef impl Interface2;
+            typedef trait Trait;
+            typedef callback Callback;
+
+            typedef dictionary R1;
+            typedef record R2;
+            typedef record R3;
+            typedef enum Enum;
+        "#,
+            |types| {
+                assert!(matches!(
+                    types.get_type_definition("Interface").unwrap(),
+                    Type::Object { name, module_path, imp: ObjectImpl::Struct } if name == "Interface" && module_path.is_empty()));
+                assert!(matches!(
+                    types.get_type_definition("Interface2").unwrap(),
+                    Type::Object { name, module_path, imp: ObjectImpl::Struct } if name == "Interface2" && module_path.is_empty()));
+                assert!(matches!(
+                    types.get_type_definition("Trait").unwrap(),
+                    Type::Object { name, module_path, imp: ObjectImpl::Trait } if name == "Trait" && module_path.is_empty()));
+                assert!(matches!(
+                    types.get_type_definition("Callback").unwrap(),
+                    Type::Object { name, module_path, imp: ObjectImpl::CallbackTrait } if name == "Callback" && module_path.is_empty()));
+                assert!(matches!(
+                    types.get_type_definition("R1").unwrap(),
+                    Type::Record { name, module_path } if name == "R1" && module_path.is_empty()));
+                assert!(matches!(
+                    types.get_type_definition("R2").unwrap(),
+                    Type::Record { name, module_path } if name == "R2" && module_path.is_empty()));
+                assert!(matches!(
+                    types.get_type_definition("R3").unwrap(),
+                    Type::Record { name, module_path } if name == "R3" && module_path.is_empty()));
+                assert!(matches!(
+                    types.get_type_definition("Enum").unwrap(),
+                    Type::Enum { name, module_path } if name == "Enum" && module_path.is_empty()));
+            },
+        );
+    }
+
+    #[test]
+    fn test_rust_attr_types() {
+        // should test more, but these are already deprecated
+        test_a_finding(
+            r#"
+            [Rust="interface"]
+            typedef extern LocalInterface;
+
+            [Rust="dictionary"]
+            typedef extern Dict;
+        "#,
+            |types| {
+                assert!(
+                    matches!(types.get_type_definition("LocalInterface").unwrap(), Type::Object { name, module_path, imp: ObjectImpl::Struct }
+                                                                                if name == "LocalInterface" && module_path.is_empty())
+                );
+                assert!(
+                    matches!(types.get_type_definition("Dict").unwrap(), Type::Record { name, module_path }
+                                                                                if name == "Dict" && module_path.is_empty())
+                );
+            },
+        );
+    }
+
     fn get_err(udl: &str) -> String {
         let parsed = weedle::parse(udl).unwrap();
         let mut types = TypeCollector::default();
@@ -299,9 +413,8 @@ mod test {
     }
 
     #[test]
-    #[should_panic]
-    fn test_typedef_error_on_no_attr() {
-        // Sorry, still working out what we want for non-imported typedefs..
-        get_err("typedef string Custom;");
+    fn test_local_type_unknown_typedef() {
+        let e = get_err("typedef xyz Foo;");
+        assert!(e.contains("unknown extern type 'xyz'"));
     }
 }
diff --git a/third_party/rust/webext-storage/.cargo-checksum.json b/third_party/rust/webext-storage/.cargo-checksum.json
index cbfa3c54246d..5ee582011067 100644
--- a/third_party/rust/webext-storage/.cargo-checksum.json
+++ b/third_party/rust/webext-storage/.cargo-checksum.json
@@ -1 +1 @@
-{"files":{"Cargo.toml":"81b4e03b6df32859fabe75be2a86051e4646b2eac61d610323beb780b7f7574b","README.md":"821cac7eb5b963fc3f3fe21dd890427ab2bbf335cb25cbae89b713b3350687c5","build.rs":"92f7d380f3d8fab1e6d80276915af57192e276321d132a5f800ea4520e9cb469","sql/create_schema.sql":"a17311a407ec10e033886b7125da4c8b84bc6d761f6b28edc9594de430e1d964","sql/create_sync_temp_tables.sql":"860ede362c94feb47d85522553fa2852f9bdb9f9b025d6438dd5dee3d4acd527","sql/tests/create_schema_v1.sql":"77cf0c90eaac3e1aea626537147e1b8ec349b68d6076c92fa7ae402aac613050","src/api.rs":"b3f0ff950178d006e443ddbeec4513e0acaa8894211053cfdfc1de104b9fb6ab","src/db.rs":"04ef67021b6aad7552a268397c7323302c4f619b3fb07fb140132beb8b37f8b5","src/error.rs":"8587813be8e2a7f5efad4216a5c4686554ed44e98cf94bfd9c2f2c9adc8e9a11","src/ffi.rs":"f66a81393bebe7a4b7e7960cb426df106ff1f02bfebcaa6e335b4b8b56c5c936","src/lib.rs":"ab25e7c6ea67fb905fe6dad866c0d2c462b1e93bcff283db947513aeabbb2d73","src/migration.rs":"8d92f82b2ba38e1039fd054c8c75078a6b896a0d3cdc1a52571456b25a32c9c3","src/schema.rs":"d8dd8f66cad71e3e369722734e0d5d16fd9423d5f6a5abba1854a27e1e814724","src/store.rs":"d208689c46fb97cd2c60a0c610ba1998a7132fb50fffa2eefa1d6b169b7c34f0","src/sync/bridge.rs":"996de05beb2904f84b3cbfc9ef85c4844078fdb4867d9068390d496156bee614","src/sync/incoming.rs":"dd77c64e2ade4f39cba258decab6d3db8ad0b5f513aa018efbd56b9869a021d9","src/sync/mod.rs":"05da064e1bc2cc449c806a534842da92d8d4b24a919f2dff2e88dc69f3e926a5","src/sync/outgoing.rs":"dacb77b956f2546fd60a89367927a199d9b662b17201d0781145f7405b61fdce","src/sync/sync_tests.rs":"bc9845312c7b08c5efd892979f61e9385b553f872a6c5d78600f4587b14421f5","src/webext-storage.udl":"0341d431ba837cf64ea210ef6157010c6664a0b5a194e89acb0414938636b391","uniffi.toml":"beeec89c2f877eb89be0090dc304dbc7c74e787385e7459bad78c6165bb66791"},"package":null}
\ No newline at end of file
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diff --git a/third_party/rust/webext-storage/Cargo.toml b/third_party/rust/webext-storage/Cargo.toml
index fcca3f82f836..7fed2e64f1c4 100644
--- a/third_party/rust/webext-storage/Cargo.toml
+++ b/third_party/rust/webext-storage/Cargo.toml
@@ -73,7 +73,7 @@ path = "../../components/sync15"
 features = ["sync-engine"]
 
 [dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 
 [dependencies.url]
 version = "2.1"
@@ -100,7 +100,7 @@ path = "../support/sql"
 path = "../support/rc_crypto/nss/nss_build_common"
 
 [build-dependencies.uniffi]
-version = "0.27.1"
+version = "0.28.0"
 features = ["build"]
 
 [features]
diff --git a/toolkit/components/uniffi-bindgen-gecko-js/Cargo.toml b/toolkit/components/uniffi-bindgen-gecko-js/Cargo.toml
index 5ef165dc73a5..9b5b8b06c297 100644
--- a/toolkit/components/uniffi-bindgen-gecko-js/Cargo.toml
+++ b/toolkit/components/uniffi-bindgen-gecko-js/Cargo.toml
@@ -13,7 +13,7 @@ anyhow = "1"
 askama = { version = "0.12", default-features = false, features = ["config"] }
 clap = { version = "4", default-features = false, features = ["std", "derive", "cargo"] }
 extend = "1.1"
-heck = "0.4"
+heck = "0.5"
 uniffi = { workspace = true }
 uniffi_bindgen = { workspace = true }
 serde = "1"