diff --git a/devtools/client/debugger/src/actions/breakpoints/breakpointPositions.js b/devtools/client/debugger/src/actions/breakpoints/breakpointPositions.js
index 89b6dff2eb1c..6e1fce8fdc0e 100644
--- a/devtools/client/debugger/src/actions/breakpoints/breakpointPositions.js
+++ b/devtools/client/debugger/src/actions/breakpoints/breakpointPositions.js
@@ -14,10 +14,12 @@ import {
   getSource,
   getSourceFromId,
   hasBreakpointPositions,
-  getBreakpointPositionsForSource
+  getBreakpointPositionsForSource,
+  getSourceActorsForSource
 } from "../../selectors";
 
 import type {
+  SourceId,
   MappedLocation,
   Range,
   SourceLocation,
@@ -30,8 +32,6 @@ import {
   type MemoizedAction
 } from "../../utils/memoizableAction";
 
-// const requests = new Map();
-
 async function mapLocations(
   generatedLocations: SourceLocation[],
   { sourceMaps }: { sourceMaps: typeof SourceMaps }
@@ -108,13 +108,18 @@ async function _setBreakpointPositions(cx, sourceId, thunkArgs) {
         };
       }
 
-      const bps = await client.getBreakpointPositions(generatedSource, range);
+      const bps = await client.getBreakpointPositions(
+        getSourceActorsForSource(getState(), generatedSource.id),
+        range
+      );
       for (const line in bps) {
         results[line] = (results[line] || []).concat(bps[line]);
       }
     }
   } else {
-    results = await client.getBreakpointPositions(generatedSource);
+    results = await client.getBreakpointPositions(
+      getSourceActorsForSource(getState(), generatedSource.id)
+    );
   }
 
   let positions = convertToList(results, generatedSource);
@@ -139,6 +144,11 @@ async function _setBreakpointPositions(cx, sourceId, thunkArgs) {
   return positions;
 }
 
+const runningFetches = {};
+export function isFetchingBreakpoints(id: SourceId) {
+  return id in runningFetches;
+}
+
 export const setBreakpointPositions: MemoizedAction<
   { cx: Context, sourceId: string },
   ?BreakpointPositions
@@ -153,10 +163,21 @@ export const setBreakpointPositions: MemoizedAction<
       isOriginalId(sourceId) ? originalToGeneratedId(sourceId) : sourceId
     );
     const actors = generatedSource
-      ? generatedSource.actors.map(({ actor }) => actor)
+      ? getSourceActorsForSource(getState(), generatedSource.id).map(
+          ({ actor }) => actor
+        )
       : [];
     return [sourceId, ...actors].join(":");
   },
-  action: ({ cx, sourceId }, thunkArgs) =>
-    _setBreakpointPositions(cx, sourceId, thunkArgs)
+  action: async ({ cx, sourceId }, thunkArgs) => {
+    runningFetches[sourceId] = (runningFetches[sourceId] | 0) + 1;
+    try {
+      return await _setBreakpointPositions(cx, sourceId, thunkArgs);
+    } finally {
+      runningFetches[sourceId] -= 0;
+      if (runningFetches[sourceId] === 0) {
+        delete runningFetches[sourceId];
+      }
+    }
+  }
 });
diff --git a/devtools/client/debugger/src/actions/breakpoints/tests/__snapshots__/breakpoints.spec.js.snap b/devtools/client/debugger/src/actions/breakpoints/tests/__snapshots__/breakpoints.spec.js.snap
index a1fdcc249e40..d4526e55a216 100644
--- a/devtools/client/debugger/src/actions/breakpoints/tests/__snapshots__/breakpoints.spec.js.snap
+++ b/devtools/client/debugger/src/actions/breakpoints/tests/__snapshots__/breakpoints.spec.js.snap
@@ -35,13 +35,6 @@ Array [
       },
     ],
     "source": Object {
-      "actors": Array [
-        Object {
-          "actor": "a-1-actor",
-          "source": "a",
-          "thread": "FakeThread",
-        },
-      ],
       "contentType": "text/javascript",
       "id": "a",
       "introductionType": null,
@@ -129,13 +122,6 @@ Array [
       },
     ],
     "source": Object {
-      "actors": Array [
-        Object {
-          "actor": "a-1-actor",
-          "source": "a",
-          "thread": "FakeThread",
-        },
-      ],
       "contentType": "text/javascript",
       "id": "a",
       "introductionType": null,
diff --git a/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js b/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js
index 310ae0b9745d..01d21a110973 100644
--- a/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js
+++ b/devtools/client/debugger/src/actions/breakpoints/tests/breakpointPositions.spec.js
@@ -11,15 +11,22 @@ import {
   makeSource,
   waitForState
 } from "../../../utils/test-head";
+import { createSource } from "../../tests/helpers/threadClient";
 
 describe("breakpointPositions", () => {
   it("fetches positions", async () => {
+    const fooContent = createSource("foo", "");
+
     const store = createStore({
-      getBreakpointPositions: async () => ({ "9": [1] })
+      getBreakpointPositions: async () => ({ "9": [1] }),
+      sourceContents: async () => fooContent
     });
 
     const { dispatch, getState, cx } = store;
-    await dispatch(actions.newGeneratedSource(makeSource("foo")));
+    const source = await dispatch(
+      actions.newGeneratedSource(makeSource("foo"))
+    );
+    await dispatch(actions.loadSourceById(cx, source.id));
 
     dispatch(actions.setBreakpointPositions({ cx, sourceId: "foo" }));
 
@@ -48,6 +55,8 @@ describe("breakpointPositions", () => {
   });
 
   it("doesn't re-fetch positions", async () => {
+    const fooContent = createSource("foo", "");
+
     let resolve = _ => {};
     let count = 0;
     const store = createStore({
@@ -55,11 +64,15 @@ describe("breakpointPositions", () => {
         new Promise(r => {
           count++;
           resolve = r;
-        })
+        }),
+      sourceContents: async () => fooContent
     });
 
     const { dispatch, getState, cx } = store;
-    await dispatch(actions.newGeneratedSource(makeSource("foo")));
+    const source = await dispatch(
+      actions.newGeneratedSource(makeSource("foo"))
+    );
+    await dispatch(actions.loadSourceById(cx, source.id));
 
     dispatch(actions.setBreakpointPositions({ cx, sourceId: "foo" }));
     dispatch(actions.setBreakpointPositions({ cx, sourceId: "foo" }));
diff --git a/devtools/client/debugger/src/actions/debuggee.js b/devtools/client/debugger/src/actions/debuggee.js
index bfe693e3ac82..85ba98a58dbe 100644
--- a/devtools/client/debugger/src/actions/debuggee.js
+++ b/devtools/client/debugger/src/actions/debuggee.js
@@ -6,8 +6,9 @@
 
 import { differenceBy } from "lodash";
 import type { Action, ThunkArgs } from "./types";
+import { removeSourceActors } from "./source-actors";
 
-import { getContext, getWorkers } from "../selectors";
+import { getContext, getWorkers, getSourceActorsForThread } from "../selectors";
 
 export function updateWorkers() {
   return async function({ dispatch, getState, client }: ThunkArgs) {
@@ -19,6 +20,11 @@ export function updateWorkers() {
     const addedWorkers = differenceBy(workers, currentWorkers, w => w.actor);
     const removedWorkers = differenceBy(currentWorkers, workers, w => w.actor);
     if (removedWorkers.length > 0) {
+      const sourceActors = getSourceActorsForThread(
+        getState(),
+        removedWorkers.map(w => w.actor)
+      );
+      dispatch(removeSourceActors(sourceActors));
       dispatch(
         ({
           type: "REMOVE_WORKERS",
diff --git a/devtools/client/debugger/src/actions/sources/blackbox.js b/devtools/client/debugger/src/actions/sources/blackbox.js
index 03680f5ae2b5..487ceb98803d 100644
--- a/devtools/client/debugger/src/actions/sources/blackbox.js
+++ b/devtools/client/debugger/src/actions/sources/blackbox.js
@@ -12,7 +12,7 @@
 import { isOriginalId, originalToGeneratedId } from "devtools-source-map";
 import { recordEvent } from "../../utils/telemetry";
 import { features } from "../../utils/prefs";
-import { getSourceFromId } from "../../selectors";
+import { getSourceActorsForSource } from "../../selectors";
 
 import { PROMISE } from "../utils/middleware/promise";
 
@@ -20,9 +20,8 @@ import type { Source, Context } from "../../types";
 import type { ThunkArgs } from "../types";
 
 async function blackboxActors(state, client, sourceId, isBlackBoxed, range?) {
-  const source = getSourceFromId(state, sourceId);
-  for (const sourceActor of source.actors) {
-    await client.blackBox(sourceActor, isBlackBoxed, range);
+  for (const actor of getSourceActorsForSource(state, sourceId)) {
+    await client.blackBox(actor, isBlackBoxed, range);
   }
   return { isBlackBoxed: !isBlackBoxed };
 }
diff --git a/devtools/client/debugger/src/actions/sources/loadSourceText.js b/devtools/client/debugger/src/actions/sources/loadSourceText.js
index 189bc432b016..72e80c5e4505 100644
--- a/devtools/client/debugger/src/actions/sources/loadSourceText.js
+++ b/devtools/client/debugger/src/actions/sources/loadSourceText.js
@@ -10,7 +10,8 @@ import {
   getSourceFromId,
   getGeneratedSource,
   getSourcesEpoch,
-  getBreakpointsForSource
+  getBreakpointsForSource,
+  getSourceActorsForSource
 } from "../../selectors";
 import { setBreakpointPositions, addBreakpoint } from "../breakpoints";
 
@@ -36,14 +37,23 @@ const telemetry = new Telemetry();
 async function loadSource(
   state,
   source: Source,
-  { sourceMaps, client }
+  { sourceMaps, client, getState }
 ): Promise<?{
   text: string,
   contentType: string
 }> {
   if (isPretty(source) && isOriginal(source)) {
     const generatedSource = getGeneratedSource(state, source);
-    return prettyPrintSource(sourceMaps, source, generatedSource);
+    if (!generatedSource) {
+      throw new Error("Unable to find minified original.");
+    }
+
+    return prettyPrintSource(
+      sourceMaps,
+      source,
+      generatedSource,
+      getSourceActorsForSource(state, generatedSource.id)
+    );
   }
 
   if (isOriginal(source)) {
@@ -58,12 +68,13 @@ async function loadSource(
     return result;
   }
 
-  if (!source.actors.length) {
+  const actors = getSourceActorsForSource(state, source.id);
+  if (!actors.length) {
     throw new Error("No source actor for loadSource");
   }
 
   telemetry.start(loadSourceHistogram, source);
-  const response = await client.sourceContents(source.actors[0]);
+  const response = await client.sourceContents(actors[0]);
   telemetry.finish(loadSourceHistogram, source);
 
   return {
@@ -82,7 +93,7 @@ async function loadSourceTextPromise(
     type: "LOAD_SOURCE_TEXT",
     sourceId: source.id,
     epoch,
-    [PROMISE]: loadSource(getState(), source, { sourceMaps, client })
+    [PROMISE]: loadSource(getState(), source, { sourceMaps, client, getState })
   });
 
   const newSource = getSource(getState(), source.id);
diff --git a/devtools/client/debugger/src/actions/sources/newSources.js b/devtools/client/debugger/src/actions/sources/newSources.js
index abc830a5b87a..fe241ea39b10 100644
--- a/devtools/client/debugger/src/actions/sources/newSources.js
+++ b/devtools/client/debugger/src/actions/sources/newSources.js
@@ -12,25 +12,32 @@
 import { generatedToOriginalId } from "devtools-source-map";
 import { flatten } from "lodash";
 
+import {
+  stringToSourceActorId,
+  type SourceActor
+} from "../../reducers/source-actors";
+import { insertSourceActors } from "../../actions/source-actors";
 import { makeSourceId } from "../../client/firefox/create";
 import { toggleBlackBox } from "./blackbox";
 import { syncBreakpoint, setBreakpointPositions } from "../breakpoints";
 import { loadSourceText } from "./loadSourceText";
+import { isFetchingBreakpoints } from "../breakpoints/breakpointPositions";
 import { togglePrettyPrint } from "./prettyPrint";
 import { selectLocation } from "../sources";
 import {
   getRawSourceURL,
   isPrettyURL,
   isOriginal,
-  isInlineScript,
-  isUrlExtension
+  isUrlExtension,
+  isInlineScript
 } from "../../utils/source";
 import {
   getBlackBoxList,
   getSource,
+  getSourceFromId,
+  hasSourceActor,
   getPendingSelectedLocation,
   getPendingBreakpointsForSource,
-  hasBreakpointPositions,
   getContext
 } from "../../selectors";
 
@@ -245,8 +252,8 @@ export function newOriginalSource(sourceInfo: OriginalSourceData) {
   };
 }
 export function newOriginalSources(sourceInfo: Array<OriginalSourceData>) {
-  return async ({ dispatch }: ThunkArgs) => {
-    const sources = sourceInfo.map(({ id, url }) => ({
+  return async ({ dispatch, getState }: ThunkArgs) => {
+    const sources: Array<Source> = sourceInfo.map(({ id, url }) => ({
       id,
       url,
       relativeUrl: url,
@@ -256,11 +263,15 @@ export function newOriginalSources(sourceInfo: Array<OriginalSourceData>) {
       loadedState: "unloaded",
       introductionUrl: null,
       introductionType: undefined,
-      isExtension: false,
-      actors: []
+      isExtension: false
     }));
 
-    return dispatch(newInnerSources(sources));
+    const cx = getContext(getState());
+    dispatch(addSources(cx, sources));
+
+    await dispatch(checkNewSources(cx, sources));
+
+    return sources;
   };
 }
 
@@ -271,65 +282,101 @@ export function newGeneratedSource(sourceInfo: GeneratedSourceData) {
   };
 }
 export function newGeneratedSources(sourceInfo: Array<GeneratedSourceData>) {
-  return async ({ dispatch, client }: ThunkArgs) => {
+  return async ({
+    dispatch,
+    getState,
+    client
+  }: ThunkArgs): Promise<Array<Source>> => {
     const supportsWasm = client.hasWasmSupport();
-    const sources: Array<Source> = sourceInfo.map(({ thread, source, id }) => {
-      id = id || makeSourceId(source);
-      const sourceActor = {
-        actor: source.actor,
-        source: id,
-        thread
-      };
-      const createdSource: any = {
-        id,
-        url: source.url,
-        relativeUrl: source.url,
-        isPrettyPrinted: false,
-        sourceMapURL: source.sourceMapURL,
-        introductionUrl: source.introductionUrl,
-        introductionType: source.introductionType,
-        isBlackBoxed: false,
-        loadedState: "unloaded",
-        isWasm: !!supportsWasm && source.introductionType === "wasm",
-        isExtension: (source.url && isUrlExtension(source.url)) || false,
-        actors: [sourceActor]
-      };
-      return createdSource;
-    });
 
-    return dispatch(newInnerSources(sources));
-  };
-}
+    const resultIds = [];
+    const newSources: Array<Source> = [];
+    const newSourceActors: Array<SourceActor> = [];
 
-function newInnerSources(sources: Source[]) {
-  return async ({ dispatch, getState }: ThunkArgs) => {
-    const cx = getContext(getState());
+    for (const { thread, source, id } of sourceInfo) {
+      const newId = id || makeSourceId(source);
 
-    const _newSources = sources.filter(
-      source => !getSource(getState(), source.id) || isInlineScript(source)
-    );
+      if (!getSource(getState(), newId)) {
+        newSources.push(
+          ({
+            id: newId,
+            url: source.url,
+            relativeUrl: source.url,
+            isPrettyPrinted: false,
+            sourceMapURL: source.sourceMapURL,
+            introductionUrl: source.introductionUrl,
+            introductionType: source.introductionType,
+            isBlackBoxed: false,
+            loadedState: "unloaded",
+            isWasm: !!supportsWasm && source.introductionType === "wasm",
+            isExtension: (source.url && isUrlExtension(source.url)) || false
+          }: any)
+        );
+      }
 
-    const sourcesNeedingPositions = _newSources.filter(source =>
-      hasBreakpointPositions(getState(), source.id)
-    );
+      const actorId = stringToSourceActorId(source.actor);
 
-    dispatch({ type: "ADD_SOURCES", cx, sources });
+      // We are sometimes notified about a new source multiple times if we
+      // request a new source list and also get a source event from the server.
+      if (!hasSourceActor(getState(), actorId)) {
+        newSourceActors.push({
+          id: actorId,
+          actor: source.actor,
+          thread,
+          source: newId,
 
-    for (const source of _newSources) {
-      dispatch(checkSelectedSource(cx, source.id));
+          isBlackBoxed: source.isBlackBoxed,
+          sourceMapURL: source.sourceMapURL,
+          url: source.url,
+          introductionUrl: source.introductionUrl,
+          introductionType: source.introductionType
+        });
+      }
+
+      resultIds.push(newId);
     }
 
+    const cx = getContext(getState());
+    dispatch(addSources(cx, newSources));
+
+    const sourceIDsNeedingPositions = newSourceActors
+      .map(actor => actor.source)
+      .filter(sourceId => {
+        const source = getSource(getState(), sourceId);
+        return (
+          source && isInlineScript(source) && isFetchingBreakpoints(sourceId)
+        );
+      });
+
+    dispatch(insertSourceActors(newSourceActors));
+
     // Adding new sources may have cleared this file's breakpoint positions
     // in cases where a new <script> loaded in the HTML, so we manually
     // re-request new breakpoint positions.
-    for (const source of sourcesNeedingPositions) {
-      if (!hasBreakpointPositions(getState(), source.id)) {
-        dispatch(setBreakpointPositions({ cx, sourceId: source.id }));
-      }
+    for (const sourceId of sourceIDsNeedingPositions) {
+      dispatch(setBreakpointPositions({ cx, sourceId }));
     }
 
-    dispatch(restoreBlackBoxedSources(cx, _newSources));
-    dispatch(loadSourceMaps(cx, _newSources));
+    await dispatch(checkNewSources(cx, newSources));
+
+    return resultIds.map(id => getSourceFromId(getState(), id));
+  };
+}
+
+function addSources(cx, sources: Array<Source>) {
+  return ({ dispatch, getState }: ThunkArgs) => {
+    dispatch({ type: "ADD_SOURCES", cx, sources });
+  };
+}
+
+function checkNewSources(cx, sources: Source[]) {
+  return async ({ dispatch, getState }: ThunkArgs) => {
+    for (const source of sources) {
+      dispatch(checkSelectedSource(cx, source.id));
+    }
+
+    dispatch(restoreBlackBoxedSources(cx, sources));
+    dispatch(loadSourceMaps(cx, sources));
 
     return sources;
   };
diff --git a/devtools/client/debugger/src/actions/sources/prettyPrint.js b/devtools/client/debugger/src/actions/sources/prettyPrint.js
index 56264747785a..90cd2a443b49 100644
--- a/devtools/client/debugger/src/actions/sources/prettyPrint.js
+++ b/devtools/client/debugger/src/actions/sources/prettyPrint.js
@@ -26,12 +26,13 @@ import {
 
 import type { Action, ThunkArgs } from "../types";
 import { selectSource } from "./select";
-import type { JsSource, Source, Context } from "../../types";
+import type { JsSource, Source, SourceActor, Context } from "../../types";
 
 export async function prettyPrintSource(
   sourceMaps: typeof SourceMaps,
   prettySource: Source,
-  generatedSource: any
+  generatedSource: Source,
+  actors: Array<SourceActor>
 ) {
   const url = getPrettySourceURL(generatedSource.url);
   const { code, mappings } = await prettyPrint({
@@ -42,8 +43,8 @@ export async function prettyPrintSource(
 
   // The source map URL service used by other devtools listens to changes to
   // sources based on their actor IDs, so apply the mapping there too.
-  for (const sourceActor of generatedSource.actors) {
-    await sourceMaps.applySourceMap(sourceActor.actor, url, code, mappings);
+  for (const { actor } of actors) {
+    await sourceMaps.applySourceMap(actor, url, code, mappings);
   }
   return {
     id: prettySource.id,
@@ -69,8 +70,7 @@ export function createPrettySource(cx: Context, sourceId: string) {
       loadedState: "loading",
       introductionUrl: null,
       introductionType: undefined,
-      isExtension: false,
-      actors: []
+      isExtension: false
     };
 
     dispatch(({ type: "ADD_SOURCE", cx, source: prettySource }: Action));
diff --git a/devtools/client/debugger/src/actions/sources/tests/__snapshots__/prettyPrint.spec.js.snap b/devtools/client/debugger/src/actions/sources/tests/__snapshots__/prettyPrint.spec.js.snap
index ee2e685780fc..849bf199aa1e 100644
--- a/devtools/client/debugger/src/actions/sources/tests/__snapshots__/prettyPrint.spec.js.snap
+++ b/devtools/client/debugger/src/actions/sources/tests/__snapshots__/prettyPrint.spec.js.snap
@@ -2,7 +2,6 @@
 
 exports[`sources - pretty print returns a pretty source for a minified file 1`] = `
 Object {
-  "actors": Array [],
   "contentType": "text/javascript",
   "id": "base.js/originalSource-36c718d4bde9a75edb388ff7733efe7f",
   "introductionType": undefined,
diff --git a/devtools/client/debugger/src/actions/sources/tests/blackbox.spec.js b/devtools/client/debugger/src/actions/sources/tests/blackbox.spec.js
index 2c4a59d5819b..0876fbeb0c26 100644
--- a/devtools/client/debugger/src/actions/sources/tests/blackbox.spec.js
+++ b/devtools/client/debugger/src/actions/sources/tests/blackbox.spec.js
@@ -27,7 +27,10 @@ describe("blackbox", () => {
       throw new Error("foo should exist");
     }
 
-    const thread = foo1Source.actors[0].thread;
+    const { thread } = selectors.getSourceActorsForSource(
+      getState(),
+      foo1Source.id
+    )[0];
     const displayedSources = selectors.getDisplayedSourcesForThread(
       getState(),
       thread
diff --git a/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js b/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js
index 870f6710bdf6..c176a31ddabc 100644
--- a/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js
+++ b/devtools/client/debugger/src/actions/sources/tests/loadSource.spec.js
@@ -64,7 +64,10 @@ describe("loadSourceText", () => {
         getOriginalLocations: async items =>
           items.map(item => ({
             ...item,
-            sourceId: fooOrigSource.id
+            sourceId:
+              item.sourceId === fooGenSource1.id
+                ? fooOrigSource1.id
+                : fooOrigSource2.id
           })),
         getOriginalSourceText: async s => ({
           text: fooOrigContent.source,
@@ -74,36 +77,66 @@ describe("loadSourceText", () => {
     );
     const { cx, dispatch, getState } = store;
 
-    const fooGenSource = await dispatch(
-      actions.newGeneratedSource(makeSource("fooGen"))
+    const fooGenSource1 = await dispatch(
+      actions.newGeneratedSource(makeSource("fooGen1"))
     );
-    const fooOrigSource = await dispatch(
-      actions.newOriginalSource(makeOriginalSource(fooGenSource))
+    const fooOrigSource1 = await dispatch(
+      actions.newOriginalSource(makeOriginalSource(fooGenSource1))
+    );
+    const fooGenSource2 = await dispatch(
+      actions.newGeneratedSource(makeSource("fooGen2"))
+    );
+    const fooOrigSource2 = await dispatch(
+      actions.newOriginalSource(makeOriginalSource(fooGenSource2))
     );
 
-    const location = {
-      sourceId: fooOrigSource.id,
-      line: 1,
-      column: 0
-    };
-    await dispatch(actions.addBreakpoint(cx, location, {}));
+    await dispatch(actions.loadSourceText({ cx, source: fooOrigSource1 }));
 
-    const breakpoint = getBreakpointsList(getState())[0];
-
-    expect(breakpoint.text).toBe("");
-    expect(breakpoint.originalText).toBe("");
-
-    await dispatch(actions.loadSourceText({ cx, source: fooOrigSource }));
+    await dispatch(
+      actions.addBreakpoint(
+        cx,
+        {
+          sourceId: fooOrigSource1.id,
+          line: 1,
+          column: 0
+        },
+        {}
+      )
+    );
 
     const breakpoint1 = getBreakpointsList(getState())[0];
     expect(breakpoint1.text).toBe("");
     expect(breakpoint1.originalText).toBe("var fooOrig = 42;");
 
-    await dispatch(actions.loadSourceText({ cx, source: fooGenSource }));
+    await dispatch(actions.loadSourceText({ cx, source: fooGenSource1 }));
 
     const breakpoint2 = getBreakpointsList(getState())[0];
     expect(breakpoint2.text).toBe("var fooGen = 42;");
     expect(breakpoint2.originalText).toBe("var fooOrig = 42;");
+
+    await dispatch(actions.loadSourceText({ cx, source: fooGenSource2 }));
+
+    await dispatch(
+      actions.addBreakpoint(
+        cx,
+        {
+          sourceId: fooGenSource2.id,
+          line: 1,
+          column: 0
+        },
+        {}
+      )
+    );
+
+    const breakpoint3 = getBreakpointsList(getState())[1];
+    expect(breakpoint3.text).toBe("var fooGen = 42;");
+    expect(breakpoint3.originalText).toBe("");
+
+    await dispatch(actions.loadSourceText({ cx, source: fooOrigSource2 }));
+
+    const breakpoint4 = getBreakpointsList(getState())[1];
+    expect(breakpoint4.text).toBe("var fooGen = 42;");
+    expect(breakpoint4.originalText).toBe("var fooOrig = 42;");
   });
 
   it("loads two sources w/ one request", async () => {
diff --git a/devtools/client/debugger/src/client/firefox/commands.js b/devtools/client/debugger/src/client/firefox/commands.js
index bc4110c6acc1..1dac80c61c8b 100644
--- a/devtools/client/debugger/src/client/firefox/commands.js
+++ b/devtools/client/debugger/src/client/firefox/commands.js
@@ -20,7 +20,6 @@ import type {
   Script,
   SourceId,
   SourceActor,
-  Source,
   Worker,
   Range
 } from "../../types";
@@ -188,7 +187,7 @@ function removeXHRBreakpoint(path: string, method: string) {
 function locationKey(location: BreakpointLocation) {
   const { sourceUrl, line, column } = location;
   const sourceId = location.sourceId || "";
-  return `${(sourceUrl: any)}:${sourceId}:${line}:${(column: any)}`;
+  return `${(sourceUrl: any)}:${(sourceId: any)}:${line}:${(column: any)}`;
 }
 
 function waitForWorkers(shouldWait: boolean) {
@@ -446,12 +445,12 @@ function getMainThread() {
 }
 
 async function getBreakpointPositions(
-  source: Source,
+  actors: Array<SourceActor>,
   range: ?Range
 ): Promise<{ [string]: number[] }> {
   const sourcePositions = {};
 
-  for (const { thread, actor } of source.actors) {
+  for (const { thread, actor } of actors) {
     const sourceThreadClient = lookupThreadClient(thread);
     const sourceClient = sourceThreadClient.source({ actor });
     const { positions } = await sourceClient.getBreakpointPositionsCompressed(
diff --git a/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap b/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap
index 20779127d860..3cc32360b268 100644
--- a/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap
+++ b/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTree.spec.js.snap
@@ -200,7 +200,6 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
         Array [
           Object {
             "contents": Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/41",
               "introductionType": undefined,
@@ -223,7 +222,6 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
             "contents": Array [
               Object {
                 "contents": Object {
-                  "actors": Array [],
                   "contentType": "text/javascript",
                   "id": "server1.conn13.child1/42",
                   "introductionType": undefined,
@@ -244,7 +242,6 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
               },
               Object {
                 "contents": Object {
-                  "actors": Array [],
                   "contentType": "text/javascript",
                   "id": "server1.conn13.child1/42/originalSource-sha",
                   "introductionType": undefined,
@@ -265,7 +262,6 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
               },
               Object {
                 "contents": Object {
-                  "actors": Array [],
                   "contentType": "text/javascript",
                   "id": "server1.conn13.child1/39",
                   "introductionType": undefined,
@@ -286,7 +282,6 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
               },
               Object {
                 "contents": Object {
-                  "actors": Array [],
                   "contentType": "text/javascript",
                   "id": "server1.conn13.child1/41",
                   "introductionType": undefined,
@@ -307,7 +302,6 @@ exports[`SourcesTree on receiving new props updates highlighted items updates hi
               },
               Object {
                 "contents": Object {
-                  "actors": Array [],
                   "contentType": "text/javascript",
                   "id": "server1.conn13.child1/40",
                   "introductionType": undefined,
diff --git a/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTreeItem.spec.js.snap b/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTreeItem.spec.js.snap
index a2cd4bb41f10..ee9e39a72e96 100644
--- a/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTreeItem.spec.js.snap
+++ b/devtools/client/debugger/src/components/PrimaryPanes/tests/__snapshots__/SourcesTreeItem.spec.js.snap
@@ -14,7 +14,6 @@ Object {
     <Connect(SourceIcon)
       source={
         Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -51,7 +50,6 @@ Object {
       "focusItem": [MockFunction],
       "item": Object {
         "contents": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -73,7 +71,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -103,7 +100,6 @@ Object {
           item={
             Object {
               "contents": Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -127,7 +123,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -158,7 +153,6 @@ Object {
           <Connect(SourceIcon)
             source={
               Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -194,7 +188,6 @@ Object {
     "focusItem": [MockFunction],
     "item": Object {
       "contents": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -216,7 +209,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -249,7 +241,6 @@ Object {
     <Connect(SourceIcon)
       source={
         Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -292,7 +283,6 @@ Object {
       "hasMatchingGeneratedSource": true,
       "item": Object {
         "contents": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -315,7 +305,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -346,7 +335,6 @@ Object {
           item={
             Object {
               "contents": Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -371,7 +359,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -402,7 +389,6 @@ Object {
           <Connect(SourceIcon)
             source={
               Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -444,7 +430,6 @@ Object {
     "hasMatchingGeneratedSource": true,
     "item": Object {
       "contents": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -467,7 +452,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -522,7 +506,6 @@ Object {
       "focusItem": [MockFunction],
       "item": Object {
         "contents": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -545,7 +528,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -576,7 +558,6 @@ Object {
           item={
             Object {
               "contents": Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -601,7 +582,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -653,7 +633,6 @@ Object {
     "focusItem": [MockFunction],
     "item": Object {
       "contents": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -676,7 +655,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -740,7 +718,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -782,7 +759,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -843,7 +819,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -908,7 +883,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -951,7 +925,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -1013,7 +986,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -1202,7 +1174,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -1243,7 +1214,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -1303,7 +1273,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -1613,7 +1582,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -1655,7 +1623,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -1716,7 +1683,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -1779,7 +1745,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -1820,7 +1785,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -1880,7 +1844,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -1913,7 +1876,6 @@ Object {
     <Connect(SourceIcon)
       source={
         Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -1950,7 +1912,6 @@ Object {
       "focusItem": [MockFunction],
       "item": Object {
         "contents": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -1973,7 +1934,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -2003,7 +1963,6 @@ Object {
           item={
             Object {
               "contents": Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -2028,7 +1987,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -2059,7 +2017,6 @@ Object {
           <Connect(SourceIcon)
             source={
               Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -2095,7 +2052,6 @@ Object {
     "focusItem": [MockFunction],
     "item": Object {
       "contents": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -2118,7 +2074,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -2151,7 +2106,6 @@ Object {
     <Connect(SourceIcon)
       source={
         Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -2190,7 +2144,6 @@ Object {
       "focused": true,
       "item": Object {
         "contents": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -2212,7 +2165,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -2244,7 +2196,6 @@ Object {
           item={
             Object {
               "contents": Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -2268,7 +2219,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -2299,7 +2249,6 @@ Object {
           <Connect(SourceIcon)
             source={
               Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -2337,7 +2286,6 @@ Object {
     "focused": true,
     "item": Object {
       "contents": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -2359,7 +2307,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
@@ -2392,7 +2339,6 @@ Object {
     <Connect(SourceIcon)
       source={
         Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -2429,7 +2375,6 @@ Object {
       "focusItem": [MockFunction],
       "item": Object {
         "contents": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "server1.conn13.child1/39",
           "introductionType": undefined,
@@ -2452,7 +2397,6 @@ Object {
       "setExpanded": [MockFunction],
       "setProjectDirectoryRoot": [MockFunction],
       "source": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -2482,7 +2426,6 @@ Object {
           item={
             Object {
               "contents": Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -2507,7 +2450,6 @@ Object {
           setProjectDirectoryRoot={[MockFunction]}
           source={
             Object {
-              "actors": Array [],
               "contentType": "text/javascript",
               "id": "server1.conn13.child1/39",
               "introductionType": undefined,
@@ -2538,7 +2480,6 @@ Object {
           <Connect(SourceIcon)
             source={
               Object {
-                "actors": Array [],
                 "contentType": "text/javascript",
                 "id": "server1.conn13.child1/39",
                 "introductionType": undefined,
@@ -2574,7 +2515,6 @@ Object {
     "focusItem": [MockFunction],
     "item": Object {
       "contents": Object {
-        "actors": Array [],
         "contentType": "text/javascript",
         "id": "server1.conn13.child1/39",
         "introductionType": undefined,
@@ -2597,7 +2537,6 @@ Object {
     "setExpanded": [MockFunction],
     "setProjectDirectoryRoot": [MockFunction],
     "source": Object {
-      "actors": Array [],
       "contentType": "text/javascript",
       "id": "server1.conn13.child1/39",
       "introductionType": undefined,
diff --git a/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frame.spec.js.snap b/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frame.spec.js.snap
index ef188fed40fd..f8d55f0c403c 100644
--- a/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frame.spec.js.snap
+++ b/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frame.spec.js.snap
@@ -37,7 +37,6 @@ exports[`Frame getFrameTitle 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
@@ -92,7 +91,6 @@ exports[`Frame getFrameTitle 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
@@ -154,7 +152,6 @@ exports[`Frame library frame 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
@@ -210,7 +207,6 @@ exports[`Frame library frame 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
@@ -271,7 +267,6 @@ exports[`Frame user frame (not selected) 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
@@ -326,7 +321,6 @@ exports[`Frame user frame (not selected) 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
@@ -387,7 +381,6 @@ exports[`Frame user frame 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
@@ -442,7 +435,6 @@ exports[`Frame user frame 1`] = `
           "type": "block",
         },
         "source": Object {
-          "actors": Array [],
           "contentType": "text/javascript",
           "id": "source",
           "introductionType": undefined,
diff --git a/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frames.spec.js.snap b/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frames.spec.js.snap
index 4cb7cd09ad78..3c0510bec655 100644
--- a/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frames.spec.js.snap
+++ b/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Frames.spec.js.snap
@@ -34,7 +34,6 @@ exports[`Frames Blackboxed Frames filters blackboxed frames 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "1",
             "introductionType": undefined,
@@ -81,7 +80,6 @@ exports[`Frames Blackboxed Frames filters blackboxed frames 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "1",
             "introductionType": undefined,
@@ -130,7 +128,6 @@ exports[`Frames Blackboxed Frames filters blackboxed frames 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "1",
             "introductionType": undefined,
@@ -177,7 +174,6 @@ exports[`Frames Blackboxed Frames filters blackboxed frames 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "1",
             "introductionType": undefined,
diff --git a/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Group.spec.js.snap b/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Group.spec.js.snap
index d973db410c4c..5c668a297036 100644
--- a/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Group.spec.js.snap
+++ b/devtools/client/debugger/src/components/SecondaryPanes/Frames/tests/__snapshots__/Group.spec.js.snap
@@ -41,7 +41,6 @@ exports[`Group displays a group 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -116,7 +115,6 @@ exports[`Group passes the getFrameTitle prop to the Frame components 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -190,7 +188,6 @@ exports[`Group passes the getFrameTitle prop to the Frame components 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -239,7 +236,6 @@ exports[`Group passes the getFrameTitle prop to the Frame components 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -301,7 +297,6 @@ exports[`Group passes the getFrameTitle prop to the Frame components 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -350,7 +345,6 @@ exports[`Group passes the getFrameTitle prop to the Frame components 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -412,7 +406,6 @@ exports[`Group passes the getFrameTitle prop to the Frame components 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -461,7 +454,6 @@ exports[`Group passes the getFrameTitle prop to the Frame components 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -528,7 +520,6 @@ exports[`Group renders group with anonymous functions 1`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -603,7 +594,6 @@ exports[`Group renders group with anonymous functions 2`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -677,7 +667,6 @@ exports[`Group renders group with anonymous functions 2`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -725,7 +714,6 @@ exports[`Group renders group with anonymous functions 2`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -787,7 +775,6 @@ exports[`Group renders group with anonymous functions 2`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -835,7 +822,6 @@ exports[`Group renders group with anonymous functions 2`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -897,7 +883,6 @@ exports[`Group renders group with anonymous functions 2`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
@@ -945,7 +930,6 @@ exports[`Group renders group with anonymous functions 2`] = `
             "type": "block",
           },
           "source": Object {
-            "actors": Array [],
             "contentType": "text/javascript",
             "id": "source",
             "introductionType": undefined,
diff --git a/devtools/client/debugger/src/components/SecondaryPanes/Scopes.js b/devtools/client/debugger/src/components/SecondaryPanes/Scopes.js
index 6e016abe93e6..aa253e89f222 100644
--- a/devtools/client/debugger/src/components/SecondaryPanes/Scopes.js
+++ b/devtools/client/debugger/src/components/SecondaryPanes/Scopes.js
@@ -122,7 +122,7 @@ class Scopes extends PureComponent<Props, State> {
     const scopes =
       (showOriginal && mapScopesEnabled && originalScopes) || generatedScopes;
 
-    if (scopes && !isLoading) {
+    if (scopes && scopes.length > 0 && !isLoading) {
       return (
         <div className="pane scopes-list">
           <ObjectInspector
diff --git a/devtools/client/debugger/src/reducers/breakpoints.js b/devtools/client/debugger/src/reducers/breakpoints.js
index 02f2f185a686..45b6febebca0 100644
--- a/devtools/client/debugger/src/reducers/breakpoints.js
+++ b/devtools/client/debugger/src/reducers/breakpoints.js
@@ -14,7 +14,6 @@ import { isEqual } from "lodash";
 
 import { makeBreakpointId, findPosition } from "../utils/breakpoint";
 import { findBreakableLines } from "../utils/breakable-lines";
-import { isInlineScript } from "../utils/source";
 
 // eslint-disable-next-line max-len
 import { getBreakpointsList as getBreakpointsListSelector } from "../selectors/breakpoints";
@@ -107,18 +106,20 @@ function update(
       };
     }
 
-    case "ADD_SOURCES": {
-      const { sources } = action;
+    case "INSERT_SOURCE_ACTORS": {
+      const { items } = action;
 
-      const scriptSources = sources.filter(source => isInlineScript(source));
+      const scriptActors = items.filter(
+        item => item.introductionType === "scriptElement"
+      );
 
-      if (scriptSources.length > 0) {
+      if (scriptActors.length > 0) {
         const { ...breakpointPositions } = state.breakpointPositions;
 
         // If new HTML sources are being added, we need to clear the breakpoint
         // positions since the new source is a <script> with new breakpoints.
-        for (const source of scriptSources) {
-          delete breakpointPositions[source.id];
+        for (const { source } of scriptActors) {
+          delete breakpointPositions[source];
         }
 
         state = { ...state, breakpointPositions };
diff --git a/devtools/client/debugger/src/reducers/source-actors.js b/devtools/client/debugger/src/reducers/source-actors.js
index 3cd6952849b8..cc45dc8b1baf 100644
--- a/devtools/client/debugger/src/reducers/source-actors.js
+++ b/devtools/client/debugger/src/reducers/source-actors.js
@@ -69,6 +69,11 @@ export default function update(
       state = removeResources(state, items);
       break;
     }
+
+    case "NAVIGATE": {
+      state = initial;
+      break;
+    }
   }
 
   return state;
diff --git a/devtools/client/debugger/src/reducers/sources.js b/devtools/client/debugger/src/reducers/sources.js
index b4802467c8f3..6db6dd49ea09 100644
--- a/devtools/client/debugger/src/reducers/sources.js
+++ b/devtools/client/debugger/src/reducers/sources.js
@@ -23,18 +23,32 @@ import {
 import { originalToGeneratedId } from "devtools-source-map";
 import { prefs } from "../utils/prefs";
 
-import type { Source, SourceId, SourceLocation, ThreadId } from "../types";
+import {
+  hasSourceActor,
+  getSourceActor,
+  getSourceActors,
+  getThreadsBySource,
+  type SourceActorId,
+  type SourceActorOuterState
+} from "./source-actors";
+import type {
+  Source,
+  SourceId,
+  SourceActor,
+  SourceLocation,
+  ThreadId
+} from "../types";
 import type { PendingSelectedLocation, Selector } from "./types";
 import type { Action, DonePromiseAction, FocusItem } from "../actions/types";
 import type { LoadSourceAction } from "../actions/types/SourceAction";
-import { mapValues, uniqBy } from "lodash";
+import { uniq } from "lodash";
 
 export type SourcesMap = { [SourceId]: Source };
 export type SourcesMapByThread = { [ThreadId]: SourcesMap };
+type SourceActorMap = { [SourceId]: Array<SourceActorId> };
 
 type UrlsMap = { [string]: SourceId[] };
-type DisplayedSources = { [ThreadId]: { [SourceId]: boolean } };
-type GetDisplayedSourcesSelector = OuterState => { [ThreadId]: SourcesMap };
+type DisplayedSources = Set<SourceId>;
 type PlainUrlsMap = { [string]: string[] };
 
 export type SourcesState = {
@@ -43,6 +57,9 @@ export type SourcesState = {
   // All known sources.
   sources: SourcesMap,
 
+  // A link between each source object and the source actor they wrap over.
+  actors: SourceActorMap,
+
   // All sources associated with a given URL. When using source maps, multiple
   // sources can have the same URL.
   urls: UrlsMap,
@@ -65,14 +82,15 @@ export type SourcesState = {
 
 const emptySources = {
   sources: {},
+  displayed: new Set(),
   urls: {},
-  plainUrls: {},
-  displayed: {}
+  plainUrls: {}
 };
 
 export function initialSourcesState(): SourcesState {
   return {
     ...emptySources,
+    actors: {},
     epoch: 1,
     selectedLocation: undefined,
     pendingSelectedLocation: prefs.pendingSelectedLocation,
@@ -97,7 +115,6 @@ export function createSource(state: SourcesState, source: Object): Source {
     error: undefined,
     loadedState: "unloaded",
     relativeUrl: getRelativeUrl(source, root),
-    actors: [],
     ...source
   };
 }
@@ -118,8 +135,11 @@ function update(
     case "ADD_SOURCES":
       return addSources(state, action.sources);
 
-    case "REMOVE_WORKERS":
-      return removeWorkers(state, action);
+    case "INSERT_SOURCE_ACTORS":
+      return insertSourceActors(state, action);
+
+    case "REMOVE_SOURCE_ACTORS":
+      return removeSourceActors(state, action);
 
     case "SET_SELECTED_LOCATION":
       location = {
@@ -228,33 +248,19 @@ function updateAllSources(state: SourcesState, callback: any) {
  * Add sources to the sources store
  * - Add the source to the sources store
  * - Add the source URL to the urls map
- * - Add the source ID to the thread displayed map
  */
-function addSources(state: SourcesState, sources: Source[]) {
+function addSources(state: SourcesState, sources: Source[]): SourcesState {
   state = {
     ...state,
     sources: { ...state.sources },
+    displayed: new Set(state.displayed),
     urls: { ...state.urls },
-    plainUrls: { ...state.plainUrls },
-    displayed: { ...state.displayed }
+    plainUrls: { ...state.plainUrls }
   };
 
   for (const source of sources) {
-    const existingSource = state.sources[source.id];
-    let updatedSource = existingSource || source;
-
-    // Merge the source actor list
-    if (existingSource && source.actors) {
-      const actors = uniqBy(
-        [...existingSource.actors, ...source.actors],
-        ({ actor }) => actor
-      );
-
-      updatedSource = (({ ...updatedSource, actors }: any): Source);
-    }
-
     // 1. Add the source to the sources map
-    state.sources[source.id] = updatedSource;
+    state.sources[source.id] = state.sources[source.id] || source;
 
     // 2. Update the source url map
     const existing = state.urls[source.url] || [];
@@ -277,29 +283,51 @@ function addSources(state: SourcesState, sources: Source[]) {
       (!source.isExtension ||
         getChromeAndExtenstionsEnabled({ sources: state }))
     ) {
-      for (const actor of getSourceActors(state, source)) {
-        if (!state.displayed[actor.thread]) {
-          state.displayed[actor.thread] = {};
-        }
-        state.displayed[actor.thread][source.id] = true;
-      }
+      state.displayed.add(source.id);
     }
   }
 
   return state;
 }
 
+function insertSourceActors(state: SourcesState, action): SourcesState {
+  const { items } = action;
+  state = {
+    ...state,
+    actors: { ...state.actors }
+  };
+
+  for (const sourceActor of items) {
+    state.actors[sourceActor.source] = [
+      ...(state.actors[sourceActor.source] || []),
+      sourceActor.id
+    ];
+  }
+
+  return state;
+}
+
 /*
  * Update sources when the worker list changes.
  * - filter source actor lists so that missing threads no longer appear
  * - NOTE: we do not remove sources for destroyed threads
  */
-function removeWorkers(state: SourcesState, action: Object) {
-  const { workers } = action;
+function removeSourceActors(state: SourcesState, action) {
+  const { items } = action;
 
-  return updateAllSources(state, source => ({
-    actors: source.actors.filter(({ thread }) => !workers.includes(thread))
-  }));
+  const actors = new Set(items.map(item => item.id));
+  const sources = new Set(items.map(item => item.source));
+
+  state = {
+    ...state,
+    actors: { ...state.actors }
+  };
+
+  for (const source of sources) {
+    state.actors[source] = state.actors[source].filter(id => !actors.has(id));
+  }
+
+  return state;
 }
 
 /*
@@ -376,14 +404,15 @@ type OuterState = { sources: SourcesState };
 
 const getSourcesState = (state: OuterState) => state.sources;
 
-function getSourceActors(state, source) {
-  if (isGenerated(source)) {
-    return source.actors;
-  }
-
-  // Original sources do not have actors, so use the generated source.
-  const generatedSource = state.sources[originalToGeneratedId(source.id)];
-  return generatedSource ? generatedSource.actors : [];
+export function getSourceThreads(
+  state: OuterState & SourceActorOuterState,
+  source: Source
+): ThreadId[] {
+  return uniq(
+    getSourceActors(state, state.sources.actors[source.id]).map(
+      actor => actor.thread
+    )
+  );
 }
 
 export function getSourceInSources(sources: SourcesMap, id: string): ?Source {
@@ -403,17 +432,14 @@ export function getSourceFromId(state: OuterState, id: string): Source {
 }
 
 export function getSourceByActorId(
-  state: OuterState,
-  actorId: string
+  state: OuterState & SourceActorOuterState,
+  actorId: SourceActorId
 ): ?Source {
-  // We don't index the sources by actor IDs, so this method should be used
-  // sparingly.
-  for (const source of getSourceList(state)) {
-    if (source.actors.some(({ actor }) => actor == actorId)) {
-      return source;
-    }
+  if (!hasSourceActor(state, actorId)) {
+    return null;
   }
-  return null;
+
+  return getSource(state, getSourceActor(state, actorId).source);
 }
 
 export function getSourcesByURLInSources(
@@ -560,7 +586,9 @@ export function getSourceList(state: OuterState): Source[] {
   return (Object.values(getSources(state)): any);
 }
 
-export function getDisplayedSourcesList(state: OuterState): Source[] {
+export function getDisplayedSourcesList(
+  state: OuterState & SourceActorOuterState
+): Source[] {
   return ((Object.values(getDisplayedSources(state)): any).flatMap(
     Object.values
   ): any);
@@ -596,7 +624,7 @@ export function getProjectDirectoryRoot(state: OuterState): string {
   return state.sources.projectDirectoryRoot;
 }
 
-function getAllDisplayedSources(state: OuterState) {
+function getAllDisplayedSources(state: OuterState): DisplayedSources {
   return state.sources.displayed;
 }
 
@@ -604,19 +632,55 @@ function getChromeAndExtenstionsEnabled(state: OuterState) {
   return state.sources.chromeAndExtenstionsEnabled;
 }
 
-export const getDisplayedSources: GetDisplayedSourcesSelector = createSelector(
-  getSources,
-  getChromeAndExtenstionsEnabled,
+type GetDisplayedSourceIDsSelector = (
+  OuterState & SourceActorOuterState
+) => { [ThreadId]: Set<SourceId> };
+const getDisplayedSourceIDs: GetDisplayedSourceIDsSelector = createSelector(
+  getThreadsBySource,
   getAllDisplayedSources,
-  (sources, chromeAndExtenstionsEnabled, displayed) => {
-    return mapValues(displayed, threadSourceIds =>
-      mapValues(threadSourceIds, (_, id) => sources[id])
-    );
+  (threadsBySource, displayedSources) => {
+    const sourceIDsByThread = {};
+
+    for (const sourceId of displayedSources) {
+      const threads =
+        threadsBySource[sourceId] ||
+        threadsBySource[originalToGeneratedId(sourceId)] ||
+        [];
+
+      for (const thread of threads) {
+        if (!sourceIDsByThread[thread]) {
+          sourceIDsByThread[thread] = new Set();
+        }
+        sourceIDsByThread[thread].add(sourceId);
+      }
+    }
+    return sourceIDsByThread;
+  }
+);
+type GetDisplayedSourcesSelector = (
+  OuterState & SourceActorOuterState
+) => { [ThreadId]: { [SourceId]: Source } };
+export const getDisplayedSources: GetDisplayedSourcesSelector = createSelector(
+  state => state.sources.sources,
+  getDisplayedSourceIDs,
+  (sources, idsByThread) => {
+    const result = {};
+
+    for (const thread of Object.keys(idsByThread)) {
+      for (const id of idsByThread[thread]) {
+        if (!result[thread]) {
+          result[thread] = {};
+        }
+        result[thread][id] = sources[id];
+      }
+    }
+
+    return result;
   }
 );
 
 export function getDisplayedSourcesForThread(
-  state: OuterState,
+  state: OuterState & SourceActorOuterState,
   thread: string
 ): SourcesMap {
   return getDisplayedSources(state)[thread] || {};
@@ -626,4 +690,16 @@ export function getFocusedSourceItem(state: OuterState): ?FocusItem {
   return state.sources.focusedItem;
 }
 
+export function getSourceActorsForSource(
+  state: OuterState & SourceActorOuterState,
+  id: SourceId
+): Array<SourceActor> {
+  const actors = state.sources.actors[id];
+  if (!actors) {
+    return [];
+  }
+
+  return getSourceActors(state, actors);
+}
+
 export default update;
diff --git a/devtools/client/debugger/src/reducers/tests/sources.spec.js b/devtools/client/debugger/src/reducers/tests/sources.spec.js
index 161068492535..960be4809c31 100644
--- a/devtools/client/debugger/src/reducers/tests/sources.spec.js
+++ b/devtools/client/debugger/src/reducers/tests/sources.spec.js
@@ -8,39 +8,29 @@ declare var it: (desc: string, func: () => void) => void;
 declare var expect: (value: any) => any;
 
 import update, { initialSourcesState, getDisplayedSources } from "../sources";
-import type { Source } from "../../types";
+import updateSourceActors from "../source-actors";
+import type { Source, SourceActor } from "../../types";
 import { prefs } from "../../utils/prefs";
 import { makeMockSource, mockcx } from "../../utils/test-mockup";
 
 const extensionSource = {
   ...makeMockSource(),
   id: "extensionId",
-  url: "http://example.com/script.js",
-  actors: [{ actor: "extensionId-actor", source: "extensionId", thread: "foo" }]
+  url: "http://example.com/script.js"
 };
 
 const firefoxExtensionSource = {
   ...makeMockSource(),
   id: "firefoxExtension",
   url: "moz-extension://id/js/content.js",
-  isExtension: true,
-  actors: [
-    {
-      actor: "firefoxExtension-actor",
-      source: "firefoxExtension",
-      thread: "foo"
-    }
-  ]
+  isExtension: true
 };
 
 const chromeExtensionSource = {
   ...makeMockSource(),
   id: "chromeExtension",
   isExtension: true,
-  url: "chrome-extension://id/js/content.js",
-  actors: [
-    { actor: "chromeExtension-actor", source: "chromeExtension", thread: "foo" }
-  ]
+  url: "chrome-extension://id/js/content.js"
 };
 
 const mockedSources = [
@@ -49,6 +39,27 @@ const mockedSources = [
   chromeExtensionSource
 ];
 
+const mockSourceActors: Array<SourceActor> = ([
+  {
+    id: "extensionId-actor",
+    actor: "extensionId-actor",
+    source: "extensionId",
+    thread: "foo"
+  },
+  {
+    id: "firefoxExtension-actor",
+    actor: "firefoxExtension-actor",
+    source: "firefoxExtension",
+    thread: "foo"
+  },
+  {
+    id: "chromeExtension-actor",
+    actor: "chromeExtension-actor",
+    source: "chromeExtension",
+    thread: "foo"
+  }
+]: any);
+
 describe("sources reducer", () => {
   it("should work", () => {
     let state = initialSourcesState();
@@ -71,7 +82,16 @@ describe("sources selectors", () => {
         cx: mockcx,
         // coercing to a Source for the purpose of this test
         sources: ((mockedSources: any): Source[])
-      })
+      }),
+      sourceActors: undefined
+    };
+    const insertAction = {
+      type: "INSERT_SOURCE_ACTORS",
+      items: mockSourceActors
+    };
+    state = {
+      sources: update(state.sources, insertAction),
+      sourceActors: updateSourceActors(state.sourceActors, insertAction)
     };
     const selectedDisplayedSources = getDisplayedSources(state);
     const threadSources = selectedDisplayedSources.foo;
@@ -87,7 +107,18 @@ describe("sources selectors", () => {
         cx: mockcx,
         // coercing to a Source for the purpose of this test
         sources: ((mockedSources: any): Source[])
-      })
+      }),
+      sourceActors: undefined
+    };
+
+    const insertAction = {
+      type: "INSERT_SOURCE_ACTORS",
+      items: mockSourceActors
+    };
+
+    state = {
+      sources: update(state.sources, insertAction),
+      sourceActors: updateSourceActors(state.sourceActors, insertAction)
     };
     const selectedDisplayedSources = getDisplayedSources(state);
     const threadSources = selectedDisplayedSources.foo;
diff --git a/devtools/client/debugger/src/reducers/types.js b/devtools/client/debugger/src/reducers/types.js
index cacaf90e808e..2c40e9407879 100644
--- a/devtools/client/debugger/src/reducers/types.js
+++ b/devtools/client/debugger/src/reducers/types.js
@@ -19,6 +19,7 @@ import type { PendingBreakpointsState } from "../selectors";
 import type { ProjectTextSearchState } from "./project-text-search";
 import type { Record } from "../utils/makeRecord";
 import type { SourcesState } from "./sources";
+import type { SourceActorsState } from "./source-actors";
 import type { TabList } from "./tabs";
 import type { UIState } from "./ui";
 import type { QuickOpenState } from "./quick-open";
@@ -33,6 +34,7 @@ export type State = {
   pendingBreakpoints: PendingBreakpointsState,
   projectTextSearch: ProjectTextSearchState,
   sources: SourcesState,
+  sourceActors: SourceActorsState,
   tabs: TabList,
   ui: Record<UIState>,
   quickOpen: Record<QuickOpenState>
diff --git a/devtools/client/debugger/src/selectors/index.js b/devtools/client/debugger/src/selectors/index.js
index 257a872324b2..9630eda4fcc6 100644
--- a/devtools/client/debugger/src/selectors/index.js
+++ b/devtools/client/debugger/src/selectors/index.js
@@ -20,7 +20,9 @@ export * from "../reducers/source-tree";
 
 export {
   getSourceActor,
-  getSourceActorsForThread,
+  hasSourceActor,
+  getSourceActors,
+  getSourceActorsForThread
 } from "../reducers/source-actors";
 
 export {
diff --git a/devtools/client/debugger/src/types.js b/devtools/client/debugger/src/types.js
index a7b665c32d3e..3ef2ea82b405 100644
--- a/devtools/client/debugger/src/types.js
+++ b/devtools/client/debugger/src/types.js
@@ -5,6 +5,9 @@
 // @flow
 
 import type { SourcePayload } from "./client/firefox/types";
+import type { SourceActorId, SourceActor } from "./reducers/source-actors";
+
+export type { SourceActorId, SourceActor };
 
 export type SearchModifiers = {
   caseSensitive: boolean,
@@ -68,7 +71,7 @@ export type GeneratedSourceData = {
 };
 
 export type SourceActorLocation = {|
-  +sourceActor: SourceActor,
+  +sourceActor: SourceActorId,
   +line: number,
   +column?: number
 |};
@@ -118,7 +121,7 @@ export type BreakpointLocation = {
   +line: number,
   +column?: number,
   +sourceUrl?: string,
-  +sourceId?: SourceId
+  +sourceId?: SourceActorId
 };
 
 export type ASTLocation = {|
@@ -352,12 +355,6 @@ export type Grip = {
   name?: string
 };
 
-export type SourceActor = {|
-  +actor: ActorId,
-  +source: SourceId,
-  +thread: ThreadId
-|};
-
 /**
  * BaseSource
  *
@@ -377,8 +374,7 @@ type BaseSource = {|
   +relativeUrl: string,
   +introductionUrl: ?string,
   +introductionType: ?string,
-  +isExtension: boolean,
-  +actors: SourceActor[]
+  +isExtension: boolean
 |};
 
 /**
diff --git a/devtools/client/debugger/src/utils/breakpoint/index.js b/devtools/client/debugger/src/utils/breakpoint/index.js
index cd43fbf07a67..9947a1c5c395 100644
--- a/devtools/client/debugger/src/utils/breakpoint/index.js
+++ b/devtools/client/debugger/src/utils/breakpoint/index.js
@@ -4,7 +4,11 @@
 
 // @flow
 
-import { getBreakpoint, getSource } from "../../selectors";
+import {
+  getBreakpoint,
+  getSource,
+  getSourceActorsForSource
+} from "../../selectors";
 import { isGenerated } from "../source";
 import { sortSelectedLocations } from "../location";
 import assert from "../assert";
@@ -75,7 +79,10 @@ export function makeBreakpointLocation(
   if (source.url) {
     breakpointLocation.sourceUrl = source.url;
   } else {
-    breakpointLocation.sourceId = source.actors[0].actor;
+    breakpointLocation.sourceId = getSourceActorsForSource(
+      state,
+      source.id
+    )[0].id;
   }
   return breakpointLocation;
 }
@@ -95,7 +102,7 @@ export function makeSourceActorLocation(
 export function makeBreakpointActorId(location: SourceActorLocation) {
   const { sourceActor, line, column } = location;
   const columnString = column || "";
-  return `${sourceActor.actor}:${line}:${columnString}`;
+  return `${(sourceActor: any)}:${line}:${columnString}`;
 }
 
 export function assertBreakpoint(breakpoint: Breakpoint) {
diff --git a/devtools/client/debugger/src/utils/sources-tree/tests/__snapshots__/updateTree.spec.js.snap b/devtools/client/debugger/src/utils/sources-tree/tests/__snapshots__/updateTree.spec.js.snap
index 002176fe64b8..4c9c2a4034d0 100644
--- a/devtools/client/debugger/src/utils/sources-tree/tests/__snapshots__/updateTree.spec.js.snap
+++ b/devtools/client/debugger/src/utils/sources-tree/tests/__snapshots__/updateTree.spec.js.snap
@@ -23,7 +23,6 @@ exports[`calls updateTree.js adds one source 1`] = `
             \\"loadedState\\": \\"unloaded\\",
             \\"relativeUrl\\": \\"https://davidwalsh.name/\\",
             \\"introductionUrl\\": null,
-            \\"actors\\": [],
             \\"isWasm\\": false,
             \\"contentType\\": \\"text/javascript\\",
             \\"isExtension\\": false,
@@ -42,7 +41,6 @@ exports[`calls updateTree.js adds one source 1`] = `
             \\"loadedState\\": \\"unloaded\\",
             \\"relativeUrl\\": \\"https://davidwalsh.name/source1.js\\",
             \\"introductionUrl\\": null,
-            \\"actors\\": [],
             \\"isWasm\\": false,
             \\"contentType\\": \\"text/javascript\\",
             \\"isExtension\\": false,
@@ -78,7 +76,6 @@ exports[`calls updateTree.js adds two sources 1`] = `
             \\"loadedState\\": \\"unloaded\\",
             \\"relativeUrl\\": \\"https://davidwalsh.name/\\",
             \\"introductionUrl\\": null,
-            \\"actors\\": [],
             \\"isWasm\\": false,
             \\"contentType\\": \\"text/javascript\\",
             \\"isExtension\\": false,
@@ -97,7 +94,6 @@ exports[`calls updateTree.js adds two sources 1`] = `
             \\"loadedState\\": \\"unloaded\\",
             \\"relativeUrl\\": \\"https://davidwalsh.name/source1.js\\",
             \\"introductionUrl\\": null,
-            \\"actors\\": [],
             \\"isWasm\\": false,
             \\"contentType\\": \\"text/javascript\\",
             \\"isExtension\\": false,
@@ -116,7 +112,6 @@ exports[`calls updateTree.js adds two sources 1`] = `
             \\"loadedState\\": \\"unloaded\\",
             \\"relativeUrl\\": \\"https://davidwalsh.name/source2.js\\",
             \\"introductionUrl\\": null,
-            \\"actors\\": [],
             \\"isWasm\\": false,
             \\"contentType\\": \\"text/javascript\\",
             \\"isExtension\\": false,
@@ -152,7 +147,6 @@ exports[`calls updateTree.js shows all the sources 1`] = `
             \\"loadedState\\": \\"unloaded\\",
             \\"relativeUrl\\": \\"https://davidwalsh.name/\\",
             \\"introductionUrl\\": null,
-            \\"actors\\": [],
             \\"isWasm\\": false,
             \\"contentType\\": \\"text/javascript\\",
             \\"isExtension\\": false,
@@ -171,7 +165,6 @@ exports[`calls updateTree.js shows all the sources 1`] = `
             \\"loadedState\\": \\"unloaded\\",
             \\"relativeUrl\\": \\"https://davidwalsh.name/source1.js\\",
             \\"introductionUrl\\": null,
-            \\"actors\\": [],
             \\"isWasm\\": false,
             \\"contentType\\": \\"text/javascript\\",
             \\"isExtension\\": false,
diff --git a/devtools/client/debugger/src/utils/test-head.js b/devtools/client/debugger/src/utils/test-head.js
index d642cc82825d..1684b755ad86 100644
--- a/devtools/client/debugger/src/utils/test-head.js
+++ b/devtools/client/debugger/src/utils/test-head.js
@@ -103,7 +103,6 @@ function createSourceObject(
     introductionUrl: props.introductionUrl || null,
     introductionType: props.introductionType || null,
     isExtension: false,
-    actors: [],
     ...(typeof props.text === "string"
       ? {
           text: props.text || "",
diff --git a/devtools/client/debugger/src/utils/test-mockup.js b/devtools/client/debugger/src/utils/test-mockup.js
index f6a6e2c46e9b..17cdc1114ead 100644
--- a/devtools/client/debugger/src/utils/test-mockup.js
+++ b/devtools/client/debugger/src/utils/test-mockup.js
@@ -40,7 +40,6 @@ function makeMockSource(
     relativeUrl: url,
     introductionUrl: null,
     introductionType: undefined,
-    actors: [],
     isWasm: false,
     contentType,
     isExtension: false,
@@ -58,7 +57,6 @@ function makeMockWasmSource(text: {| binary: Object |}): WasmSource {
     relativeUrl: "url",
     introductionUrl: null,
     introductionType: undefined,
-    actors: [],
     isWasm: true,
     isExtension: false,
     text
diff --git a/devtools/client/debugger/src/workers/parser/tests/sources.spec.js b/devtools/client/debugger/src/workers/parser/tests/sources.spec.js
index 5e9d2c82ee28..bc41b3250977 100644
--- a/devtools/client/debugger/src/workers/parser/tests/sources.spec.js
+++ b/devtools/client/debugger/src/workers/parser/tests/sources.spec.js
@@ -21,8 +21,7 @@ describe("sources", () => {
       isPrettyPrinted: false,
       isWasm: false,
       loadedState: "loaded",
-      isExtension: false,
-      actors: []
+      isExtension: false
     };
 
     expect(hasSource(sourceId)).toEqual(false);
diff --git a/devtools/client/debugger/test/mochitest/browser_dbg-html-breakpoints.js b/devtools/client/debugger/test/mochitest/browser_dbg-html-breakpoints.js
index 20c93a0072d9..49f9f1c5489d 100644
--- a/devtools/client/debugger/test/mochitest/browser_dbg-html-breakpoints.js
+++ b/devtools/client/debugger/test/mochitest/browser_dbg-html-breakpoints.js
@@ -12,6 +12,7 @@ add_task(async function() {
   // about new actors being created in the page content.
   await reload(dbg, "doc-html-breakpoints.html");
 
+  await waitForBreakableLine(dbg, "doc-html-breakpoints.html", 8);
   await addBreakpoint(dbg, "doc-html-breakpoints.html", 8);
 
   // Ensure that the breakpoints get added once the later scripts load.