Add Module Composer API (#33284)

* Spec composer API

* Add composer api implementation

* Tests

* Copyright

* update sigs

* cleanup

* a snap

* cleanup

* linting

* Tidy up

* Adjust

apps/web/test/unit-tests/components/structures/RoomView-test.tsx

@@ -71,6 +71,7 @@ import ErrorDialog from "../../../../src/components/views/dialogs/ErrorDialog.ts
 import * as pinnedEventHooks from "../../../../src/hooks/usePinnedEvents";
 import { TimelineRenderingType } from "../../../../src/contexts/RoomContext";
 import { ModuleApi } from "../../../../src/modules/Api";
+import { type ComposerInsertPayload, ComposerType } from "../../../../src/dispatcher/payloads/ComposerInsertPayload.ts";
 
 // Used by group calls
 jest.spyOn(MediaDeviceHandler, "getDevices").mockResolvedValue({
@@ -1075,6 +1076,80 @@ describe("RoomView", () => {
         expect(onRoomViewUpdateMock).toHaveBeenCalledWith(true);
     });
 
+    describe("handles Action.ComposerInsert", () => {
+        it("redispatches an empty composerType, timelineRenderingType with the current state", async () => {
+            await mountRoomView();
+            const promise = untilDispatch((payload) => {
+                try {
+                    expect(payload).toEqual({
+                        action: Action.ComposerInsert,
+                        text: "Hello world",
+                        timelineRenderingType: TimelineRenderingType.Room,
+                        composerType: ComposerType.Send,
+                    });
+                } catch {
+                    return false;
+                }
+                return true;
+            }, defaultDispatcher);
+            defaultDispatcher.dispatch({
+                action: Action.ComposerInsert,
+                text: "Hello world",
+            } satisfies ComposerInsertPayload);
+            await promise;
+        });
+        it("redispatches an empty composerType with the current state", async () => {
+            await mountRoomView();
+            const promise = untilDispatch((payload) => {
+                try {
+                    expect(payload).toEqual({
+                        action: Action.ComposerInsert,
+                        text: "Hello world",
+                        timelineRenderingType: TimelineRenderingType.Room,
+                        composerType: ComposerType.Send,
+                    });
+                } catch {
+                    return false;
+                }
+                return true;
+            }, defaultDispatcher);
+            defaultDispatcher.dispatch({
+                action: Action.ComposerInsert,
+                text: "Hello world",
+                timelineRenderingType: TimelineRenderingType.Room,
+            } satisfies ComposerInsertPayload);
+            await promise;
+        });
+        it("ignores payloads with a timelineRenderingType != TimelineRenderingType.Thread", async () => {
+            await mountRoomView();
+            const promise = untilDispatch(
+                (payload) => {
+                    try {
+                        expect(payload).toStrictEqual({
+                            action: Action.ComposerInsert,
+                            text: "Hello world",
+                            timelineRenderingType: TimelineRenderingType.Thread,
+                            composerType: ComposerType.Send,
+                        });
+                    } catch {
+                        return false;
+                    }
+                    return true;
+                },
+                defaultDispatcher,
+                500,
+            );
+            defaultDispatcher.dispatch({
+                action: Action.ComposerInsert,
+                text: "Hello world",
+                composerType: ComposerType.Send,
+                timelineRenderingType: TimelineRenderingType.Room,
+                viaTest: true,
+            } satisfies ComposerInsertPayload);
+            await expect(promise).rejects.toThrow();
+        });
+    });
+
     describe("when there is a RoomView", () => {
         const widget1Id = "widget1";
         const widget2Id = "widget2";

apps/web/test/unit-tests/components/structures/ThreadView-test.tsx

@@ -34,6 +34,9 @@ import { getRoomContext } from "../../../test-utils/room";
 import { mkMessage, stubClient } from "../../../test-utils/test-utils";
 import { mkThread } from "../../../test-utils/threads";
 import { ScopedRoomContextProvider } from "../../../../src/contexts/ScopedRoomContext.tsx";
+import { untilDispatch } from "../../../test-utils/utilities.ts";
+import { TimelineRenderingType } from "../../../../src/contexts/RoomContext.ts";
+import { type ComposerInsertPayload, ComposerType } from "../../../../src/dispatcher/payloads/ComposerInsertPayload.ts";
 
 describe("ThreadView", () => {
     const ROOM_ID = "!roomId:example.org";
@@ -209,4 +212,87 @@ describe("ThreadView", () => {
             metricsTrigger: undefined,
         });
     });
+
+    describe("handles Action.ComposerInsert", () => {
+        it("redispatches a payload of timelineRenderingType=Thread", async () => {
+            await getComponent();
+            const promise = untilDispatch((payload) => {
+                try {
+                    expect(payload).toEqual({
+                        action: Action.ComposerInsert,
+                        text: "Hello world",
+                        timelineRenderingType: TimelineRenderingType.Thread,
+                        composerType: ComposerType.Send,
+                    });
+                } catch {
+                    return false;
+                }
+                return true;
+            }, dispatcher);
+            dispatcher.dispatch({
+                action: Action.ComposerInsert,
+                text: "Hello world",
+                timelineRenderingType: TimelineRenderingType.Thread,
+            } satisfies ComposerInsertPayload);
+            await promise;
+        });
+        it("ignores payloads with a composerType", async () => {
+            await getComponent();
+            const promise = untilDispatch(
+                (payload) => {
+                    try {
+                        expect(payload).toStrictEqual({
+                            action: Action.ComposerInsert,
+                            text: "Hello world",
+                            timelineRenderingType: TimelineRenderingType.Thread,
+                            composerType: ComposerType.Send,
+                        });
+                    } catch {
+                        return false;
+                    }
+                    return true;
+                },
+                dispatcher,
+                500,
+            );
+            dispatcher.dispatch({
+                action: Action.ComposerInsert,
+                text: "Hello world",
+                composerType: ComposerType.Send,
+                timelineRenderingType: TimelineRenderingType.Thread,
+                // Ensure we don't accidentally pick up this emit by strictly checking above.
+                viaTest: true,
+            } satisfies ComposerInsertPayload);
+            await expect(promise).rejects.toThrow();
+        });
+        it("ignores payloads with a timelineRenderingType != TimelineRenderingType.Thread", async () => {
+            await getComponent();
+            const promise = untilDispatch(
+                (payload) => {
+                    try {
+                        expect(payload).toStrictEqual({
+                            action: Action.ComposerInsert,
+                            text: "Hello world",
+                            timelineRenderingType: TimelineRenderingType.Thread,
+                            composerType: ComposerType.Send,
+                        });
+                    } catch {
+                        return false;
+                    }
+                    return true;
+                },
+                dispatcher,
+                500,
+            );
+            dispatcher.dispatch({
+                action: Action.ComposerInsert,
+                text: "Hello world",
+                composerType: ComposerType.Send,
+                timelineRenderingType: TimelineRenderingType.Room,
+                // Ensure we don't accidentally pick up this emit by strictly checking above.
+                viaTest: true,
+            } satisfies ComposerInsertPayload);
+            await expect(promise).rejects.toThrow();
+        });
+    });
 });

apps/web/test/unit-tests/components/views/rooms/wysiwyg_composer/EditWysiwygComposer-test.tsx

@@ -283,8 +283,10 @@ describe("EditWysiwygComposer", () => {
         // It adds the composerType fields where the value refers if the composer is in editing or not
         // The listeners in the RTE ignore the message if the composerType is missing in the payload
         const dispatcherRef = defaultDispatcher.register((payload: ActionPayload) => {
+            const insertPayload = payload as ComposerInsertPayload;
             defaultDispatcher.dispatch<ComposerInsertPayload>({
-                ...(payload as ComposerInsertPayload),
+                ...insertPayload,
+                timelineRenderingType: insertPayload.timelineRenderingType!,
                 composerType: ComposerType.Edit,
             });
         });

apps/web/test/unit-tests/components/views/rooms/wysiwyg_composer/SendWysiwygComposer-test.tsx

@@ -48,11 +48,13 @@ describe("SendWysiwygComposer", () => {
     const registerId = defaultDispatcher.register((payload) => {
         switch (payload.action) {
             case Action.ComposerInsert: {
-                if (payload.composerType) break;
+                const insertPayload = payload as ComposerInsertPayload;
+                if (insertPayload.composerType) break;
 
                 // re-dispatch to the correct composer
                 defaultDispatcher.dispatch<ComposerInsertPayload>({
-                    ...(payload as ComposerInsertPayload),
+                    ...insertPayload,
+                    timelineRenderingType: insertPayload.timelineRenderingType!,
                     composerType: ComposerType.Send,
                 });
                 break;

apps/web/test/unit-tests/modules/ComposerApi-test.ts

@@ -0,0 +1,24 @@
+/*
+Copyright 2026 Element Creations Ltd.
+
+SPDX-License-Identifier: AGPL-3.0-only OR GPL-3.0-only OR LicenseRef-Element-Commercial
+Please see LICENSE files in the repository root for full details.
+*/
+
+import { Action } from "../../../src/dispatcher/actions";
+import type { MatrixDispatcher } from "../../../src/dispatcher/dispatcher";
+import { ComposerApi } from "../../../src/modules/ComposerApi";
+
+describe("ComposerApi", () => {
+    it("should be able to insert text via insertTextIntoComposer()", () => {
+        const dispatcher = {
+            dispatch: jest.fn(),
+        } as unknown as MatrixDispatcher;
+        const api = new ComposerApi(dispatcher);
+        api.insertPlaintextIntoComposer("Hello world");
+        expect(dispatcher.dispatch).toHaveBeenCalledWith({
+            action: Action.ComposerInsert,
+            text: "Hello world",
+        });
+    });
+});