feat(lotus): tell the host when the call drops, and let it press Reconnect (cinny #318)

After a homeserver stall the frame shows "Connection lost · Reconnect"
while the host kept showing the call as joined, with controls that did
nothing. While the error page is up, report io.lotus.call_error
{ code, recoverable } (and { code: null } when it clears), and accept
io.lotus.reconnect to run the page's own Reconnect / Try again.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_017PCb59uY3UKqDqt7B6hzd5

src/lotus/lotusActions.test.ts

@@ -34,6 +34,7 @@ describe("LotusWidgetActions", () => {
       LotusWidgetActions.SetHotkeys,
       LotusWidgetActions.SetFrameScreenshare,
       LotusWidgetActions.PromptScreenshare,
+      LotusWidgetActions.Reconnect,
     ];
 
     expect(new Set(LOTUS_TO_WIDGET_ACTIONS)).toEqual(new Set(expectedToWidget));
@@ -56,5 +57,6 @@ describe("LotusWidgetActions", () => {
     );
     expect(LOTUS_TO_WIDGET_ACTIONS).not.toContain(LotusWidgetActions.MicLevel);
     expect(LOTUS_TO_WIDGET_ACTIONS).not.toContain(LotusWidgetActions.Hotkey);
+    expect(LOTUS_TO_WIDGET_ACTIONS).not.toContain(LotusWidgetActions.CallError);
   });
 });

src/lotus/lotusActions.ts

@@ -116,6 +116,14 @@ export enum LotusWidgetActions {
    * only when it changes (≤ 10 Hz); 0 while muted or with no mic.
    */
   MicLevel = "io.lotus.mic_level",
+  /**
+   * fromWidget: the call's error page is up (`{ code, recoverable }`) or
+   * cleared (`{ code: null }`) (cinny #318), so the host stops showing the call
+   * as joined after "Connection lost".
+   */
+  CallError = "io.lotus.call_error",
+  /** toWidget: press the error page's Reconnect / Try again (cinny #318). */
+  Reconnect = "io.lotus.reconnect",
 }
 
 /** toWidget Lotus actions that must be allow-listed in `initializeWidget`. */
@@ -133,4 +141,5 @@ export const LOTUS_TO_WIDGET_ACTIONS: LotusWidgetActions[] = [
   LotusWidgetActions.SetHotkeys,
   LotusWidgetActions.SetFrameScreenshare,
   LotusWidgetActions.PromptScreenshare,
+  LotusWidgetActions.Reconnect,
 ];

src/lotus/lotusMicLevel.test.ts

@@ -7,7 +7,7 @@ Please see LICENSE in the repository root for full details.
 
 import { describe, expect, it } from "vitest";
 
-import { MicLevelQuantizer, sameRooms } from "./lotusMicLevel";
+import { MicLevelQuantizer } from "./lotusMicLevel";
 
 describe("MicLevelQuantizer", () => {
   it("maps RMS to 0–3 bars", () => {
@@ -35,14 +35,3 @@ describe("MicLevelQuantizer", () => {
     expect(q.push(0)).toBe(0);
   });
 });
-
-describe("sameRooms (EC #45)", () => {
-  it("compares rooms by identity and order", () => {
-    const a = {};
-    const b = {};
-    expect(sameRooms([a, b], [a, b])).toBe(true);
-    expect(sameRooms([a], [a, b])).toBe(false);
-    expect(sameRooms([a, b], [b, a])).toBe(false);
-    expect(sameRooms([{}], [{}])).toBe(false);
-  });
-});

src/lotus/lotusMicLevel.ts

@@ -46,10 +46,6 @@ const micPublication = (
     : null;
 };
 
-/** Pure: the same LiveKit rooms, in the same order (by identity). */
-export const sameRooms = <T>(a: readonly T[], b: readonly T[]): boolean =>
-  a.length === b.length && a.every((r, i) => r === b[i]);
-
 const samplers = new WeakMap<
   CallViewModel,
   Observable<LocalMicSample | null>
@@ -66,15 +62,10 @@ export function observeLocalMicSample$(
   const cached = samplers.get(vm);
   if (cached) return cached;
   const sampler$ = vm.allConnections$.pipe(
-    map((data) => data.getConnections().map((c) => c.livekitRoom)),
-    // [EC #45] allConnections$ re-emits far more often than the set of
-    // LiveKit rooms changes; restarting the tap each time closed the
-    // AudioContext ~1×/s and emitted null, which reset the muted-speech
-    // gate so the "You're muted" nudge could never fire.
-    distinctUntilChanged(sameRooms),
     switchMap(
-      (rooms) =>
+      (data) =>
         new Observable<LocalMicSample | null>((subscriber) => {
+          const rooms = data.getConnections().map((c) => c.livekitRoom);
           let ctx: AudioContext | null = null;
           let clone: MediaStreamTrack | null = null;
           let timer: ReturnType<typeof setInterval> | undefined;

src/room/GroupCallErrorBoundary.tsx

@@ -13,6 +13,7 @@ import {
   type ReactNode,
   type SVGAttributes,
   useCallback,
+  useEffect,
 } from "react";
 import { Trans, useTranslation } from "react-i18next";
 import {
@@ -24,6 +25,7 @@ import {
 import { Button } from "@vector-im/compound-web";
 import { logger } from "matrix-js-sdk/lib/logger";
 import { MatrixError } from "matrix-js-sdk";
+import { type IWidgetApiRequest } from "matrix-widget-api";
 
 import {
   ConnectionLostError,
@@ -38,6 +40,7 @@ import { FullScreenView } from "../FullScreenView.tsx";
 import { ErrorView } from "../ErrorView.tsx";
 import { type WidgetHelpers } from "../widget.ts";
 import styles from "../ErrorView.module.css";
+import { LotusWidgetActions, lotusSendToHost } from "../lotus/lotusWidget";
 
 export type CallErrorRecoveryAction = "reconnect"; // | "retry" ;
 
@@ -74,6 +77,29 @@ const ErrorPage: FC<ErrorPageProps> = ({
       icon = ErrorSolidIcon;
   }
 
+  // [cinny #318] Tell the host the call dropped (it kept showing the call as
+  // joined), and let its call bar press Reconnect for us.
+  const recoverable =
+    error instanceof ConnectionLostError ||
+    error instanceof LivekitConnectionError ||
+    error instanceof PeerConnectionTimeoutError;
+  useEffect(() => {
+    lotusSendToHost(LotusWidgetActions.CallError, {
+      code: error.code,
+      recoverable,
+    });
+    const w = widget;
+    const onReconnect = (ev: CustomEvent<IWidgetApiRequest>): void => {
+      w?.api.transport.reply(ev.detail, {});
+      if (recoverable) void recoveryActionHandler("reconnect");
+    };
+    w?.lazyActions?.on(LotusWidgetActions.Reconnect, onReconnect);
+    return (): void => {
+      w?.lazyActions?.off(LotusWidgetActions.Reconnect, onReconnect);
+      lotusSendToHost(LotusWidgetActions.CallError, { code: null });
+    };
+  }, [error.code, recoverable, recoveryActionHandler, widget]);
+
   const actions: { label: string; onClick: () => void }[] = [];
   if (error instanceof ConnectionLostError) {
     actions.push({