fix(lotus): restart the shared mic sampler only when the LiveKit rooms change (#45)

observeLocalMicSample$ switchMapped on every allConnections$ emission,
which re-emits far more often than the set of rooms changes. Each one
stopped the clone, closed the AudioContext and emitted null, and the
null reset the muted-speech gate, so the "You're muted" nudge could
never stay true long enough to fire. Map to the room list and only
restart when it actually changes.

Fixes #45

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

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 } from "./lotusMicLevel";
+import { MicLevelQuantizer, sameRooms } from "./lotusMicLevel";
 
 describe("MicLevelQuantizer", () => {
   it("maps RMS to 0–3 bars", () => {
@@ -35,3 +35,14 @@ 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

@@ -46,6 +46,10 @@ 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>
@@ -62,10 +66,15 @@ 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(
-      (data) =>
+      (rooms) =>
         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;