Log remote member participant matching and tile waiting state

A tile shows "Waiting for media" for as long as its MatrixRTC member
cannot be matched to a LiveKit participant. Log each transition of that
match and of the tile's waitingForMedia state so rageshakes can tie a
stuck tile to the LiveKit participant and track events.

src/state/CallViewModel/remoteMembers/MatrixLivekitMembers.test.ts

@@ -5,7 +5,8 @@ SPDX-License-Identifier: AGPL-3.0-only OR LicenseRef-Element-Commercial
 Please see LICENSE in the repository root for full details.
 */
 
-import { describe, test, expect, beforeEach, afterEach } from "vitest";
+import { describe, test, expect, beforeEach, afterEach, vi } from "vitest";
+import { logger } from "matrix-js-sdk/lib/logger";
 import {
   type CallMembership,
   type LivekitTransport,
@@ -77,6 +78,7 @@ function epochMeWith$<T, U>(
 }
 
 test("should signal participant not yet connected to livekit", async () => {
+  const info = vi.spyOn(logger, "info");
   const mockedMemberships$ = new BehaviorSubject([bobMembership]);
   const mockConnectionManagerData$ = new BehaviorSubject(
     new ConnectionManagerData(),
@@ -108,6 +110,9 @@ test("should signal participant not yet connected to livekit", async () => {
       return true;
     },
   );
+  expect(info).toHaveBeenCalledWith(
+    "[RemoteMatrixLivekitMembers] @bob:example.org:DEV000: LiveKit participant missing",
+  );
 });
 
 // Helper to create epoch'ed memberships$ and membershipsWithTransport$ from memberships observable.

src/state/CallViewModel/remoteMembers/MatrixLivekitMembers.ts

@@ -11,6 +11,7 @@ import {
   type LivekitTransportConfig,
 } from "matrix-js-sdk/lib/matrixrtc";
 import { combineLatest, filter, map } from "rxjs";
+import { logger } from "matrix-js-sdk/lib/logger";
 
 import { type Behavior } from "../../Behavior";
 import { type IConnectionManager } from "./ConnectionManager";
@@ -133,8 +134,15 @@ export function createRemoteMatrixLivekitMembers$({
           }
         },
         // Each update where the key of the generator array do not change will result in updates to the `data$` behavior.
-        (scope, data$, userId, _deviceId, _memberId, _rtcBackendIdentity) => {
+        (scope, data$, userId, _deviceId, _memberId, rtcBackendIdentity) => {
           const { participant$, ...rest } = scope.splitBehavior(data$);
+          // Log whether the member could be matched to a LiveKit participant,
+          // since a tile shows "waiting for media" for as long as it cannot.
+          participant$.pipe(scope.bind()).subscribe((p) => {
+            logger.info(
+              `[RemoteMatrixLivekitMembers] ${rtcBackendIdentity}: LiveKit participant ${p ? `matched (${p.sid})` : "missing"}`,
+            );
+          });
           // will only get called once per backend identity.
           // updates to data$ and as a result to displayName$ and mxcAvatarUrl$ are more frequent.
           return {

src/state/media/RemoteUserMediaViewModel.ts

@@ -8,6 +8,7 @@ Please see LICENSE in the repository root for full details.
 
 import { type RemoteParticipant } from "livekit-client";
 import { combineLatest, map, of, switchMap } from "rxjs";
+import { logger } from "matrix-js-sdk/lib/logger";
 
 import { type Behavior } from "../Behavior";
 import { createVolumeControls, type VolumeControls } from "../VolumeControls";
@@ -45,6 +46,20 @@ export function createRemoteUserMedia(
     statsType: "inbound-rtp",
   });
 
+  const waitingForMedia$ = scope.behavior(
+    combineLatest(
+      [inputs.livekitRoom$, inputs.participant$],
+      (livekitRoom, participant) =>
+        // If livekitRoom is undefined, the user is not attempting to publish on
+        // any transport and so we shouldn't expect a participant. (They might
+        // be a subscribe-only bot for example.)
+        livekitRoom !== undefined && participant === null,
+    ),
+  );
+  waitingForMedia$.pipe(scope.bind()).subscribe((waiting) => {
+    logger.info(`[RemoteUserMedia ${inputs.id}] waitingForMedia=${waiting}`);
+  });
+
   return {
     ...baseUserMedia,
     ...createVolumeControls(scope, {
@@ -68,15 +83,6 @@ export function createRemoteUserMedia(
         ),
       ),
     ),
-    waitingForMedia$: scope.behavior(
-      combineLatest(
-        [inputs.livekitRoom$, inputs.participant$],
-        (livekitRoom, participant) =>
-          // If livekitRoom is undefined, the user is not attempting to publish on
-          // any transport and so we shouldn't expect a participant. (They might
-          // be a subscribe-only bot for example.)
-          livekitRoom !== undefined && participant === null,
-      ),
-    ),
+    waitingForMedia$,
   };
 }