Delegate delayed leaves in LocalMember rather than LocalTransport

IMO this is where the delegation calls should have lived all along, since the leave event is part of the membership lifecycle, and we otherwise end up with an awkward hack to ignore transport updates.

Doing this now ensures that the client won't send any delegation requests if delegation is unsupported, and prepares the code for a future change in which we use the dedicated delegation endpoint from the CS API.

src/state/CallViewModel/localMember/LocalTransport.ts

@@ -10,14 +10,7 @@ import {
   type LivekitTransportConfig,
 } from "matrix-js-sdk/lib/matrixrtc";
 import { type MatrixClient } from "matrix-js-sdk";
-import {
-  combineLatest,
-  distinctUntilChanged,
-  from,
-  map,
-  of,
-  switchMap,
-} from "rxjs";
+import { distinctUntilChanged, from, map, of, switchMap } from "rxjs";
 import { logger as rootLogger, type Logger } from "matrix-js-sdk/lib/logger";
 import { type CallMembershipIdentityParts } from "matrix-js-sdk/lib/matrixrtc/EncryptionManager";
 
@@ -47,15 +40,11 @@ interface Props {
   scope: ObservableScope;
   ownMembershipIdentity: CallMembershipIdentityParts;
   memberships$: Behavior<Epoch<CallMembership[]>>;
-  client: Pick<
-    MatrixClient,
-    "getDomain" | "baseUrl" | "_unstable_getRTCTransports"
-  > &
+  client: Pick<MatrixClient, "getDomain" | "_unstable_getRTCTransports"> &
     OpenIDClientParts;
   // Used by the jwt service to create the livekit room and compute the livekit alias.
   roomId: string;
   matrixRTCMode: MatrixRTCMode;
-  delayId$: Behavior<string | null>;
 }
 
 // TODO livekit_alias-cleanup
@@ -119,7 +108,6 @@ export const createLocalTransport$ = ({
   client,
   roomId,
   matrixRTCMode,
-  delayId$,
 }: Props): LocalTransport => {
   const logger = rootLogger.getChild("[LocalTransport]");
 
@@ -134,32 +122,29 @@ export const createLocalTransport$ = ({
     transportDiscovery.discoverPreferredTransport(),
   );
 
-  const preferredConfig$ = customLivekitUrl.value$
-    .pipe(
-      switchMap((customUrl) => {
-        if (customUrl) {
-          return of({
-            type: "livekit",
-            livekit_service_url: customUrl,
-          } as LivekitTransportConfig);
-        } else {
-          return discoveredTransport$;
-        }
-      }),
-    )
-    .pipe(
-      map((config) => {
-        if (!config) {
-          // Bubbled up from the preferredConfig$ observable.
-          throw new MatrixRTCTransportMissingError(client.getDomain() ?? "");
-        }
-        return config;
-      }),
-      distinctUntilChanged(areLivekitTransportsEqual),
-    );
+  const preferredConfig$ = customLivekitUrl.value$.pipe(
+    switchMap((customUrl) => {
+      if (customUrl) {
+        return of({
+          type: "livekit",
+          livekit_service_url: customUrl,
+        } as LivekitTransportConfig);
+      } else {
+        return discoveredTransport$;
+      }
+    }),
+    map((config) => {
+      if (!config) {
+        // Bubbled up from the preferredConfig$ observable.
+        throw new MatrixRTCTransportMissingError(client.getDomain() ?? "");
+      }
+      return config;
+    }),
+    distinctUntilChanged(areLivekitTransportsEqual),
+  );
 
-  const preferredTransport$ = combineLatest([preferredConfig$, delayId$]).pipe(
-    switchMap(async ([transport, delayId]) => {
+  const preferredTransport$ = preferredConfig$.pipe(
+    switchMap(async (transport) => {
       try {
         return await doOpenIdAndJWTFromUrl(
           transport,
@@ -167,7 +152,6 @@ export const createLocalTransport$ = ({
           ownMembershipIdentity,
           roomId,
           client,
-          delayId ?? undefined,
           logger,
         );
       } catch (e) {
@@ -189,21 +173,7 @@ export const createLocalTransport$ = ({
       ),
       null,
     ),
-    active$: scope.behavior(
-      preferredTransport$.pipe(
-        // XXX: WORK AROUND due to a reconnection glitch.
-        // To remove when we have a proper way to refresh the delegation event ID without refreshing
-        // the whole credentials.
-        // We deliberately hide any changes to the SFU config because we
-        // do not want the app to reconnect whenever the JWT
-        // token changes due to us delegating a new delayed event. The
-        // initial SFU config for the transport is all the app needs.
-        distinctUntilChanged((prev, next) =>
-          areLivekitTransportsEqual(prev.transport, next.transport),
-        ),
-      ),
-      null,
-    ),
+    active$: scope.behavior(preferredTransport$, null),
   };
 };
 
@@ -219,7 +189,6 @@ export const createLocalTransport$ = ({
  *  @param membership The identity of the local member.
  *  @param roomId The room ID to use for the JWT.
  *  @param client The client to use for the OpenID token.
- *  @param delayId The delayId to use for the JWT.
  *
  *  @throws FailToGetOpenIdToken, NoMatrix2AuthorizationService
  */
@@ -228,12 +197,7 @@ async function doOpenIdAndJWTFromUrl(
   matrixRTCMode: MatrixRTCMode,
   membership: CallMembershipIdentityParts,
   roomId: string,
-  client: Pick<
-    MatrixClient,
-    "getDomain" | "baseUrl" | "_unstable_getRTCTransports"
-  > &
-    OpenIDClientParts,
-  delayId?: string,
+  client: Pick<MatrixClient, "_unstable_getRTCTransports"> & OpenIDClientParts,
   logger?: Logger,
 ): Promise<LocalTransportWithSFUConfig> {
   const sfuConfig = await getSFUConfigWithOpenID(
@@ -241,11 +205,7 @@ async function doOpenIdAndJWTFromUrl(
     membership,
     transport.livekit_service_url,
     roomId,
-    {
-      matrixRTCMode,
-      delayEndpointBaseUrl: client.baseUrl,
-      delayId,
-    },
+    { matrixRTCMode },
     logger,
   );
   return {