refactor(lotus-spotlight): extract manual-override into src/lotus/lotusSpotlight.ts

Remove the rebase hazard from CallViewModel: upstream's spotlightSpeaker$
auto-selection had been renamed to autoSpotlightSpeaker$ and an inline
manual-override + screenshare-coexistence block was spliced into
spotlightAndPip$. Both diverge from upstream and would conflict on every
rebase.

Restore spotlightSpeaker$ to its byte-for-byte upstream form and move the
[lotus #4] override into a pure wrapper, overrideSpotlight$(), invoked at a
single call point in spotlightAndPip$. Behaviour is unchanged: identical to
upstream while manualSpotlightUserId$ is null (the default), and preserves the
"pin a participant" and "focus camera during screenshare" (#4 / A5) rules when
the host sends io.lotus.focus_participant.

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

src/state/CallViewModel/CallViewModel.ts

@@ -151,6 +151,9 @@ import { type UserMediaViewModel } from "../media/UserMediaViewModel.ts";
 import { type MediaViewModel } from "../media/MediaViewModel.ts";
 import { type LocalUserMediaViewModel } from "../media/LocalUserMediaViewModel.ts";
 import { type RemoteUserMediaViewModel } from "../media/RemoteUserMediaViewModel.ts";
+// [lotus #4] Manual spotlight override, extracted so this file stays byte-close
+// to upstream (see the file for the behaviour contract).
+import { overrideSpotlight$ } from "../../lotus/lotusSpotlight";
 import {
   createRingingMedia,
   type RingingMediaViewModel,
@@ -903,7 +906,7 @@ export function createCallViewModel$(
       merge(userHangup$, widgetHangup$).pipe(map(() => "user" as const)),
     ).pipe(scope.share);
 
-  const autoSpotlightSpeaker$ = scope.behavior<UserMediaViewModel | undefined>(
+  const spotlightSpeaker$ = scope.behavior<UserMediaViewModel | undefined>(
     userMedia$.pipe(
       switchMap((mediaItems) =>
         mediaItems.length === 0
@@ -939,28 +942,10 @@ export function createCallViewModel$(
     ),
   );
 
-  // [lotus] Manual spotlight override (#4 focus-participant widget action).
-  // When set to a userId still present in the call, that participant is
-  // spotlighted instead of the auto-selected active speaker; null restores the
-  // default speaker-follows behaviour. Defaults to null, so without the host
-  // using io.lotus.focus_participant this is a no-op.
+  // [lotus #4] Host-pinned spotlight target (io.lotus.focus_participant). null =
+  // follow the active speaker (upstream default), so this is inert unless the
+  // host pins someone. Consumed by overrideSpotlight$ in spotlightAndPip$.
   const manualSpotlightUserId$ = new BehaviorSubject<string | null>(null);
-  const spotlightSpeaker$ = scope.behavior<UserMediaViewModel | undefined>(
-    combineLatest([
-      autoSpotlightSpeaker$,
-      manualSpotlightUserId$,
-      userMedia$,
-    ]).pipe(
-      map(([auto, manualUserId, mediaItems]) => {
-        if (manualUserId !== null) {
-          const pinned = mediaItems.find((m) => m.userId === manualUserId);
-          if (pinned) return pinned;
-        }
-        return auto;
-      }),
-    ),
-    undefined,
-  );
 
   const grid$ = scope.behavior<UserMediaViewModel[]>(
     userMedia$.pipe(
@@ -1009,36 +994,17 @@ export function createCallViewModel$(
         if (ringingMedia.length > 0)
           return of({ spotlight: ringingMedia, pip$: localUserMediaForPip$ });
 
-        return screenShares$.pipe(
-          switchMap((screenShares) => {
-            if (screenShares.length > 0)
-              // [lotus #4/A5] During a screenshare, if the host has explicitly
-              // pinned a participant, surface that camera in the spotlight
-              // alongside the shared screen (the whole point of "focus camera
-              // during screenshare"). With no manual pin this is unchanged:
-              // the screenshare alone is spotlighted.
-              return combineLatest([manualSpotlightUserId$, userMedia$]).pipe(
-                map(([manualUserId, mediaItems]) => {
-                  const pinned =
-                    manualUserId !== null
-                      ? mediaItems.find((m) => m.userId === manualUserId)
-                      : undefined;
-                  return pinned
-                    ? { spotlight: [...screenShares, pinned], pip$: of(undefined) }
-                    : { spotlight: screenShares, pip$: spotlightSpeaker$ };
-                }),
-              );
-
-            return spotlightSpeaker$.pipe(
-              map((speaker) => ({
-                spotlight: speaker ? [speaker] : [],
-                // Hide PiP if redundant (i.e. if local user is already in spotlight)
-                pip$: localUserMediaForPip$.pipe(
-                  map((m) => (m === speaker ? undefined : m)),
-                ),
-              })),
-            );
-          }),
+        // [lotus #4] Route the screenshare/spotlight computation through the
+        // manual-spotlight wrapper. This is byte-for-byte upstream behaviour
+        // unless the host pins a participant via io.lotus.focus_participant;
+        // see src/lotus/lotusSpotlight.ts. Kept out-of-line so CallViewModel
+        // stays close to upstream and rebases cleanly.
+        return overrideSpotlight$(
+          spotlightSpeaker$,
+          manualSpotlightUserId$,
+          screenShares$,
+          localUserMediaForPip$,
+          userMedia$,
         );
       }),
     ),