Swap shows only the new media, no guessed endings, quieter screen

- A swap stops the previous media at once; buffer counts only for the
  media the player holds (client) and the current mediaId (server), so
  the old video can no longer start the new one.
- The automatic frozen-picture reload is gone (false alarms on still
  scenes); Reload video stays.
- The "Next episode" pill shows only from a known ending.
- A web link's thumbnail is its cover, under the video's own name.
- While playing, the unread chip stays off the picture; chat pop-ups
  can be All / Only when paused / Off.
- Server fetch failures say when the server has no cookies.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

apps/desktop/test/frame_watchdog_test.dart

@@ -1,108 +0,0 @@
-import 'dart:typed_data';
-
-import 'package:flutter_test/flutter_test.dart';
-import 'package:watch_together/src/playback/frame_watchdog.dart';
-
-final _t0 = DateTime.utc(2026, 1, 1);
-
-/// Feeds one sample per second; [frames]/[pos] give the value at second i.
-List<bool> _run(
-  FrameWatchdog w,
-  int seconds, {
-  required int? Function(int i) frames,
-  double Function(int i)? pos,
-  bool Function(int i)? eligible,
-  int start = 0,
-}) {
-  return [
-    for (var i = start; i < start + seconds; i++)
-      w.feed(FrameSample(
-        at: _t0.add(Duration(seconds: i)),
-        position: pos?.call(i) ?? i.toDouble(),
-        frames: frames(i),
-        eligible: eligible?.call(i) ?? true,
-      )),
-  ];
-}
-
-void main() {
-  test('hashes tell frames apart and ignore the edges', () {
-    final a = ByteData(100 * 60 * 4);
-    final b = ByteData(100 * 60 * 4);
-    expect(hashCenterPixels(a, 100, 60), hashCenterPixels(b, 100, 60));
-    b.setUint8((2 * 100 + 2) * 4, 255); // corner: overlay area
-    expect(hashCenterPixels(a, 100, 60), hashCenterPixels(b, 100, 60));
-    b.setUint8((30 * 100 + 50) * 4, 255); // centre: video
-    expect(hashCenterPixels(a, 100, 60), isNot(hashCenterPixels(b, 100, 60)));
-    final raw = Uint8List(1 << 20);
-    final h = hashSpread(raw);
-    raw[raw.length ~/ 2 - (raw.length ~/ 2) % (raw.length ~/ 4096)] = 1;
-    expect(hashSpread(raw), isNot(h));
-  });
-
-  test('frames advancing never fires', () {
-    final w = FrameWatchdog();
-    expect(_run(w, 30, frames: (i) => i * 30), everyElement(isFalse));
-  });
-
-  test('frames stuck while position advances fires once after ~3 s', () {
-    final w = FrameWatchdog();
-    final fired = _run(w, 20, frames: (i) => i < 5 ? i * 30 : 150);
-    expect(fired.where((f) => f).length, 1);
-    expect(fired.indexOf(true), 8, reason: 'stuck from t=5, 3 s later');
-  });
-
-  test('pause, buffering, missing data and seeks do not fire', () {
-    final w = FrameWatchdog();
-    // Paused / buffering: not eligible.
-    expect(_run(w, 10, frames: (_) => 100, eligible: (_) => false),
-        everyElement(isFalse));
-    // No video output (headless / audio-only).
-    expect(_run(w, 10, frames: (_) => null, start: 10), everyElement(isFalse));
-    // Position stuck too (network stall): not a frozen picture.
-    expect(_run(w, 10, frames: (_) => 100, pos: (_) => 50, start: 20),
-        everyElement(isFalse));
-    // Seeking every 2 s with frames stuck in between: jumps reset it.
-    expect(
-        _run(w, 12,
-            frames: (_) => 100,
-            pos: (i) => i.isEven ? i * 10.0 : i * 10.0 - 9,
-            start: 30),
-        everyElement(isFalse));
-  });
-
-  test('no reload loop: re-arms only after 10 s of healthy frames', () {
-    final w = FrameWatchdog();
-    expect(_run(w, 10, frames: (_) => 7).where((f) => f).length, 1);
-    w.reset(); // new player
-    // Brief healthy spell, then stuck again: must not fire.
-    expect(
-        _run(w, 15, frames: (i) => i < 13 ? i : 13, start: 10)
-            .where((f) => f)
-            .length,
-        0);
-    // Healthy for 10 s+, then stuck: fires again.
-    w.reset();
-    expect(
-        _run(w, 25, frames: (i) => i < 42 ? i : 42, start: 30)
-            .where((f) => f)
-            .length,
-        1);
-  });
-
-  test('still scene: dismiss re-arms after another full stall', () {
-    final w = FrameWatchdog();
-    final fired = <int>[];
-    for (var i = 0; i < 20; i++) {
-      if (w.feed(FrameSample(
-          at: _t0.add(Duration(seconds: i)),
-          position: i.toDouble(),
-          frames: 5,
-          eligible: true))) {
-        fired.add(i);
-        w.dismiss();
-      }
-    }
-    expect(fired, [3, 6, 9, 12, 15, 18]);
-  });
-}

apps/desktop/test/jellyfin_e2e_test.dart

@@ -301,9 +301,9 @@ void main() {
         a.toggleReady();
         await _poll(() => all.every((x) => x.playback.player.state.playing), 'playing again');
 
-        // Account holders see the "Next episode" prompt (this item is
-        // shorter than its 2 min lead); the guest cannot put it up.
-        await _poll(() => a.nextPromptVisible.peek(), 'next prompt');
+        // No known ending (no Outro segment, no ED chapter): no floating
+        // "Next episode" prompt mid-episode, only the card at the end.
+        expect(a.nextPromptVisible.peek(), isFalse);
         expect(b.nextPromptVisible.peek(), isFalse);
 
         // Alice and the guest pick English; it carries to the next episode.

apps/desktop/test/jellyfin_session_test.dart

@@ -321,9 +321,9 @@ void main() {
       expect(media.jellyfin!.subtitle, 'Black Summoner · S1E7');
     });
 
-    test('the floating prompt starts two minutes before the end', () {
-      expect(nextPromptStart(null, const Duration(minutes: 24)), const Duration(minutes: 22));
-      expect(nextPromptStart(null, const Duration(seconds: 90)), Duration.zero);
+    test('no floating prompt without a known ending', () {
+      expect(nextPromptStart(null, const Duration(minutes: 24)), isNull);
+      expect(nextPromptStart(null, const Duration(seconds: 90)), isNull);
     });
 
     test('one auto-advance swapper: the lowest id among members with their own account', () {

apps/desktop/test/media_marks_test.dart

@@ -154,14 +154,14 @@ void main() {
   });
 
   group('next episode prompt', () {
-    test('at the ED start when known, else the last two minutes', () {
+    test('at the ED start when known, else none (never a guessed time)', () {
       expect(nextPromptStart(null, m(24), endingStart: m(20)), m(20));
-      expect(nextPromptStart(null, m(24)), m(22));
-      expect(nextPromptStart(null, m(24), endingStart: null), m(22));
-      // Nonsense ending starts fall back.
-      expect(nextPromptStart(null, m(24), endingStart: m(25)), m(22));
-      expect(nextPromptStart(null, m(24), endingStart: Duration.zero), m(22));
-      expect(nextPromptStart(null, s(90)), Duration.zero);
+      expect(nextPromptStart(null, m(24)), isNull);
+      expect(nextPromptStart(null, m(24), endingStart: null), isNull);
+      // Nonsense ending starts count as unknown.
+      expect(nextPromptStart(null, m(24), endingStart: m(25)), isNull);
+      expect(nextPromptStart(null, m(24), endingStart: Duration.zero), isNull);
+      expect(nextPromptStart(null, s(90)), isNull);
     });
   });
 

apps/desktop/test/shell_test.dart

@@ -374,19 +374,19 @@ void main() {
     final app = shellToastFor(ToastItem(id: 3, text: 'Bob joined', at: at), who);
     expect(app.who, isNull);
     expect(app.text, 'Bob joined');
-    final froze = shellToastFor(ToastItem(id: 4, text: 'Video froze — reloaded', at: at), who);
-    expect(froze.who, isNull);
+    final notice = shellToastFor(ToastItem(id: 4, text: 'Shaders off', at: at), who);
+    expect(notice.who, isNull);
   });
 
   testWidgets('toasts slide in with an avatar and leave after their time', (tester) async {
     await tester.pumpWidget(const MaterialApp(home: Scaffold(body: PartyToasts(life: Duration(seconds: 1)))));
-    coord.toasts.value = [ToastItem(id: 1, text: 'Video froze — reloaded', at: DateTime.now())];
+    coord.toasts.value = [ToastItem(id: 1, text: 'Shaders off', at: DateTime.now())];
     await tester.pump();
     await tester.pump();
-    expect(find.text('Video froze — reloaded'), findsOneWidget);
+    expect(find.text('Shaders off'), findsOneWidget);
     await tester.pump(const Duration(seconds: 1));
     await tester.pumpAndSettle();
-    expect(find.text('Video froze — reloaded'), findsNothing);
+    expect(find.text('Shaders off'), findsNothing);
   });
 
   testWidgets('status avatar fills its box at any size', (tester) async {