fix: update loop, ghost queue item, briefing card scroll trap

- Update dialog no longer re-appears on every shell re-mount; check()
  is skipped if status is already available/upToDate/downloading
- Offline queue dequeue now happens before the mounted check, preventing
  ghost items when the widget disposes mid-drain
- Briefing digest card and messages now share a CustomScrollView so
  expanding the card doesn't trap the user without scroll access

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

lib/app.dart

@@ -152,10 +152,14 @@ class _ShellState extends ConsumerState<_Shell> {
   @override
   void initState() {
     super.initState();
-    // Silent update check on first app load.
+    // Silent update check — only if we haven't already checked this session.
+    // Skipping when status is not idle/error prevents the dialog from
+    // re-appearing every time the shell re-mounts (e.g. after visiting settings).
     WidgetsBinding.instance.addPostFrameCallback((_) {
       final repoUrl = ref.read(forgejoRepoUrlProvider);
-      if (repoUrl != null && repoUrl.isNotEmpty) {
+      if (repoUrl == null || repoUrl.isEmpty) return;
+      final status = ref.read(updateProvider).status;
+      if (status == UpdateStatus.idle || status == UpdateStatus.error) {
         ref.read(updateProvider.notifier).check(repoUrl);
       }
     });
@@ -356,8 +360,10 @@ class _QuickCaptureBarState extends ConsumerState<_QuickCaptureBar> {
       if (!mounted) break;
       try {
         final result = await api.capture(text);
-        if (!mounted) break;
+        // Dequeue before the mounted check — SharedPreferences doesn't need
+        // the widget alive, and skipping this would leave a ghost item.
         await ref.read(captureQueueProvider.notifier).dequeue(text);
+        if (!mounted) break;
         switch (result.type) {
           case 'note':
             ref.invalidate(notesProvider);
@@ -368,9 +374,9 @@ class _QuickCaptureBarState extends ConsumerState<_QuickCaptureBar> {
       } on NetworkException {
         break;
       } catch (_) {
-        if (mounted) {
+        // Server error or unexpected failure — drop from queue to prevent
-          await ref.read(captureQueueProvider.notifier).dequeue(text);
+        // ghost items that can never be cleared.
-        }
+        await ref.read(captureQueueProvider.notifier).dequeue(text);
       }
     }
   }

lib/screens/briefing/briefing_screen.dart

@@ -154,39 +154,52 @@ class _BriefingScreenState extends ConsumerState<BriefingScreen> {
 
           return Column(
             children: [
-              // Digest card header
+              // Digest card + messages share one scroll view so expanding the
-              BriefingDigestCard(
+              // card doesn't trap the user — the whole page just becomes taller.
-                message: firstAssistant,
-                onGenerateNow: _refresh,
-              ),
-
-              // Divider + label
-              if (conv.messages.isNotEmpty) ...[
-                const SizedBox(height: 4),
-                Row(children: [
-                  const Expanded(child: Divider()),
-                  Padding(
-                    padding: const EdgeInsets.symmetric(horizontal: 10),
-                    child: Text(
-                      'Conversation',
-                      style: Theme.of(context).textTheme.labelSmall?.copyWith(
-                            color: scheme.onSurfaceVariant,
-                          ),
-                    ),
-                  ),
-                  const Expanded(child: Divider()),
-                ]),
-              ],
-
-              // Message list
               Expanded(
-                child: ListView.builder(
+                child: CustomScrollView(
                   controller: _scrollController,
-                  padding: const EdgeInsets.symmetric(
+                  slivers: [
-                      horizontal: 8, vertical: 8),
+                    SliverToBoxAdapter(
-                  itemCount: conv.messages.length,
+                      child: BriefingDigestCard(
-                  itemBuilder: (_, i) =>
+                        message: firstAssistant,
-                      ChatMessageBubble(message: conv.messages[i]),
+                        onGenerateNow: _refresh,
+                      ),
+                    ),
+
+                    if (conv.messages.isNotEmpty)
+                      SliverToBoxAdapter(
+                        child: Padding(
+                          padding: const EdgeInsets.symmetric(vertical: 4),
+                          child: Row(children: [
+                            const Expanded(child: Divider()),
+                            Padding(
+                              padding:
+                                  const EdgeInsets.symmetric(horizontal: 10),
+                              child: Text(
+                                'Conversation',
+                                style: Theme.of(context)
+                                    .textTheme
+                                    .labelSmall
+                                    ?.copyWith(
+                                        color: scheme.onSurfaceVariant),
+                              ),
+                            ),
+                            const Expanded(child: Divider()),
+                          ]),
+                        ),
+                      ),
+
+                    SliverPadding(
+                      padding: const EdgeInsets.symmetric(
+                          horizontal: 8, vertical: 8),
+                      sliver: SliverList.builder(
+                        itemCount: conv.messages.length,
+                        itemBuilder: (_, i) =>
+                            ChatMessageBubble(message: conv.messages[i]),
+                      ),
+                    ),
+                  ],
                 ),
               ),