fix(mobile): stop asking for an API token when the channel list is refused (#9327)

## Summary
- When the relay refused the channel-list request (HTTP 401), the mobile
app said "Not authorized. Check your API token." The app has no API
token, so the advice could not be followed.
- The message now reads "This community couldn't authenticate the
request. Try again." Retry stays: for org and hosted communities the
refused token is dropped and Retry gets a fresh one, and a self-hosted
relay that refuses the key has no other recovery on this screen.
- One exception: when the organization sign-in has ended, the app sends
reads unsigned and Retry can never succeed, while the Home banner
already offers a working Sign in. In that state the channel list says
"Use the sign-in prompt below to reconnect." and hides Retry.

## Details
- `_ErrorView`
(`mobile/lib/features/channels/channels_page/badges.dart`) only appears
on a cold load with no saved channel list. It replaces the list, so
Retry is the only control on that screen.
- It reuses the shared `organizationSignInPromptVisible` predicate, the
same one the Home banner and the community switcher use, so the error
view and the banner agree on who owns the action.
- The 403 "Access denied." message is unchanged.
- Widget tests cover the new 401 copy with Retry, and the signed-out
organization state with no Retry.

## Screenshots
Android emulator, debug build, against a local test relay that refuses
the channel-list read with HTTP 401 (no saved channel list, so the error
view shows):

<img
src="https://github.com/user-attachments/assets/feebc324-a4cf-49ca-876a-1ae026bda753"
alt="Channel list error: This community couldn't authenticate the
request. Try again. With a Retry button" width="360">


🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Signed-off-by: Logan Johnson <loganj@squareup.com>
Co-authored-by: Larry <627498bd4bd1f281a16431e3c6cce3b5c25b6692798c78672298aefbf2f8f8b5@buzz.block.builderlab.xyz>
Co-authored-by: Tom Brow <tomb@squareup.com>
Co-authored-by: Claude Opus 5.5 <noreply@anthropic.com>

mobile/lib/features/channels/channels_page/badges.dart

@@ -27,7 +27,7 @@ class _EphemeralBadge extends StatelessWidget {
   }
 }
 
-class _ErrorView extends StatelessWidget {
+class _ErrorView extends HookConsumerWidget {
   final Object error;
   final VoidCallback onRetry;
 
@@ -35,8 +35,11 @@ class _ErrorView extends StatelessWidget {
 
   static String _userMessage(Object error) {
     if (error is RelayException) {
+      // There is no API token to check. A protected community's Retry gets a
+      // fresh token; once the organization sign-in has ended, the shell
+      // banner owns the action instead (see build).
       if (error.statusCode == 401) {
-        return 'Not authorized. Check your API token.';
+        return "This community couldn't authenticate the request. Try again.";
       }
       if (error.statusCode == 403) {
         return 'Access denied.';
@@ -50,7 +53,20 @@ class _ErrorView extends StatelessWidget {
   }
 
   @override
-  Widget build(BuildContext context) {
+  Widget build(BuildContext context, WidgetRef ref) {
+    final signIn = ref.watch(organizationSignInProvider);
+    final auth = ref.watch(hostedRelayAuthProvider);
+    useListenable(signIn);
+    useListenable(auth);
+    // When the relay refuses the read while the Home banner is up, the banner
+    // shows the working action. Other errors keep their message and Retry: a
+    // relay that does not require the organization sign-in can still serve
+    // the read.
+    final config = ref.watch(relayConfigProvider);
+    final signInOwned =
+        error is RelayException &&
+        (error as RelayException).statusCode == 401 &&
+        organizationSignInPromptVisible(signIn, auth, config);
     return Center(
       child: Padding(
         padding: const EdgeInsets.all(Grid.sm),
@@ -65,7 +81,9 @@ class _ErrorView extends StatelessWidget {
             ),
             const SizedBox(height: Grid.xxs),
             Text(
-              _userMessage(error),
+              signInOwned
+                  ? 'Use the prompt above to reconnect.'
+                  : _userMessage(error),
               style: context.textTheme.bodySmall?.copyWith(
                 color: context.colors.onSurfaceVariant,
               ),
@@ -73,12 +91,14 @@ class _ErrorView extends StatelessWidget {
               maxLines: 3,
               overflow: TextOverflow.ellipsis,
             ),
-            const SizedBox(height: Grid.xs),
-            FilledButton.icon(
-              onPressed: onRetry,
-              icon: const Icon(BuzzIcons.refreshCw),
-              label: const Text('Retry'),
-            ),
+            if (!signInOwned) ...[
+              const SizedBox(height: Grid.xs),
+              FilledButton.icon(
+                onPressed: onRetry,
+                icon: const Icon(BuzzIcons.refreshCw),
+                label: const Text('Retry'),
+              ),
+            ],
           ],
         ),
       ),

mobile/test/features/channels/channels_page_test.dart

@@ -3547,6 +3547,79 @@ void main() {
     expect(find.text('Retry'), findsOneWidget);
   });
 
+  testWidgets('a refused sign-in names no API token and keeps retry', (
+    tester,
+  ) async {
+    await tester.pumpWidget(
+      buildTestable(
+        overrides: [
+          channelsProvider.overrideWith(() => _UnauthorizedNotifier()),
+        ],
+      ),
+    );
+    await tester.pump();
+    await tester.pump(const Duration(seconds: 3));
+    await tester.pump();
+
+    expect(
+      find.text("This community couldn't authenticate the request. Try again."),
+      findsOneWidget,
+    );
+    expect(find.textContaining('API token'), findsNothing);
+    expect(find.text('Retry'), findsOneWidget);
+  });
+
+  testWidgets(
+    'an ended organization sign-in leaves the action to the banner, not Retry',
+    (tester) async {
+      final account = BuilderlabAccountClient();
+      final signIn = OrganizationSignIn(
+        account: account,
+        browser: BrowserAuth(),
+        reconnect: () async {},
+      )..status = OrganizationSessionStatus.signedOut;
+      final auth = HostedRelayAuth(
+        BuilderlabAccountClient(),
+        organization: account,
+        organizationRelay: (_) => true,
+      );
+      addTearDown(() {
+        signIn.dispose();
+        auth.dispose();
+        account.dispose();
+      });
+      Future<void> pumpError(ChannelsNotifier Function() notifier) async {
+        await tester.pumpWidget(const SizedBox());
+        await tester.pumpWidget(
+          buildTestable(
+            overrides: [
+              organizationSignInProvider.overrideWithValue(signIn),
+              hostedRelayAuthProvider.overrideWithValue(auth),
+              channelsProvider.overrideWith(notifier),
+            ],
+          ),
+        );
+        await tester.pump();
+        await tester.pump(const Duration(seconds: 3));
+        await tester.pump();
+      }
+
+      await pumpError(_UnauthorizedNotifier.new);
+      expect(find.text('Could not load channels'), findsOneWidget);
+      expect(find.text('Use the prompt above to reconnect.'), findsOneWidget);
+      expect(find.text('Retry'), findsNothing);
+
+      // A relay that does not require the sign-in can still serve the read,
+      // so an error other than the refusal keeps its message and Retry.
+      await pumpError(_ErrorNotifier.new);
+      expect(
+        find.text('Something went wrong. Check your connection.'),
+        findsOneWidget,
+      );
+      expect(find.text('Retry'), findsOneWidget);
+    },
+  );
+
   testWidgets('bolds and clears unread channel labels', (tester) async {
     final channels = [
       Channel(
@@ -3966,6 +4039,12 @@ class _ErrorNotifier extends ChannelsNotifier {
   Future<List<Channel>> build() => Future.error('Connection refused');
 }
 
+class _UnauthorizedNotifier extends ChannelsNotifier {
+  @override
+  Future<List<Channel>> build() =>
+      Future.error(RelayException(401, 'authentication required\n'));
+}
+
 class _LoadingNotifier extends ChannelsNotifier {
   @override
   Future<List<Channel>> build() => Completer<List<Channel>>().future;