fix(mobile): disambiguate same-named agents

mobile/lib/features/channels/compose_bar.dart

@@ -22,6 +22,7 @@ import 'channels_provider.dart';
 import 'emoji_picker.dart';
 import 'mentions/mention_candidates.dart';
 import 'mentions/mention_candidates_provider.dart';
+import 'mentions/mention_display_name.dart';
 import 'mentions/mention_ranking.dart';
 
 part 'compose_bar/helpers.dart';

mobile/lib/features/channels/compose_bar/suggestions.dart

@@ -17,6 +17,10 @@ class _MentionSuggestions extends StatelessWidget {
 
   @override
   Widget build(BuildContext context) {
+    final nameCounts = countVisibleMentionDisplayNames(
+      suggestions.map((candidate) => candidate.label),
+    );
+
     return Container(
       constraints: const BoxConstraints(maxHeight: 240),
       clipBehavior: Clip.hardEdge,
@@ -41,6 +45,22 @@ class _MentionSuggestions extends StatelessWidget {
         itemBuilder: (context, index) {
           final candidate = suggestions[index];
           final name = candidate.label;
+          final ownerLabel = candidate.isAgent
+              ? formatOwnerLabel(
+                  candidate.ownerPubkey,
+                  currentPubkey,
+                  userCache,
+                )
+              : null;
+          final displayName = formatDisambiguatedMentionDisplayName(
+            displayName: name,
+            hasNameCollision: hasVisibleMentionDisplayNameCollision(
+              name,
+              nameCounts,
+            ),
+            isAgent: candidate.isAgent,
+            ownerLabel: ownerLabel,
+          );
           final avatarUrl =
               candidate.avatarUrl ?? userCache[candidate.pubkey]?.avatarUrl;
 
@@ -58,7 +78,7 @@ class _MentionSuggestions extends StatelessWidget {
                 ),
               ),
             ),
-            title: Text(name, style: context.textTheme.bodyMedium),
+            title: Text(displayName, style: context.textTheme.bodyMedium),
             subtitle: _MentionSuggestionInfo.build(
               context,
               candidate: candidate,

mobile/lib/features/channels/mentions/mention_display_name.dart

@@ -0,0 +1,37 @@
+/// Case-insensitive display-name counts for the currently visible suggestions.
+Map<String, int> countVisibleMentionDisplayNames(
+  Iterable<String> displayNames,
+) {
+  final counts = <String, int>{};
+  for (final displayName in displayNames) {
+    final normalizedName = displayName.trim().toLowerCase();
+    if (normalizedName.isEmpty) continue;
+    counts[normalizedName] = (counts[normalizedName] ?? 0) + 1;
+  }
+  return counts;
+}
+
+bool hasVisibleMentionDisplayNameCollision(
+  String displayName,
+  Map<String, int> counts,
+) {
+  return (counts[displayName.trim().toLowerCase()] ?? 0) > 1;
+}
+
+/// Adds an agent's owner only when its name collides with another visible
+/// suggestion. The original candidate label remains unchanged for insertion.
+String formatDisambiguatedMentionDisplayName({
+  required String displayName,
+  required bool hasNameCollision,
+  required bool isAgent,
+  required String? ownerLabel,
+}) {
+  final normalizedOwnerLabel = ownerLabel?.trim();
+  if (!hasNameCollision ||
+      !isAgent ||
+      normalizedOwnerLabel == null ||
+      normalizedOwnerLabel.isEmpty) {
+    return displayName;
+  }
+  return '$displayName ($normalizedOwnerLabel)';
+}

mobile/test/features/channels/compose_bar_test.dart

@@ -116,6 +116,7 @@ Widget _buildComposeBar({
   List<ChannelMember> members = const <ChannelMember>[],
   Future<List<ChannelMember>>? membersFuture,
   List<AgentDirectoryEntry> relayAgents = const <AgentDirectoryEntry>[],
+  Map<String, String> agentOwners = const <String, String>{},
   List<Channel> channels = const <Channel>[],
   String? currentPubkey,
   bool? supportsShowingSystemContextMenu,
@@ -128,7 +129,7 @@ Widget _buildComposeBar({
         'channel-1',
       ).overrideWith((ref) => membersFuture ?? Future.value(members)),
       agentDirectoryProvider.overrideWith((ref) async => relayAgents),
-      agentOwnersProvider.overrideWith((ref) async => const <String, String>{}),
+      agentOwnersProvider.overrideWith((ref) async => agentOwners),
       relayClientProvider.overrideWithValue(
         RelayClient(baseUrl: 'http://localhost:3000'),
       ),
@@ -844,6 +845,62 @@ void main() {
       );
     });
 
+    testWidgets(
+      'disambiguates colliding agent titles without changing selection text',
+      (tester) async {
+        final currentPubkey = 'a' * 64;
+        final ownedAgentPubkey = 'b' * 64;
+        final remoteAgentPubkey = 'c' * 64;
+
+        await tester.pumpWidget(
+          _buildComposeBar(
+            uploadService: _testUploadService(nostr.Keys.generate().nsec),
+            currentPubkey: currentPubkey,
+            relayAgents: [
+              AgentDirectoryEntry(
+                pubkey: ownedAgentPubkey,
+                displayName: 'Bumble',
+                respondTo: 'anyone',
+                channelIds: const ['shared-channel'],
+              ),
+              AgentDirectoryEntry(
+                pubkey: remoteAgentPubkey,
+                displayName: 'bUmBlE',
+                respondTo: 'anyone',
+                channelIds: const ['shared-channel'],
+              ),
+            ],
+            agentOwners: {
+              ownedAgentPubkey: currentPubkey,
+              remoteAgentPubkey: 'd' * 64,
+            },
+            channels: [_makeCurrentChannel(), _makeSharedMemberChannel()],
+            onSend:
+                (
+                  content,
+                  mentionPubkeys, {
+                  mediaTags = const <List<String>>[],
+                }) async {},
+          ),
+        );
+
+        await tester.enterText(find.byType(TextField), '@bum');
+        await tester.pumpAndSettle();
+
+        expect(find.text('Bumble (you)'), findsOneWidget);
+        expect(find.text('bUmBlE (dddddddd…)'), findsOneWidget);
+        expect(find.text('owned by you · not in channel'), findsOneWidget);
+
+        await tester.tap(find.text('Bumble (you)'));
+        await tester.pumpAndSettle();
+        expect(find.byType(TextField), findsOneWidget);
+        expect(
+          tester.widget<TextField>(find.byType(TextField)).controller?.text,
+          '@Bumble ',
+        );
+      },
+    );
+
     testWidgets('adds a selected non-member agent as a bot before sending', (
       tester,
     ) async {

mobile/test/features/channels/mentions/mention_display_name_test.dart

@@ -0,0 +1,57 @@
+import 'package:buzz/features/channels/mentions/mention_display_name.dart';
+import 'package:flutter_test/flutter_test.dart';
+
+void main() {
+  test('appends owner labels to colliding agents', () {
+    expect(
+      formatDisambiguatedMentionDisplayName(
+        displayName: 'Bumble',
+        hasNameCollision: true,
+        isAgent: true,
+        ownerLabel: 'sergior',
+      ),
+      'Bumble (sergior)',
+    );
+    expect(
+      formatDisambiguatedMentionDisplayName(
+        displayName: 'Bumble',
+        hasNameCollision: true,
+        isAgent: true,
+        ownerLabel: 'you',
+      ),
+      'Bumble (you)',
+    );
+  });
+
+  test('leaves humans and unique agents unchanged', () {
+    expect(
+      formatDisambiguatedMentionDisplayName(
+        displayName: 'Bumble',
+        hasNameCollision: true,
+        isAgent: false,
+        ownerLabel: null,
+      ),
+      'Bumble',
+    );
+    expect(
+      formatDisambiguatedMentionDisplayName(
+        displayName: 'Bumble',
+        hasNameCollision: false,
+        isAgent: true,
+        ownerLabel: 'sergior',
+      ),
+      'Bumble',
+    );
+  });
+
+  test('detects visible display-name collisions case-insensitively', () {
+    final counts = countVisibleMentionDisplayNames([
+      'Bumble',
+      ' bUmBlE ',
+      'Fizz',
+    ]);
+
+    expect(hasVisibleMentionDisplayNameCollision('bumble', counts), isTrue);
+    expect(hasVisibleMentionDisplayNameCollision('Fizz', counts), isFalse);
+  });
+}