feat(mobile): implement forum posts and threads (#356)

Co-authored-by: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

mobile/lib/features/activity/activity_page.dart

@@ -59,7 +59,8 @@ class ActivityPage extends HookConsumerWidget {
                     child: ListView.separated(
                       padding: const EdgeInsets.symmetric(vertical: Grid.xxs),
                       itemCount: items.length,
-                      separatorBuilder: (_, _) => const Divider(height: 1),
+                      separatorBuilder: (_, _) =>
+                          const SizedBox(height: Grid.half),
                       itemBuilder: (context, index) {
                         final item = items[index];
                         return _FeedItemTile(

mobile/lib/features/channels/channel_detail_page.dart

@@ -12,6 +12,7 @@ import '../profile/presence_cache_provider.dart';
 import '../profile/profile_provider.dart';
 import '../profile/user_cache_provider.dart';
 import '../profile/user_profile.dart';
+import '../forum/forum_posts_view.dart';
 import 'channel.dart';
 import 'channel_management_provider.dart';
 import 'channel_messages_provider.dart';
@@ -145,7 +146,10 @@ class ChannelDetailPage extends HookConsumerWidget {
         children: [
           Expanded(
             child: resolvedChannel.isForum
-                ? _ForumPlaceholder(channel: resolvedChannel)
+                ? ForumPostsView(
+                    channel: resolvedChannel,
+                    currentPubkey: currentPubkey,
+                  )
                 : messagesState.when(
                     loading: () =>
                         const Center(child: CircularProgressIndicator()),
@@ -190,8 +194,7 @@ class ChannelDetailPage extends HookConsumerWidget {
                     mentionPubkeys: mentionPubkeys,
                   ),
             )
-          else if (!resolvedChannel.isForum &&
-              !resolvedChannel.isDm &&
+          else if (!resolvedChannel.isDm &&
               (!resolvedChannel.isMember || resolvedChannel.isArchived))
             _ReadOnlyNotice(channel: resolvedChannel),
         ],
@@ -1027,55 +1030,6 @@ IconData channelIcon(Channel channel) {
   return LucideIcons.hash;
 }
 
-class _ForumPlaceholder extends StatelessWidget {
-  final Channel channel;
-
-  const _ForumPlaceholder({required this.channel});
-
-  @override
-  Widget build(BuildContext context) {
-    return Center(
-      child: Padding(
-        padding: const EdgeInsets.symmetric(horizontal: Grid.sm),
-        child: Column(
-          mainAxisSize: MainAxisSize.min,
-          children: [
-            Icon(
-              LucideIcons.messageSquareText,
-              size: Grid.xl,
-              color: context.colors.outline,
-            ),
-            const SizedBox(height: Grid.xs),
-            Text(
-              'Forum threads are not on mobile yet',
-              style: context.textTheme.titleMedium,
-              textAlign: TextAlign.center,
-            ),
-            const SizedBox(height: Grid.xxs),
-            Text(
-              'You can still view channel context, canvas, and members from the actions above.',
-              style: context.textTheme.bodyMedium?.copyWith(
-                color: context.colors.onSurfaceVariant,
-              ),
-              textAlign: TextAlign.center,
-            ),
-            if (channel.description.trim().isNotEmpty) ...[
-              const SizedBox(height: Grid.xs),
-              Text(
-                channel.description,
-                style: context.textTheme.bodySmall?.copyWith(
-                  color: context.colors.outline,
-                ),
-                textAlign: TextAlign.center,
-              ),
-            ],
-          ],
-        ),
-      ),
-    );
-  }
-}
-
 class _ReadOnlyNotice extends StatelessWidget {
   final Channel channel;
 

mobile/lib/features/forum/forum_models.dart

@@ -0,0 +1,195 @@
+import 'package:flutter/foundation.dart';
+
+/// A top-level forum post with an optional thread summary.
+@immutable
+class ForumPost {
+  final String eventId;
+  final String pubkey;
+  final String content;
+  final int kind;
+  final int createdAt;
+  final String channelId;
+  final List<List<String>> tags;
+  final ForumThreadSummary? threadSummary;
+
+  const ForumPost({
+    required this.eventId,
+    required this.pubkey,
+    required this.content,
+    required this.kind,
+    required this.createdAt,
+    required this.channelId,
+    required this.tags,
+    this.threadSummary,
+  });
+
+  factory ForumPost.fromJson(Map<String, dynamic> json) {
+    final rawSummary = json['thread_summary'] as Map<String, dynamic>?;
+    return ForumPost(
+      eventId: json['event_id'] as String,
+      pubkey: json['pubkey'] as String,
+      content: json['content'] as String,
+      kind: json['kind'] as int,
+      createdAt: json['created_at'] as int,
+      channelId: json['channel_id'] as String,
+      tags: (json['tags'] as List<dynamic>)
+          .map((t) => (t as List<dynamic>).map((e) => e as String).toList())
+          .toList(),
+      threadSummary: rawSummary != null
+          ? ForumThreadSummary.fromJson(rawSummary)
+          : null,
+    );
+  }
+
+  /// Extract mention pubkeys from p-tags.
+  List<String> get mentionPubkeys => [
+    for (final tag in tags)
+      if (tag.length >= 2 && tag[0] == 'p') tag[1],
+  ];
+}
+
+/// Summary of replies on a forum post.
+@immutable
+class ForumThreadSummary {
+  final int replyCount;
+  final int descendantCount;
+  final int? lastReplyAt;
+  final List<String> participants;
+
+  const ForumThreadSummary({
+    required this.replyCount,
+    required this.descendantCount,
+    this.lastReplyAt,
+    required this.participants,
+  });
+
+  factory ForumThreadSummary.fromJson(Map<String, dynamic> json) {
+    return ForumThreadSummary(
+      replyCount: json['reply_count'] as int? ?? 0,
+      descendantCount: json['descendant_count'] as int? ?? 0,
+      lastReplyAt: json['last_reply_at'] as int?,
+      participants:
+          (json['participants'] as List<dynamic>?)
+              ?.map((e) => e as String)
+              .toList() ??
+          const [],
+    );
+  }
+}
+
+/// A reply within a forum thread.
+@immutable
+class ThreadReply {
+  final String eventId;
+  final String pubkey;
+  final String content;
+  final int kind;
+  final int createdAt;
+  final String channelId;
+  final List<List<String>> tags;
+  final String? parentEventId;
+  final String? rootEventId;
+  final int depth;
+
+  const ThreadReply({
+    required this.eventId,
+    required this.pubkey,
+    required this.content,
+    required this.kind,
+    required this.createdAt,
+    required this.channelId,
+    required this.tags,
+    this.parentEventId,
+    this.rootEventId,
+    required this.depth,
+  });
+
+  factory ThreadReply.fromJson(Map<String, dynamic> json) {
+    return ThreadReply(
+      eventId: json['event_id'] as String,
+      pubkey: json['pubkey'] as String,
+      content: json['content'] as String,
+      kind: json['kind'] as int,
+      createdAt: json['created_at'] as int,
+      channelId: json['channel_id'] as String,
+      tags: (json['tags'] as List<dynamic>)
+          .map((t) => (t as List<dynamic>).map((e) => e as String).toList())
+          .toList(),
+      parentEventId: json['parent_event_id'] as String?,
+      rootEventId: json['root_event_id'] as String?,
+      depth: json['depth'] as int? ?? 0,
+    );
+  }
+
+  /// Extract mention pubkeys from p-tags.
+  List<String> get mentionPubkeys => [
+    for (final tag in tags)
+      if (tag.length >= 2 && tag[0] == 'p') tag[1],
+  ];
+}
+
+/// Paginated response for forum posts.
+@immutable
+class ForumPostsResponse {
+  final List<ForumPost> posts;
+  final int? nextCursor;
+
+  const ForumPostsResponse({required this.posts, this.nextCursor});
+
+  factory ForumPostsResponse.fromJson(Map<String, dynamic> json) {
+    final messages = json['messages'] as List<dynamic>? ?? const [];
+    return ForumPostsResponse(
+      posts: messages
+          .cast<Map<String, dynamic>>()
+          .map(ForumPost.fromJson)
+          .toList(),
+      nextCursor: json['next_cursor'] as int?,
+    );
+  }
+}
+
+/// Response for a single forum thread with replies.
+@immutable
+class ForumThreadResponse {
+  final ForumPost post;
+  final List<ThreadReply> replies;
+  final int totalReplies;
+  final String? nextCursor;
+
+  const ForumThreadResponse({
+    required this.post,
+    required this.replies,
+    required this.totalReplies,
+    this.nextCursor,
+  });
+
+  factory ForumThreadResponse.fromJson(Map<String, dynamic> json) {
+    final repliesJson = json['replies'] as List<dynamic>? ?? const [];
+    return ForumThreadResponse(
+      post: ForumPost.fromJson(json['root'] as Map<String, dynamic>),
+      replies: repliesJson
+          .cast<Map<String, dynamic>>()
+          .map(ThreadReply.fromJson)
+          .toList(),
+      totalReplies: json['total_replies'] as int? ?? 0,
+      nextCursor: json['next_cursor'] as String?,
+    );
+  }
+}
+
+/// Format a unix timestamp as a relative time string (e.g. "2h ago").
+String formatRelativeTime(int timestamp) {
+  final now = DateTime.now().millisecondsSinceEpoch ~/ 1000;
+  final diff = now - timestamp;
+
+  if (diff < 60) return 'just now';
+  if (diff < 3600) return '${diff ~/ 60}m ago';
+  if (diff < 86400) return '${diff ~/ 3600}h ago';
+  if (diff < 604800) return '${diff ~/ 86400}d ago';
+
+  final dt = DateTime.fromMillisecondsSinceEpoch(
+    timestamp * 1000,
+    isUtc: true,
+  ).toLocal();
+  return '${dt.month}/${dt.day}/${dt.year}';
+}

mobile/lib/features/forum/forum_post_card.dart

@@ -0,0 +1,253 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
+
+import '../../shared/theme/theme.dart';
+import '../profile/user_cache_provider.dart';
+import '../profile/user_profile.dart';
+import 'forum_models.dart';
+
+/// Card displaying a forum post preview in the posts list.
+///
+/// Long-press opens an action sheet (copy, delete) matching the stream
+/// message pattern from channel_detail_page.dart.
+class ForumPostCard extends ConsumerWidget {
+  final ForumPost post;
+  final String? currentPubkey;
+  final VoidCallback onTap;
+  final void Function(String eventId)? onDelete;
+
+  const ForumPostCard({
+    super.key,
+    required this.post,
+    required this.currentPubkey,
+    required this.onTap,
+    this.onDelete,
+  });
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final pk = post.pubkey.toLowerCase();
+    final profile =
+        ref.watch(userCacheProvider.select((cache) => cache[pk])) ??
+        ref.read(userCacheProvider.notifier).get(pk);
+    final displayName = profile?.label ?? _shortPubkey(post.pubkey);
+    final preview = post.content.length > 200
+        ? '${post.content.substring(0, 200)}...'
+        : post.content;
+    final summary = post.threadSummary;
+
+    return GestureDetector(
+      onTap: onTap,
+      onLongPress: () => _showActions(context),
+      child: Container(
+        width: double.infinity,
+        padding: const EdgeInsets.all(Grid.twelve),
+        decoration: BoxDecoration(
+          color: context.colors.surfaceContainerHighest,
+          borderRadius: BorderRadius.circular(Radii.lg),
+          border: Border.all(
+            color: context.colors.outlineVariant.withValues(alpha: 0.5),
+          ),
+        ),
+        child: Column(
+          crossAxisAlignment: CrossAxisAlignment.start,
+          children: [
+            // Author row
+            Row(
+              children: [
+                _PostAvatar(profile: profile, pubkey: post.pubkey),
+                const SizedBox(width: Grid.xxs),
+                Expanded(
+                  child: Text(
+                    displayName,
+                    style: context.textTheme.labelMedium?.copyWith(
+                      fontWeight: FontWeight.w600,
+                    ),
+                    overflow: TextOverflow.ellipsis,
+                  ),
+                ),
+                Text(
+                  formatRelativeTime(post.createdAt),
+                  style: context.textTheme.labelSmall?.copyWith(
+                    color: context.colors.outline,
+                  ),
+                ),
+                const SizedBox(width: Grid.half),
+                SizedBox(
+                  width: 24,
+                  height: 24,
+                  child: IconButton(
+                    onPressed: () => _showActions(context),
+                    icon: Icon(
+                      LucideIcons.ellipsis,
+                      size: 16,
+                      color: context.colors.outline,
+                    ),
+                    padding: EdgeInsets.zero,
+                    visualDensity: VisualDensity.compact,
+                  ),
+                ),
+              ],
+            ),
+            const SizedBox(height: Grid.xxs),
+
+            // Content preview
+            Text(
+              preview,
+              style: context.textTheme.bodyMedium?.copyWith(
+                color: context.colors.onSurface,
+              ),
+              maxLines: 4,
+              overflow: TextOverflow.ellipsis,
+            ),
+
+            // Thread summary
+            if (summary != null && summary.replyCount > 0) ...[
+              const SizedBox(height: Grid.xxs),
+              Row(
+                children: [
+                  Icon(
+                    LucideIcons.messageSquare,
+                    size: 14,
+                    color: context.colors.outline,
+                  ),
+                  const SizedBox(width: Grid.half),
+                  Text(
+                    '${summary.replyCount} ${summary.replyCount == 1 ? 'reply' : 'replies'}',
+                    style: context.textTheme.labelSmall?.copyWith(
+                      color: context.colors.outline,
+                    ),
+                  ),
+                  if (summary.lastReplyAt != null) ...[
+                    const SizedBox(width: Grid.half),
+                    Text(
+                      '\u00b7',
+                      style: context.textTheme.labelSmall?.copyWith(
+                        color: context.colors.outline.withValues(alpha: 0.5),
+                      ),
+                    ),
+                    const SizedBox(width: Grid.half),
+                    Text(
+                      'last ${formatRelativeTime(summary.lastReplyAt!)}',
+                      style: context.textTheme.labelSmall?.copyWith(
+                        color: context.colors.outline,
+                      ),
+                    ),
+                  ],
+                ],
+              ),
+            ],
+          ],
+        ),
+      ),
+    );
+  }
+
+  void _showActions(BuildContext context) {
+    final isOwn =
+        currentPubkey != null &&
+        post.pubkey.toLowerCase() == currentPubkey!.toLowerCase();
+
+    showModalBottomSheet<void>(
+      context: context,
+      showDragHandle: true,
+      builder: (sheetContext) => SafeArea(
+        child: Padding(
+          padding: const EdgeInsets.fromLTRB(Grid.xs, 0, Grid.xs, Grid.xs),
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              ListTile(
+                leading: const Icon(LucideIcons.copy),
+                title: const Text('Copy text'),
+                onTap: () {
+                  Navigator.of(sheetContext).pop();
+                  Clipboard.setData(ClipboardData(text: post.content));
+                },
+              ),
+              if (isOwn && onDelete != null)
+                ListTile(
+                  leading: Icon(
+                    LucideIcons.trash2,
+                    color: Theme.of(sheetContext).colorScheme.error,
+                  ),
+                  title: Text(
+                    'Delete post',
+                    style: TextStyle(
+                      color: Theme.of(sheetContext).colorScheme.error,
+                    ),
+                  ),
+                  onTap: () {
+                    Navigator.of(sheetContext).pop();
+                    _confirmDelete(context);
+                  },
+                ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  void _confirmDelete(BuildContext context) {
+    showDialog<void>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: const Text('Delete post'),
+        content: const Text('This cannot be undone.'),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.of(dialogContext).pop(),
+            child: const Text('Cancel'),
+          ),
+          FilledButton(
+            onPressed: () {
+              Navigator.of(dialogContext).pop();
+              onDelete?.call(post.eventId);
+            },
+            style: FilledButton.styleFrom(
+              backgroundColor: Theme.of(dialogContext).colorScheme.error,
+            ),
+            child: const Text('Delete'),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _PostAvatar extends StatelessWidget {
+  final UserProfile? profile;
+  final String pubkey;
+
+  const _PostAvatar({required this.profile, required this.pubkey});
+
+  @override
+  Widget build(BuildContext context) {
+    final initial =
+        profile?.initial ?? (pubkey.isNotEmpty ? pubkey[0].toUpperCase() : '?');
+    final avatarUrl = profile?.avatarUrl;
+
+    return CircleAvatar(
+      radius: 14,
+      backgroundColor: context.colors.primaryContainer,
+      backgroundImage: avatarUrl != null ? NetworkImage(avatarUrl) : null,
+      child: avatarUrl == null
+          ? Text(
+              initial,
+              style: context.textTheme.labelSmall?.copyWith(
+                color: context.colors.onPrimaryContainer,
+                fontWeight: FontWeight.w600,
+              ),
+            )
+          : null,
+    );
+  }
+}
+
+String _shortPubkey(String pubkey) {
+  if (pubkey.length > 12) return '${pubkey.substring(0, 8)}\u2026';
+  return pubkey;
+}

mobile/lib/features/forum/forum_posts_view.dart

@@ -0,0 +1,197 @@
+import 'dart:async';
+
+import 'package:flutter/material.dart';
+import 'package:flutter_hooks/flutter_hooks.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
+
+import '../../shared/theme/theme.dart';
+import '../channels/channel.dart';
+import '../channels/compose_bar.dart';
+import 'forum_models.dart';
+import 'forum_post_card.dart';
+import 'forum_provider.dart';
+import 'forum_thread_page.dart';
+
+/// Main forum view — replaces the old _ForumPlaceholder.
+///
+/// Shows a list of forum posts for the channel with a FAB to open the compose
+/// bar, and navigates to [ForumThreadPage] when a post is tapped.
+class ForumPostsView extends HookConsumerWidget {
+  final Channel channel;
+  final String? currentPubkey;
+
+  const ForumPostsView({
+    super.key,
+    required this.channel,
+    required this.currentPubkey,
+  });
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final postsAsync = ref.watch(forumPostsProvider(channel.id));
+    final isComposing = useState(false);
+
+    // Periodic refresh (every 15s, matching desktop).
+    useEffect(() {
+      final timer = Stream.periodic(const Duration(seconds: 15)).listen((_) {
+        ref.invalidate(forumPostsProvider(channel.id));
+      });
+      return timer.cancel;
+    }, [channel.id]);
+
+    final canPost = channel.isMember && !channel.isArchived;
+
+    return Column(
+      children: [
+        Expanded(
+          child: Scaffold(
+            // Transparent so the parent Scaffold's background shows through.
+            backgroundColor: Colors.transparent,
+            floatingActionButton: canPost && !isComposing.value
+                ? FloatingActionButton(
+                    onPressed: () => isComposing.value = true,
+                    tooltip: 'New post',
+                    shape: const CircleBorder(),
+                    child: const Icon(LucideIcons.plus),
+                  )
+                : null,
+            body: postsAsync.when(
+              loading: () => const Center(child: CircularProgressIndicator()),
+              error: (e, _) => Center(
+                child: Text(
+                  'Failed to load posts',
+                  style: context.textTheme.bodyMedium?.copyWith(
+                    color: context.colors.error,
+                  ),
+                ),
+              ),
+              data: (response) {
+                final posts = response.posts;
+                if (posts.isEmpty) {
+                  return _EmptyState(
+                    isMember: channel.isMember,
+                    isArchived: channel.isArchived,
+                  );
+                }
+                return RefreshIndicator(
+                  onRefresh: () async {
+                    ref.invalidate(forumPostsProvider(channel.id));
+                    await ref.read(forumPostsProvider(channel.id).future);
+                  },
+                  child: ListView.separated(
+                    padding: const EdgeInsets.all(Grid.xs),
+                    itemCount: posts.length,
+                    separatorBuilder: (_, _) =>
+                        const SizedBox(height: Grid.xxs),
+                    itemBuilder: (context, index) {
+                      final post = posts[index];
+                      return ForumPostCard(
+                        post: post,
+                        currentPubkey: currentPubkey,
+                        onTap: () => _openThread(context, post),
+                        onDelete: (eventId) async {
+                          await deleteForumEvent(
+                            ref,
+                            channelId: channel.id,
+                            eventId: eventId,
+                          );
+                        },
+                      );
+                    },
+                  ),
+                );
+              },
+            ),
+          ),
+        ),
+        if (isComposing.value) ...[
+          Align(
+            alignment: Alignment.centerRight,
+            child: Padding(
+              padding: const EdgeInsets.only(right: Grid.xxs),
+              child: IconButton(
+                onPressed: () => isComposing.value = false,
+                icon: const Icon(LucideIcons.x, size: 18),
+                tooltip: 'Dismiss',
+                visualDensity: VisualDensity.compact,
+              ),
+            ),
+          ),
+          ComposeBar(
+            channelId: channel.id,
+            hintText: 'Write your post\u2026',
+            onSend: (content, mentionPubkeys) async {
+              await createForumPost(
+                ref,
+                channelId: channel.id,
+                content: content,
+                mentionPubkeys: mentionPubkeys,
+              );
+              if (context.mounted) isComposing.value = false;
+            },
+          ),
+        ],
+      ],
+    );
+  }
+
+  void _openThread(BuildContext context, ForumPost post) {
+    Navigator.of(context).push(
+      MaterialPageRoute<void>(
+        builder: (_) => ForumThreadPage(
+          channelId: channel.id,
+          postEventId: post.eventId,
+          currentPubkey: currentPubkey,
+          isMember: channel.isMember,
+          isArchived: channel.isArchived,
+        ),
+      ),
+    );
+  }
+}
+
+class _EmptyState extends StatelessWidget {
+  final bool isMember;
+  final bool isArchived;
+
+  const _EmptyState({required this.isMember, required this.isArchived});
+
+  @override
+  Widget build(BuildContext context) {
+    return Center(
+      child: Padding(
+        padding: const EdgeInsets.symmetric(horizontal: Grid.sm),
+        child: Column(
+          mainAxisSize: MainAxisSize.min,
+          children: [
+            Icon(
+              LucideIcons.messageSquareText,
+              size: Grid.xl,
+              color: context.colors.outline,
+            ),
+            const SizedBox(height: Grid.xxs),
+            Text(
+              'No posts yet',
+              style: context.textTheme.bodyLarge?.copyWith(
+                color: context.colors.onSurfaceVariant,
+              ),
+            ),
+            const SizedBox(height: Grid.half),
+            Text(
+              isArchived
+                  ? 'This forum is archived.'
+                  : isMember
+                  ? 'Start a discussion by creating the first post.'
+                  : 'Join this forum to create posts.',
+              style: context.textTheme.bodySmall?.copyWith(
+                color: context.colors.outline,
+              ),
+              textAlign: TextAlign.center,
+            ),
+          ],
+        ),
+      ),
+    );
+  }
+}

mobile/lib/features/forum/forum_provider.dart

@@ -0,0 +1,119 @@
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+
+import '../../shared/relay/relay.dart';
+import '../channels/channel_management_provider.dart';
+import 'forum_models.dart';
+
+/// Fetches forum posts for a channel from the REST API.
+///
+/// Posts are top-level kind-45001 events with thread summaries.
+/// Invalidate to refresh (e.g. after creating a new post).
+final forumPostsProvider = FutureProvider.family<ForumPostsResponse, String>((
+  ref,
+  channelId,
+) async {
+  final client = ref.watch(relayClientProvider);
+  final json =
+      await client.get(
+            '/api/channels/$channelId/messages',
+            queryParams: {'kinds': '${EventKind.forumPost}', 'limit': '50'},
+          )
+          as Map<String, dynamic>;
+  return ForumPostsResponse.fromJson(json);
+});
+
+/// Fetches a forum thread (root post + replies) from the REST API.
+final forumThreadProvider =
+    FutureProvider.family<
+      ForumThreadResponse,
+      ({String channelId, String eventId})
+    >((ref, args) async {
+      final client = ref.watch(relayClientProvider);
+      final json =
+          await client.get(
+                '/api/channels/${args.channelId}/threads/${args.eventId}',
+                queryParams: {'limit': '100'},
+              )
+              as Map<String, dynamic>;
+      return ForumThreadResponse.fromJson(json);
+    });
+
+/// Creates a new forum post (kind 45001).
+Future<void> createForumPost(
+  WidgetRef ref, {
+  required String channelId,
+  required String content,
+  List<String> mentionPubkeys = const [],
+}) async {
+  final config = ref.read(relayConfigProvider);
+  final client = ref.read(relayClientProvider);
+  final relay = SignedEventRelay(client: client, nsec: config.nsec);
+
+  final selfPubkey = relay.pubkey?.toLowerCase();
+  final seen = <String>{?selfPubkey};
+  final normalizedMentions = [
+    for (final pk in mentionPubkeys)
+      if (seen.add(pk.toLowerCase())) pk,
+  ];
+
+  await relay.submit(
+    kind: EventKind.forumPost,
+    content: content,
+    tags: [
+      ['h', channelId],
+      for (final pk in normalizedMentions) ['p', pk],
+    ],
+  );
+  ref.invalidate(forumPostsProvider(channelId));
+}
+
+/// Creates a reply to a forum post (kind 45003).
+Future<void> createForumReply(
+  WidgetRef ref, {
+  required String channelId,
+  required String parentEventId,
+  required String content,
+  List<String> mentionPubkeys = const [],
+}) async {
+  final config = ref.read(relayConfigProvider);
+  final client = ref.read(relayClientProvider);
+  final relay = SignedEventRelay(client: client, nsec: config.nsec);
+
+  final selfPubkey = relay.pubkey?.toLowerCase();
+  final seen = <String>{?selfPubkey};
+  final normalizedMentions = [
+    for (final pk in mentionPubkeys)
+      if (seen.add(pk.toLowerCase())) pk,
+  ];
+
+  await relay.submit(
+    kind: EventKind.forumComment,
+    content: content,
+    tags: [
+      ['h', channelId],
+      ['e', parentEventId, '', 'reply'],
+      for (final pk in normalizedMentions) ['p', pk],
+    ],
+  );
+  ref.invalidate(forumPostsProvider(channelId));
+  ref.invalidate(
+    forumThreadProvider((channelId: channelId, eventId: parentEventId)),
+  );
+}
+
+/// Deletes a forum post or reply and invalidates relevant caches.
+Future<void> deleteForumEvent(
+  WidgetRef ref, {
+  required String channelId,
+  required String eventId,
+  String? rootEventId,
+}) async {
+  final actions = ref.read(channelActionsProvider);
+  await actions.deleteMessage(eventId);
+  ref.invalidate(forumPostsProvider(channelId));
+  if (rootEventId != null) {
+    ref.invalidate(
+      forumThreadProvider((channelId: channelId, eventId: rootEventId)),
+    );
+  }
+}

mobile/lib/features/forum/forum_thread_page.dart

@@ -0,0 +1,550 @@
+import 'package:flutter/material.dart';
+import 'package:flutter/services.dart';
+import 'package:flutter_hooks/flutter_hooks.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
+
+import '../../shared/theme/theme.dart';
+import '../channels/compose_bar.dart';
+import '../channels/message_content.dart';
+import '../profile/user_cache_provider.dart';
+import '../profile/user_profile.dart';
+import 'forum_models.dart';
+import 'forum_provider.dart';
+
+/// Full-screen page showing a forum post and its replies.
+class ForumThreadPage extends HookConsumerWidget {
+  final String channelId;
+  final String postEventId;
+  final String? currentPubkey;
+  final bool isMember;
+  final bool isArchived;
+
+  const ForumThreadPage({
+    super.key,
+    required this.channelId,
+    required this.postEventId,
+    required this.currentPubkey,
+    required this.isMember,
+    required this.isArchived,
+  });
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final threadAsync = ref.watch(
+      forumThreadProvider((channelId: channelId, eventId: postEventId)),
+    );
+
+    // Periodic refresh (every 10s, matching desktop).
+    useEffect(() {
+      final timer = Stream.periodic(const Duration(seconds: 10)).listen((_) {
+        ref.invalidate(
+          forumThreadProvider((channelId: channelId, eventId: postEventId)),
+        );
+      });
+      return timer.cancel;
+    }, [channelId, postEventId]);
+
+    final isOwnPost =
+        threadAsync
+            .whenData(
+              (t) =>
+                  currentPubkey != null &&
+                  t.post.pubkey.toLowerCase() == currentPubkey!.toLowerCase(),
+            )
+            .value ??
+        false;
+
+    return Scaffold(
+      appBar: AppBar(
+        title: const Text('Thread'),
+        actions: [
+          if (isOwnPost)
+            IconButton(
+              onPressed: () =>
+                  _showPostActions(context, ref, threadAsync.value!),
+              tooltip: 'Post actions',
+              icon: const Icon(LucideIcons.ellipsis),
+            ),
+        ],
+      ),
+      body: threadAsync.when(
+        loading: () => const Center(child: CircularProgressIndicator()),
+        error: (e, _) => Center(
+          child: Text(
+            'Failed to load thread',
+            style: context.textTheme.bodyMedium?.copyWith(
+              color: context.colors.error,
+            ),
+          ),
+        ),
+        data: (thread) => _ThreadContent(
+          thread: thread,
+          channelId: channelId,
+          currentPubkey: currentPubkey,
+          isMember: isMember,
+          isArchived: isArchived,
+        ),
+      ),
+    );
+  }
+
+  void _showPostActions(
+    BuildContext context,
+    WidgetRef ref,
+    ForumThreadResponse thread,
+  ) {
+    showModalBottomSheet<void>(
+      context: context,
+      showDragHandle: true,
+      builder: (sheetContext) => SafeArea(
+        child: Padding(
+          padding: const EdgeInsets.fromLTRB(Grid.xs, 0, Grid.xs, Grid.xs),
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              ListTile(
+                leading: const Icon(LucideIcons.copy),
+                title: const Text('Copy text'),
+                onTap: () {
+                  Navigator.of(sheetContext).pop();
+                  Clipboard.setData(ClipboardData(text: thread.post.content));
+                },
+              ),
+              ListTile(
+                leading: Icon(
+                  LucideIcons.trash2,
+                  color: Theme.of(sheetContext).colorScheme.error,
+                ),
+                title: Text(
+                  'Delete post',
+                  style: TextStyle(
+                    color: Theme.of(sheetContext).colorScheme.error,
+                  ),
+                ),
+                onTap: () {
+                  Navigator.of(sheetContext).pop();
+                  _confirmDeletePost(context, ref, thread.post.eventId);
+                },
+              ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  void _confirmDeletePost(BuildContext context, WidgetRef ref, String eventId) {
+    showDialog<void>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: const Text('Delete post'),
+        content: const Text('This cannot be undone.'),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.of(dialogContext).pop(),
+            child: const Text('Cancel'),
+          ),
+          FilledButton(
+            onPressed: () async {
+              Navigator.of(dialogContext).pop();
+              await deleteForumEvent(
+                ref,
+                channelId: channelId,
+                eventId: eventId,
+              );
+              if (context.mounted) {
+                Navigator.of(context).pop();
+              }
+            },
+            style: FilledButton.styleFrom(
+              backgroundColor: Theme.of(dialogContext).colorScheme.error,
+            ),
+            child: const Text('Delete'),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _ThreadContent extends HookConsumerWidget {
+  final ForumThreadResponse thread;
+  final String channelId;
+  final String? currentPubkey;
+  final bool isMember;
+  final bool isArchived;
+
+  const _ThreadContent({
+    required this.thread,
+    required this.channelId,
+    required this.currentPubkey,
+    required this.isMember,
+    required this.isArchived,
+  });
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final post = thread.post;
+    final replies = thread.replies;
+
+    // Preload profiles for all participants.
+    final allPubkeys = useMemoized(() {
+      final pks = <String>{post.pubkey};
+      for (final reply in replies) {
+        pks.add(reply.pubkey);
+      }
+      return pks.toList();
+    }, [post, replies]);
+
+    useEffect(() {
+      if (allPubkeys.isNotEmpty) {
+        ref.read(userCacheProvider.notifier).preload(allPubkeys);
+      }
+      return null;
+    }, [allPubkeys]);
+
+    return Column(
+      children: [
+        Expanded(
+          child: ListView(
+            padding: const EdgeInsets.only(bottom: Grid.xs),
+            children: [
+              // Original post
+              _OriginalPost(post: post),
+
+              // Replies header
+              Padding(
+                padding: const EdgeInsets.symmetric(
+                  horizontal: Grid.xs,
+                  vertical: Grid.xxs,
+                ),
+                child: Row(
+                  children: [
+                    Icon(
+                      LucideIcons.messageSquare,
+                      size: 16,
+                      color: context.colors.outline,
+                    ),
+                    const SizedBox(width: Grid.half),
+                    Text(
+                      '${replies.length} ${replies.length == 1 ? 'reply' : 'replies'}',
+                      style: context.textTheme.labelMedium?.copyWith(
+                        color: context.colors.outline,
+                        fontWeight: FontWeight.w600,
+                      ),
+                    ),
+                  ],
+                ),
+              ),
+
+              // Reply list
+              if (replies.isEmpty)
+                Padding(
+                  padding: const EdgeInsets.all(Grid.sm),
+                  child: Text(
+                    'No replies yet. Be the first to respond.',
+                    style: context.textTheme.bodyMedium?.copyWith(
+                      color: context.colors.outline,
+                    ),
+                    textAlign: TextAlign.center,
+                  ),
+                )
+              else
+                for (final reply in replies)
+                  _ReplyRow(
+                    reply: reply,
+                    currentPubkey: currentPubkey,
+                    channelId: channelId,
+                    rootEventId: post.eventId,
+                  ),
+            ],
+          ),
+        ),
+
+        // Reply composer
+        if (isMember && !isArchived)
+          ComposeBar(
+            channelId: channelId,
+            hintText: 'Reply to this post\u2026',
+            onSend: (content, mentionPubkeys) => createForumReply(
+              ref,
+              channelId: channelId,
+              parentEventId: post.eventId,
+              content: content,
+              mentionPubkeys: mentionPubkeys,
+            ),
+          ),
+      ],
+    );
+  }
+}
+
+class _OriginalPost extends ConsumerWidget {
+  final ForumPost post;
+
+  const _OriginalPost({required this.post});
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final pk = post.pubkey.toLowerCase();
+    final profile =
+        ref.watch(userCacheProvider.select((cache) => cache[pk])) ??
+        ref.read(userCacheProvider.notifier).get(pk);
+    final displayName = profile?.label ?? _shortPubkey(post.pubkey);
+
+    final userCache = ref.watch(userCacheProvider);
+    final mentionNames = _buildMentionNames(post.mentionPubkeys, userCache);
+
+    return Padding(
+      padding: const EdgeInsets.all(Grid.xs),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Row(
+            children: [
+              _Avatar(profile: profile, pubkey: post.pubkey, radius: 16),
+              const SizedBox(width: Grid.xxs),
+              Expanded(
+                child: Column(
+                  crossAxisAlignment: CrossAxisAlignment.start,
+                  children: [
+                    Text(
+                      displayName,
+                      style: context.textTheme.labelMedium?.copyWith(
+                        fontWeight: FontWeight.w600,
+                      ),
+                    ),
+                    Text(
+                      formatRelativeTime(post.createdAt),
+                      style: context.textTheme.labelSmall?.copyWith(
+                        color: context.colors.outline,
+                      ),
+                    ),
+                  ],
+                ),
+              ),
+            ],
+          ),
+          const SizedBox(height: Grid.xxs),
+          MessageContent(content: post.content, mentionNames: mentionNames),
+        ],
+      ),
+    );
+  }
+}
+
+class _ReplyRow extends ConsumerWidget {
+  final ThreadReply reply;
+  final String? currentPubkey;
+  final String channelId;
+  final String rootEventId;
+
+  const _ReplyRow({
+    required this.reply,
+    required this.currentPubkey,
+    required this.channelId,
+    required this.rootEventId,
+  });
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    final pk = reply.pubkey.toLowerCase();
+    final profile =
+        ref.watch(userCacheProvider.select((cache) => cache[pk])) ??
+        ref.read(userCacheProvider.notifier).get(pk);
+    final displayName = profile?.label ?? _shortPubkey(reply.pubkey);
+
+    final userCache = ref.watch(userCacheProvider);
+    final mentionNames = _buildMentionNames(reply.mentionPubkeys, userCache);
+
+    return Padding(
+      padding: const EdgeInsets.symmetric(
+        horizontal: Grid.xs,
+        vertical: Grid.xxs,
+      ),
+      child: Column(
+        crossAxisAlignment: CrossAxisAlignment.start,
+        children: [
+          Row(
+            children: [
+              _Avatar(profile: profile, pubkey: reply.pubkey, radius: 12),
+              const SizedBox(width: Grid.xxs),
+              Expanded(
+                child: Row(
+                  children: [
+                    Text(
+                      displayName,
+                      style: context.textTheme.labelMedium?.copyWith(
+                        fontWeight: FontWeight.w600,
+                      ),
+                    ),
+                    const SizedBox(width: Grid.xxs),
+                    Text(
+                      formatRelativeTime(reply.createdAt),
+                      style: context.textTheme.labelSmall?.copyWith(
+                        color: context.colors.outline,
+                      ),
+                    ),
+                  ],
+                ),
+              ),
+              SizedBox(
+                width: 28,
+                height: 28,
+                child: IconButton(
+                  onPressed: () => _showActions(context, ref),
+                  icon: Icon(
+                    LucideIcons.ellipsis,
+                    size: 16,
+                    color: context.colors.outline,
+                  ),
+                  padding: EdgeInsets.zero,
+                  visualDensity: VisualDensity.compact,
+                ),
+              ),
+            ],
+          ),
+          Padding(
+            padding: const EdgeInsets.only(left: 32, top: Grid.half),
+            child: MessageContent(
+              content: reply.content,
+              mentionNames: mentionNames,
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+
+  void _showActions(BuildContext context, WidgetRef ref) {
+    final isOwn =
+        currentPubkey != null &&
+        reply.pubkey.toLowerCase() == currentPubkey!.toLowerCase();
+
+    showModalBottomSheet<void>(
+      context: context,
+      showDragHandle: true,
+      builder: (sheetContext) => SafeArea(
+        child: Padding(
+          padding: const EdgeInsets.fromLTRB(Grid.xs, 0, Grid.xs, Grid.xs),
+          child: Column(
+            mainAxisSize: MainAxisSize.min,
+            children: [
+              ListTile(
+                leading: const Icon(LucideIcons.copy),
+                title: const Text('Copy text'),
+                onTap: () {
+                  Navigator.of(sheetContext).pop();
+                  Clipboard.setData(ClipboardData(text: reply.content));
+                },
+              ),
+              if (isOwn)
+                ListTile(
+                  leading: Icon(
+                    LucideIcons.trash2,
+                    color: Theme.of(sheetContext).colorScheme.error,
+                  ),
+                  title: Text(
+                    'Delete reply',
+                    style: TextStyle(
+                      color: Theme.of(sheetContext).colorScheme.error,
+                    ),
+                  ),
+                  onTap: () {
+                    Navigator.of(sheetContext).pop();
+                    _confirmDelete(context, ref);
+                  },
+                ),
+            ],
+          ),
+        ),
+      ),
+    );
+  }
+
+  void _confirmDelete(BuildContext context, WidgetRef ref) {
+    showDialog<void>(
+      context: context,
+      builder: (dialogContext) => AlertDialog(
+        title: const Text('Delete reply'),
+        content: const Text('This cannot be undone.'),
+        actions: [
+          TextButton(
+            onPressed: () => Navigator.of(dialogContext).pop(),
+            child: const Text('Cancel'),
+          ),
+          FilledButton(
+            onPressed: () async {
+              Navigator.of(dialogContext).pop();
+              await deleteForumEvent(
+                ref,
+                channelId: channelId,
+                eventId: reply.eventId,
+                rootEventId: rootEventId,
+              );
+            },
+            style: FilledButton.styleFrom(
+              backgroundColor: Theme.of(dialogContext).colorScheme.error,
+            ),
+            child: const Text('Delete'),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+class _Avatar extends StatelessWidget {
+  final UserProfile? profile;
+  final String pubkey;
+  final double radius;
+
+  const _Avatar({
+    required this.profile,
+    required this.pubkey,
+    required this.radius,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final initial =
+        profile?.initial ?? (pubkey.isNotEmpty ? pubkey[0].toUpperCase() : '?');
+    final avatarUrl = profile?.avatarUrl;
+
+    return CircleAvatar(
+      radius: radius,
+      backgroundColor: context.colors.primaryContainer,
+      backgroundImage: avatarUrl != null ? NetworkImage(avatarUrl) : null,
+      child: avatarUrl == null
+          ? Text(
+              initial,
+              style: TextStyle(
+                fontSize: radius * 0.75,
+                fontWeight: FontWeight.w600,
+                color: context.colors.onPrimaryContainer,
+              ),
+            )
+          : null,
+    );
+  }
+}
+
+Map<String, String> _buildMentionNames(
+  List<String> mentionPubkeys,
+  Map<String, UserProfile> userCache,
+) {
+  final names = <String, String>{};
+  for (final pk in mentionPubkeys) {
+    final p = userCache[pk.toLowerCase()];
+    if (p?.displayName != null) {
+      names[pk.toLowerCase()] = p!.displayName!;
+    }
+  }
+  return names;
+}
+
+String _shortPubkey(String pubkey) {
+  if (pubkey.length > 12) return '${pubkey.substring(0, 8)}\u2026';
+  return pubkey;
+}

mobile/test/features/channels/channel_detail_page_test.dart

@@ -178,7 +178,7 @@ Finder findRichText(String text) {
 
 void main() {
   group('ChannelDetailPage', () {
-    testWidgets('shows forum placeholder for forum channels', (tester) async {
+    testWidgets('shows forum posts view for forum channels', (tester) async {
       final forumChannel = Channel(
         id: _channelId,
         name: 'design-forum',
@@ -194,10 +194,14 @@ void main() {
       await tester.pumpWidget(
         _buildTestable(messages: const [], channel: forumChannel),
       );
-      await tester.pumpAndSettle();
+      // Allow the forum posts future provider to settle. It will error
+      // because the stub relay has no real backend, but the ForumPostsView
+      // should still render (showing an error or loading state).
+      await tester.pump(const Duration(seconds: 1));
 
-      expect(find.text('Forum threads are not on mobile yet'), findsOneWidget);
-      expect(find.text('Talk through design changes'), findsOneWidget);
+      // The old placeholder text should be gone.
+      expect(find.text('Forum threads are not on mobile yet'), findsNothing);
+      // The compose bar for stream messages should not appear.
       expect(find.text('Message…'), findsNothing);
     });
 

mobile/test/features/forum/forum_models_test.dart

@@ -0,0 +1,265 @@
+import 'package:flutter_test/flutter_test.dart';
+import 'package:sprout_mobile/features/forum/forum_models.dart';
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+Map<String, dynamic> _postJson({
+  String eventId = 'evt1',
+  String pubkey = 'alice',
+  String content = 'Hello world',
+  int kind = 45001,
+  int createdAt = 1000,
+  String channelId = 'ch1',
+  List<List<String>>? tags,
+  Map<String, dynamic>? threadSummary,
+}) => {
+  'event_id': eventId,
+  'pubkey': pubkey,
+  'content': content,
+  'kind': kind,
+  'created_at': createdAt,
+  'channel_id': channelId,
+  'tags':
+      tags ??
+      [
+        ['h', channelId],
+      ],
+  ...?threadSummary != null ? {'thread_summary': threadSummary} : null,
+};
+
+Map<String, dynamic> _replyJson({
+  String eventId = 'reply1',
+  String pubkey = 'bob',
+  String content = 'Nice post',
+  int kind = 45003,
+  int createdAt = 2000,
+  String channelId = 'ch1',
+  String? parentEventId = 'evt1',
+  String? rootEventId = 'evt1',
+  int depth = 1,
+}) => {
+  'event_id': eventId,
+  'pubkey': pubkey,
+  'content': content,
+  'kind': kind,
+  'created_at': createdAt,
+  'channel_id': channelId,
+  'tags': [
+    ['h', channelId],
+  ],
+  'parent_event_id': parentEventId,
+  'root_event_id': rootEventId,
+  'depth': depth,
+};
+
+Map<String, dynamic> _summaryJson({
+  int replyCount = 3,
+  int descendantCount = 5,
+  int? lastReplyAt = 3000,
+  List<String> participants = const ['bob', 'carol'],
+}) => {
+  'reply_count': replyCount,
+  'descendant_count': descendantCount,
+  'last_reply_at': lastReplyAt,
+  'participants': participants,
+};
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+void main() {
+  group('ForumPost.fromJson', () {
+    test('parses complete post with thread summary', () {
+      final json = _postJson(
+        threadSummary: _summaryJson(),
+        tags: [
+          ['h', 'ch1'],
+          ['p', 'bob'],
+        ],
+      );
+      final post = ForumPost.fromJson(json);
+
+      expect(post.eventId, 'evt1');
+      expect(post.pubkey, 'alice');
+      expect(post.content, 'Hello world');
+      expect(post.kind, 45001);
+      expect(post.createdAt, 1000);
+      expect(post.channelId, 'ch1');
+      expect(post.tags, hasLength(2));
+      expect(post.threadSummary, isNotNull);
+      expect(post.threadSummary!.replyCount, 3);
+      expect(post.threadSummary!.descendantCount, 5);
+      expect(post.threadSummary!.lastReplyAt, 3000);
+      expect(post.threadSummary!.participants, ['bob', 'carol']);
+    });
+
+    test('parses post without thread summary', () {
+      final post = ForumPost.fromJson(_postJson());
+      expect(post.threadSummary, isNull);
+    });
+
+    test('extracts mention pubkeys from p-tags', () {
+      final post = ForumPost.fromJson(
+        _postJson(
+          tags: [
+            ['h', 'ch1'],
+            ['p', 'bob'],
+            ['p', 'carol'],
+          ],
+        ),
+      );
+      expect(post.mentionPubkeys, ['bob', 'carol']);
+    });
+
+    test('returns empty mentions when no p-tags', () {
+      final post = ForumPost.fromJson(
+        _postJson(
+          tags: [
+            ['h', 'ch1'],
+          ],
+        ),
+      );
+      expect(post.mentionPubkeys, isEmpty);
+    });
+
+    test('skips malformed p-tags with length < 2', () {
+      final post = ForumPost.fromJson(
+        _postJson(
+          tags: [
+            ['h', 'ch1'],
+            ['p'],
+            ['p', 'bob'],
+          ],
+        ),
+      );
+      expect(post.mentionPubkeys, ['bob']);
+    });
+  });
+
+  group('ForumThreadSummary.fromJson', () {
+    test('parses all fields', () {
+      final summary = ForumThreadSummary.fromJson(_summaryJson());
+      expect(summary.replyCount, 3);
+      expect(summary.descendantCount, 5);
+      expect(summary.lastReplyAt, 3000);
+      expect(summary.participants, ['bob', 'carol']);
+    });
+
+    test('defaults missing fields', () {
+      final summary = ForumThreadSummary.fromJson(const <String, dynamic>{});
+      expect(summary.replyCount, 0);
+      expect(summary.descendantCount, 0);
+      expect(summary.lastReplyAt, isNull);
+      expect(summary.participants, isEmpty);
+    });
+  });
+
+  group('ThreadReply.fromJson', () {
+    test('parses a full reply', () {
+      final reply = ThreadReply.fromJson(_replyJson());
+      expect(reply.eventId, 'reply1');
+      expect(reply.pubkey, 'bob');
+      expect(reply.content, 'Nice post');
+      expect(reply.kind, 45003);
+      expect(reply.parentEventId, 'evt1');
+      expect(reply.rootEventId, 'evt1');
+      expect(reply.depth, 1);
+    });
+
+    test('defaults depth to 0 when missing', () {
+      final json = _replyJson();
+      json.remove('depth');
+      final reply = ThreadReply.fromJson(json);
+      expect(reply.depth, 0);
+    });
+
+    test('handles null parent and root', () {
+      final reply = ThreadReply.fromJson(
+        _replyJson(parentEventId: null, rootEventId: null),
+      );
+      expect(reply.parentEventId, isNull);
+      expect(reply.rootEventId, isNull);
+    });
+  });
+
+  group('ForumPostsResponse.fromJson', () {
+    test('parses paginated response', () {
+      final response = ForumPostsResponse.fromJson({
+        'messages': [_postJson(), _postJson(eventId: 'evt2')],
+        'next_cursor': 900,
+      });
+      expect(response.posts, hasLength(2));
+      expect(response.nextCursor, 900);
+    });
+
+    test('handles empty messages', () {
+      final response = ForumPostsResponse.fromJson({
+        'messages': <dynamic>[],
+        'next_cursor': null,
+      });
+      expect(response.posts, isEmpty);
+      expect(response.nextCursor, isNull);
+    });
+
+    test('handles missing messages key', () {
+      final response = ForumPostsResponse.fromJson(const <String, dynamic>{});
+      expect(response.posts, isEmpty);
+    });
+  });
+
+  group('ForumThreadResponse.fromJson', () {
+    test('parses thread with root and replies', () {
+      final response = ForumThreadResponse.fromJson({
+        'root': _postJson(),
+        'replies': [_replyJson(), _replyJson(eventId: 'reply2')],
+        'total_replies': 2,
+        'next_cursor': 'abc',
+      });
+      expect(response.post.eventId, 'evt1');
+      expect(response.replies, hasLength(2));
+      expect(response.totalReplies, 2);
+      expect(response.nextCursor, 'abc');
+    });
+
+    test('handles empty replies', () {
+      final response = ForumThreadResponse.fromJson({
+        'root': _postJson(),
+        'replies': <dynamic>[],
+        'total_replies': 0,
+      });
+      expect(response.replies, isEmpty);
+      expect(response.totalReplies, 0);
+      expect(response.nextCursor, isNull);
+    });
+  });
+
+  group('formatRelativeTime', () {
+    int now() => DateTime.now().millisecondsSinceEpoch ~/ 1000;
+
+    test('returns just now for < 60s', () {
+      expect(formatRelativeTime(now() - 30), 'just now');
+    });
+
+    test('returns minutes format', () {
+      expect(formatRelativeTime(now() - 120), '2m ago');
+    });
+
+    test('returns hours format', () {
+      expect(formatRelativeTime(now() - 7200), '2h ago');
+    });
+
+    test('returns days format', () {
+      expect(formatRelativeTime(now() - 172800), '2d ago');
+    });
+
+    test('returns date format for > 7 days', () {
+      final ts = now() - (8 * 86400);
+      final result = formatRelativeTime(ts);
+      // Should be M/D/YYYY format.
+      expect(result, matches(RegExp(r'^\d{1,2}/\d{1,2}/\d{4}$')));
+    });
+  });
+}

mobile/test/features/forum/forum_widgets_test.dart

@@ -0,0 +1,538 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:sprout_mobile/features/channels/channel.dart';
+import 'package:sprout_mobile/features/forum/forum_models.dart';
+import 'package:sprout_mobile/features/forum/forum_post_card.dart';
+import 'package:sprout_mobile/features/forum/forum_posts_view.dart';
+import 'package:sprout_mobile/features/forum/forum_provider.dart';
+import 'package:sprout_mobile/features/forum/forum_thread_page.dart';
+import 'package:sprout_mobile/features/profile/profile_provider.dart';
+import 'package:sprout_mobile/features/profile/user_cache_provider.dart';
+import 'package:sprout_mobile/features/profile/user_profile.dart';
+import 'package:sprout_mobile/shared/relay/relay.dart';
+import 'package:sprout_mobile/shared/theme/theme.dart';
+
+// ---------------------------------------------------------------------------
+// Test fixtures
+// ---------------------------------------------------------------------------
+
+const _channelId = 'forum-channel';
+
+final _forumChannel = Channel(
+  id: _channelId,
+  name: 'design-forum',
+  channelType: 'forum',
+  visibility: 'open',
+  description: '',
+  createdBy: 'abc123',
+  createdAt: DateTime(2025),
+  memberCount: 5,
+  isMember: true,
+);
+
+ForumPost _makePost({
+  String eventId = 'post1',
+  String pubkey = 'alice',
+  String content = 'Hello forum',
+  int createdAt = 1000,
+  ForumThreadSummary? threadSummary,
+}) => ForumPost(
+  eventId: eventId,
+  pubkey: pubkey,
+  content: content,
+  kind: 45001,
+  createdAt: createdAt,
+  channelId: _channelId,
+  tags: const [
+    ['h', 'forum-channel'],
+  ],
+  threadSummary: threadSummary,
+);
+
+const _aliceProfile = UserProfile(pubkey: 'alice', displayName: 'Alice');
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+Widget _buildPostCard({
+  required ForumPost post,
+  String? currentPubkey = 'self',
+  Map<String, UserProfile> users = const {},
+  VoidCallback? onTap,
+  void Function(String)? onDelete,
+}) {
+  return ProviderScope(
+    overrides: [
+      userCacheProvider.overrideWith(() => _FakeUserCacheNotifier(users)),
+    ],
+    child: MaterialApp(
+      theme: AppTheme.lightTheme,
+      home: Scaffold(
+        body: ForumPostCard(
+          post: post,
+          currentPubkey: currentPubkey,
+          onTap: onTap ?? () {},
+          onDelete: onDelete,
+        ),
+      ),
+    ),
+  );
+}
+
+Widget _buildPostsView({
+  required ForumPostsResponse postsResponse,
+  Channel? channel,
+  Map<String, UserProfile> users = const {},
+}) {
+  final ch = channel ?? _forumChannel;
+  return ProviderScope(
+    overrides: [
+      userCacheProvider.overrideWith(() => _FakeUserCacheNotifier(users)),
+      profileProvider.overrideWith(() => _FakeProfileNotifier()),
+      forumPostsProvider(ch.id).overrideWith((ref) async => postsResponse),
+      relayClientProvider.overrideWithValue(
+        RelayClient(baseUrl: 'http://localhost:3000'),
+      ),
+    ],
+    child: MaterialApp(
+      theme: AppTheme.lightTheme,
+      home: Scaffold(
+        body: ForumPostsView(channel: ch, currentPubkey: 'self'),
+      ),
+    ),
+  );
+}
+
+Widget _buildThreadPage({
+  required ForumThreadResponse threadResponse,
+  String postEventId = 'post1',
+  String? currentPubkey = 'self',
+  bool isMember = true,
+  bool isArchived = false,
+  Map<String, UserProfile> users = const {},
+}) {
+  return ProviderScope(
+    overrides: [
+      userCacheProvider.overrideWith(() => _FakeUserCacheNotifier(users)),
+      profileProvider.overrideWith(() => _FakeProfileNotifier()),
+      forumThreadProvider((
+        channelId: _channelId,
+        eventId: postEventId,
+      )).overrideWith((ref) async => threadResponse),
+      relayClientProvider.overrideWithValue(
+        RelayClient(baseUrl: 'http://localhost:3000'),
+      ),
+    ],
+    child: MaterialApp(
+      theme: AppTheme.lightTheme,
+      home: ForumThreadPage(
+        channelId: _channelId,
+        postEventId: postEventId,
+        currentPubkey: currentPubkey,
+        isMember: isMember,
+        isArchived: isArchived,
+      ),
+    ),
+  );
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+void main() {
+  group('ForumPostCard', () {
+    testWidgets('renders author name and content', (tester) async {
+      await tester.pumpWidget(
+        _buildPostCard(
+          post: _makePost(),
+          users: const {'alice': _aliceProfile},
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice'), findsOneWidget);
+      expect(find.text('Hello forum'), findsOneWidget);
+    });
+
+    testWidgets('shows truncated pubkey when no profile', (tester) async {
+      await tester.pumpWidget(
+        _buildPostCard(post: _makePost(pubkey: 'abcdef1234567890')),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('abcdef12\u2026'), findsOneWidget);
+    });
+
+    testWidgets('truncates long content', (tester) async {
+      final longContent = 'A' * 300;
+      await tester.pumpWidget(
+        _buildPostCard(post: _makePost(content: longContent)),
+      );
+      await tester.pumpAndSettle();
+
+      // Should show 200 chars + "..."
+      expect(find.textContaining('${'A' * 200}...'), findsOneWidget);
+    });
+
+    testWidgets('shows reply count with correct pluralization', (tester) async {
+      await tester.pumpWidget(
+        _buildPostCard(
+          post: _makePost(
+            threadSummary: const ForumThreadSummary(
+              replyCount: 1,
+              descendantCount: 1,
+              participants: [],
+            ),
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+      expect(find.text('1 reply'), findsOneWidget);
+
+      await tester.pumpWidget(
+        _buildPostCard(
+          post: _makePost(
+            threadSummary: const ForumThreadSummary(
+              replyCount: 5,
+              descendantCount: 5,
+              participants: [],
+            ),
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+      expect(find.text('5 replies'), findsOneWidget);
+    });
+
+    testWidgets('hides thread summary when reply count is 0', (tester) async {
+      await tester.pumpWidget(
+        _buildPostCard(
+          post: _makePost(
+            threadSummary: const ForumThreadSummary(
+              replyCount: 0,
+              descendantCount: 0,
+              participants: [],
+            ),
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+      expect(find.text('0 replies'), findsNothing);
+    });
+
+    testWidgets('calls onTap when tapped', (tester) async {
+      var tapped = false;
+      await tester.pumpWidget(
+        _buildPostCard(post: _makePost(), onTap: () => tapped = true),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.tap(find.text('Hello forum'));
+      expect(tapped, isTrue);
+    });
+
+    testWidgets('long press opens action sheet with Copy text', (tester) async {
+      await tester.pumpWidget(_buildPostCard(post: _makePost()));
+      await tester.pumpAndSettle();
+
+      await tester.longPress(find.text('Hello forum'));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Copy text'), findsOneWidget);
+    });
+
+    testWidgets('long press shows Delete only for own posts', (tester) async {
+      // Own post — Delete should appear.
+      await tester.pumpWidget(
+        _buildPostCard(
+          post: _makePost(pubkey: 'self'),
+          currentPubkey: 'self',
+          onDelete: (_) {},
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.longPress(find.text('Hello forum'));
+      await tester.pumpAndSettle();
+      expect(find.text('Delete post'), findsOneWidget);
+
+      // Dismiss sheet.
+      await tester.tapAt(Offset.zero);
+      await tester.pumpAndSettle();
+
+      // Other's post — Delete should NOT appear.
+      await tester.pumpWidget(
+        _buildPostCard(
+          post: _makePost(pubkey: 'other'),
+          currentPubkey: 'self',
+          onDelete: (_) {},
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      await tester.longPress(find.text('Hello forum'));
+      await tester.pumpAndSettle();
+      expect(find.text('Delete post'), findsNothing);
+    });
+
+    testWidgets('delete confirmation dialog triggers onDelete', (tester) async {
+      String? deletedId;
+      await tester.pumpWidget(
+        _buildPostCard(
+          post: _makePost(pubkey: 'self', eventId: 'evt-to-delete'),
+          currentPubkey: 'self',
+          onDelete: (id) => deletedId = id,
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      // Long press → action sheet.
+      await tester.longPress(find.text('Hello forum'));
+      await tester.pumpAndSettle();
+
+      // Tap Delete post.
+      await tester.tap(find.text('Delete post'));
+      await tester.pumpAndSettle();
+
+      // Confirmation dialog appears.
+      expect(find.text('This cannot be undone.'), findsOneWidget);
+
+      // Tap Delete button.
+      await tester.tap(find.widgetWithText(FilledButton, 'Delete'));
+      await tester.pumpAndSettle();
+
+      expect(deletedId, 'evt-to-delete');
+    });
+  });
+
+  group('ForumPostsView', () {
+    testWidgets('shows empty state for members', (tester) async {
+      await tester.pumpWidget(
+        _buildPostsView(postsResponse: const ForumPostsResponse(posts: [])),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('No posts yet'), findsOneWidget);
+      expect(
+        find.text('Start a discussion by creating the first post.'),
+        findsOneWidget,
+      );
+    });
+
+    testWidgets('shows empty state for non-members', (tester) async {
+      await tester.pumpWidget(
+        _buildPostsView(
+          postsResponse: const ForumPostsResponse(posts: []),
+          channel: Channel(
+            id: _channelId,
+            name: 'design-forum',
+            channelType: 'forum',
+            visibility: 'open',
+            description: '',
+            createdBy: 'abc123',
+            createdAt: DateTime(2025),
+            memberCount: 5,
+            isMember: false,
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Join this forum to create posts.'), findsOneWidget);
+    });
+
+    testWidgets('shows FAB for members', (tester) async {
+      await tester.pumpWidget(
+        _buildPostsView(postsResponse: const ForumPostsResponse(posts: [])),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.byType(FloatingActionButton), findsOneWidget);
+      expect(find.byTooltip('New post'), findsOneWidget);
+    });
+
+    testWidgets('hides FAB for non-members', (tester) async {
+      await tester.pumpWidget(
+        _buildPostsView(
+          postsResponse: const ForumPostsResponse(posts: []),
+          channel: Channel(
+            id: _channelId,
+            name: 'design-forum',
+            channelType: 'forum',
+            visibility: 'open',
+            description: '',
+            createdBy: 'abc123',
+            createdAt: DateTime(2025),
+            memberCount: 5,
+            isMember: false,
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.byType(FloatingActionButton), findsNothing);
+    });
+
+    testWidgets('renders post list', (tester) async {
+      await tester.pumpWidget(
+        _buildPostsView(
+          postsResponse: ForumPostsResponse(
+            posts: [
+              _makePost(content: 'First post'),
+              _makePost(eventId: 'post2', content: 'Second post'),
+            ],
+          ),
+          users: const {'alice': _aliceProfile},
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('First post'), findsOneWidget);
+      expect(find.text('Second post'), findsOneWidget);
+    });
+  });
+
+  group('ForumThreadPage', () {
+    testWidgets('shows original post and replies header', (tester) async {
+      await tester.pumpWidget(
+        _buildThreadPage(
+          threadResponse: ForumThreadResponse(
+            post: _makePost(content: 'Thread root'),
+            replies: const [],
+            totalReplies: 0,
+          ),
+          users: const {'alice': _aliceProfile},
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Thread'), findsOneWidget); // App bar title
+      expect(find.text('0 replies'), findsOneWidget);
+      expect(
+        find.text('No replies yet. Be the first to respond.'),
+        findsOneWidget,
+      );
+    });
+
+    testWidgets('shows reply count with replies', (tester) async {
+      await tester.pumpWidget(
+        _buildThreadPage(
+          threadResponse: ForumThreadResponse(
+            post: _makePost(),
+            replies: [
+              const ThreadReply(
+                eventId: 'r1',
+                pubkey: 'bob',
+                content: 'Great post!',
+                kind: 45003,
+                createdAt: 2000,
+                channelId: _channelId,
+                tags: [
+                  ['h', _channelId],
+                ],
+                depth: 1,
+              ),
+            ],
+            totalReplies: 1,
+          ),
+          users: const {
+            'alice': _aliceProfile,
+            'bob': UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('1 reply'), findsOneWidget);
+      expect(find.text('Bob'), findsOneWidget);
+    });
+
+    testWidgets('shows compose bar for members', (tester) async {
+      await tester.pumpWidget(
+        _buildThreadPage(
+          threadResponse: ForumThreadResponse(
+            post: _makePost(),
+            replies: const [],
+            totalReplies: 0,
+          ),
+          isMember: true,
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Reply to this post\u2026'), findsOneWidget);
+    });
+
+    testWidgets('hides compose bar for non-members', (tester) async {
+      await tester.pumpWidget(
+        _buildThreadPage(
+          threadResponse: ForumThreadResponse(
+            post: _makePost(),
+            replies: const [],
+            totalReplies: 0,
+          ),
+          isMember: false,
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Reply to this post\u2026'), findsNothing);
+    });
+
+    testWidgets('shows 3-dot in app bar for own post', (tester) async {
+      await tester.pumpWidget(
+        _buildThreadPage(
+          threadResponse: ForumThreadResponse(
+            post: _makePost(pubkey: 'self'),
+            replies: const [],
+            totalReplies: 0,
+          ),
+          currentPubkey: 'self',
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.byTooltip('Post actions'), findsOneWidget);
+    });
+
+    testWidgets('hides 3-dot in app bar for others post', (tester) async {
+      await tester.pumpWidget(
+        _buildThreadPage(
+          threadResponse: ForumThreadResponse(
+            post: _makePost(pubkey: 'alice'),
+            replies: const [],
+            totalReplies: 0,
+          ),
+          currentPubkey: 'self',
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.byTooltip('Post actions'), findsNothing);
+    });
+  });
+}
+
+// ---------------------------------------------------------------------------
+// Fakes
+// ---------------------------------------------------------------------------
+
+class _FakeUserCacheNotifier extends UserCacheNotifier {
+  final Map<String, UserProfile> _users;
+  _FakeUserCacheNotifier(this._users);
+
+  @override
+  Map<String, UserProfile> build() => _users;
+
+  @override
+  UserProfile? get(String pubkey) => _users[pubkey.toLowerCase()];
+}
+
+class _FakeProfileNotifier extends ProfileNotifier {
+  @override
+  Future<UserProfile?> build() async =>
+      const UserProfile(pubkey: 'self', displayName: 'Self');
+}