[codex] Add mobile chat timeline rendering and hardening (#327)

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

AGENTS.md

@@ -129,6 +129,55 @@ just desktop-app   # full Tauri app with native shell
 
 ---
 
+## Mobile App (Flutter)
+
+The mobile app lives in `mobile/` — a Flutter app using Riverpod + Hooks.
+
+### Architecture
+
+- **State management:** Riverpod + `flutter_hooks` (`HookConsumerWidget`)
+- **Theme:** Catppuccin Latte (light) / Macchiato (dark) — matches desktop
+- **Features:** Isolated under `lib/features/`, shared code in `lib/shared/`
+- **Nostr models:** `lib/shared/relay/nostr_models.dart` — event kinds must
+  stay in sync with `desktop/src/shared/constants/kinds.ts`
+
+### Rules
+
+- **NEVER use `StatefulWidget`** — always use `HookConsumerWidget` or
+  `ConsumerWidget` with `flutter_hooks` for local state.
+- **NEVER run `flutter run`, `flutter build`, `flutter clean`, or
+  `flutter upgrade`** — only `flutter test`, `flutter analyze`, and
+  `dart format` are safe for agents to run.
+- **Do NOT use `print()`** — use `debugPrint()` or structured logging.
+- Prefer `context.colors` and `context.textTheme` (via theme extensions)
+  over raw `Theme.of(context)` calls.
+- Keep widgets small and composable.
+- Feature modules must not import from other feature modules — only from
+  `shared/`.
+- Use `Grid` tokens for spacing, `Radii` for border radius.
+
+### Quality Checks
+
+```bash
+cd mobile
+dart format --output=none --set-exit-if-changed .
+flutter analyze
+flutter test
+```
+
+Or from repo root: `just mobile-check` and `just mobile-test`.
+
+### Testing Conventions
+
+- Prefer **widget tests** over unit tests for UI components — test the
+  whole widget tree, not individual methods.
+- Use `ProviderScope(overrides: [...])` to inject fake notifiers.
+- Fake notifiers should extend the real notifier class and override `build()`.
+- Use the `WidgetHelpers.testable()` wrapper for simple widget tests or
+  build a custom `ProviderScope` + `MaterialApp` when you need specific overrides.
+
+---
+
 ## See Also
 
 - [CONTRIBUTING.md](CONTRIBUTING.md) — setup, code style, PR process, how to add event kinds / MCP tools / API endpoints

Cargo.lock

@@ -3196,9 +3196,9 @@ checksum = "f87165f0995f63a9fbeea62b64d10b4d9d8e78ec6d7d51fb2125fda7bb36788f"
 
 [[package]]
 name = "rustls-webpki"
-version = "0.103.10"
+version = "0.103.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "df33b2b81ac578cabaf06b89b0631153a3f416b0a886e8a7a1707fb51abbd1ef"
+checksum = "8279bb85272c9f10811ae6a6c547ff594d6a7f3c6c6b02ee9726d1d0dcfcdd06"
 dependencies = [
  "aws-lc-rs",
  "ring",

deny.toml

@@ -3,13 +3,6 @@ ignore = [
     # instant 0.1.13 — unmaintained crate. Transitive dep: nostr → instant.
     # Will be resolved when nostr crate updates its dependencies.
     { id = "RUSTSEC-2024-0384", reason = "transitive dep via nostr; no upstream fix available" },
-    # rustls-webpki 0.101.7 — CRL distribution point matching bug. Transitive dep pinned by
-    # old rustls 0.21 stack (via rust-s3). 0.103 branch updated; 0.101 has no fix available.
-    { id = "RUSTSEC-2026-0049", reason = "transitive dep via rust-s3 → old rustls stack; 0.101 branch has no fix" },
-    # rustls-pemfile 1.0.4 — unmaintained crate. Transitive dep: rust-s3 → rustls-native-certs 0.6 → rustls-pemfile.
-    # The tokio-rustls-tls feature of rust-s3 pins an old rustls 0.21 stack internally.
-    # Not a security vulnerability — just an unmaintained notice. No fix until rust-s3 updates.
-    { id = "RUSTSEC-2025-0134", reason = "transitive dep via rust-s3; no upstream fix available" },
 ]
 
 [licenses]

mobile/lib/features/channels/channel_detail_page.dart

@@ -10,12 +10,17 @@ import '../profile/user_profile.dart';
 import 'channel.dart';
 import 'channel_messages_provider.dart';
 import 'channel_typing_provider.dart';
+import 'channels_provider.dart';
+import 'message_content.dart';
 import 'send_message_provider.dart';
+import 'timeline_message.dart';
 
 /// Fetch channel members and preload their profiles into the user cache.
 Future<void> _preloadMembers(WidgetRef ref, String channelId) async {
+  // Capture references before async gap to avoid using disposed ref.
+  final client = ref.read(relayClientProvider);
+  final notifier = ref.read(userCacheProvider.notifier);
   try {
-    final client = ref.read(relayClientProvider);
     final json =
         await client.get('/api/channels/$channelId/members')
             as Map<String, dynamic>;
@@ -24,7 +29,7 @@ Future<void> _preloadMembers(WidgetRef ref, String channelId) async {
         .map((m) => (m as Map<String, dynamic>)['pubkey'] as String)
         .toList();
     if (pubkeys.isNotEmpty) {
-      ref.read(userCacheProvider.notifier).preload(pubkeys);
+      notifier.preload(pubkeys);
     }
   } catch (_) {
     // Non-fatal — mentions will just fall back to cache from messages.
@@ -76,8 +81,10 @@ class ChannelDetailPage extends HookConsumerWidget {
                   ),
                 ),
               ),
-              data: (messages) =>
+              data: (events) {
-                  _MessageList(messages: messages, channelId: channel.id),
+                final messages = formatTimeline(events);
+                return _MessageList(messages: messages, channelId: channel.id);
+              },
             ),
           ),
           if (typingEntries.isNotEmpty)
@@ -90,7 +97,7 @@ class ChannelDetailPage extends HookConsumerWidget {
 }
 
 class _MessageList extends ConsumerWidget {
-  final List<NostrEvent> messages;
+  final List<TimelineMessage> messages;
   final String channelId;
 
   const _MessageList({required this.messages, required this.channelId});
@@ -126,14 +133,14 @@ class _MessageList extends ConsumerWidget {
       );
     }
 
-    // Filter to only renderable message events for display and grouping.
+    // Build channel names map once for all message bubbles.
-    final displayMessages = messages
+    final channelsAsync = ref.watch(channelsProvider);
-        .where(
+    final channelNamesMap = <String, String>{};
-          (e) =>
+    channelsAsync.whenData((channels) {
-              e.kind == EventKind.streamMessage ||
+      for (final ch in channels) {
-              e.kind == EventKind.streamMessageV2,
+        channelNamesMap[ch.name.toLowerCase()] = ch.id;
-        )
+      }
-        .toList();
+    });
 
     return ListView.builder(
       reverse: true,
@@ -141,39 +148,134 @@ class _MessageList extends ConsumerWidget {
         horizontal: Grid.xs,
         vertical: Grid.xxs,
       ),
-      itemCount: displayMessages.length,
+      itemCount: messages.length,
       itemBuilder: (context, index) {
         // Reversed list: index 0 = newest (bottom of screen).
-        final chronIdx = displayMessages.length - 1 - index;
+        final chronIdx = messages.length - 1 - index;
-        final message = displayMessages[chronIdx];
+        final message = messages[chronIdx];
-        // The message visually above is the one earlier in time.
-        final prevMessage = chronIdx > 0 ? displayMessages[chronIdx - 1] : null;
 
+        if (message.isSystem) {
+          return _SystemMessageRow(message: message);
+        }
+
+        // The message visually above is the one earlier in time.
+        final prevMessage = chronIdx > 0 ? messages[chronIdx - 1] : null;
         final showAuthor =
             prevMessage == null ||
+            prevMessage.isSystem ||
             prevMessage.pubkey.toLowerCase() != message.pubkey.toLowerCase() ||
             (message.createdAt - prevMessage.createdAt) > 300;
 
-        return _MessageBubble(event: message, showAuthor: showAuthor);
+        return _MessageBubble(
+          message: message,
+          showAuthor: showAuthor,
+          channelNames: channelNamesMap,
+          currentChannelId: channelId,
+        );
       },
     );
   }
 }
 
-class _MessageBubble extends ConsumerWidget {
+// ---------------------------------------------------------------------------
-  final NostrEvent event;
+// System message row
-  final bool showAuthor;
+// ---------------------------------------------------------------------------
 
-  const _MessageBubble({required this.event, required this.showAuthor});
+class _SystemMessageRow extends ConsumerWidget {
+  final TimelineMessage message;
+
+  const _SystemMessageRow({required this.message});
 
   @override
   Widget build(BuildContext context, WidgetRef ref) {
-    // Look up the user profile for display name.
+    final systemEvent = message.systemEvent;
+    if (systemEvent == null) return const SizedBox.shrink();
+
     final userCache = ref.watch(userCacheProvider);
+
+    String resolveLabel(String? pubkey) {
+      if (pubkey == null) return 'Someone';
+      final profile =
+          userCache[pubkey.toLowerCase()] ??
+          ref.read(userCacheProvider.notifier).get(pubkey.toLowerCase());
+      return profile?.label ?? _shortPubkey(pubkey);
+    }
+
+    final description = systemEvent.describe(resolveLabel);
+
+    return Padding(
+      padding: const EdgeInsets.symmetric(vertical: Grid.half),
+      child: Row(
+        children: [
+          Container(
+            width: 20,
+            height: 20,
+            decoration: BoxDecoration(
+              color: context.colors.surfaceContainerHighest,
+              shape: BoxShape.circle,
+            ),
+            child: Icon(
+              LucideIcons.arrowLeftRight,
+              size: 12,
+              color: context.colors.outline,
+            ),
+          ),
+          const SizedBox(width: Grid.xxs),
+          Expanded(
+            child: Text(
+              description,
+              style: context.textTheme.bodySmall?.copyWith(
+                color: context.colors.outline,
+              ),
+            ),
+          ),
+          Text(
+            _formatTime(message.createdAt),
+            style: context.textTheme.labelSmall?.copyWith(
+              color: context.colors.outline.withValues(alpha: 0.6),
+            ),
+          ),
+        ],
+      ),
+    );
+  }
+}
+
+// ---------------------------------------------------------------------------
+// User message bubble
+// ---------------------------------------------------------------------------
+
+class _MessageBubble extends ConsumerWidget {
+  final TimelineMessage message;
+  final bool showAuthor;
+  final Map<String, String> channelNames;
+  final String currentChannelId;
+
+  const _MessageBubble({
+    required this.message,
+    required this.showAuthor,
+    required this.channelNames,
+    required this.currentChannelId,
+  });
+
+  @override
+  Widget build(BuildContext context, WidgetRef ref) {
+    // Watch only this user's profile to avoid rebuilding on unrelated cache changes.
+    final pk = message.pubkey.toLowerCase();
     final profile =
-        userCache[event.pubkey.toLowerCase()] ??
+        ref.watch(userCacheProvider.select((cache) => cache[pk])) ??
-        ref.read(userCacheProvider.notifier).get(event.pubkey.toLowerCase());
+        ref.read(userCacheProvider.notifier).get(pk);
-    final displayName = profile?.label ?? _shortPubkey(event.pubkey);
+    final displayName = profile?.label ?? _shortPubkey(message.pubkey);
+
+    // Build mention names map from event p-tags.
+    final userCache = ref.watch(userCacheProvider);
+    final mentionNames = <String, String>{};
+    for (final mpk in message.mentionPubkeys) {
+      final p = userCache[mpk.toLowerCase()];
+      if (p?.displayName != null) {
+        mentionNames[mpk.toLowerCase()] = p!.displayName!;
+      }
+    }
 
     return Padding(
       padding: EdgeInsets.only(top: showAuthor ? Grid.xxs : Grid.quarter),
@@ -181,7 +283,7 @@ class _MessageBubble extends ConsumerWidget {
         crossAxisAlignment: CrossAxisAlignment.start,
         children: [
           if (showAuthor)
-            _UserAvatar(profile: profile, pubkey: event.pubkey)
+            _UserAvatar(profile: profile, pubkey: message.pubkey)
           else
             const SizedBox(width: 28),
           const SizedBox(width: Grid.xxs),
@@ -203,19 +305,51 @@ class _MessageBubble extends ConsumerWidget {
                         ),
                         const SizedBox(width: Grid.xxs),
                         Text(
-                          _formatTime(event.createdAt),
+                          _formatTime(message.createdAt),
                           style: context.textTheme.labelSmall?.copyWith(
                             color: context.colors.outline,
                           ),
                         ),
+                        if (message.edited) ...[
+                          const SizedBox(width: Grid.half),
+                          Text(
+                            '(edited)',
+                            style: context.textTheme.labelSmall?.copyWith(
+                              color: context.colors.outline,
+                              fontStyle: FontStyle.italic,
+                            ),
+                          ),
+                        ],
                       ],
                     ),
                   ),
-                Text(
+                MessageContent(
-                  event.content,
+                  content: message.content,
-                  style: context.textTheme.bodyMedium?.copyWith(
+                  mentionNames: mentionNames,
-                    color: context.colors.onSurface,
+                  channelNames: channelNames,
-                  ),
+                  onChannelTap: (channelId) {
+                    if (channelId == currentChannelId) {
+                      return;
+                    }
+                    final channelsAsync = ref.read(channelsProvider);
+                    final channels = channelsAsync.hasValue
+                        ? channelsAsync.value
+                        : null;
+                    Channel? targetChannel;
+                    for (final channel in channels ?? const <Channel>[]) {
+                      if (channel.id == channelId) {
+                        targetChannel = channel;
+                        break;
+                      }
+                    }
+                    if (targetChannel == null) return;
+                    Navigator.of(context).push(
+                      MaterialPageRoute<void>(
+                        builder: (_) =>
+                            ChannelDetailPage(channel: targetChannel!),
+                      ),
+                    );
+                  },
                 ),
               ],
             ),
@@ -224,29 +358,6 @@ class _MessageBubble extends ConsumerWidget {
       ),
     );
   }
-
-  static String _shortPubkey(String pubkey) {
-    if (pubkey.length > 12) {
-      return '${pubkey.substring(0, 8)}…';
-    }
-    return pubkey;
-  }
-
-  static String _formatTime(int createdAt) {
-    final dt = DateTime.fromMillisecondsSinceEpoch(
-      createdAt * 1000,
-      isUtc: true,
-    ).toLocal();
-    final now = DateTime.now();
-    final diff = now.difference(dt);
-
-    if (diff.inDays > 0) {
-      return '${dt.month}/${dt.day} ${_pad(dt.hour)}:${_pad(dt.minute)}';
-    }
-    return '${_pad(dt.hour)}:${_pad(dt.minute)}';
-  }
-
-  static String _pad(int n) => n.toString().padLeft(2, '0');
 }
 
 class _UserAvatar extends StatelessWidget {
@@ -278,6 +389,10 @@ class _UserAvatar extends StatelessWidget {
   }
 }
 
+// ---------------------------------------------------------------------------
+// Typing indicator
+// ---------------------------------------------------------------------------
+
 class _TypingIndicator extends ConsumerWidget {
   final List<TypingEntry> entries;
 
@@ -313,13 +428,12 @@ class _TypingIndicator extends ConsumerWidget {
       ),
     );
   }
-
-  static String _shortPubkey(String pubkey) {
-    if (pubkey.length > 12) return '${pubkey.substring(0, 8)}…';
-    return pubkey;
-  }
 }
 
+// ---------------------------------------------------------------------------
+// Compose bar
+// ---------------------------------------------------------------------------
+
 class _ComposeBar extends HookConsumerWidget {
   final String channelId;
 
@@ -339,9 +453,9 @@ class _ComposeBar extends HookConsumerWidget {
         await ref
             .read(sendMessageProvider)
             .call(channelId: channelId, content: text);
-        controller.clear();
+        if (context.mounted) controller.clear();
       } finally {
-        isSending.value = false;
+        if (context.mounted) isSending.value = false;
       }
     }
 
@@ -409,3 +523,28 @@ class _ComposeBar extends HookConsumerWidget {
     );
   }
 }
+
+// ---------------------------------------------------------------------------
+// Shared helpers
+// ---------------------------------------------------------------------------
+
+String _shortPubkey(String pubkey) {
+  if (pubkey.length > 12) return '${pubkey.substring(0, 8)}…';
+  return pubkey;
+}
+
+String _formatTime(int createdAt) {
+  final dt = DateTime.fromMillisecondsSinceEpoch(
+    createdAt * 1000,
+    isUtc: true,
+  ).toLocal();
+  final now = DateTime.now();
+  final diff = now.difference(dt);
+
+  if (diff.inDays > 0) {
+    return '${dt.month}/${dt.day} ${_pad(dt.hour)}:${_pad(dt.minute)}';
+  }
+  return '${_pad(dt.hour)}:${_pad(dt.minute)}';
+}
+
+String _pad(int n) => n.toString().padLeft(2, '0');

mobile/lib/features/channels/message_content.dart

@@ -0,0 +1,252 @@
+import 'package:flutter/material.dart';
+import 'package:gpt_markdown/gpt_markdown.dart';
+import 'package:gpt_markdown/custom_widgets/markdown_config.dart';
+import 'package:url_launcher/url_launcher.dart';
+
+import '../../shared/theme/theme.dart';
+
+/// Renders message content with markdown formatting, @mentions, and
+/// #channel links using [GptMarkdown] plus custom inline components for
+/// Sprout-specific tokens.
+class MessageContent extends StatelessWidget {
+  final String content;
+
+  /// Display names for mentioned pubkeys, extracted from event p-tags.
+  /// Keys are lowercase pubkeys, values are display names.
+  final Map<String, String> mentionNames;
+
+  /// Known channel names for #channel links. Keys are lowercase channel
+  /// names, values are channel IDs.
+  final Map<String, String> channelNames;
+
+  /// Called when a #channel link is tapped.
+  final void Function(String channelId)? onChannelTap;
+
+  final TextStyle? baseStyle;
+
+  const MessageContent({
+    super.key,
+    required this.content,
+    this.mentionNames = const {},
+    this.channelNames = const {},
+    this.onChannelTap,
+    this.baseStyle,
+  });
+
+  @override
+  Widget build(BuildContext context) {
+    final style =
+        baseStyle ??
+        context.textTheme.bodyMedium?.copyWith(color: context.colors.onSurface);
+
+    return GptMarkdown(
+      content,
+      style: style,
+      followLinkColor: false,
+      linkBuilder: (context, linkText, url, linkStyle) =>
+          _buildLink(context, linkText, url, linkStyle, style),
+      inlineComponents: [
+        _MentionMd(mentionNames: mentionNames),
+        _ChannelLinkMd(channelNames: channelNames, onChannelTap: onChannelTap),
+        ...MarkdownComponent.inlineComponents,
+      ],
+    );
+  }
+
+  // ---------------------------------------------------------------------------
+  // Link builder (URL scheme validation)
+  // ---------------------------------------------------------------------------
+
+  Widget _buildLink(
+    BuildContext context,
+    InlineSpan linkText,
+    String url,
+    TextStyle linkStyle,
+    TextStyle? fallbackStyle,
+  ) {
+    String text = '';
+    linkText.visitChildren((span) {
+      if (span is TextSpan && span.text != null) {
+        text += span.text!;
+      }
+      return true;
+    });
+
+    final baseStyle = fallbackStyle ?? linkStyle;
+
+    return GestureDetector(
+      onTap: () {
+        final uri = Uri.tryParse(url);
+        if (uri != null && (uri.scheme == 'http' || uri.scheme == 'https')) {
+          launchUrl(uri, mode: LaunchMode.externalApplication);
+        }
+      },
+      child: Text(
+        text,
+        style: baseStyle.copyWith(
+          color: context.colors.primary,
+          decoration: TextDecoration.underline,
+          decorationColor: context.colors.primary,
+        ),
+      ),
+    );
+  }
+}
+
+class _MentionMd extends InlineMd {
+  final Map<String, String> mentionNames;
+  late final RegExp _exp = _buildPrefixPattern(
+    prefix: '@',
+    knownNames: _mentionAliases(mentionNames.values),
+    genericTokenPattern: r'[A-Za-z0-9_][A-Za-z0-9_-]*',
+  );
+
+  _MentionMd({required this.mentionNames});
+
+  @override
+  RegExp get exp => _exp;
+
+  @override
+  InlineSpan span(
+    BuildContext context,
+    String text,
+    final GptMarkdownConfig config,
+  ) {
+    final raw = exp.firstMatch(text.trim())?.group(0);
+    if (raw == null) {
+      return TextSpan(text: text, style: config.style);
+    }
+
+    final name = raw.substring(1).toLowerCase();
+    String? displayName;
+    for (final entry in mentionNames.entries) {
+      final entryName = entry.value.toLowerCase();
+      final firstName = entryName.split(RegExp(r'\s+')).first;
+      if (entryName == name || firstName == name) {
+        displayName = entry.value;
+        break;
+      }
+    }
+
+    return WidgetSpan(
+      alignment: PlaceholderAlignment.baseline,
+      baseline: TextBaseline.alphabetic,
+      child: _TokenPill(
+        text: '@${displayName ?? raw.substring(1)}',
+        textStyle: config.style,
+      ),
+    );
+  }
+}
+
+class _ChannelLinkMd extends InlineMd {
+  final Map<String, String> channelNames;
+  final void Function(String channelId)? onChannelTap;
+  late final RegExp _exp = _buildPrefixPattern(
+    prefix: '#',
+    knownNames: channelNames.keys,
+    genericTokenPattern: r'[A-Za-z0-9_][A-Za-z0-9_-]*',
+  );
+
+  _ChannelLinkMd({required this.channelNames, this.onChannelTap});
+
+  @override
+  RegExp get exp => _exp;
+
+  @override
+  InlineSpan span(
+    BuildContext context,
+    String text,
+    final GptMarkdownConfig config,
+  ) {
+    final raw = exp.firstMatch(text.trim())?.group(0);
+    if (raw == null) {
+      return TextSpan(text: text, style: config.style);
+    }
+
+    final channelId = channelNames[raw.substring(1).toLowerCase()];
+    final child = _TokenPill(
+      text: raw,
+      textStyle: config.style?.copyWith(fontWeight: FontWeight.w500),
+    );
+
+    return WidgetSpan(
+      alignment: PlaceholderAlignment.baseline,
+      baseline: TextBaseline.alphabetic,
+      child: channelId != null && onChannelTap != null
+          ? GestureDetector(onTap: () => onChannelTap!(channelId), child: child)
+          : child,
+    );
+  }
+}
+
+class _TokenPill extends StatelessWidget {
+  final String text;
+  final TextStyle? textStyle;
+
+  const _TokenPill({required this.text, this.textStyle});
+
+  @override
+  Widget build(BuildContext context) {
+    return Container(
+      padding: const EdgeInsets.symmetric(horizontal: 4, vertical: 1),
+      decoration: BoxDecoration(
+        color: context.colors.primary.withValues(alpha: 0.15),
+        borderRadius: BorderRadius.circular(Radii.sm),
+      ),
+      child: Text(
+        text,
+        style:
+            textStyle?.copyWith(color: context.colors.primary) ??
+            context.textTheme.bodyMedium?.copyWith(
+              color: context.colors.primary,
+            ),
+      ),
+    );
+  }
+}
+
+RegExp _buildPrefixPattern({
+  required String prefix,
+  required Iterable<String> knownNames,
+  required String genericTokenPattern,
+}) {
+  final names =
+      knownNames
+          .map((name) => name.trim())
+          .where((name) => name.isNotEmpty)
+          .toSet()
+          .toList()
+        ..sort((a, b) => b.length.compareTo(a.length));
+
+  final escapedPrefix = RegExp.escape(prefix);
+  const leadingBoundary = r'(?<![\w./:-])';
+  const trailingBoundary = r'(?=$|[\s,;.!?:)\]}])';
+
+  if (names.isEmpty) {
+    return RegExp(
+      '$leadingBoundary$escapedPrefix(?:$genericTokenPattern)$trailingBoundary',
+      caseSensitive: false,
+      multiLine: true,
+    );
+  }
+
+  final knownAlternatives = names.map(RegExp.escape).join('|');
+  return RegExp(
+    '$leadingBoundary$escapedPrefix(?:(?:$knownAlternatives)$trailingBoundary|(?:$genericTokenPattern)$trailingBoundary)',
+    caseSensitive: false,
+    multiLine: true,
+  );
+}
+
+Iterable<String> _mentionAliases(Iterable<String> mentionNames) sync* {
+  for (final name in mentionNames) {
+    final trimmed = name.trim();
+    if (trimmed.isEmpty) continue;
+    yield trimmed;
+    final firstName = trimmed.split(RegExp(r'\s+')).first;
+    if (firstName.isNotEmpty) {
+      yield firstName;
+    }
+  }
+}

mobile/lib/features/channels/timeline_message.dart

@@ -0,0 +1,238 @@
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+
+import '../../shared/relay/relay.dart';
+
+// ---------------------------------------------------------------------------
+// System event types (kind 40099)
+// ---------------------------------------------------------------------------
+
+enum SystemEventType {
+  memberJoined,
+  memberLeft,
+  memberRemoved,
+  topicChanged,
+  purposeChanged,
+  channelCreated,
+  channelArchived,
+  channelUnarchived,
+}
+
+@immutable
+class SystemEvent {
+  final SystemEventType type;
+  final String? actorPubkey;
+  final String? targetPubkey;
+  final String? topic;
+  final String? purpose;
+
+  const SystemEvent({
+    required this.type,
+    this.actorPubkey,
+    this.targetPubkey,
+    this.topic,
+    this.purpose,
+  });
+
+  /// Parse a system event from the JSON content of a kind-40099 event.
+  /// Returns null if the payload is unrecognised.
+  static SystemEvent? fromContent(String content) {
+    final Map<dynamic, dynamic> json;
+    try {
+      final decoded = jsonDecode(content);
+      if (decoded is! Map) {
+        return null;
+      }
+      json = decoded;
+    } catch (_) {
+      return null;
+    }
+
+    final type = switch (_readString(json, 'type')) {
+      'member_joined' => SystemEventType.memberJoined,
+      'member_left' => SystemEventType.memberLeft,
+      'member_removed' => SystemEventType.memberRemoved,
+      'topic_changed' => SystemEventType.topicChanged,
+      'purpose_changed' => SystemEventType.purposeChanged,
+      'channel_created' => SystemEventType.channelCreated,
+      'channel_archived' => SystemEventType.channelArchived,
+      'channel_unarchived' => SystemEventType.channelUnarchived,
+      _ => null,
+    };
+
+    if (type == null) return null;
+
+    return SystemEvent(
+      type: type,
+      actorPubkey: _readString(json, 'actor'),
+      targetPubkey: _readString(json, 'target'),
+      topic: _readString(json, 'topic'),
+      purpose: _readString(json, 'purpose'),
+    );
+  }
+
+  /// Human-readable description. [resolveLabel] maps a pubkey to a display
+  /// name — the caller provides it so this class stays free of provider deps.
+  String describe(String Function(String? pubkey) resolveLabel) {
+    final actor = resolveLabel(actorPubkey);
+
+    return switch (type) {
+      SystemEventType.memberJoined => () {
+        if (actorPubkey != null && actorPubkey == targetPubkey) {
+          return '$actor joined the channel';
+        }
+        final target = resolveLabel(targetPubkey);
+        return '$actor added $target to the channel';
+      }(),
+      SystemEventType.memberLeft => '$actor left the channel',
+      SystemEventType.memberRemoved => () {
+        final target = resolveLabel(targetPubkey);
+        return '$actor removed $target from the channel';
+      }(),
+      SystemEventType.topicChanged => '$actor changed the topic to "$topic"',
+      SystemEventType.purposeChanged =>
+        '$actor changed the purpose to "$purpose"',
+      SystemEventType.channelCreated => '$actor created this channel',
+      SystemEventType.channelArchived => '$actor archived this channel',
+      SystemEventType.channelUnarchived => '$actor unarchived this channel',
+    };
+  }
+}
+
+// ---------------------------------------------------------------------------
+// TimelineMessage — a processed, display-ready message
+// ---------------------------------------------------------------------------
+
+@immutable
+class TimelineMessage {
+  final String id;
+  final String pubkey;
+  final int createdAt;
+  final String content;
+  final bool isSystem;
+  final bool edited;
+  final SystemEvent? systemEvent;
+
+  /// Pubkeys mentioned in this message (from p-tags).
+  final List<String> mentionPubkeys;
+
+  const TimelineMessage({
+    required this.id,
+    required this.pubkey,
+    required this.createdAt,
+    required this.content,
+    this.isSystem = false,
+    this.edited = false,
+    this.systemEvent,
+    this.mentionPubkeys = const [],
+  });
+}
+
+// ---------------------------------------------------------------------------
+// formatTimeline — converts raw NostrEvents into display-ready messages
+// ---------------------------------------------------------------------------
+
+/// Process a chronologically-sorted list of [NostrEvent]s into a list of
+/// [TimelineMessage]s, applying deletions, edits, and system event parsing.
+///
+/// Mirrors the desktop's `formatTimelineMessages` logic.
+List<TimelineMessage> formatTimeline(List<NostrEvent> events) {
+  // 1. Collect deletion targets.
+  final deletedIds = <String>{};
+  for (final event in events) {
+    if (event.kind != EventKind.deletion) continue;
+    for (final tag in event.tags) {
+      if (tag.length >= 2 && tag[0] == 'e') {
+        deletedIds.add(tag[1]);
+      }
+    }
+  }
+
+  // 2. Build edit map: targetId → latest edit content.
+  final edits = <String, _Edit>{};
+  for (final event in events) {
+    if (event.kind != EventKind.streamMessageEdit) continue;
+    if (deletedIds.contains(event.id)) continue;
+
+    final targetId = _lastETag(event.tags);
+    if (targetId == null || deletedIds.contains(targetId)) continue;
+
+    final existing = edits[targetId];
+    if (existing == null || event.createdAt > existing.createdAt) {
+      edits[targetId] = _Edit(
+        content: event.content,
+        createdAt: event.createdAt,
+      );
+    }
+  }
+
+  // 3. Filter to visible content events and build TimelineMessages.
+  final result = <TimelineMessage>[];
+  for (final event in events) {
+    if (deletedIds.contains(event.id)) continue;
+
+    if (event.kind == EventKind.systemMessage) {
+      final systemEvent = SystemEvent.fromContent(event.content);
+      if (systemEvent != null) {
+        result.add(
+          TimelineMessage(
+            id: event.id,
+            pubkey: event.pubkey,
+            createdAt: event.createdAt,
+            content: event.content,
+            isSystem: true,
+            systemEvent: systemEvent,
+          ),
+        );
+      }
+      continue;
+    }
+
+    if (event.kind == EventKind.streamMessage ||
+        event.kind == EventKind.streamMessageV2 ||
+        event.kind == EventKind.streamMessageDiff) {
+      final edit = edits[event.id];
+      final mentions = <String>[
+        for (final tag in event.tags)
+          if (tag.length >= 2 && tag[0] == 'p') tag[1],
+      ];
+      result.add(
+        TimelineMessage(
+          id: event.id,
+          pubkey: event.pubkey,
+          createdAt: event.createdAt,
+          content: edit?.content ?? event.content,
+          edited: edit != null,
+          mentionPubkeys: mentions,
+        ),
+      );
+    }
+  }
+
+  return result;
+}
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+class _Edit {
+  final String content;
+  final int createdAt;
+  const _Edit({required this.content, required this.createdAt});
+}
+
+/// Get the last `e` tag value (reaction/edit target convention).
+String? _lastETag(List<List<String>> tags) {
+  for (var i = tags.length - 1; i >= 0; i--) {
+    final tag = tags[i];
+    if (tag.length >= 2 && tag[0] == 'e') return tag[1];
+  }
+  return null;
+}
+
+String? _readString(Map<dynamic, dynamic> json, String key) {
+  final value = json[key];
+  return value is String ? value : null;
+}

mobile/pubspec.lock

@@ -286,6 +286,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "6.0.0"
+  flutter_math_fork:
+    dependency: transitive
+    description:
+      name: flutter_math_fork
+      sha256: "6d5f2f1aa57ae539ffb0a04bb39d2da67af74601d685a161aff7ce5bda5fa407"
+      url: "https://pub.dev"
+    source: hosted
+    version: "0.7.4"
   flutter_riverpod:
     dependency: transitive
     description:
@@ -342,6 +350,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "3.1.2"
+  flutter_svg:
+    dependency: transitive
+    description:
+      name: flutter_svg
+      sha256: "1ded017b39c8e15c8948ea855070a5ff8ff8b3d5e83f3446e02d6bb12add7ad9"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.2.4"
   flutter_test:
     dependency: "direct dev"
     description: flutter
@@ -376,6 +392,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "2.1.3"
+  gpt_markdown:
+    dependency: "direct main"
+    description:
+      name: gpt_markdown
+      sha256: "5c565a438e569b3b546023d0d4eccccf87e260a3289a17c4e241c41d5e7545df"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.6"
   hooks:
     dependency: transitive
     description:
@@ -560,6 +584,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.17.6"
+  nested:
+    dependency: transitive
+    description:
+      name: nested
+      sha256: "03bac4c528c64c95c722ec99280375a6f2fc708eec17c7b3f07253b626cd2a20"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.0.0"
   nm:
     dependency: transitive
     description:
@@ -608,6 +640,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.9.1"
+  path_parsing:
+    dependency: transitive
+    description:
+      name: path_parsing
+      sha256: "883402936929eac138ee0a45da5b0f2c80f89913e6dc3bf77eb65b84b409c6ca"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.0"
   path_provider:
     dependency: transitive
     description:
@@ -696,6 +736,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.5.2"
+  provider:
+    dependency: transitive
+    description:
+      name: provider
+      sha256: "4e82183fa20e5ca25703ead7e05de9e4cceed1fbd1eadc1ac3cb6f565a09f272"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.1.5+1"
   pub_semver:
     dependency: transitive
     description:
@@ -933,6 +981,14 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "0.6.16"
+  tuple:
+    dependency: transitive
+    description:
+      name: tuple
+      sha256: a97ce2013f240b2f3807bcbaf218765b6f301c3eff91092bcfa23a039e7dd151
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.0.2"
   typed_data:
     dependency: transitive
     description:
@@ -941,6 +997,70 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "1.4.0"
+  url_launcher:
+    dependency: "direct main"
+    description:
+      name: url_launcher
+      sha256: f6a7e5c4835bb4e3026a04793a4199ca2d14c739ec378fdfe23fc8075d0439f8
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.2"
+  url_launcher_android:
+    dependency: transitive
+    description:
+      name: url_launcher_android
+      sha256: "3bb000251e55d4a209aa0e2e563309dc9bb2befea2295fd0cec1f51760aac572"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.3.29"
+  url_launcher_ios:
+    dependency: transitive
+    description:
+      name: url_launcher_ios
+      sha256: "580fe5dfb51671ae38191d316e027f6b76272b026370708c2d898799750a02b0"
+      url: "https://pub.dev"
+    source: hosted
+    version: "6.4.1"
+  url_launcher_linux:
+    dependency: transitive
+    description:
+      name: url_launcher_linux
+      sha256: d5e14138b3bc193a0f63c10a53c94b91d399df0512b1f29b94a043db7482384a
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.2"
+  url_launcher_macos:
+    dependency: transitive
+    description:
+      name: url_launcher_macos
+      sha256: "368adf46f71ad3c21b8f06614adb38346f193f3a59ba8fe9a2fd74133070ba18"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.2.5"
+  url_launcher_platform_interface:
+    dependency: transitive
+    description:
+      name: url_launcher_platform_interface
+      sha256: "552f8a1e663569be95a8190206a38187b531910283c3e982193e4f2733f01029"
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.3.2"
+  url_launcher_web:
+    dependency: transitive
+    description:
+      name: url_launcher_web
+      sha256: d0412fcf4c6b31ecfdb7762359b7206ffba3bbffd396c6d9f9c4616ece476c1f
+      url: "https://pub.dev"
+    source: hosted
+    version: "2.4.2"
+  url_launcher_windows:
+    dependency: transitive
+    description:
+      name: url_launcher_windows
+      sha256: "712c70ab1b99744ff066053cbe3e80c73332b38d46e5e945c98689b2e66fc15f"
+      url: "https://pub.dev"
+    source: hosted
+    version: "3.1.5"
   uuid:
     dependency: transitive
     description:
@@ -949,6 +1069,30 @@ packages:
       url: "https://pub.dev"
     source: hosted
     version: "4.5.3"
+  vector_graphics:
+    dependency: transitive
+    description:
+      name: vector_graphics
+      sha256: "81da85e9ca8885ade47f9685b953cb098970d11be4821ac765580a6607ea4373"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.21"
+  vector_graphics_codec:
+    dependency: transitive
+    description:
+      name: vector_graphics_codec
+      sha256: "99fd9fbd34d9f9a32efd7b6a6aae14125d8237b10403b422a6a6dfeac2806146"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.1.13"
+  vector_graphics_compiler:
+    dependency: transitive
+    description:
+      name: vector_graphics_compiler
+      sha256: "5a88dd14c0954a5398af544651c7fb51b457a2a556949bfb25369b210ef73a74"
+      url: "https://pub.dev"
+    source: hosted
+    version: "1.2.0"
   vector_math:
     dependency: transitive
     description:

mobile/pubspec.yaml

@@ -19,6 +19,8 @@ dependencies:
   web_socket_channel: ^3.0.1
   connectivity_plus: ^6.1.4
   nostr: ^1.5.0
+  url_launcher: ^6.3.2
+  gpt_markdown: ^1.1.6
 
 dev_dependencies:
   flutter_test:

mobile/test/features/channels/channel_detail_page_test.dart

@@ -0,0 +1,926 @@
+import 'dart:convert';
+
+import 'package:flutter/foundation.dart';
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:hooks_riverpod/hooks_riverpod.dart';
+import 'package:lucide_icons_flutter/lucide_icons.dart';
+import 'package:sprout_mobile/features/channels/channel.dart';
+import 'package:sprout_mobile/features/channels/channel_detail_page.dart';
+import 'package:sprout_mobile/features/channels/channel_messages_provider.dart';
+import 'package:sprout_mobile/features/channels/channel_typing_provider.dart';
+import 'package:sprout_mobile/features/channels/channels_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 = 'test-channel';
+
+final _testChannel = Channel(
+  id: _channelId,
+  name: 'general',
+  channelType: 'stream',
+  visibility: 'open',
+  description: 'General discussion',
+  createdBy: 'abc123',
+  createdAt: DateTime(2025),
+  memberCount: 5,
+  isMember: true,
+);
+
+NostrEvent _textMsg({
+  required String id,
+  required String pubkey,
+  required String content,
+  int createdAt = 1000,
+}) => NostrEvent(
+  id: id,
+  pubkey: pubkey,
+  createdAt: createdAt,
+  kind: EventKind.streamMessage,
+  tags: [
+    ['h', _channelId],
+  ],
+  content: content,
+  sig: '',
+);
+
+NostrEvent _systemMsg({
+  required String id,
+  required Map<String, dynamic> payload,
+  int createdAt = 1000,
+}) => NostrEvent(
+  id: id,
+  pubkey: 'relay',
+  createdAt: createdAt,
+  kind: EventKind.systemMessage,
+  tags: [
+    ['h', _channelId],
+  ],
+  content: jsonEncode(payload),
+  sig: '',
+);
+
+NostrEvent _deletion({
+  required String id,
+  required List<String> targetIds,
+  int createdAt = 2000,
+}) => NostrEvent(
+  id: id,
+  pubkey: 'abc123',
+  createdAt: createdAt,
+  kind: EventKind.deletion,
+  tags: [
+    ['h', _channelId],
+    for (final t in targetIds) ['e', t],
+  ],
+  content: '',
+  sig: '',
+);
+
+NostrEvent _edit({
+  required String id,
+  required String targetId,
+  required String content,
+  int createdAt = 2000,
+}) => NostrEvent(
+  id: id,
+  pubkey: 'abc123',
+  createdAt: createdAt,
+  kind: EventKind.streamMessageEdit,
+  tags: [
+    ['h', _channelId],
+    ['e', targetId],
+  ],
+  content: content,
+  sig: '',
+);
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+Widget _buildTestable({
+  required List<NostrEvent> messages,
+  List<TypingEntry> typing = const [],
+  Map<String, UserProfile> users = const {},
+  Channel? channel,
+  List<Channel>? channels,
+  List<NavigatorObserver> navigatorObservers = const [],
+}) {
+  return ProviderScope(
+    overrides: [
+      channelMessagesProvider(
+        _channelId,
+      ).overrideWith(() => _FakeMessagesNotifier(messages)),
+      channelTypingProvider(
+        _channelId,
+      ).overrideWith(() => _FakeTypingNotifier(typing)),
+      userCacheProvider.overrideWith(() => _FakeUserCacheNotifier(users)),
+      channelsProvider.overrideWith(
+        () => _FakeChannelsNotifier(channels ?? [channel ?? _testChannel]),
+      ),
+      // Stub the relay client provider so preloadMembers doesn't crash.
+      relayClientProvider.overrideWithValue(
+        RelayClient(baseUrl: 'http://localhost:3000'),
+      ),
+    ],
+    child: MaterialApp(
+      theme: AppTheme.lightTheme,
+      navigatorObservers: navigatorObservers,
+      home: ChannelDetailPage(channel: channel ?? _testChannel),
+    ),
+  );
+}
+
+/// Finder that searches for text within RichText spans. [find.text] only
+/// matches the top-level text property; this also searches nested TextSpans.
+Finder findRichText(String text) {
+  return find.byWidgetPredicate((widget) {
+    if (widget is RichText) {
+      return widget.text.toPlainText().contains(text);
+    }
+    return false;
+  }, description: 'RichText containing "$text"');
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+void main() {
+  group('ChannelDetailPage', () {
+    testWidgets('shows empty state when no messages', (tester) async {
+      await tester.pumpWidget(_buildTestable(messages: []));
+      await tester.pumpAndSettle();
+
+      expect(find.text('No messages yet'), findsOneWidget);
+      expect(find.text('Be the first to say something!'), findsOneWidget);
+    });
+
+    testWidgets('renders text messages with author and content', (
+      tester,
+    ) async {
+      final messages = [
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'Hello world!',
+          createdAt: 1000,
+        ),
+        _textMsg(
+          id: 'msg2',
+          pubkey: 'bob',
+          content: 'Hey Alice!',
+          createdAt: 1100,
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(findRichText('Hello world!'), findsOneWidget);
+      expect(findRichText('Hey Alice!'), findsOneWidget);
+      expect(find.text('Alice'), findsOneWidget);
+      expect(find.text('Bob'), findsOneWidget);
+    });
+
+    testWidgets('groups consecutive messages from same author', (tester) async {
+      final messages = [
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'First message',
+          createdAt: 1000,
+        ),
+        _textMsg(
+          id: 'msg2',
+          pubkey: 'alice',
+          content: 'Second message',
+          createdAt: 1060, // within 5 min
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      // Author name should appear only once (grouped).
+      expect(find.text('Alice'), findsOneWidget);
+      expect(findRichText('First message'), findsOneWidget);
+      expect(findRichText('Second message'), findsOneWidget);
+    });
+
+    testWidgets('shows author again after 5min gap', (tester) async {
+      final messages = [
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'First',
+          createdAt: 1000,
+        ),
+        _textMsg(
+          id: 'msg2',
+          pubkey: 'alice',
+          content: 'Second',
+          createdAt: 1400, // 6+ min later
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      // Author name appears twice since messages are >5min apart.
+      expect(find.text('Alice'), findsNWidgets(2));
+    });
+
+    testWidgets('shows pubkey fallback when no profile', (tester) async {
+      final messages = [
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'abcdef1234567890',
+          content: 'Hi',
+          createdAt: 1000,
+        ),
+      ];
+
+      await tester.pumpWidget(_buildTestable(messages: messages));
+      await tester.pumpAndSettle();
+
+      expect(findRichText('Hi'), findsOneWidget);
+      // Should show first 8 chars of pubkey + ellipsis
+      expect(find.text('abcdef12…'), findsOneWidget);
+    });
+  });
+
+  group('System messages', () {
+    testWidgets('renders channel_created system event', (tester) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {'type': 'channel_created', 'actor': 'alice'},
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice created this channel'), findsOneWidget);
+    });
+
+    testWidgets('renders member_joined (self-join) system event', (
+      tester,
+    ) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {'type': 'member_joined', 'actor': 'bob', 'target': 'bob'},
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob')},
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Bob joined the channel'), findsOneWidget);
+    });
+
+    testWidgets('renders member_joined (added by other) system event', (
+      tester,
+    ) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {'type': 'member_joined', 'actor': 'alice', 'target': 'bob'},
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice added Bob to the channel'), findsOneWidget);
+    });
+
+    testWidgets('renders member_left system event', (tester) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {'type': 'member_left', 'actor': 'bob'},
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob')},
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Bob left the channel'), findsOneWidget);
+    });
+
+    testWidgets('renders member_removed system event', (tester) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {
+            'type': 'member_removed',
+            'actor': 'alice',
+            'target': 'bob',
+          },
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice removed Bob from the channel'), findsOneWidget);
+    });
+
+    testWidgets('renders topic_changed system event', (tester) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {
+            'type': 'topic_changed',
+            'actor': 'alice',
+            'topic': 'Release planning',
+          },
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(
+        find.text('Alice changed the topic to "Release planning"'),
+        findsOneWidget,
+      );
+    });
+
+    testWidgets('renders purpose_changed system event', (tester) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {
+            'type': 'purpose_changed',
+            'actor': 'alice',
+            'purpose': 'Team standup notes',
+          },
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(
+        find.text('Alice changed the purpose to "Team standup notes"'),
+        findsOneWidget,
+      );
+    });
+
+    testWidgets('system message breaks author grouping', (tester) async {
+      final messages = [
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'Before',
+          createdAt: 1000,
+        ),
+        _systemMsg(
+          id: 'sys1',
+          payload: {'type': 'member_joined', 'actor': 'bob', 'target': 'bob'},
+          createdAt: 1010,
+        ),
+        _textMsg(
+          id: 'msg2',
+          pubkey: 'alice',
+          content: 'After',
+          createdAt: 1020,
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      // Alice should appear twice — system message breaks grouping.
+      expect(find.text('Alice'), findsNWidgets(2));
+    });
+
+    testWidgets('skips unknown system event types', (tester) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {'type': 'unknown_future_type', 'actor': 'alice'},
+        ),
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'Hello',
+          createdAt: 1100,
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      // Only the text message should render, unknown system event is skipped.
+      expect(findRichText('Hello'), findsOneWidget);
+      // No system message row rendered for unknown type.
+      expect(find.byIcon(LucideIcons.arrowLeftRight), findsNothing);
+    });
+  });
+
+  group('Deletions', () {
+    testWidgets('deleted messages are not shown', (tester) async {
+      final messages = [
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'Keep this',
+          createdAt: 1000,
+        ),
+        _textMsg(
+          id: 'msg2',
+          pubkey: 'bob',
+          content: 'Delete this',
+          createdAt: 1100,
+        ),
+        _deletion(id: 'del1', targetIds: ['msg2'], createdAt: 1200),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(findRichText('Keep this'), findsOneWidget);
+      expect(findRichText('Delete this'), findsNothing);
+    });
+
+    testWidgets('deletion of multiple messages', (tester) async {
+      final messages = [
+        _textMsg(id: 'msg1', pubkey: 'a', content: 'One', createdAt: 1000),
+        _textMsg(id: 'msg2', pubkey: 'a', content: 'Two', createdAt: 1100),
+        _textMsg(id: 'msg3', pubkey: 'a', content: 'Three', createdAt: 1200),
+        _deletion(id: 'del1', targetIds: ['msg1', 'msg3'], createdAt: 1300),
+      ];
+
+      await tester.pumpWidget(_buildTestable(messages: messages));
+      await tester.pumpAndSettle();
+
+      expect(findRichText('One'), findsNothing);
+      expect(findRichText('Two'), findsOneWidget);
+      expect(findRichText('Three'), findsNothing);
+    });
+  });
+
+  group('Edits', () {
+    testWidgets('edited message shows updated content and (edited) label', (
+      tester,
+    ) async {
+      final messages = [
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'Original text',
+          createdAt: 1000,
+        ),
+        _edit(
+          id: 'edit1',
+          targetId: 'msg1',
+          content: 'Edited text',
+          createdAt: 1100,
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(findRichText('Edited text'), findsOneWidget);
+      expect(findRichText('Original text'), findsNothing);
+      expect(find.text('(edited)'), findsOneWidget);
+    });
+
+    testWidgets('latest edit wins when multiple edits exist', (tester) async {
+      final messages = [
+        _textMsg(id: 'msg1', pubkey: 'alice', content: 'V1', createdAt: 1000),
+        _edit(id: 'e1', targetId: 'msg1', content: 'V2', createdAt: 1100),
+        _edit(id: 'e2', targetId: 'msg1', content: 'V3', createdAt: 1200),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(findRichText('V3'), findsOneWidget);
+      expect(findRichText('V1'), findsNothing);
+      expect(findRichText('V2'), findsNothing);
+    });
+  });
+
+  group('Typing indicator', () {
+    testWidgets('shows single typer', (tester) async {
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: [],
+          typing: [
+            TypingEntry(
+              pubkey: 'alice',
+              expiresAtMs: DateTime.now().millisecondsSinceEpoch + 8000,
+            ),
+          ],
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice is typing…'), findsOneWidget);
+    });
+
+    testWidgets('shows two typers', (tester) async {
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: [],
+          typing: [
+            TypingEntry(
+              pubkey: 'alice',
+              expiresAtMs: DateTime.now().millisecondsSinceEpoch + 8000,
+            ),
+            TypingEntry(
+              pubkey: 'bob',
+              expiresAtMs: DateTime.now().millisecondsSinceEpoch + 8000,
+            ),
+          ],
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice and Bob are typing…'), findsOneWidget);
+    });
+
+    testWidgets('shows N others for 3+ typers', (tester) async {
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: [],
+          typing: [
+            TypingEntry(
+              pubkey: 'alice',
+              expiresAtMs: DateTime.now().millisecondsSinceEpoch + 8000,
+            ),
+            TypingEntry(
+              pubkey: 'bob',
+              expiresAtMs: DateTime.now().millisecondsSinceEpoch + 8000,
+            ),
+            TypingEntry(
+              pubkey: 'carol',
+              expiresAtMs: DateTime.now().millisecondsSinceEpoch + 8000,
+            ),
+          ],
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+            'carol': const UserProfile(pubkey: 'carol', displayName: 'Carol'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice and 2 others are typing…'), findsOneWidget);
+    });
+  });
+
+  group('Compose bar', () {
+    testWidgets('shows text field and send button', (tester) async {
+      await tester.pumpWidget(_buildTestable(messages: []));
+      await tester.pumpAndSettle();
+
+      expect(find.byType(TextField), findsOneWidget);
+      expect(find.byIcon(LucideIcons.sendHorizontal), findsOneWidget);
+    });
+
+    testWidgets('shows hint text', (tester) async {
+      await tester.pumpWidget(_buildTestable(messages: []));
+      await tester.pumpAndSettle();
+
+      expect(find.text('Message…'), findsOneWidget);
+    });
+  });
+
+  group('App bar', () {
+    testWidgets('shows channel name with hash icon', (tester) async {
+      await tester.pumpWidget(_buildTestable(messages: []));
+      await tester.pumpAndSettle();
+
+      expect(find.text('general'), findsOneWidget);
+      expect(find.byIcon(LucideIcons.hash), findsOneWidget);
+    });
+
+    testWidgets('shows lock icon for private channel', (tester) async {
+      final privateChannel = Channel(
+        id: _channelId,
+        name: 'secret',
+        channelType: 'stream',
+        visibility: 'private',
+        description: 'Private channel',
+        createdBy: 'abc',
+        createdAt: DateTime(2025),
+        memberCount: 3,
+        isMember: true,
+      );
+
+      await tester.pumpWidget(
+        _buildTestable(messages: [], channel: privateChannel),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('secret'), findsOneWidget);
+      expect(find.byIcon(LucideIcons.lock), findsOneWidget);
+    });
+  });
+
+  group('Error and loading states', () {
+    testWidgets('shows error message on failure', (tester) async {
+      await tester.pumpWidget(
+        ProviderScope(
+          overrides: [
+            channelMessagesProvider(
+              _channelId,
+            ).overrideWith(() => _ErrorMessagesNotifier()),
+            channelTypingProvider(
+              _channelId,
+            ).overrideWith(() => _FakeTypingNotifier([])),
+            userCacheProvider.overrideWith(() => _FakeUserCacheNotifier({})),
+            channelsProvider.overrideWith(
+              () => _FakeChannelsNotifier([_testChannel]),
+            ),
+            relayClientProvider.overrideWithValue(
+              RelayClient(baseUrl: 'http://localhost:3000'),
+            ),
+          ],
+          child: MaterialApp(
+            theme: AppTheme.lightTheme,
+            home: ChannelDetailPage(channel: _testChannel),
+          ),
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Failed to load messages'), findsOneWidget);
+    });
+  });
+
+  group('Mixed message timeline', () {
+    testWidgets('interleaves text and system messages correctly', (
+      tester,
+    ) async {
+      final messages = [
+        _systemMsg(
+          id: 'sys1',
+          payload: {'type': 'channel_created', 'actor': 'alice'},
+          createdAt: 900,
+        ),
+        _textMsg(
+          id: 'msg1',
+          pubkey: 'alice',
+          content: 'Welcome everyone!',
+          createdAt: 1000,
+        ),
+        _systemMsg(
+          id: 'sys2',
+          payload: {'type': 'member_joined', 'actor': 'bob', 'target': 'bob'},
+          createdAt: 1100,
+        ),
+        _textMsg(
+          id: 'msg2',
+          pubkey: 'bob',
+          content: 'Thanks for the invite!',
+          createdAt: 1200,
+        ),
+      ];
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: messages,
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+            'bob': const UserProfile(pubkey: 'bob', displayName: 'Bob'),
+          },
+        ),
+      );
+      await tester.pumpAndSettle();
+
+      expect(find.text('Alice created this channel'), findsOneWidget);
+      expect(findRichText('Welcome everyone!'), findsOneWidget);
+      expect(find.text('Bob joined the channel'), findsOneWidget);
+      expect(findRichText('Thanks for the invite!'), findsOneWidget);
+    });
+  });
+
+  group('Channel links', () {
+    testWidgets('tapping a channel link opens that channel', (tester) async {
+      final randomChannel = Channel(
+        id: 'random-channel',
+        name: 'random',
+        channelType: 'stream',
+        visibility: 'open',
+        description: 'Random discussion',
+        createdBy: 'abc123',
+        createdAt: DateTime(2025),
+        memberCount: 3,
+        isMember: true,
+      );
+      final observer = _TestNavigatorObserver();
+
+      await tester.pumpWidget(
+        _buildTestable(
+          messages: [
+            _textMsg(
+              id: 'msg1',
+              pubkey: 'alice',
+              content: 'Take this to #random',
+              createdAt: 1000,
+            ),
+          ],
+          users: {
+            'alice': const UserProfile(pubkey: 'alice', displayName: 'Alice'),
+          },
+          channels: [_testChannel, randomChannel],
+          navigatorObservers: [observer],
+        ),
+      );
+      await tester.pumpAndSettle();
+      final initialPushCount = observer.pushCount;
+
+      await tester.tap(find.text('#random'));
+      await tester.pumpAndSettle();
+
+      expect(observer.pushCount, initialPushCount + 1);
+    });
+  });
+}
+
+// ---------------------------------------------------------------------------
+// Fake providers
+// ---------------------------------------------------------------------------
+
+class _FakeMessagesNotifier extends ChannelMessagesNotifier {
+  final List<NostrEvent> _messages;
+  _FakeMessagesNotifier(this._messages) : super(_channelId);
+
+  @override
+  AsyncValue<List<NostrEvent>> build() => AsyncData(_messages);
+}
+
+class _ErrorMessagesNotifier extends ChannelMessagesNotifier {
+  _ErrorMessagesNotifier() : super(_channelId);
+
+  @override
+  AsyncValue<List<NostrEvent>> build() =>
+      AsyncError('Connection failed', StackTrace.current);
+}
+
+class _FakeTypingNotifier extends ChannelTypingNotifier {
+  final List<TypingEntry> _entries;
+  _FakeTypingNotifier(this._entries) : super(_channelId);
+
+  @override
+  List<TypingEntry> build() => _entries;
+}
+
+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 _FakeChannelsNotifier extends ChannelsNotifier {
+  final List<Channel> _channels;
+  _FakeChannelsNotifier(this._channels);
+
+  @override
+  Future<List<Channel>> build() => SynchronousFuture(_channels);
+}
+
+class _TestNavigatorObserver extends NavigatorObserver {
+  int pushCount = 0;
+
+  @override
+  void didPush(Route<dynamic> route, Route<dynamic>? previousRoute) {
+    pushCount += 1;
+    super.didPush(route, previousRoute);
+  }
+}

mobile/test/features/channels/message_content_test.dart

@@ -0,0 +1,355 @@
+import 'package:flutter/material.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:sprout_mobile/features/channels/message_content.dart';
+import 'package:sprout_mobile/shared/theme/theme.dart';
+
+Widget _testable(Widget child) {
+  return MaterialApp(
+    theme: AppTheme.lightTheme,
+    home: Scaffold(body: child),
+  );
+}
+
+/// Extracts all plain text from all RichText widgets in the tree.
+String _allRichText(WidgetTester tester) {
+  final richTexts = tester.widgetList<RichText>(find.byType(RichText));
+  return richTexts.map((rt) => rt.text.toPlainText()).join('\n');
+}
+
+/// Finds a RichText widget whose plain text contains [text].
+Finder _findRich(String text) {
+  return find.byWidgetPredicate(
+    (widget) => widget is RichText && widget.text.toPlainText().contains(text),
+    description: 'RichText containing "$text"',
+  );
+}
+
+/// Checks that the given text appears as bold (fontWeight >= w600) in some
+/// TextSpan within any RichText widget.
+bool _hasBoldSpan(WidgetTester tester, String text) {
+  for (final rt in tester.widgetList<RichText>(find.byType(RichText))) {
+    if (_spanHasStyle(
+      rt.text,
+      text,
+      (s) =>
+          s.fontWeight != null && s.fontWeight!.value >= FontWeight.w600.value,
+    )) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool _hasItalicSpan(WidgetTester tester, String text) {
+  for (final rt in tester.widgetList<RichText>(find.byType(RichText))) {
+    if (_spanHasStyle(rt.text, text, (s) => s.fontStyle == FontStyle.italic)) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool _hasStrikethroughSpan(WidgetTester tester, String text) {
+  for (final rt in tester.widgetList<RichText>(find.byType(RichText))) {
+    if (_spanHasStyle(
+      rt.text,
+      text,
+      (s) => s.decoration == TextDecoration.lineThrough,
+    )) {
+      return true;
+    }
+  }
+  return false;
+}
+
+bool _spanHasStyle(
+  InlineSpan root,
+  String text,
+  bool Function(TextStyle) check,
+) {
+  var found = false;
+  root.visitChildren((span) {
+    if (span is TextSpan &&
+        span.text != null &&
+        span.text!.contains(text) &&
+        span.style != null &&
+        check(span.style!)) {
+      found = true;
+      return false; // stop visiting
+    }
+    return true;
+  });
+  return found;
+}
+
+void main() {
+  group('MessageContent', () {
+    group('plain text', () {
+      testWidgets('renders simple text', (tester) async {
+        await tester.pumpWidget(
+          _testable(const MessageContent(content: 'Hello world')),
+        );
+
+        expect(_findRich('Hello world'), findsOneWidget);
+      });
+
+      testWidgets('renders empty content', (tester) async {
+        await tester.pumpWidget(_testable(const MessageContent(content: '')));
+
+        // Should not crash.
+        expect(find.byType(MessageContent), findsOneWidget);
+      });
+    });
+
+    group('inline formatting', () {
+      testWidgets('renders bold text', (tester) async {
+        await tester.pumpWidget(
+          _testable(const MessageContent(content: 'This is **bold** text')),
+        );
+
+        final allText = _allRichText(tester);
+        expect(allText, contains('bold'));
+        expect(allText, isNot(contains('**')));
+        expect(_hasBoldSpan(tester, 'bold'), isTrue);
+      });
+
+      testWidgets('renders italic text', (tester) async {
+        await tester.pumpWidget(
+          _testable(const MessageContent(content: 'This is *italic* text')),
+        );
+
+        final allText = _allRichText(tester);
+        expect(allText, contains('italic'));
+        expect(_hasItalicSpan(tester, 'italic'), isTrue);
+      });
+
+      testWidgets('renders strikethrough text', (tester) async {
+        await tester.pumpWidget(
+          _testable(const MessageContent(content: 'This is ~~struck~~ text')),
+        );
+
+        final allText = _allRichText(tester);
+        expect(allText, contains('struck'));
+        expect(allText, isNot(contains('~~')));
+        expect(_hasStrikethroughSpan(tester, 'struck'), isTrue);
+      });
+
+      testWidgets('renders inline code', (tester) async {
+        await tester.pumpWidget(
+          _testable(const MessageContent(content: 'Use `flutter test` to run')),
+        );
+
+        // Inline code is rendered inside a styled span.
+        expect(_findRich('flutter test'), findsWidgets);
+      });
+
+      testWidgets('renders markdown link', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: 'Check [Sprout](https://example.com)',
+            ),
+          ),
+        );
+
+        final allText = _allRichText(tester);
+        expect(allText, contains('Sprout'));
+        // Should not show raw markdown syntax.
+        expect(allText, isNot(contains('[Sprout]')));
+        expect(allText, isNot(contains('(https://example.com)')));
+      });
+
+      testWidgets('renders bare URL as link', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(content: 'Visit https://example.com today'),
+          ),
+        );
+
+        final allText = _allRichText(tester);
+        expect(allText, contains('https://example.com'));
+      });
+    });
+
+    group('code blocks', () {
+      testWidgets('renders fenced code block', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(content: 'Before\n```\ncode here\n```\nAfter'),
+          ),
+        );
+
+        expect(_findRich('code here'), findsWidgets);
+        expect(_findRich('Before'), findsWidgets);
+        expect(_findRich('After'), findsWidgets);
+      });
+
+      testWidgets('renders code block with language tag', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(content: '```dart\nvoid main() {}\n```'),
+          ),
+        );
+
+        expect(_findRich('void main() {}'), findsWidgets);
+      });
+    });
+
+    group('blockquotes', () {
+      testWidgets('renders blockquote with left border', (tester) async {
+        await tester.pumpWidget(
+          _testable(const MessageContent(content: '> This is a quote')),
+        );
+
+        final allText = _allRichText(tester);
+        expect(allText, contains('This is a quote'));
+        // Should strip the > prefix.
+        expect(allText, isNot(contains('> This')));
+      });
+    });
+
+    group('@mentions', () {
+      testWidgets('renders @mention with highlight', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: 'Hey @Alice check this out',
+              mentionNames: {'pk1': 'Alice'},
+            ),
+          ),
+        );
+
+        // Mention should be rendered as @Alice in a highlighted container.
+        expect(find.text('@Alice'), findsOneWidget);
+      });
+
+      testWidgets('renders unknown @mention as-is', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: 'Hey @unknown check this',
+              mentionNames: {},
+            ),
+          ),
+        );
+
+        expect(find.text('@unknown'), findsOneWidget);
+      });
+
+      testWidgets('does not treat email addresses as mentions', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: 'Email alice@example.com for access',
+              mentionNames: {'pk1': 'Alice'},
+            ),
+          ),
+        );
+
+        expect(_allRichText(tester), contains('alice@example.com'));
+        expect(find.text('@example.com'), findsNothing);
+      });
+    });
+
+    group('#channel links', () {
+      testWidgets('renders #channel with highlight', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: 'Check out #general',
+              channelNames: {'general': 'ch-id-1'},
+            ),
+          ),
+        );
+
+        expect(find.text('#general'), findsOneWidget);
+      });
+
+      testWidgets('channel tap callback fires', (tester) async {
+        String? tappedId;
+        await tester.pumpWidget(
+          _testable(
+            MessageContent(
+              content: 'See #general',
+              channelNames: const {'general': 'ch-id-1'},
+              onChannelTap: (id) => tappedId = id,
+            ),
+          ),
+        );
+
+        await tester.tap(find.text('#general'));
+        expect(tappedId, 'ch-id-1');
+      });
+
+      testWidgets('unknown channel renders without tap', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(content: 'Check #unknown', channelNames: {}),
+          ),
+        );
+
+        expect(find.text('#unknown'), findsOneWidget);
+      });
+
+      testWidgets('does not treat URL fragments as channel links', (
+        tester,
+      ) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: 'See https://example.com/docs#frag',
+              channelNames: {'frag': 'ch-id-1'},
+            ),
+          ),
+        );
+
+        expect(_allRichText(tester), contains('https://example.com/docs#frag'));
+        expect(find.text('#frag'), findsNothing);
+      });
+    });
+
+    group('mixed content', () {
+      testWidgets('renders bold with mentions', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: '**Important** @Alice please review',
+              mentionNames: {'pk1': 'Alice'},
+            ),
+          ),
+        );
+
+        expect(_hasBoldSpan(tester, 'Important'), isTrue);
+        expect(find.text('@Alice'), findsOneWidget);
+      });
+
+      testWidgets('preserves markdown around mentions', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: '**@Alice** please review',
+              mentionNames: {'pk1': 'Alice'},
+            ),
+          ),
+        );
+
+        expect(find.text('@Alice'), findsOneWidget);
+        expect(_allRichText(tester), isNot(contains('**')));
+      });
+
+      testWidgets('renders code block between paragraphs', (tester) async {
+        await tester.pumpWidget(
+          _testable(
+            const MessageContent(
+              content: 'Try this:\n```\nflutter test\n```\nDid it work?',
+            ),
+          ),
+        );
+
+        expect(_findRich('flutter test'), findsWidgets);
+        expect(_findRich('Try this:'), findsWidgets);
+        expect(_findRich('Did it work?'), findsWidgets);
+      });
+    });
+  });
+}

mobile/test/features/channels/timeline_message_test.dart

@@ -0,0 +1,446 @@
+import 'dart:convert';
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:sprout_mobile/features/channels/timeline_message.dart';
+import 'package:sprout_mobile/shared/relay/relay.dart';
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+NostrEvent _textMsg({
+  required String id,
+  String pubkey = 'alice',
+  String content = 'hello',
+  int createdAt = 1000,
+}) => NostrEvent(
+  id: id,
+  pubkey: pubkey,
+  createdAt: createdAt,
+  kind: EventKind.streamMessage,
+  tags: [
+    ['h', 'ch1'],
+  ],
+  content: content,
+  sig: '',
+);
+
+NostrEvent _systemMsg({
+  required String id,
+  required Map<String, dynamic> payload,
+  int createdAt = 1000,
+}) => NostrEvent(
+  id: id,
+  pubkey: 'relay',
+  createdAt: createdAt,
+  kind: EventKind.systemMessage,
+  tags: [
+    ['h', 'ch1'],
+  ],
+  content: jsonEncode(payload),
+  sig: '',
+);
+
+NostrEvent _deletion({
+  required String id,
+  required List<String> targets,
+  int createdAt = 2000,
+}) => NostrEvent(
+  id: id,
+  pubkey: 'alice',
+  createdAt: createdAt,
+  kind: EventKind.deletion,
+  tags: [
+    ['h', 'ch1'],
+    for (final t in targets) ['e', t],
+  ],
+  content: '',
+  sig: '',
+);
+
+NostrEvent _edit({
+  required String id,
+  required String targetId,
+  required String content,
+  int createdAt = 2000,
+}) => NostrEvent(
+  id: id,
+  pubkey: 'alice',
+  createdAt: createdAt,
+  kind: EventKind.streamMessageEdit,
+  tags: [
+    ['h', 'ch1'],
+    ['e', targetId],
+  ],
+  content: content,
+  sig: '',
+);
+
+NostrEvent _reaction({
+  required String id,
+  required String targetId,
+  int createdAt = 2000,
+}) => NostrEvent(
+  id: id,
+  pubkey: 'bob',
+  createdAt: createdAt,
+  kind: EventKind.reaction,
+  tags: [
+    ['h', 'ch1'],
+    ['e', targetId],
+  ],
+  content: '👍',
+  sig: '',
+);
+
+// ---------------------------------------------------------------------------
+// SystemEvent.fromContent
+// ---------------------------------------------------------------------------
+
+void main() {
+  group('SystemEvent.fromContent', () {
+    test('parses all known event types', () {
+      final types = {
+        'member_joined': SystemEventType.memberJoined,
+        'member_left': SystemEventType.memberLeft,
+        'member_removed': SystemEventType.memberRemoved,
+        'topic_changed': SystemEventType.topicChanged,
+        'purpose_changed': SystemEventType.purposeChanged,
+        'channel_created': SystemEventType.channelCreated,
+        'channel_archived': SystemEventType.channelArchived,
+        'channel_unarchived': SystemEventType.channelUnarchived,
+      };
+
+      for (final entry in types.entries) {
+        final event = SystemEvent.fromContent(
+          jsonEncode({'type': entry.key, 'actor': 'pk1'}),
+        );
+        expect(event, isNotNull, reason: 'Failed for ${entry.key}');
+        expect(event!.type, entry.value);
+        expect(event.actorPubkey, 'pk1');
+      }
+    });
+
+    test('returns null for unknown type', () {
+      final event = SystemEvent.fromContent(
+        jsonEncode({'type': 'unknown_type'}),
+      );
+      expect(event, isNull);
+    });
+
+    test('returns null for invalid JSON', () {
+      expect(SystemEvent.fromContent('not json'), isNull);
+    });
+
+    test('returns null for wrong JSON field types', () {
+      expect(
+        SystemEvent.fromContent(
+          jsonEncode({
+            'type': ['member_joined'],
+            'actor': 123,
+          }),
+        ),
+        isNull,
+      );
+    });
+
+    test('parses target, topic, and purpose fields', () {
+      final event = SystemEvent.fromContent(
+        jsonEncode({
+          'type': 'topic_changed',
+          'actor': 'pk1',
+          'target': 'pk2',
+          'topic': 'New topic',
+          'purpose': 'New purpose',
+        }),
+      );
+
+      expect(event, isNotNull);
+      expect(event!.targetPubkey, 'pk2');
+      expect(event.topic, 'New topic');
+      expect(event.purpose, 'New purpose');
+    });
+  });
+
+  group('SystemEvent.describe', () {
+    String resolve(String? pk) => pk == 'pk1' ? 'Alice' : 'Bob';
+
+    test('member_joined self', () {
+      final event = SystemEvent(
+        type: SystemEventType.memberJoined,
+        actorPubkey: 'pk1',
+        targetPubkey: 'pk1',
+      );
+      expect(event.describe(resolve), 'Alice joined the channel');
+    });
+
+    test('member_joined by other', () {
+      final event = SystemEvent(
+        type: SystemEventType.memberJoined,
+        actorPubkey: 'pk1',
+        targetPubkey: 'pk2',
+      );
+      expect(event.describe(resolve), 'Alice added Bob to the channel');
+    });
+
+    test('member_left', () {
+      final event = SystemEvent(
+        type: SystemEventType.memberLeft,
+        actorPubkey: 'pk1',
+      );
+      expect(event.describe(resolve), 'Alice left the channel');
+    });
+
+    test('member_removed', () {
+      final event = SystemEvent(
+        type: SystemEventType.memberRemoved,
+        actorPubkey: 'pk1',
+        targetPubkey: 'pk2',
+      );
+      expect(event.describe(resolve), 'Alice removed Bob from the channel');
+    });
+
+    test('topic_changed', () {
+      final event = SystemEvent(
+        type: SystemEventType.topicChanged,
+        actorPubkey: 'pk1',
+        topic: 'Release v2',
+      );
+      expect(
+        event.describe(resolve),
+        'Alice changed the topic to "Release v2"',
+      );
+    });
+
+    test('purpose_changed', () {
+      final event = SystemEvent(
+        type: SystemEventType.purposeChanged,
+        actorPubkey: 'pk1',
+        purpose: 'Daily standups',
+      );
+      expect(
+        event.describe(resolve),
+        'Alice changed the purpose to "Daily standups"',
+      );
+    });
+
+    test('channel_created', () {
+      final event = SystemEvent(
+        type: SystemEventType.channelCreated,
+        actorPubkey: 'pk1',
+      );
+      expect(event.describe(resolve), 'Alice created this channel');
+    });
+
+    test('channel_archived', () {
+      final event = SystemEvent(
+        type: SystemEventType.channelArchived,
+        actorPubkey: 'pk1',
+      );
+      expect(event.describe(resolve), 'Alice archived this channel');
+    });
+
+    test('channel_unarchived', () {
+      final event = SystemEvent(
+        type: SystemEventType.channelUnarchived,
+        actorPubkey: 'pk1',
+      );
+      expect(event.describe(resolve), 'Alice unarchived this channel');
+    });
+  });
+
+  group('formatTimeline', () {
+    test('passes through text messages', () {
+      final events = [
+        _textMsg(id: 'a', content: 'hello'),
+        _textMsg(id: 'b', content: 'world', createdAt: 1100),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(2));
+      expect(result[0].content, 'hello');
+      expect(result[1].content, 'world');
+      expect(result[0].isSystem, false);
+      expect(result[0].edited, false);
+    });
+
+    test('filters deleted messages', () {
+      final events = [
+        _textMsg(id: 'a', content: 'keep'),
+        _textMsg(id: 'b', content: 'delete', createdAt: 1100),
+        _deletion(id: 'd1', targets: ['b']),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(1));
+      expect(result[0].content, 'keep');
+    });
+
+    test('applies edits', () {
+      final events = [
+        _textMsg(id: 'a', content: 'original'),
+        _edit(id: 'e1', targetId: 'a', content: 'edited'),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(1));
+      expect(result[0].content, 'edited');
+      expect(result[0].edited, true);
+    });
+
+    test('latest edit wins', () {
+      final events = [
+        _textMsg(id: 'a', content: 'v1'),
+        _edit(id: 'e1', targetId: 'a', content: 'v2', createdAt: 2000),
+        _edit(id: 'e2', targetId: 'a', content: 'v3', createdAt: 3000),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result[0].content, 'v3');
+    });
+
+    test('deleted edit is ignored', () {
+      final events = [
+        _textMsg(id: 'a', content: 'original'),
+        _edit(id: 'e1', targetId: 'a', content: 'edited'),
+        _deletion(id: 'd1', targets: ['e1']),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result[0].content, 'original');
+      expect(result[0].edited, false);
+    });
+
+    test('edit of deleted message is ignored', () {
+      final events = [
+        _textMsg(id: 'a', content: 'original'),
+        _edit(id: 'e1', targetId: 'a', content: 'edited'),
+        _deletion(id: 'd1', targets: ['a']),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, isEmpty);
+    });
+
+    test('system messages are parsed', () {
+      final events = [
+        _systemMsg(
+          id: 's1',
+          payload: {'type': 'channel_created', 'actor': 'pk1'},
+        ),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(1));
+      expect(result[0].isSystem, true);
+      expect(result[0].systemEvent, isNotNull);
+      expect(result[0].systemEvent!.type, SystemEventType.channelCreated);
+    });
+
+    test('unknown system messages are dropped', () {
+      final events = [
+        _systemMsg(id: 's1', payload: {'type': 'unknown'}),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, isEmpty);
+    });
+
+    test('malformed system messages are skipped safely', () {
+      final events = [
+        _systemMsg(
+          id: 's1',
+          payload: {
+            'type': ['member_joined'],
+            'actor': 123,
+          },
+        ),
+        _textMsg(id: 'a', content: 'hello', createdAt: 1100),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(1));
+      expect(result[0].content, 'hello');
+    });
+
+    test('reactions and typing indicators are filtered out', () {
+      final events = [
+        _textMsg(id: 'a', content: 'hello'),
+        _reaction(id: 'r1', targetId: 'a'),
+        NostrEvent(
+          id: 'typing1',
+          pubkey: 'bob',
+          createdAt: 1000,
+          kind: EventKind.typingIndicator,
+          tags: [
+            ['h', 'ch1'],
+          ],
+          content: '',
+          sig: '',
+        ),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(1));
+      expect(result[0].content, 'hello');
+    });
+
+    test('preserves chronological order', () {
+      final events = [
+        _textMsg(id: 'a', content: 'first', createdAt: 1000),
+        _systemMsg(
+          id: 's1',
+          payload: {'type': 'member_joined', 'actor': 'pk1', 'target': 'pk1'},
+          createdAt: 1100,
+        ),
+        _textMsg(id: 'b', content: 'second', createdAt: 1200),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(3));
+      expect(result[0].content, 'first');
+      expect(result[1].isSystem, true);
+      expect(result[2].content, 'second');
+    });
+
+    test('streamMessageV2 events are included', () {
+      final events = [
+        NostrEvent(
+          id: 'v2msg',
+          pubkey: 'alice',
+          createdAt: 1000,
+          kind: EventKind.streamMessageV2,
+          tags: [
+            ['h', 'ch1'],
+          ],
+          content: 'legacy message',
+          sig: '',
+        ),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(1));
+      expect(result[0].content, 'legacy message');
+    });
+
+    test('streamMessageDiff events are included', () {
+      final events = [
+        NostrEvent(
+          id: 'diff1',
+          pubkey: 'alice',
+          createdAt: 1000,
+          kind: EventKind.streamMessageDiff,
+          tags: [
+            ['h', 'ch1'],
+          ],
+          content: '```diff\n-old\n+new\n```',
+          sig: '',
+        ),
+      ];
+
+      final result = formatTimeline(events);
+      expect(result, hasLength(1));
+      expect(result[0].content, contains('diff'));
+    });
+  });
+}