[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