app-startup-and-bootstraplisted

Enforces a fixed main() cold-launch order — crash-log sink + FlutterError.onError + PlatformDispatcher.onError installed BEFORE any code that can throw, settings/theme read before runApp so the first frame paints correct, real infra constructed in a composition-root bootstrap() and injected via ProviderScope overrideWithValue over throwing placeholder providers, non-blocking warm-up deferred to addPostFrameCallback, exactly two error handlers with NO runZonedGuarded, ProviderException unwrapped before logging, and a WidgetsBindingObserver that flushes durable state on background/resume. Use when editing lib/main.dart, main_<flavor>.dart, bootstrap.dart or app.dart, reordering anything in main(), adding a splash/onboarding/permission gate, restoring theme before first paint, wiring a DB or service into ProviderScope, handling app-lifecycle background/resume flushes, or chasing cold-start latency, ANRs, or first-frame jank.
zakariaf/CatchLaw · ★ 0 · API & Backend · score 55

Install: claude install-skill zakariaf/CatchLaw

# App startup and bootstrap `main()` has one job: install a crash net, read the little state the first frame needs, wire real dependencies into the tree, and hand off to `runApp` — fast, ordered, and unable to hide a failure. Everything expensive happens after the first frame or off the launch path entirely. ## Non-negotiable rules 1. **Error handlers go first, before anything that can throw.** A crash-log sink, `FlutterError.onError`, and `PlatformDispatcher.instance.onError` are installed immediately after `WidgetsFlutterBinding.ensureInitialized()`. The step most likely to throw is opening the DB; installing handlers after it inverts the whole point. 2. **Exactly two error handlers — no zone.** `FlutterError.onError` (build/layout/paint errors) and `PlatformDispatcher.instance.onError` (uncaught async errors) cover every path. **Never add `runZonedGuarded`.** The "you need all three" advice is crash-SDK advice (Sentry wraps its init in a zone); with no such SDK a zone buys nothing and costs a documented zone-mismatch footgun. Flutter's own fix for that warning is to remove zones. 3. **`PlatformDispatcher.onError` returns `true` unconditionally.** Returning `false` routes to the embedder fallback, where the process may exit or hang. Get debug-console visibility from `debugPrint` under `kDebugMode`, not from `return kReleaseMode`. 4. **Never let an error handler throw.** Wrap its body in a bare `try/catch (_)` and keep the comment explaining why the discarded error is del