app.start.cold / app.start.warm → allow nesting; or make it be controlled somehow #5936

Activity

1. alwx

   added

   React-Native

   on Mar 31, 2026
2. linear-code commented on Mar 31, 2026

   

   linear-codebot

   on Mar 31, 2026 – with Linear Code

   More actions

   RN-566
3. christophaigner

   added

   Improvement

   on Apr 1, 2026
4. christophaigner

   added

   Spans

   on Apr 14, 2026
5. romtsn commented on Apr 17, 2026

   

   romtsn

   on Apr 17, 2026

   Contributor

   More actions

   See iOS/Android issues for more details around the new API. I think we can repurpose this issue to implement that API first, which will make it possible to customize the app start span as you see fit, e.g.:

   // Must be called before the first frame is drawn
   const launchSpan = Sentry.extendAppLaunch();
   
   // 1. Granular breakdown — attach child spans to app.start.cold
   const configSpan = launchSpan?.startChild({ name: "fetch_remote_config", op: "app.init" });
   await fetchRemoteConfig();
   configSpan?.finish();
   
   const cacheSpan = launchSpan?.startChild({ name: "hydrate_cache", op: "app.init" });
   await hydrateCache();
   cacheSpan?.finish();
   
   const authSpan = launchSpan?.startChild({ name: "auth_token_refresh", op: "app.init" });
   await refreshAuthToken();
   authSpan?.finish();
   
   const flagsSpan = launchSpan?.startChild({ name: "initialize_feature_flags", op: "app.init" });
   await initFeatureFlags();
   flagsSpan?.finish();
   
   // 2. Custom attributes on the app start span itself
   launchSpan?.setAttribute("app_version", "1.4.2");
   launchSpan?.setAttribute("launch_source", "push_notification");
   
   // 3. Framework-level instrumentation (e.g. inside Redux enhancer)
   const reduxSpan = launchSpan?.startChild({ name: "redux_store_init", op: "app.init.redux" });
   const store = configureStore({ reducer });
   reduxSpan?.finish();
   
   // Mark the app as launched (or let it default to firstFrameDrawn)
   launchSpan?.finish();
   
   // Optional: separately mark full display (e.g. after data is rendered)
   launchSpan?.fullyDisplayed();
6. antonis

   self-assigned this

   on Jun 26, 2026
7. antonis

   closed this as completedin #6392on Jul 7, 2026
8. github-actions commented on Jul 9, 2026

   

   github-actionsbot

   on Jul 9, 2026 – with GitHub Actions

   Contributor

   More actions

   A PR closing this issue has just been released 🚀

   This issue was referenced by PR #6392, which was included in the 8.18.0 release.