fix(tracing): Keep launch-screen TTID/TTFD anchored to navigation on delayed first navigation - #6626
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fix(tracing): Keep launch-screen TTID/TTFD anchored to navigation on delayed first navigation#6626antonis wants to merge 2 commits into
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Semver Impact of This PR⚪ None (no version bump detected) 📋 Changelog PreviewThis is how your changes will appear in the changelog.
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…delayed first navigation For non-standalone app start tracking, attaching app start to the first navigation transaction re-anchored its start_timestamp to process init, which made auto time_to_initial_display/time_to_full_display absorb the uninstrumented gap before a delayed first navigation (splash / auth / loading). The later 30s TTID/TTFD cap then right-censored this into a large plateau. When the gap between app start end and the first navigation start exceeds 5s, report the app_start_cold/app_start_warm measurement but leave the screen TTID/TTFD anchored to the navigation start, so they measure the actual screen render. Genuine cold-start displays (first navigation follows app start promptly) keep the existing app-start-anchored behavior unchanged. Fixes #6618 Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
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Contributor
iOS (legacy) Performance metrics 🚀
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| Revision | Plain | With Sentry | Diff |
|---|---|---|---|
| 64630e5+dirty | 3842.70 ms | 1218.11 ms | -2624.60 ms |
| b0d3373+dirty | 3831.75 ms | 1227.29 ms | -2604.46 ms |
| b04af96+dirty | 3818.92 ms | 1219.76 ms | -2599.16 ms |
| 3d31fcf+dirty | 3838.09 ms | 1223.46 ms | -2614.63 ms |
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| af33f3b+dirty | 3849.98 ms | 1236.45 ms | -2613.53 ms |
| 09a902f+dirty | 3835.67 ms | 1217.11 ms | -2618.57 ms |
| 5a316ea+dirty | 3820.11 ms | 1211.28 ms | -2608.83 ms |
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| acd838e+dirty | 3849.78 ms | 1230.00 ms | -2619.78 ms |
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| Revision | Plain | With Sentry | Diff |
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| 64630e5+dirty | 4.98 MiB | 6.46 MiB | 1.49 MiB |
| b0d3373+dirty | 5.15 MiB | 6.68 MiB | 1.53 MiB |
| b04af96+dirty | 4.98 MiB | 6.54 MiB | 1.56 MiB |
| 3d31fcf+dirty | 4.98 MiB | 6.56 MiB | 1.58 MiB |
| a0a3177+dirty | 4.98 MiB | 6.55 MiB | 1.58 MiB |
| af33f3b+dirty | 4.98 MiB | 6.51 MiB | 1.54 MiB |
| 09a902f+dirty | 4.98 MiB | 6.46 MiB | 1.49 MiB |
| 5a316ea+dirty | 4.98 MiB | 6.51 MiB | 1.53 MiB |
| 403b9f3+dirty | 5.08 MiB | 6.72 MiB | 1.64 MiB |
| acd838e+dirty | 5.15 MiB | 6.70 MiB | 1.55 MiB |
Contributor
Android (new) Performance metrics 🚀
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| Revision | Plain | With Sentry | Diff |
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| 44c8b3f+dirty | 492.13 ms | 563.47 ms | 71.34 ms |
| f6ce4ff+dirty | 484.92 ms | 507.50 ms | 22.58 ms |
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App size
| Revision | Plain | With Sentry | Diff |
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| f6ce4ff+dirty | 49.74 MiB | 55.45 MiB | 5.71 MiB |
| a858ac3+dirty | 49.74 MiB | 55.08 MiB | 5.34 MiB |
| 822d35b+dirty | 49.74 MiB | 54.84 MiB | 5.10 MiB |
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| 2e64504+dirty | 49.74 MiB | 55.45 MiB | 5.71 MiB |
| d038a14+dirty | 48.30 MiB | 53.49 MiB | 5.19 MiB |
| 5b7e8a7+dirty | 48.30 MiB | 53.58 MiB | 5.28 MiB |
Contributor
iOS (new) Performance metrics 🚀
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| Revision | Plain | With Sentry | Diff |
|---|---|---|---|
| 3ce5254+dirty | 1217.70 ms | 1224.69 ms | 6.99 ms |
| 0b1b5e3+dirty | 3820.72 ms | 1207.94 ms | -2612.78 ms |
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App size
| Revision | Plain | With Sentry | Diff |
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| 3ce5254+dirty | 3.38 MiB | 4.76 MiB | 1.38 MiB |
| 0b1b5e3+dirty | 5.15 MiB | 6.70 MiB | 1.54 MiB |
| 44abcc2+dirty | 4.98 MiB | 6.55 MiB | 1.57 MiB |
| 1d3572b+dirty | 4.98 MiB | 6.56 MiB | 1.58 MiB |
| 6177334+dirty | 5.15 MiB | 6.68 MiB | 1.53 MiB |
| 5ee78d6+dirty | 5.15 MiB | 6.69 MiB | 1.53 MiB |
| 083e3ef+dirty | 4.98 MiB | 6.55 MiB | 1.57 MiB |
| ce7b368+dirty | 4.98 MiB | 6.51 MiB | 1.53 MiB |
| 7887847+dirty | 4.98 MiB | 6.46 MiB | 1.48 MiB |
| 1122a96+dirty | 5.15 MiB | 6.68 MiB | 1.53 MiB |
Contributor
Android (legacy) Performance metrics 🚀
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| Revision | Plain | With Sentry | Diff |
|---|---|---|---|
| f9c1ed4+dirty | 431.00 ms | 466.22 ms | 35.22 ms |
| c2e182c+dirty | 471.64 ms | 553.59 ms | 81.95 ms |
| 41d6254+dirty | 424.45 ms | 474.34 ms | 49.89 ms |
| af33f3b+dirty | 434.90 ms | 506.14 ms | 71.24 ms |
| 882f8ae+dirty | 399.98 ms | 427.06 ms | 27.08 ms |
| 0b5120f+dirty | 503.22 ms | 538.60 ms | 35.38 ms |
| 774257e+dirty | 407.09 ms | 447.46 ms | 40.37 ms |
| bf168a4+dirty | 418.21 ms | 489.74 ms | 71.53 ms |
| 5569641+dirty | 406.43 ms | 428.51 ms | 22.08 ms |
| c151573+dirty | 530.34 ms | 559.43 ms | 29.09 ms |
App size
| Revision | Plain | With Sentry | Diff |
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| f9c1ed4+dirty | 49.74 MiB | 54.86 MiB | 5.12 MiB |
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| 41d6254+dirty | 48.30 MiB | 53.60 MiB | 5.30 MiB |
| af33f3b+dirty | 49.74 MiB | 55.09 MiB | 5.35 MiB |
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| 0b5120f+dirty | 48.30 MiB | 53.58 MiB | 5.28 MiB |
| 774257e+dirty | 48.30 MiB | 53.58 MiB | 5.28 MiB |
| bf168a4+dirty | 49.74 MiB | 55.09 MiB | 5.35 MiB |
| 5569641+dirty | 48.30 MiB | 53.48 MiB | 5.18 MiB |
| c151573+dirty | 48.30 MiB | 53.54 MiB | 5.24 MiB |
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📢 Type of change
📜 Description
On non-standalone app start tracking, attaching app start to the first navigation transaction rewrites its
start_timestampto process init and re-anchors the TTID/TTFD spans to it;timeToDisplay(which runs after) then derivestime_to_initial_display/time_to_full_displayfrom that rewritten start.On a delayed first navigation — a splash / auth / loading screen held for several seconds — this makes TTID/TTFD span the uninstrumented app-ready → navigation gap instead of the screen render, inflating them by an order of magnitude (e.g. ~0.9s → ~23s in #6618; the 30s cap from #6210 flattens the overflow into a plateau).
This adds a gap check: when
first navigation start − app start end > 5s, the SDK still reports theapp_start_cold/app_start_warmmeasurement but leavesstart_timestamp(and therefore TTID/TTFD) at the navigation start, so they measure the real render. Prompt cold-start displays (gap ≤ 5s) are unchanged. Scoped to non-standalone, non-__DEV__, and runs after the existing age/duration guards.The
5scutoff is a heuristic; a root-cause fix would use a native initial-display signal instead of elapsed time (see Next steps).💡 Motivation and Context
React Native decouples JS navigation from native app start, so the first
navigationtransaction can fire arbitrarily late. The TTID/TTFD spec anchors first-screen TTID to app start with no gap guard, because on native the first Activity is the app start — they can't be seconds apart. On RN they can, producing a gap the spec never contemplated.Fixes #6618
💚 How did you test it?
appStart.test.ts: delayed nav keepsstart_timestampat the navigation start and adds noCold Start/Warm Startspan while still reportingapp_start_cold/warm; prompt nav (< 5s) keeps the existing app-start-anchored behavior; dev build skips the branch.appStart.test.ts(94 passing, incl. snapshots) andtimeToDisplayIntegration.test.tspass;yarn build, TS/JS lint, circular-dep check, andapi-report:checkall clean (no public API change).📝 Checklist
sendDefaultPIIis enabled.🔮 Next steps