feat(extend-app-start): [3/4] Eagerly create the extended app start transaction

[buenaflor]

PR Stack (Extend App Start)

• feat(extend-app-start): App start extension API #5604
• feat(extend-app-start): [1/4] Add IAppStartExtender bridge #5605
• feat(extend-app-start): [2/4] Extract AppStartExtension component #5606
• feat(extend-app-start): [3/4] Eagerly create the extended app start transaction #5608
• feat(extend-app-start): [4/4] Add public Sentry app start extension API #5628

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📜 Description

Registers the extend-listener and wires the extension through to the trace and the vital, making the feature work end-to-end. The extension is eager and standalone-only — only the standalone app.start transaction is independent of an activity and can be created in Application.onCreate.

Class	Change
ActivityLifecycleIntegration	Registers the extend-listener, but only when enableStandaloneAppStartTracing is on (this is what makes the API standalone-only). On Sentry.extendAppStart() the listener eagerly creates the standalone app.start transaction (waitForChildren + deadline) and its app.start.extended child, and returns them as an ExtendedAppStart.
PerformanceAndroidEventProcessor	App start vital is now max(natural first-frame duration, extended end), so an early finish never shortens it. On deadline the measurement is suppressed entirely (no inflated ~30s value); spans still attach. Non-extended starts are unchanged.
AppStartExtension	Adds isExtended() (the processor's gate) and setData(...) (to attach the screen once the first activity is known).

Notes

• The transaction is owned by the extension, not the integration's appStartTransaction field, so per-activity cleanup can't cancel it.
• The first activity continues the eager trace into ui.load (via isActive()) instead of starting a second app.start, and attaches the screen so the foreground app.start keeps its app.vitals.start.screen.
• The first frame finishes the transaction; waitForChildren holds it open until Sentry.finishAppStart(). Headless finishes it at the headless stop time. A shared createStandaloneAppStartTransaction(...) helper backs both paths.
• The legacy deferred-span path and the non-standalone (ui.load) extension path are removed — eager creation makes them unnecessary.

💡 Motivation and Context

Part of the app start extension API stack (#5553). This is where the extension actually affects the trace and the vital, scoped to standalone app start tracing because only the standalone app.start transaction can be created eagerly in onCreate.

💚 How did you test it?

Unit tests (TDD):

• ActivityLifecycleIntegrationTest — eager app.start + extended child on extend; first activity continues the trace with no second app.start and the screen attached; standalone & headless stay open until finishAppStart(); standalone-off is a no-op; the eager txn survives activity destroy.
• PerformanceAndroidEventProcessorTest — extended end drives the cold measurement; an early finish never reports shorter than the first-frame duration; a deadline finish suppresses the measurement.

apiCheck, spotless, and the :sentry-android-core unit suite pass.

📝 Checklist

• I added GH Issue ID & Linear ID
• I added tests to verify the changes.
• No new PII added or SDK only sends newly added PII if sendDefaultPII is enabled.
• I updated the docs if needed.
• I updated the wizard if needed.
• Review from the native team if needed.
• No breaking change or entry added to the changelog.
• No breaking change for hybrid SDKs or communicated to hybrid SDKs.

🔮 Next steps

[4/4] — add the public Sentry.extendAppStart() / Sentry.finishAppStart() / Sentry.getExtendedAppStartSpan() facade.

⚠️ Merge this PR using a merge commit (not squash). Only the collection branch is squash-merged into main.

#skip-changelog

[github-actions]

	Messages
📖	Do not forget to update Sentry-docs with your feature once the pull request gets approved.

Generated by 🚫 dangerJS against 571416e

[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.44.1 (1)	release

⚙️ sentry-android Build Distribution Settings

[github-actions]

Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	309.45 ms	363.17 ms	53.72 ms
Size	0 B	0 B	0 B

Baseline results on branch: feat/app-start-extension-android

Startup times

Revision	Plain	With Sentry	Diff
201a6fd	326.00 ms	371.92 ms	45.92 ms
388ffc5	315.18 ms	362.43 ms	47.25 ms
db5be2f	311.84 ms	365.94 ms	54.10 ms
b76203f	336.02 ms	403.42 ms	67.40 ms

App size

Revision	Plain	With Sentry	Diff
201a6fd	0 B	0 B	0 B
388ffc5	0 B	0 B	0 B
db5be2f	0 B	0 B	0 B
b76203f	0 B	0 B	0 B

Previous results on branch: feat/app-start-extension-materialize

Startup times

Revision	Plain	With Sentry	Diff
4cf89ba	340.51 ms	416.92 ms	76.41 ms
4451634	321.21 ms	376.21 ms	55.00 ms
20bbe9a	305.48 ms	387.25 ms	81.77 ms
69caaee	313.73 ms	373.92 ms	60.19 ms

App size

Revision	Plain	With Sentry	Diff
4cf89ba	0 B	0 B	0 B
4451634	0 B	0 B	0 B
20bbe9a	0 B	0 B	0 B
69caaee	0 B	0 B	0 B

[cursor]

Headless path duplicates finished extension

Medium Severity

onHeadlessAppStart only skips creating a new standalone app.start when AppStartExtension.isActive() is true. If Sentry.finishAppStart() completes the eager extended transaction before the main-looper headless idle runs, isActive() is false and a second standalone app.start is created and finished, duplicating headless app-start tracing for one launch.

 

^{Reviewed by Cursor Bugbot for commit 66cd87d. Configure here.}

[cursor]

Extended headless omits end time

Low Severity

When headless startup reuses an active extended eager transaction, onHeadlessAppStart calls finishTransaction and returns without calling setAppStartEndTime. The non-extended headless path persists that end time so a later ui.load can use the one-minute continuation window; extended headless always treats the gap as unknown and may continue the trace incorrectly.

Additional Locations (1)

• sentry-android-core/src/main/java/io/sentry/android/core/ActivityLifecycleIntegration.java#L1035-L1038

 

^{Reviewed by Cursor Bugbot for commit 66cd87d. Configure here.}

[sentry]

Bug: An extended headless app start fails to set appStartEndTime, causing all subsequent activities to be incorrectly attached to the initial app start trace.
_{Severity: MEDIUM}

Suggested Fix

After the call to metrics.getAppStartExtension().finishTransaction(endTime) in the extended headless start code path, add a call to metrics.setAppStartEndTime(endTime) to properly close the app start time window.

Prompt for AI Agent

Review the code at the location below. A potential bug has been identified by an AI
agent. Verify if this is a real issue. If it is, propose a fix; if not, explain why it's
not valid.

Location:
sentry-android-core/src/main/java/io/sentry/android/core/ActivityLifecycleIntegration.java#L1029-L1032

Potential issue: In the case of an extended headless app start, the code finishes the
transaction but fails to call `metrics.setAppStartEndTime(endTime)`. Consequently,
`AppStartMetrics.getInstance().getAppStartEndTime()` returns `null`. This causes the
`isWithinAppStartContinuationWindow` check to always return `true`, effectively creating
an infinite time window for trace continuation. As a result, all subsequent activities,
even those occurring much later, are incorrectly attached to the initial app start
trace, leading to inaccurate performance metrics.

_{Did we get this right? 👍 / 👎 to inform future reviews.}

[Copilot]

Pull request overview

Implements end-to-end wiring for the Android “extend app start” feature by registering an extend listener (standalone-only), eagerly creating/holding open a standalone app.start transaction + extended child span, and updating app start vital calculation logic to account for the extension (including deadline suppression).

Changes:

• ActivityLifecycleIntegration registers the extend listener when standalone app start tracing is enabled, eagerly creates the standalone app.start transaction + app.start.extended_app_start span on extension, and continues the trace into ui.load while attaching the first activity screen to the eager transaction.
• PerformanceAndroidEventProcessor computes the app start measurement as max(natural first-frame duration, extended end) when extended, and suppresses the measurement entirely on deadline while still attaching app start spans.
• AppStartExtension adds isExtended() (processor gate) and setData(...) (attach screen name to the eager transaction once known), with expanded unit test coverage.

Reviewed changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated no comments.

Show a summary per file

File	Description
sentry-android-core/src/main/java/io/sentry/android/core/ActivityLifecycleIntegration.java	Registers extend listener (standalone-only), eagerly creates standalone app.start + extended span, continues trace into ui.load, and finishes the eager txn at first-frame/headless end while waiting for children.
sentry-android-core/src/main/java/io/sentry/android/core/PerformanceAndroidEventProcessor.java	Adjusts app start measurement logic for extended flows (never shorten; suppress on deadline) while still finalizing/attaching app start spans.
sentry-android-core/src/main/java/io/sentry/android/core/AppStartExtension.java	Adds setData for eager txn mutation and isExtended for processor gating.
sentry-android-core/src/test/java/io/sentry/android/core/ActivityLifecycleIntegrationTest.kt	Adds tests covering eager standalone app.start creation, trace continuation into ui.load, screen attachment, wait-for-children behavior, standalone-off no-op, and survival across activity destroy.
sentry-android-core/src/test/java/io/sentry/android/core/PerformanceAndroidEventProcessorTest.kt	Adds tests for extended end driving cold measurement, never reporting shorter than natural duration, and deadline suppression behavior.
sentry-android-core/src/test/java/io/sentry/android/core/AppStartExtensionTest.kt	Adds test ensuring isExtended remains true after the transaction finishes.
sentry-android-core/api/sentry-android-core.api	API dump updated for new AppStartExtension methods (isExtended, setData).

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[cursor]

Cursor Bugbot has reviewed your changes and found 1 potential issue.

There are 3 total unresolved issues (including 2 from previous reviews).

^{❌ Bugbot Autofix is OFF. To automatically fix reported issues with cloud agents, enable autofix in the Cursor dashboard.}

^{Reviewed by Cursor Bugbot for commit 571416e. Configure here.}

[cursor]

Extended headless vitals dropped after screen

Medium Severity

Attaching app.vitals.start.screen to the eager extended app.start transaction makes the processor classify it as non-headless, while shouldSendStartMeasurements still requires appLaunchedInForeground. Headless extended starts that later open an activity can skip cold/warm app-start measurements entirely.

Additional Locations (1)

• sentry-android-core/src/main/java/io/sentry/android/core/PerformanceAndroidEventProcessor.java#L95-L101

 

^{Reviewed by Cursor Bugbot for commit 571416e. Configure here.}