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GeezerVison is showing github.com — fix(replay): Preserve segment ID after buffer-to-session conversion by romtsn · Pull Request #5753 · getsentry/sentry-java

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romtsn commented Jul 10, 2026

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📜 Description

After a buffer-to-session conversion (BufferCaptureStrategy.convert()), the replayType stays BUFFER (intentionally — it tells the backend this replay was triggered by an error). However, if the app crashes after the conversion and finalizePreviousReplay() recovers the last segment on next launch, ReplayCache.fromDisk() was normalizing the segment ID to 0 for all BUFFER-type replays.

This created a duplicate segment 0 with a late timestamp that overwrote the original segment 0 from the buffer flush, effectively losing the first segment of the replay.

The fix adds a persisted isFlushed flag that is set when the buffer is successfully flushed. fromDisk() now only normalizes the segment ID to 0 when the buffer was never flushed (i.e., no segments were ever sent to the server — the crash happened before any error triggered captureReplay).

💡 Motivation and Context

Customers reported the first segment of error-triggered replays sometimes being missing or showing content from the wrong time range. This was caused by finalizePreviousReplay creating a duplicate segment 0 that replaced the original.

💚 How did you test it?

Unit tests: updated existing test and added new test for the flushed case in ReplayCacheTest
Manual test on emulator: configured sample app for buffer-only replay, triggered captureException, waited for session segments, force-killed, relaunched — verified the finalized segment has the correct sequential ID (not 0)
Verified rrweb recording shows sequential segment IDs with proper timestamps

📝 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

Investigate error-to-replay linkage issue (frozen transaction baggage doesn't pick up replayId set by captureReplay in buffer mode)

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romtsn and others added 2 commits

July 10, 2026 12:06


          fix(replay): Preserve segment ID after buffer-to-session conversion

bb2d445

After a buffer-to-session conversion, the replay type stays BUFFER
but the segment counter reflects the real sequence. If the app
crashes and finalizePreviousReplay recovers the last segment,
fromDisk() was normalizing the segment ID to 0 for all BUFFER
replays, creating a duplicate segment 0 that overwrites the original.

Add a persisted isFlushed flag set when the buffer is successfully
flushed. fromDisk() now only normalizes to 0 when the buffer was
never flushed (no segments were ever sent to the server).

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>


          changelog

819aada

sentry Bot commented Jul 10, 2026 •

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📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.48.0 (1)	release

⚙️ sentry-android Build Distribution Settings

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github-actions Bot commented Jul 10, 2026 •

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Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	329.48 ms	382.31 ms	52.83 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
`6b019b7`	319.84 ms	333.15 ms	13.31 ms
`eb95ded`	317.51 ms	369.08 ms	51.57 ms
`319f256`	317.53 ms	370.83 ms	53.29 ms
`b3d8889`	420.46 ms	453.71 ms	33.26 ms
`6b019b7`	403.90 ms	546.09 ms	142.19 ms
`889ecea`	367.58 ms	437.52 ms	69.94 ms
`d15471f`	303.49 ms	439.08 ms	135.59 ms
`d364ace`	384.53 ms	453.51 ms	68.98 ms
`6ea4329`	309.06 ms	353.48 ms	44.42 ms
`c8125f3`	383.82 ms	441.66 ms	57.84 ms

App size

Revision	Plain	With Sentry	Diff
`6b019b7`	0 B	0 B	0 B
`eb95ded`	0 B	0 B	0 B
`319f256`	1.58 MiB	2.19 MiB	619.79 KiB
`b3d8889`	1.58 MiB	2.10 MiB	535.07 KiB
`6b019b7`	0 B	0 B	0 B
`889ecea`	1.58 MiB	2.11 MiB	539.75 KiB
`d15471f`	1.58 MiB	2.13 MiB	559.54 KiB
`d364ace`	1.58 MiB	2.11 MiB	539.75 KiB
`6ea4329`	1.58 MiB	2.29 MiB	719.82 KiB
`c8125f3`	1.58 MiB	2.10 MiB	532.32 KiB

Previous results on branch: rz/fix/replay-segment-id-normalization

Startup times

Revision	Plain	With Sentry	Diff
`39e4c55`	352.43 ms	446.94 ms	94.51 ms
`048e40b`	322.47 ms	362.69 ms	40.22 ms
`94ec28b`	317.49 ms	407.84 ms	90.35 ms
`a5d4b7b`	413.28 ms	506.54 ms	93.26 ms

App size

Revision	Plain	With Sentry	Diff
`39e4c55`	0 B	0 B	0 B
`048e40b`	0 B	0 B	0 B
`94ec28b`	0 B	0 B	0 B
`a5d4b7b`	0 B	0 B	0 B

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romtsn commented

Jul 10, 2026

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CHANGELOG.md Resolved

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          Apply suggestion from @romtsn

08237cf

romtsn marked this pull request as ready for review

July 10, 2026 10:50

romtsn requested review from 0xadam-brown, adinauer, markushi and runningcode as code owners

July 10, 2026 10:50

sentry Bot reviewed

Jul 10, 2026

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sentry-android-replay/src/main/java/io/sentry/android/replay/ReplayIntegration.kt Resolved

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          Add comment explaining isFlushed flag purpose

49846bc

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

cursor Bot reviewed

Jul 10, 2026

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sentry-android-replay/src/main/java/io/sentry/android/replay/ReplayCache.kt Resolved

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romtsn and others added 2 commits

July 10, 2026 15:42


          fix(replay): Use persisted timestamp for flushed buffer recovery

33127b6

After buffer-to-session conversion, use the persisted segmentTimestamp
(which chains with previous segments) instead of the first frame
timestamp, avoiding gaps in the recovered segment timeline.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>


          Revert timestamp normalization change

354056d

The gap from using first-frame timestamp vs persisted segmentTimestamp
is at most ~1s (1/frameRate) — negligible for crash recovery.

Co-Authored-By: Claude Opus 4.6 (1M context) <[email protected]>

sentry Bot reviewed

Jul 10, 2026

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sentry-android-replay/src/main/java/io/sentry/android/replay/ReplayIntegration.kt Resolved

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markushi approved these changes

Jul 13, 2026

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          Merge branch 'main' into rz/fix/replay-segment-id-normalization

0f4db61

romtsn enabled auto-merge (squash)

July 13, 2026 19:29

cursor Bot reviewed

Jul 13, 2026

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

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

^{Reviewed by Cursor Bugbot for commit 0f4db61. Configure here.}

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sentry-android-replay/src/main/java/io/sentry/android/replay/ReplayIntegration.kt Resolved

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romtsn merged commit 31c558e into main

Jul 13, 2026

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romtsn deleted the rz/fix/replay-segment-id-normalization branch

July 13, 2026 19:53

sentry-release-bot Bot mentioned this pull request

Jul 16, 2026

publish: getsentry/[email protected] getsentry/publish#8917

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romtsn commented Jul 10, 2026

📜 Description

💡 Motivation and Context

💚 How did you test it?

📝 Checklist

🔮 Next steps

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sentry Bot commented Jul 10, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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📲 Install Builds

Android

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github-actions Bot commented Jul 10, 2026 • edited Loading Uh oh! There was an error while loading. Please reload this page.

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Performance metrics 🚀

Baseline results on branch: main

Startup times

App size

Previous results on branch: rz/fix/replay-segment-id-normalization

Startup times

App size

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sentry Bot commented Jul 10, 2026 •

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