feat(replay): Record segment names (transaction names)

[sentry-junior]

Note: Sentry is moving away from the concept of transactions and instead calls them now segments.

Record transaction segment names on replay events so replays can be queried by the named transaction that occurred during each segment.

This is needed in Sentry Flutter to report segment names that occurred during replays. (getsentry/sentry-dart#3865)

Replay context

Adds ReplayController.registerSegmentName, collects unique names alongside trace IDs with the same 100-value limit, and clears both collections when a replay segment is created. Successfully captured native transactions register their transaction name automatically.

Payload

Replay events now serialize and deserialize the collected names as segment_names, with coverage for protocol round trips, deduplication, limits, and per-segment clearing.

Related work in Sentry Javascript getsentry/sentry-javascript#21851

Requested by Gino Buenaflor via Junior.

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

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[sentry]

📲 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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Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	321.36 ms	376.41 ms	55.05 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
6b019b7	403.90 ms	546.09 ms	142.19 ms
e63ad34	310.20 ms	366.84 ms	56.63 ms
5865051	319.74 ms	365.60 ms	45.86 ms
a1eadfa	345.67 ms	411.26 ms	65.59 ms
b193867	319.59 ms	403.09 ms	83.50 ms
0eaac1e	316.82 ms	357.34 ms	40.52 ms
22ff2c7	306.60 ms	336.65 ms	30.05 ms
d15471f	286.65 ms	314.68 ms	28.03 ms
05aa61d	310.43 ms	372.40 ms	61.97 ms
fcec2f2	311.35 ms	384.94 ms	73.59 ms

App size

Revision	Plain	With Sentry	Diff
6b019b7	0 B	0 B	0 B
e63ad34	0 B	0 B	0 B
5865051	0 B	0 B	0 B
a1eadfa	0 B	0 B	0 B
b193867	1.58 MiB	2.19 MiB	620.00 KiB
0eaac1e	1.58 MiB	2.19 MiB	619.17 KiB
22ff2c7	0 B	0 B	0 B
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
05aa61d	0 B	0 B	0 B
fcec2f2	1.58 MiB	2.12 MiB	551.51 KiB

Previous results on branch: feat/replay-segment-names

Startup times

Revision	Plain	With Sentry	Diff
6a556d4	360.77 ms	417.23 ms	56.46 ms

App size

Revision	Plain	With Sentry	Diff
6a556d4	0 B	0 B	0 B

[Copilot]

Pull request overview

Adds support for recording segment names (transaction names) in Session Replay so replay events can be queried by the named segment(s) that occurred during each replay segment.

Changes:

• Extend the ReplayController API with registerSegmentName, and register transaction names from SentryClient.captureTransaction.
• Persist segment names in SentryReplayEvent payloads as segment_names (including serialization/deserialization support).
• Track, deduplicate, cap (100), and clear segment names per replay segment in the Android replay capture strategies, with added tests.

Reviewed changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
sentry/src/test/resources/json/sentry_replay_event.json	Updates replay event golden JSON to include segment_names.
sentry/src/test/java/io/sentry/SentryClientTest.kt	Adds/updates tests to verify segment name registration via ReplayController.
sentry/src/test/java/io/sentry/protocol/SentryReplayEventSerializationTest.kt	Ensures replay event protocol round-trip includes segmentNames.
sentry/src/main/java/io/sentry/SentryReplayEvent.java	Adds segmentNames field with JSON key segment_names plus (de)serialization and equality updates.
sentry/src/main/java/io/sentry/SentryClient.java	Registers captured transaction name with replay controller when a transaction is successfully sent.
sentry/src/main/java/io/sentry/ReplayController.java	Adds new internal API hook registerSegmentName.
sentry/src/main/java/io/sentry/NoOpReplayController.java	Implements the new no-op registerSegmentName method.
sentry/api/sentry.api	Updates public API dump for ReplayController, NoOpReplayController, and SentryReplayEvent.
sentry-android-replay/src/test/java/io/sentry/android/replay/capture/SessionCaptureStrategyTest.kt	Adds tests for deduplication, limit, and per-segment clearing of segment names.
sentry-android-replay/src/main/java/io/sentry/android/replay/ReplayIntegration.kt	Forwards registerSegmentName to the active capture strategy when recording.
sentry-android-replay/src/main/java/io/sentry/android/replay/capture/CaptureStrategy.kt	Extends internal replay segment creation flow to include segmentNames.
sentry-android-replay/src/main/java/io/sentry/android/replay/capture/BaseCaptureStrategy.kt	Implements collection/dedup/limit/clear logic for segment names alongside trace IDs.
sentry-android-replay/api/sentry-android-replay.api	Updates Android replay module API dump for ReplayIntegration.
CHANGELOG.md	Adds an unreleased changelog entry for the new replay segment name capability.

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