feat(core): Unhandled Sessions

[buenaflor]

PR Stack (Unhandled Sessions)

• feat(core): Unhandled Sessions #5915 (collection)
• feat(core): [Unhandled Sessions 1] Add Unhandled session state and non-terminating error flag #5919
• fix(core): [Unhandled Sessions 2] Make session cache writes session-id aware #5920
• feat(android): [Unhandled Sessions 3] Add internal non-terminating envelope capture #5921

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Collection PR for the Unhandled Sessions stack. Squash-merge this once all stack PRs are merged.

📜 Description

Teaches the SDK the session protocol's unhandled status: an unhandled error that did not terminate the process. Adds an internal capture entry point so hybrid runtimes such as Flutter can report those exceptions without ending the session as crashed.

Split out of #5795 into three reviewable pieces:

1. feat(core): [Unhandled Sessions 1] Add Unhandled session state and non-terminating error flag #5919 — the Session model: State.Unhandled and the nonTerminatingUnhandledError flag.
2. fix(core): [Unhandled Sessions 2] Make session cache writes session-id aware #5920 — EnvelopeCache: session-id-aware session file writes, so a snapshot cannot be clobbered by a delayed start or end.
3. feat(android): [Unhandled Sessions 3] Add internal non-terminating envelope capture #5921 — InternalSentrySdk.captureEnvelopeNonTerminating plus the changelog entry.

💡 Motivation and Context

Flutter forwards handled=false events through the terminating hybrid capture path. That marks the session crashed and may start a replacement session even though the Flutter process keeps running, incorrectly lowering crash-free session rates.

💚 How did you test it?

See the individual stack PRs; each carries its own tests.

#skip-changelog

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

Generated by 🚫 dangerJS against 0e52a46

[sentry]

📲 Install Builds

Android

🔗 App Name	App ID	Version	Configuration
SDK Size	io.sentry.tests.size	8.52.0 (1)	release

⚙️ sentry-android Build Distribution Settings

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🚨 Detected changes in high risk code 🚨

High-risk code has higher potential to break the SDK and may be hard to test. To prevent severe bugs, apply the rollout process for releasing such changes and be extra careful when changing and reviewing these files:

• sentry-android-core/src/main/java/io/sentry/android/core/InternalSentrySdk.java

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Performance metrics 🚀

	Plain	With Sentry	Diff
Startup time	339.37 ms	422.63 ms	83.26 ms
Size	0 B	0 B	0 B

Baseline results on branch: main

Startup times

Revision	Plain	With Sentry	Diff
6b019b7	343.31 ms	417.23 ms	73.91 ms
d15471f	286.65 ms	314.68 ms	28.03 ms
d217708	409.83 ms	474.72 ms	64.89 ms
d500866	326.13 ms	378.70 ms	52.58 ms
fcec2f2	314.96 ms	373.66 ms	58.70 ms
d501a7e	314.55 ms	343.34 ms	28.79 ms
7414e9b	322.49 ms	378.88 ms	56.39 ms
fcec2f2	357.47 ms	447.32 ms	89.85 ms
a416a65	316.52 ms	359.67 ms	43.15 ms
983e0f0	350.64 ms	386.44 ms	35.79 ms

App size

Revision	Plain	With Sentry	Diff
6b019b7	0 B	0 B	0 B
d15471f	1.58 MiB	2.13 MiB	559.54 KiB
d217708	1.58 MiB	2.10 MiB	532.97 KiB
d500866	0 B	0 B	0 B
fcec2f2	1.58 MiB	2.12 MiB	551.50 KiB
d501a7e	0 B	0 B	0 B
7414e9b	0 B	0 B	0 B
fcec2f2	1.58 MiB	2.12 MiB	551.50 KiB
a416a65	1.58 MiB	2.12 MiB	555.26 KiB
983e0f0	0 B	0 B	0 B