[Vadman97]

Demo (test transcript): team-o11y:artifacts/sf8t4/test-output.txt

On React Native, every cold start (and every load after the 15-minute inactivity timeout) begins a new session, so a user journey that crosses a relaunch, such as tapping an email link, is split. With this change, when a JS load starts a new session in place of a persisted one, SessionManager keeps the replaced session's ID and adds session.previous_id to the session attributes. Those are spread onto the OTel Resource, so every span, log, error and metric of the new session carries it. Resumed sessions and first launches omit it. The attribute name and semantics match the browser SDK's session.previous_id (#857).

Testing

• yarn workspace @launchdarkly/observability-react-native test: 17 files, 149 tests pass
• yarn workspace @launchdarkly/observability-react-native typegen: clean
• New tests in SessionManager.test.ts (stale session, cold start, resume, nothing persisted) and ObservabilityClient.test.ts (attribute present/absent on the Resource). 5 of them fail with the SessionManager change reverted.

Notes for the reviewer

• The attribute lives on the Resource, so it covers the whole process lifetime of the new session. Because the session ID never rotates in-process, that equals the whole session for this JS load.
• Not changed, but noticed: ObservabilityClient sets 'highlight.session_id': sessionAttributes.sessionId, and getSessionAttributes() has no sessionId key, so that resource attribute is always undefined. Worth fixing separately if anything still reads it.

🤖 Generated with Claude Code

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Note

Overview
When a React Native JS load starts a new session instead of resuming a persisted one (inactivity timeout or cold start), SessionManager now remembers the replaced session ID and exposes it as session.previous_id in getSessionAttributes(), alongside existing session.id and session.start_time.

That attribute is omitted when the session is resumed within the resume window or when nothing was stored. Init failures clear the link. getPreviousSessionId() is added for direct access. Because ObservabilityClient merges session attributes onto the OTel Resource, the new field applies to spans, logs, errors, and metrics for the whole new session—matching browser SDK semantics for stitching journeys across relaunches.

Coverage adds SessionManager cases (stale, cold start, resume, empty store) and ObservabilityClient Resource assertions for presence/absence of session.previous_id.

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[Vadman97]

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