fix: identify anonymous user when id already matches persisted distinct id

[ioannisj]

💡 Motivation and Context

Calling identify(id) where id already equals the persisted distinct ID left the user anonymous: no transition fired, no person-processed event was sent, and $is_identified stayed false. It's easy to hit after a non-identified bootstrap seeds the same ID.

The SDK now upgrades the user to identified and captures one person-processed $set (no $identify, since there's no anonymous ID to merge). The transition is decided and persisted atomically under identifiedLock, so two concurrent identify() calls can't both emit a person event for the same transition. Ports PostHog/posthog-js#4328.

💚 How did you test it?

Added a regression test for the matching-ID-while-anonymous path in PostHogBootstrapTest: the user ends up identified, one $set is captured (no $identify), and flags reload only when the caller supplies properties that affect evaluation. Ran the unit suite.

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed.
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran pnpm changeset to generate a changeset file

🤖 Agent context

DRI: @ioannisj
Autonomy: Human-driven (agent-assisted)

[github-actions]

posthog-android Compliance Report

Date: 2026-07-30 19:09:50 UTC
Duration: 118392ms

✅ All Tests Passed!

46/46 tests passed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	401ms
Format Validation.Event Has Uuid	✅	31ms
Format Validation.Event Has Lib Properties	✅	30ms
Format Validation.Distinct Id Is String	✅	25ms
Format Validation.Token Is Present	✅	26ms
Format Validation.Custom Properties Preserved	✅	29ms
Format Validation.Event Has Timestamp	✅	24ms
Retry Behavior.Retries On 503	✅	7024ms
Retry Behavior.Does Not Retry On 400	✅	4023ms
Retry Behavior.Does Not Retry On 401	✅	4023ms
Retry Behavior.Respects Retry After Header	✅	7026ms
Retry Behavior.Implements Backoff	✅	17034ms
Retry Behavior.Retries On 500	✅	7019ms
Retry Behavior.Retries On 502	✅	7021ms
Retry Behavior.Retries On 504	✅	7017ms
Retry Behavior.Max Retries Respected	✅	17039ms
Deduplication.Generates Unique Uuids	✅	37ms
Deduplication.Preserves Uuid On Retry	✅	7016ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	12019ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	7019ms
Deduplication.No Duplicate Events In Batch	✅	36ms
Deduplication.Different Events Have Different Uuids	✅	24ms
Compression.Sends Gzip When Enabled	✅	18ms
Batch Format.Uses Proper Batch Structure	✅	17ms
Batch Format.Flush With No Events Sends Nothing	✅	12ms
Batch Format.Multiple Events Batched Together	✅	32ms
Error Handling.Does Not Retry On 403	✅	4017ms
Error Handling.Does Not Retry On 413	✅	4019ms
Error Handling.Retries On 408	✅	5025ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	31ms
Request Payload.Flags Request Uses V2 Query Param	✅	22ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	35ms
Request Payload.Flags Request Omits Authorization Header	✅	21ms
Request Payload.Token In Flags Body Matches Init	✅	21ms
Request Payload.Groups Round Trip	✅	23ms
Request Payload.Groups Default To Empty Object	✅	23ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	21ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	21ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	20ms
Request Lifecycle.No Flags Request On Init Alone	✅	8ms
Request Lifecycle.No Flags Request On Normal Capture	✅	23ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	34ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	21ms
Retry Behavior.Retries Flags On 502	✅	322ms
Retry Behavior.Retries Flags On 504	✅	323ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	21ms

[greptile-apps]

_{Reviews (1): Last reviewed commit: "chore: declare posthog core in changeset" | Re-trigger Greptile}

[marandaneto]

unblocking, check for concurrency issues if not yet