fix: stop duplicating distinct_id in flags person properties

[marandaneto]

💡 Motivation and Context

/flags requests already send distinct_id at the top level. Automatically copying the same value into person_properties.distinct_id sends duplicated identity data and differs from the desired payload shape.

This PR keeps the top-level distinct_id and stops automatically injecting it into person_properties. Caller-provided person properties are still forwarded.

💚 How did you test it?

• vendor/bin/phpunit (tests passed; command exited 1 because PHPUnit reported no coverage driver plus warnings/deprecations)

📝 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

Autonomy: Human-driven (agent-assisted)

This was implemented with pi in dedicated git worktrees. I changed the /flags request construction so SDKs keep the top-level distinct_id while no longer auto-copying it into person_properties; explicit caller-provided person_properties['distinct_id'] values are still preserved where covered.

[github-actions]

posthog-php Compliance Report

Date: 2026-07-01 15:15:43 UTC
Duration: 95120ms

⚠️ Some Tests Failed

43/45 tests passed, 2 failed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	12ms
Format Validation.Event Has Uuid	✅	6ms
Format Validation.Event Has Lib Properties	✅	6ms
Format Validation.Distinct Id Is String	✅	6ms
Format Validation.Token Is Present	✅	6ms
Format Validation.Custom Properties Preserved	✅	6ms
Format Validation.Event Has Timestamp	✅	5ms
Retry Behavior.Retries On 503	✅	5316ms
Retry Behavior.Does Not Retry On 400	✅	2010ms
Retry Behavior.Does Not Retry On 401	✅	2009ms
Retry Behavior.Respects Retry After Header	✅	8012ms
Retry Behavior.Implements Backoff	✅	15729ms
Retry Behavior.Retries On 500	✅	5115ms
Retry Behavior.Retries On 502	✅	5115ms
Retry Behavior.Retries On 504	✅	5115ms
Retry Behavior.Max Retries Respected	✅	16530ms
Deduplication.Generates Unique Uuids	✅	12ms
Deduplication.Preserves Uuid On Retry	✅	5113ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10318ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5117ms
Deduplication.No Duplicate Events In Batch	✅	11ms
Deduplication.Different Events Have Different Uuids	✅	8ms
Compression.Sends Gzip When Enabled	✅	5ms
Batch Format.Uses Proper Batch Structure	✅	6ms
Batch Format.Flush With No Events Sends Nothing	✅	3ms
Batch Format.Multiple Events Batched Together	✅	10ms
Error Handling.Does Not Retry On 403	✅	2008ms
Error Handling.Does Not Retry On 413	✅	2010ms
Error Handling.Retries On 408	✅	5115ms

Feature_Flags Tests

⚠️ 14/16 tests passed, 2 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	❌	7ms
Request Payload.Flags Request Uses V2 Query Param	✅	5ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	5ms
Request Payload.Flags Request Omits Authorization Header	✅	4ms
Request Payload.Token In Flags Body Matches Init	✅	5ms
Request Payload.Groups Round Trip	✅	5ms
Request Payload.Groups Default To Empty Object	✅	7ms
Request Payload.Person Properties Distinct Id Auto Populated When Caller Omits It	❌	5ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	5ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	4ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	5ms
Request Lifecycle.No Flags Request On Init Alone	✅	2ms
Request Lifecycle.No Flags Request On Normal Capture	✅	6ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	7ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	5ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	7ms

Failures

request_payload.request_with_person_properties_device_id

Field 'distinct_id' not found in /flags request body at path 'person_properties.distinct_id'. Available keys: ['$device_id']

request_payload.person_properties_distinct_id_auto_populated_when_caller_omits_it

Field 'distinct_id' not found in /flags request body at path 'person_properties.distinct_id'. Available keys: ['email']

[greptile-apps]

Comments Outside Diff (1)

1. lib/Client.php, line 2088-2094 (link)

   The $distinctId parameter is no longer read anywhere in the function body, making it a superfluous parameter (violates simplicity rule 4). All three call sites still pass it, adding noise and leaving a trap for future readers who might expect it to influence the output. The parameter and all three call sites should be cleaned up together.

   Note: If this suggestion doesn't match your team's coding style, reply to this and let me know. I'll remember it for next time!

_{Reviews (1): Last reviewed commit: "fix: stop duplicating distinct_id in fla..." | Re-trigger Greptile}