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?

• bundle config set path vendor/bundle && bundle install && bundle exec rspec spec/posthog/client_spec.rb spec/posthog/feature_flag_spec.rb

📝 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-ruby Compliance Report

Date: 2026-07-02 11:40:58 UTC
Duration: 98512ms

⚠️ Some Tests Failed

44/46 tests passed, 2 failed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	110ms
Format Validation.Event Has Uuid	✅	105ms
Format Validation.Event Has Lib Properties	✅	109ms
Format Validation.Distinct Id Is String	✅	106ms
Format Validation.Token Is Present	✅	106ms
Format Validation.Custom Properties Preserved	✅	106ms
Format Validation.Event Has Timestamp	✅	107ms
Retry Behavior.Retries On 503	✅	5414ms
Retry Behavior.Does Not Retry On 400	✅	2109ms
Retry Behavior.Does Not Retry On 401	✅	2108ms
Retry Behavior.Respects Retry After Header	✅	8117ms
Retry Behavior.Implements Backoff	✅	15708ms
Retry Behavior.Retries On 500	✅	5213ms
Retry Behavior.Retries On 502	✅	5213ms
Retry Behavior.Retries On 504	✅	5212ms
Retry Behavior.Max Retries Respected	✅	15722ms
Deduplication.Generates Unique Uuids	✅	112ms
Deduplication.Preserves Uuid On Retry	✅	5212ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10413ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5215ms
Deduplication.No Duplicate Events In Batch	✅	112ms
Deduplication.Different Events Have Different Uuids	✅	107ms
Compression.Sends Gzip When Enabled	✅	107ms
Batch Format.Uses Proper Batch Structure	✅	107ms
Batch Format.Flush With No Events Sends Nothing	✅	5ms
Batch Format.Multiple Events Batched Together	✅	110ms
Error Handling.Does Not Retry On 403	✅	2109ms
Error Handling.Does Not Retry On 413	✅	2109ms
Error Handling.Retries On 408	✅	5212ms

Feature_Flags Tests

⚠️ 15/17 tests passed, 2 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	109ms
Request Payload.Flags Request Uses V2 Query Param	✅	109ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	110ms
Request Payload.Flags Request Omits Authorization Header	✅	107ms
Request Payload.Token In Flags Body Matches Init	✅	108ms
Request Payload.Groups Round Trip	✅	107ms
Request Payload.Groups Default To Empty Object	✅	108ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	107ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	108ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	107ms
Request Lifecycle.No Flags Request On Init Alone	✅	4ms
Request Lifecycle.No Flags Request On Normal Capture	✅	106ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	112ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	106ms
Retry Behavior.Retries Flags On 502	❌	108ms
Retry Behavior.Retries Flags On 504	❌	107ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	109ms

Failures

retry_behavior.retries_flags_on_502

Expected 2 /flags requests, got 1

retry_behavior.retries_flags_on_504

Expected 2 /flags requests, got 1

[greptile-apps]

Comments Outside Diff (1)

1. lib/posthog/client.rb, line 1064-1073 (link)

   Superfluous alias — all_person_properties is now a trivial alias for person_properties with no transformation applied. Under the "no superfluous parts" simplicity rule, the extra variable and the dead parameter distinct_id it used to consume can be removed, and the return value written directly.

   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}

[greptile-apps]

_{Reviews (2): Last reviewed commit: "Keep distinct_id available for local fla..." | Re-trigger Greptile}