fix: Retry flags requests on 502 and 504

[marandaneto]

💡 Motivation and Context

Remote /flags/?v=2 evaluations retried transient transport failures via feature_flag_request_max_retries, but HTTP 502/504 responses were surfaced immediately. The SDK compliance harness expects /flags to retry transient gateway responses while keeping retry behavior scoped to feature flag evaluation.

This replaces the fork-based PR #208 with an equivalent branch pushed directly to PostHog/posthog-ruby.

💚 How did you test it?

ruby -c lib/posthog/feature_flags.rb
bundle exec rspec spec/posthog/flags_spec.rb
bundle exec rubocop lib/posthog/feature_flags.rb spec/posthog/flags_spec.rb

Validation from the original branch:

• ruby -c lib/posthog/feature_flags.rb → Syntax OK
• bundle exec rspec spec/posthog/flags_spec.rb → 80 examples, 0 failures
• bundle exec rubocop lib/posthog/feature_flags.rb spec/posthog/flags_spec.rb → 2 files inspected, no offenses detected

📝 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)

Implemented by an AI coding agent under human direction. The change keeps HTTP status-code retries scoped to the /flags remote evaluation request path and adds focused specs for 502/504 retry behavior, non-retry statuses, and max-retries opt-out. A changeset covers both posthog-ruby and posthog-rails, since Rails consumes the Ruby SDK behavior.

[github-actions]

posthog-ruby Compliance Report

Date: 2026-07-02 12:22:20 UTC
Duration: 98009ms

✅ All Tests Passed!

45/45 tests passed

---

Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	110ms
Format Validation.Event Has Uuid	✅	106ms
Format Validation.Event Has Lib Properties	✅	109ms
Format Validation.Distinct Id Is String	✅	107ms
Format Validation.Token Is Present	✅	108ms
Format Validation.Custom Properties Preserved	✅	106ms
Format Validation.Event Has Timestamp	✅	108ms
Retry Behavior.Retries On 503	✅	5414ms
Retry Behavior.Does Not Retry On 400	✅	2109ms
Retry Behavior.Does Not Retry On 401	✅	2109ms
Retry Behavior.Respects Retry After Header	✅	8117ms
Retry Behavior.Implements Backoff	✅	15622ms
Retry Behavior.Retries On 500	✅	5214ms
Retry Behavior.Retries On 502	✅	5212ms
Retry Behavior.Retries On 504	✅	5212ms
Retry Behavior.Max Retries Respected	✅	15522ms
Deduplication.Generates Unique Uuids	✅	112ms
Deduplication.Preserves Uuid On Retry	✅	5213ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10318ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5214ms
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	✅	2110ms
Error Handling.Does Not Retry On 413	✅	2109ms
Error Handling.Retries On 408	✅	5212ms

Feature_Flags Tests

✅ 16/16 tests passed

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	✅	109ms
Request Payload.Flags Request Omits Authorization Header	✅	108ms
Request Payload.Token In Flags Body Matches Init	✅	108ms
Request Payload.Groups Round Trip	✅	108ms
Request Payload.Groups Default To Empty Object	✅	107ms
Request Payload.Person Properties Distinct Id Auto Populated When Caller Omits It	✅	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	✅	108ms
Request Lifecycle.No Flags Request On Init Alone	✅	3ms
Request Lifecycle.No Flags Request On Normal Capture	✅	106ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	111ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	106ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	110ms

[greptile-apps]

Comments Outside Diff (1)

1. spec/posthog/flags_spec.rb, line 342-352 (link)

   Missing HTTP-status retry coverage for max_retries > 1

   The "set to a higher count" context (max_retries = 3) only exercises the Errno::ECONNRESET exception path — it has no equivalent test for the new HTTP 502/504 retry branch. Without it there is no verification that attempts <= @feature_flag_request_max_retries fires the correct number of times for status-code retries, and a future refactor could silently break the exhaustion path for those codes. A parameterised example over [502, 504] that stubs persistent gateway errors and asserts 4 total requests (1 + 3 retries) would give the same coverage that already exists for exception retries.

   Rule Used: When implementing retry logic, include comprehensi... (source)

   Learned From
   PostHog/posthog#32651

   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: "chore: include rails SDK in flags retry ..." | Re-trigger Greptile}

[marandaneto]

Addressed Greptile outside-diff comment from #209 (comment) in 5eefd01 by adding parameterized 502/504 coverage for feature_flag_request_max_retries = 3. The new examples assert 4 total requests (initial + 3 retries), the final exhausted response, and 3 backoff sleeps. Validation passed: bundle exec rspec spec/posthog/flags_spec.rb (82 examples, 0 failures), bundle exec rubocop spec/posthog/flags_spec.rb, and ruby -c lib/posthog/feature_flags.rb.