[marandaneto]

💡 Motivation and Context

The latest Rails CI job fails because it installs mcp 1.8.0. This is a dependency compatibility regression, not a timing flake.

That version passes auth_info: to MCP::Server#handle_request. Our prepended wrapper rejects the keyword, so requests return JSON-RPC internal errors. This also affects uninstrumented servers once instrumentation has been installed in the process.

The wrapper now accepts and forwards additional request keywords unchanged. This preserves authentication context without requiring the new keyword on older MCP versions. It follows the MCP analytics spec's observer-only requirement.

💚 How did you test it?

• Reproduced all 48 MCP failures with the latest dependency bundle.
• Added regression tests for handle and handle_json, covering instrumented and uninstrumented servers. Both tests fail before the fix and pass afterward. They verify the tool receives the original authentication context and only the instrumented server emits telemetry.
• Full default suite: 1,560 examples, zero failures, four expected pending tests.
• Full latest Rails/OpenTelemetry suite with MCP 1.8.0: 1,560 examples, zero failures.
• MCP suite with seeds 1, 42, and 2026: 182 examples, zero failures per run.
• RuboCop and rake public_api:check pass.
• Branch autoreview reports no actionable findings.

📝 Checklist

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

If releasing new changes

• Added a patch changeset for posthog-ruby manually.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Pi coding agent used read, bash, edit, write, and codemode, plus the isolated Pi autoreview helper. Session ID: 01a167df-4039-74b6-b44a-02aea7314678 (no shared session URL).

The investigation identified a dependency change rather than test nondeterminism. The fix forwards keywords instead of pinning MCP or changing test expectations. Human review is required.

[posthog]

PostHog Review · Standard · reviewed d269ec9: no findings.

This Standard review started from the posthog-review label. Comment @posthog review --deep for a Deep review, or @posthog help to see all commands.

[github-actions]

posthog-ruby-sync Compliance Report

Date: 2026-10-23T08:40:48.868803+00:00
Duration: 94096ms

⚠️ Some Tests Failed

45/47 tests passed, 2 failed

---

Capture Tests

⚠️ 29/30 tests passed, 1 failed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	10ms
Format Validation.Event Has Uuid	✅	6ms
Format Validation.Event Has Lib Properties	✅	7ms
Format Validation.Distinct Id Is String	✅	9ms
Format Validation.Token Is Present	✅	8ms
Format Validation.Custom Properties Preserved	✅	7ms
Format Validation.Event Has Timestamp	✅	9ms
Format Validation.Non Utc Event Timestamp Is Converted To Utc	✅	7ms
Retry Behavior.Retries On 503	✅	5249ms
Retry Behavior.Does Not Retry On 400	✅	2011ms
Retry Behavior.Does Not Retry On 401	✅	2010ms
Retry Behavior.Respects Retry After Header	✅	8016ms
Retry Behavior.Implements Backoff	✅	15265ms
Retry Behavior.Retries On 500	✅	5161ms
Retry Behavior.Retries On 502	✅	5161ms
Retry Behavior.Retries On 504	✅	5117ms
Retry Behavior.Max Retries Respected	✅	15575ms
Deduplication.Generates Unique Uuids	✅	22ms
Deduplication.Preserves Uuid On Retry	✅	5149ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10333ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5122ms
Deduplication.No Duplicate Events In Batch	✅	19ms
Deduplication.Different Events Have Different Uuids	✅	9ms
Compression.Sends Gzip When Enabled	✅	6ms
Batch Format.Uses Proper Batch Structure	✅	6ms
Batch Format.Flush With No Events Sends Nothing	✅	4ms
Batch Format.Multiple Events Batched Together	❌	17ms
Error Handling.Does Not Retry On 403	✅	2007ms
Error Handling.Does Not Retry On 413	✅	2010ms
Error Handling.Retries On 408	✅	5116ms

Failures

batch_format.multiple_events_batched_together

Expected 1 requests, got 5

Feature_Flags Tests

⚠️ 16/17 tests passed, 1 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	9ms
Request Payload.Flags Request Uses V2 Query Param	✅	6ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	7ms
Request Payload.Flags Request Omits Authorization Header	✅	7ms
Request Payload.Token In Flags Body Matches Init	✅	8ms
Request Payload.Groups Round Trip	✅	8ms
Request Payload.Groups Default To Empty Object	✅	9ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	8ms
Request Payload.Disable Geoip Omitted Defaults To False	❌	7ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	7ms
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	✅	10ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	6ms
Retry Behavior.Retries Flags On 502	✅	110ms
Retry Behavior.Retries Flags On 504	✅	152ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	8ms

Failures

request_payload.disable_geoip_omitted_defaults_to_false

Field 'geoip_disable' not found in /flags request body at path 'geoip_disable'. Available keys: ['distinct_id', 'groups', 'person_properties', 'group_properties', 'flag_keys_to_evaluate', 'token']

[github-actions]

posthog-ruby-async Compliance Report

Date: 2026-10-23T08:40:55.474148+00:00
Duration: 98551ms

⚠️ Some Tests Failed

46/47 tests passed, 1 failed

---

Capture Tests

✅ 30/30 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	108ms
Format Validation.Event Has Uuid	✅	106ms
Format Validation.Event Has Lib Properties	✅	110ms
Format Validation.Distinct Id Is String	✅	107ms
Format Validation.Token Is Present	✅	106ms
Format Validation.Custom Properties Preserved	✅	108ms
Format Validation.Event Has Timestamp	✅	107ms
Format Validation.Non Utc Event Timestamp Is Converted To Utc	✅	10ms
Retry Behavior.Retries On 503	✅	5411ms
Retry Behavior.Does Not Retry On 400	✅	2109ms
Retry Behavior.Does Not Retry On 401	✅	2108ms
Retry Behavior.Respects Retry After Header	✅	8115ms
Retry Behavior.Implements Backoff	✅	15608ms
Retry Behavior.Retries On 500	✅	5214ms
Retry Behavior.Retries On 502	✅	5212ms
Retry Behavior.Retries On 504	✅	5212ms
Retry Behavior.Max Retries Respected	✅	15723ms
Deduplication.Generates Unique Uuids	✅	111ms
Deduplication.Preserves Uuid On Retry	✅	5212ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10308ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5216ms
Deduplication.No Duplicate Events In Batch	✅	111ms
Deduplication.Different Events Have Different Uuids	✅	108ms
Compression.Sends Gzip When Enabled	✅	107ms
Batch Format.Uses Proper Batch Structure	✅	106ms
Batch Format.Flush With No Events Sends Nothing	✅	5ms
Batch Format.Multiple Events Batched Together	✅	110ms
Error Handling.Does Not Retry On 403	✅	2108ms
Error Handling.Does Not Retry On 413	✅	2109ms
Error Handling.Retries On 408	✅	5212ms

Feature_Flags Tests

⚠️ 16/17 tests passed, 1 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	108ms
Request Payload.Flags Request Uses V2 Query Param	✅	107ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	107ms
Request Payload.Flags Request Omits Authorization Header	✅	108ms
Request Payload.Token In Flags Body Matches Init	✅	109ms
Request Payload.Groups Round Trip	✅	108ms
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	❌	107ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	107ms
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	✅	107ms
Retry Behavior.Retries Flags On 502	✅	257ms
Retry Behavior.Retries Flags On 504	✅	209ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	109ms

Failures

request_payload.disable_geoip_omitted_defaults_to_false

Field 'geoip_disable' not found in /flags request body at path 'geoip_disable'. Available keys: ['distinct_id', 'groups', 'person_properties', 'group_properties', 'flag_keys_to_evaluate', 'token']