chore: add AI contribution policy

[dustinbyrne]

Problem

PostHog's main repo has an AI contributions policy and PR-template agent context section. The SDK and agent-extension repos should set the same expectations so AI-assisted contributions are easier to review consistently.

Changes

• Add AI_POLICY.md at the repository root.
• Add an Agent context section to the PR template.
• Adapt the proof-of-work guidance for SDK and agent-extension projects by using repo-neutral testing guidance and calling out example-project smoke tests where applicable.

How did you test this code?

• Verified the markdown changes locally.
• Ran git diff --check.
• Verified the PR template contains exactly one ## 🤖 Agent context section.

Checklist

• Accounted for backwards compatibility of any changes (no breaking changes!)
• Documentation-only change

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Pi was used to apply the same policy/template update across the SDK and agent-extension repositories. The change was prepared in isolated git worktrees to avoid disturbing existing local branches, then reviewed for duplicate Agent context sections and markdown whitespace issues.

[greptile-apps]

_{Reviews (1): Last reviewed commit: "chore: add AI contribution policy" | Re-trigger Greptile}

[github-actions]

posthog-elixir Compliance Report

Date: 2026-06-15 21:05:42 UTC
Duration: 107472ms

⚠️ Some Tests Failed

42/45 tests passed, 3 failed

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Capture Tests

✅ 29/29 tests passed

View Details

Test	Status	Duration
Format Validation.Event Has Required Fields	✅	610ms
Format Validation.Event Has Uuid	✅	610ms
Format Validation.Event Has Lib Properties	✅	610ms
Format Validation.Distinct Id Is String	✅	610ms
Format Validation.Token Is Present	✅	610ms
Format Validation.Custom Properties Preserved	✅	611ms
Format Validation.Event Has Timestamp	✅	610ms
Retry Behavior.Retries On 503	✅	5615ms
Retry Behavior.Does Not Retry On 400	✅	2613ms
Retry Behavior.Does Not Retry On 401	✅	2614ms
Retry Behavior.Respects Retry After Header	✅	5616ms
Retry Behavior.Implements Backoff	✅	15626ms
Retry Behavior.Retries On 500	✅	5617ms
Retry Behavior.Retries On 502	✅	5615ms
Retry Behavior.Retries On 504	✅	5617ms
Retry Behavior.Max Retries Respected	✅	15622ms
Deduplication.Generates Unique Uuids	✅	622ms
Deduplication.Preserves Uuid On Retry	✅	5617ms
Deduplication.Preserves Uuid And Timestamp On Retry	✅	10621ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	5618ms
Deduplication.No Duplicate Events In Batch	✅	616ms
Deduplication.Different Events Have Different Uuids	✅	613ms
Compression.Sends Gzip When Enabled	✅	609ms
Batch Format.Uses Proper Batch Structure	✅	611ms
Batch Format.Flush With No Events Sends Nothing	✅	607ms
Batch Format.Multiple Events Batched Together	✅	615ms
Error Handling.Does Not Retry On 403	✅	2614ms
Error Handling.Does Not Retry On 413	✅	2612ms
Error Handling.Retries On 408	✅	5616ms

Feature_Flags Tests

⚠️ 13/16 tests passed, 3 failed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	9ms
Request Payload.Flags Request Uses V2 Query Param	✅	10ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	8ms
Request Payload.Flags Request Omits Authorization Header	✅	9ms
Request Payload.Token In Flags Body Matches Init	✅	8ms
Request Payload.Groups Round Trip	✅	9ms
Request Payload.Groups Default To Empty Object	✅	9ms
Request Payload.Person Properties Distinct Id Auto Populated When Caller Omits It	✅	8ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	8ms
Request Payload.Disable Geoip Omitted Defaults To False	❌	8ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	9ms
Request Lifecycle.No Flags Request On Init Alone	✅	3ms
Request Lifecycle.No Flags Request On Normal Capture	✅	610ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	13ms
Request Lifecycle.Mock Response Value Is Returned To Caller	❌	8ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	❌	612ms

Failures

request_payload.disable_geoip_omitted_defaults_to_false

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

request_lifecycle.mock_response_value_is_returned_to_caller

Last action result missing field 'value'. Keys: ['error', 'success']

side_effect_events.get_feature_flag_captures_feature_flag_called_event

Expected 1 events with name '$feature_flag_called', got 0