feat: capture_ai public beta

[carlos-marchal-ph]

💡 Motivation and Context

Takes the AI capture lane public as a beta, per RFC 1198 and the cross-SDK contract in sdk-specs (capture-ai capability, branch feat(aio)/add-capture-ai). The private _capture_ai (shipped since 7.29.0) becomes capture_ai — public on Client and module level, returning the event UUID — and the two private flags collapse into one public enable_full_ai_capture (wrapper routing + no truncation + media passthrough; privacy_mode always wins), with _use_ai_lane / _enable_multimodal_capture kept as silent deprecated aliases for the transition window. capture_ai returns the captured event's UUID (a client-generated one when the caller supplies none), which is what makes at-least-once delivery dedupe-safe. The compliance adapter opts into the new capture_ai harness suite (capture_ai_v0).

💚 How did you test it?

• New/updated unit tests: UUID return + wire equality + supplied-uuid preservation, flag matrix, alias mapping (constructor / properties / module-global setup() sync), privacy-mode-wins, lane isolation both directions. posthog/test/test_ai_capture_lane.py green; full make test green (pre-existing env-only failures identical on base).
• make public_api_check clean; snapshot regenerated.
• End-to-end: posthog-sdk-test-harness capture_ai suite 4/4 against this branch's compliance adapter.

📝 Checklist

• I reviewed the submitted code.
• I added tests to verify the changes.
• I updated the docs if needed. (docs PR on posthog.com, branch feat(aio)/capture-ai-docs)
• No breaking change or entry added to the changelog.

If releasing new changes

• Ran sampo add to generate a changeset file

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

• Authored with PostHog Code (Claude), directed by Carlos Marchal; implementation, tests, and cross-repo consistency checks were agent-executed with human review gates.
• Key decisions: one flag instead of splitting fidelity/media/routing knobs (large-event cases move together); UUID generation left to the shared capture path (a UUIDv7 upgrade was reverted as out of scope — one for the client-libraries fleet migration); deprecated flags aliased via properties so direct attribute writes keep working through the transition window.

---

Created with PostHog Code

[github-actions]

posthog-python Compliance Report

Date: 2026-08-13 09:41:54 UTC
Duration: 256515ms

✅ All Tests Passed!

111/111 tests passed

---

Capture_V1 Tests

✅ 94/94 tests passed

View Details

Test	Status	Duration
Endpoint And Method.Targets V1 Endpoint	✅	518ms
Endpoint And Method.Does Not Use Legacy Endpoints	✅	511ms
Required Headers.Has Authorization Bearer Header	✅	511ms
Required Headers.Has Content Type Json	✅	510ms
Required Headers.Has Posthog Sdk Info Format	✅	512ms
Required Headers.Has Posthog Attempt Header	✅	510ms
Required Headers.Has Posthog Request Id	✅	511ms
Required Headers.Has Posthog Request Timestamp	✅	510ms
Required Headers.Has User Agent	✅	511ms
Body Format.Body Has Created At And Batch	✅	511ms
Body Format.No Api Key In Body	✅	510ms
Body Format.No Sent At In Body	✅	511ms
Event Format.Event Has Required Root Fields	✅	511ms
Event Format.Event Uuid Is Valid	✅	511ms
Event Format.Event Timestamp Is Rfc3339	✅	512ms
Event Format.Distinct Id Is String	✅	510ms
Event Format.Distinct Id At Root Not Properties	✅	511ms
Event Format.Custom Properties Preserved	✅	511ms
Event Format.Set Properties Preserved	✅	511ms
Event Format.Set Once Properties Preserved	✅	511ms
Event Format.Groups Properties Preserved	✅	511ms
Event Format.Sdk Generates Uuid If Not Provided	✅	510ms
Event Format.Event Has Required Root Fields Batch	✅	514ms
Event Format.Event Uuid Is Valid Batch	✅	514ms
Event Format.Event Timestamp Is Rfc3339 Batch	✅	515ms
Event Format.Distinct Id Is String Batch	✅	514ms
Event Format.Distinct Id At Root Not Properties Batch	✅	514ms
Event Format.Custom Properties Preserved Batch	✅	514ms
Event Format.Set Properties Preserved Batch	✅	515ms
Event Format.Set Once Properties Preserved Batch	✅	514ms
Event Format.Groups Properties Preserved Batch	✅	515ms
Event Format.Sdk Generates Uuid If Not Provided Batch	✅	514ms
Batch Behavior.Multiple Events In Single Batch	✅	518ms
Batch Behavior.Batch Envelope Smoke	✅	516ms
Batch Behavior.Flush With No Events Sends Nothing	✅	506ms
Batch Behavior.Flush At Triggers Batch	✅	1012ms
Batch Behavior.Created At Reflects Batch Creation Time	✅	512ms
Deduplication.Generates Unique Uuids	✅	518ms
Deduplication.Different Events Same Content Different Uuids	✅	513ms
Deduplication.Preserves Uuid On Retry	✅	6517ms
Deduplication.Preserves Timestamp On Retry	✅	6520ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	6520ms
Deduplication.No Duplicate Events In Batch	✅	519ms
Header Behavior On Retry.Attempt Header Starts At One	✅	511ms
Header Behavior On Retry.Attempt Header Increments On Retry	✅	13522ms
Header Behavior On Retry.Request Id Preserved On Retry	✅	6520ms
Header Behavior On Retry.Different Requests Have Different Request Ids	✅	3021ms
Header Behavior On Retry.Request Timestamp Changes On Retry	✅	6519ms
Response Format Validation.Success Response Has Uuid Keyed Results	✅	511ms
Response Format Validation.Success Response Has Ok For Each Event	✅	515ms
Response Format Validation.Success No Retry After When All Ok	✅	513ms
Response Format Validation.Success Retry After Present When Retry Events	✅	1516ms
Response Format Validation.Success No Retry After When Drop Only	✅	513ms
Response Format Validation.Response Echoes Request Id	✅	511ms
Retry Behavior.Retries On 408	✅	6521ms
Retry Behavior.Retries On 500	✅	6520ms
Retry Behavior.Retries On 503	✅	8520ms
Retry Behavior.Retries On 504	✅	6520ms
Retry Behavior.Retryable Errors Have Retry After	✅	3518ms
Retry Behavior.Respects Retry After On Retryable Error	✅	11523ms
Retry Behavior.Does Not Retry On 400	✅	2514ms
Retry Behavior.Does Not Retry On 401	✅	2514ms
Retry Behavior.Does Not Retry On 402	✅	2514ms
Retry Behavior.Does Not Retry On 413	✅	2514ms
Retry Behavior.Does Not Retry On 415	✅	2514ms
Retry Behavior.Non Retryable Errors Have No Retry After	✅	2514ms
Retry Behavior.Implements Backoff	✅	22537ms
Retry Behavior.Max Retries Respected	✅	22534ms
Partial Batch Handling.Handles 200 Full Success	✅	2514ms
Partial Batch Handling.Handles 200 With All Ok	✅	3517ms
Partial Batch Handling.Does Not Retry Dropped Events	✅	3518ms
Partial Batch Handling.Does Not Retry Limited Events	✅	3514ms
Partial Batch Handling.Prunes Ok Events On Partial Retry	✅	6523ms
Partial Batch Handling.Prunes Dropped Events On Partial Retry	✅	6521ms
Partial Batch Handling.Retries Only Retry Events From Partial	✅	6523ms
Partial Batch Handling.Partial Retry Preserves Uuids	✅	6523ms
Partial Batch Handling.Partial Retry Attempt Header Increments	✅	6522ms
Partial Batch Handling.Partial Retry Request Id Preserved	✅	6523ms
Partial Batch Handling.Respects Retry After On Partial	✅	8523ms
Partial Batch Handling.Unknown Result Treated As Terminal	✅	3517ms
Partial Batch Handling.Mixed Ok Drop Limited No Retry	✅	3519ms
Compression.Sends Gzip Content Encoding	✅	512ms
Compression.No Content Encoding When Disabled	✅	511ms
Compression.Compressed Body Is Decompressible	✅	511ms
Error Handling.Does Not Retry On Unknown 4Xx	✅	2513ms
Event Options.Cookieless Mode Override	✅	512ms
Event Options.Disable Skew Correction Override	✅	511ms
Event Options.Process Person Profile Override	✅	511ms
Event Options.Product Tour Id Override	✅	511ms
Event Options.Unset Options Omitted	✅	510ms
Event Options.Options Override In Batch	✅	515ms
Geoip And Historical Migration.Geoip Disable Injected Into Properties	✅	511ms
Geoip And Historical Migration.Historical Migration Set In Body	✅	511ms
Geoip And Historical Migration.Historical Migration Absent By Default	✅	511ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	12ms
Request Payload.Flags Request Uses V2 Query Param	✅	11ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	11ms
Request Payload.Flags Request Omits Authorization Header	✅	10ms
Request Payload.Token In Flags Body Matches Init	✅	11ms
Request Payload.Groups Round Trip	✅	11ms
Request Payload.Groups Default To Empty Object	✅	11ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	12ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	11ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	12ms
Request Lifecycle.No Flags Request On Init Alone	✅	4ms
Request Lifecycle.No Flags Request On Normal Capture	✅	511ms
Request Lifecycle.Two Flag Calls Produce Two Remote Requests	✅	16ms
Request Lifecycle.Mock Response Value Is Returned To Caller	✅	11ms
Retry Behavior.Retries Flags On 502	✅	316ms
Retry Behavior.Retries Flags On 504	✅	314ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	513ms

[greptile-apps]

Prompt To Fix All With AI

### Issue 1
posthog/client.py:1503
**AI events retain UUIDv4 fallback**

When `capture_ai` is called without a UUID, it delegates to the shared `_capture` and `_enqueue` path, which generates a UUIDv4. The returned and transmitted identifier therefore violates the new capture-ai UUIDv7 contract and lacks the intended time-ordering semantics.

---

For each issue above, determine whether it is valid and should be fixed. If so, fix it directly.

_{Reviews (1): Last reviewed commit: "feat: capture ai public beta" | Re-trigger Greptile}

[marandaneto]

Automated review findings.

[marandaneto]

blocking: Returned UUID can differ from the transmitted UUID

This promises that capture_ai() returns the event UUID, but _enqueue() snapshots sent_uuid before invoking before_send. Because that supported callback can replace or remove msg["uuid"], the queued event can differ from the returned UUID, breaking the deduplication contract. Please normalize/generate the UUID after before_send, return the final queued UUID, and add regression coverage for callbacks that replace or remove it.

[carlos-marchal-ph]

Fixed!