docs: Refresh and simplify SDK agent guidance

[marandaneto]

💡 Motivation and Context

The agent instructions contain stale references or repeat details maintained elsewhere. Keep repository-specific safeguards and make the instructions easier to use for focused SDK changes.

Shorten AGENTS.md while retaining the key capture, retry, compression, drop, and backoff safeguards. Direct capture changes to the implementation and tests instead of maintaining a separate protocol guide. Centralize validation and provider guidance in CONTRIBUTING.md. Correct the uv sources configuration name and warn that make prep_local deletes and recreates the sibling local mirror. Warn that make build_release_analytics clears dist/ and require publishing or preserving posthog artifacts first.

The capture-protocol document introduced earlier in this PR has been removed. The final diff only changes AGENTS.md and CONTRIBUTING.md.

💚 How did you test it?

Checked local Markdown links, exact Git path casing, anchors, code fences, whitespace, changed-file scope, and preservation of the API approval and scoped spec-review rules. Verified the artifact warning against the Makefile and release workflow without running destructive build targets. SDK runtime builds and tests were not run for this documentation-only change. Autoreview was skipped because every changed file is documentation.

📝 Checklist

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

No SDK code changes. Runtime tests and release changesets are not needed for this documentation-only PR.

If releasing new changes

• Ran sampo add to generate a changeset file

Not applicable. This PR does not release SDK changes.

🤖 Agent context

Autonomy: Human-driven (agent-assisted)

Tools: Pi, Git, and GitHub CLI. The SDK-wide documentation audit used Pi subagents for implementation and independent reviews. The human driver approved the audit and simplification plan, then requested removing the separate capture protocol reference. Core capture safeguards remain in AGENTS.md. Human review is still required. No public session link is available.

[greptile-apps]

[Low risk] Updates SDK agent and contributor guidance documentation.

The PR appears safe to merge, though the existing release-artifact guidance should be corrected.

_{Reviews (2) · Last reviewed commit: "docs: Remove redundant capture protocol ..."}

[github-actions]

posthog-python Compliance Report

Date: 2026-10-05T10:41:30.481470+00:00
Duration: 259249ms

✅ All Tests Passed!

121/121 tests passed

---

Capture_V1 Tests

✅ 95/95 tests passed

View Details

Test	Status	Duration
Endpoint And Method.Targets V1 Endpoint	✅	513ms
Endpoint And Method.Does Not Use Legacy Endpoints	✅	508ms
Required Headers.Has Authorization Bearer Header	✅	508ms
Required Headers.Has Content Type Json	✅	508ms
Required Headers.Has Posthog Sdk Info Format	✅	508ms
Required Headers.Has Posthog Attempt Header	✅	507ms
Required Headers.Has Posthog Request Id	✅	508ms
Required Headers.Has Posthog Request Timestamp	✅	508ms
Required Headers.Has User Agent	✅	507ms
Body Format.Body Has Created At And Batch	✅	508ms
Body Format.No Api Key In Body	✅	508ms
Body Format.No Sent At In Body	✅	507ms
Event Format.Event Has Required Root Fields	✅	508ms
Event Format.Event Uuid Is Valid	✅	508ms
Event Format.Event Timestamp Is Rfc3339	✅	508ms
Event Format.Non Utc Event Timestamp Is Converted To Utc	✅	511ms
Event Format.Distinct Id Is String	✅	508ms
Event Format.Distinct Id At Root Not Properties	✅	507ms
Event Format.Custom Properties Preserved	✅	508ms
Event Format.Set Properties Preserved	✅	507ms
Event Format.Set Once Properties Preserved	✅	508ms
Event Format.Groups Properties Preserved	✅	507ms
Event Format.Sdk Generates Uuid If Not Provided	✅	508ms
Event Format.Event Has Required Root Fields Batch	✅	510ms
Event Format.Event Uuid Is Valid Batch	✅	510ms
Event Format.Event Timestamp Is Rfc3339 Batch	✅	510ms
Event Format.Distinct Id Is String Batch	✅	511ms
Event Format.Distinct Id At Root Not Properties Batch	✅	510ms
Event Format.Custom Properties Preserved Batch	✅	510ms
Event Format.Set Properties Preserved Batch	✅	510ms
Event Format.Set Once Properties Preserved Batch	✅	509ms
Event Format.Groups Properties Preserved Batch	✅	510ms
Event Format.Sdk Generates Uuid If Not Provided Batch	✅	510ms
Batch Behavior.Multiple Events In Single Batch	✅	513ms
Batch Behavior.Batch Envelope Smoke	✅	512ms
Batch Behavior.Flush With No Events Sends Nothing	✅	512ms
Batch Behavior.Flush At Triggers Batch	✅	1008ms
Batch Behavior.Created At Reflects Batch Creation Time	✅	508ms
Deduplication.Generates Unique Uuids	✅	512ms
Deduplication.Different Events Same Content Different Uuids	✅	509ms
Deduplication.Preserves Uuid On Retry	✅	6516ms
Deduplication.Preserves Timestamp On Retry	✅	6515ms
Deduplication.Preserves Uuid And Timestamp On Batch Retry	✅	6514ms
Deduplication.No Duplicate Events In Batch	✅	512ms
Header Behavior On Retry.Attempt Header Starts At One	✅	508ms
Header Behavior On Retry.Attempt Header Increments On Retry	✅	13524ms
Header Behavior On Retry.Request Id Preserved On Retry	✅	6512ms
Header Behavior On Retry.Different Requests Have Different Request Ids	✅	3016ms
Header Behavior On Retry.Request Timestamp Changes On Retry	✅	6516ms
Response Format Validation.Success Response Has Uuid Keyed Results	✅	508ms
Response Format Validation.Success Response Has Ok For Each Event	✅	511ms
Response Format Validation.Success No Retry After When All Ok	✅	509ms
Response Format Validation.Success Retry After Present When Retry Events	✅	1513ms
Response Format Validation.Success No Retry After When Drop Only	✅	509ms
Response Format Validation.Response Echoes Request Id	✅	508ms
Retry Behavior.Retries On 408	✅	6516ms
Retry Behavior.Retries On 500	✅	6515ms
Retry Behavior.Retries On 503	✅	8515ms
Retry Behavior.Retries On 504	✅	6512ms
Retry Behavior.Retryable Errors Have Retry After	✅	3513ms
Retry Behavior.Respects Retry After On Retryable Error	✅	11520ms
Retry Behavior.Does Not Retry On 400	✅	2511ms
Retry Behavior.Does Not Retry On 401	✅	2511ms
Retry Behavior.Does Not Retry On 402	✅	2510ms
Retry Behavior.Does Not Retry On 413	✅	2512ms
Retry Behavior.Does Not Retry On 415	✅	2510ms
Retry Behavior.Non Retryable Errors Have No Retry After	✅	2510ms
Retry Behavior.Implements Backoff	✅	22532ms
Retry Behavior.Max Retries Respected	✅	22536ms
Partial Batch Handling.Handles 200 Full Success	✅	2510ms
Partial Batch Handling.Handles 200 With All Ok	✅	3511ms
Partial Batch Handling.Does Not Retry Dropped Events	✅	3513ms
Partial Batch Handling.Does Not Retry Limited Events	✅	3513ms
Partial Batch Handling.Prunes Ok Events On Partial Retry	✅	6513ms
Partial Batch Handling.Prunes Dropped Events On Partial Retry	✅	6518ms
Partial Batch Handling.Retries Only Retry Events From Partial	✅	6516ms
Partial Batch Handling.Partial Retry Preserves Uuids	✅	6538ms
Partial Batch Handling.Partial Retry Attempt Header Increments	✅	6519ms
Partial Batch Handling.Partial Retry Request Id Preserved	✅	6518ms
Partial Batch Handling.Respects Retry After On Partial	✅	8519ms
Partial Batch Handling.Unknown Result Treated As Terminal	✅	3511ms
Partial Batch Handling.Mixed Ok Drop Limited No Retry	✅	3516ms
Compression.Sends Gzip Content Encoding	✅	509ms
Compression.No Content Encoding When Disabled	✅	508ms
Compression.Compressed Body Is Decompressible	✅	508ms
Error Handling.Does Not Retry On Unknown 4Xx	✅	2511ms
Event Options.Cookieless Mode Override	✅	508ms
Event Options.Disable Skew Correction Override	✅	507ms
Event Options.Process Person Profile Override	✅	507ms
Event Options.Product Tour Id Override	✅	508ms
Event Options.Unset Options Omitted	✅	508ms
Event Options.Options Override In Batch	✅	510ms
Geoip And Historical Migration.Geoip Disable Injected Into Properties	✅	508ms
Geoip And Historical Migration.Historical Migration Set In Body	✅	509ms
Geoip And Historical Migration.Historical Migration Absent By Default	✅	507ms

Capture_Ai Tests

✅ 5/5 tests passed

View Details

Test	Status	Duration
Routing.Capture Ai Posts To Ai Endpoint	✅	508ms
Routing.Capture Does Not Reroute Ai Named Events	✅	507ms
Identity.Capture Ai Event Has Uuid	✅	509ms
Identity.Capture Ai Keeps Supplied Uuid	✅	507ms
Timestamp Format.Non Utc Event Timestamp Is Converted To Utc	✅	509ms

Feature_Flags Tests

✅ 17/17 tests passed

View Details

Test	Status	Duration
Request Payload.Request With Person Properties Device Id	✅	9ms
Request Payload.Flags Request Uses V2 Query Param	✅	7ms
Request Payload.Flags Request Hits Flags Path Not Decide	✅	6ms
Request Payload.Flags Request Omits Authorization Header	✅	7ms
Request Payload.Token In Flags Body Matches Init	✅	6ms
Request Payload.Groups Round Trip	✅	6ms
Request Payload.Groups Default To Empty Object	✅	7ms
Request Payload.Disable Geoip False Propagates As Geoip Disable False	✅	7ms
Request Payload.Disable Geoip Omitted Defaults To False	✅	6ms
Request Payload.Flag Keys To Evaluate Contains Only Requested Key	✅	6ms
Request Lifecycle.No Flags Request On Init Alone	✅	3ms
Request Lifecycle.No Flags Request On Normal Capture	✅	506ms
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	✅	309ms
Retry Behavior.Retries Flags On 504	✅	310ms
Side Effect Events.Get Feature Flag Captures Feature Flag Called Event	✅	509ms

Feature_Flags_Local_Evaluation Tests

✅ 4/4 tests passed

View Details

Test	Status	Duration
Versioned Boolean Matching.Matching Version Missing	✅	49ms
Versioned Boolean Matching.Matching Version 1	✅	46ms
Versioned Boolean Matching.Matching Version 2	✅	45ms
Versioned Boolean Matching.Version Only Reload 1 2 1 2 Missing	✅	25ms