---
title: "Record a support-safe Buzz human-adoption browser milestone"
method: POST
path: "/buzz-human-adoptions/v1/{buzz_human_adoption_id}/milestones"
tags: ["Buzz Control Plane"]
---

# Record a support-safe Buzz human-adoption browser milestone

`POST /buzz-human-adoptions/v1/{buzz_human_adoption_id}/milestones`

## Request

- Base URL: `https://api.run402.com`
- URL: `https://api.run402.com/buzz-human-adoptions/v1/{buzz_human_adoption_id}/milestones`
- Auth: HTTP bearer

Records one allowlisted observational stage for the exact target human session. It never changes attempt, offer, membership, authenticator, or credential state and accepts no signed proof or arbitrary text.

## Path parameters

- `buzz_human_adoption_id` string, required

## Headers

- `Idempotency-Key` string, required

## Request body

- BuzzHumanAdoptionMilestoneRequest
  - `milestone` 'buzz_open_requested' | 'callback_received' | 'callback_invalid_observed' | 'manual_proof_submitted' | 'manual_proof_invalid_observed' | 'completion_error_observed', required
  - `related_trace_id` string: Allowed only for completion_error_observed; the trace handle from the failed completion response.
  - `result_code` string: Allowed only for completion_error_observed; a stable machine-readable result code.

## Response `201`

Milestone recorded without changing authority state

- BuzzHumanAdoptionMilestoneReceipt
  - `attempt_reference` string, required
  - `stage` 'buzz_open_requested' | 'callback_received' | 'callback_invalid_observed' | 'manual_proof_submitted' | 'manual_proof_invalid_observed' | 'completion_error_observed', required
  - `observed_at` string, date-time, required
  - `trace_id` string, nullable, required
  - `result_code` string, nullable, required

## Other responses

- `403`: Canonical Buzz control-plane error. Authorization is existence-obscuring; proof failures never consume a challenge or partially create authority.
- `409`: Canonical Buzz control-plane error. Authorization is existence-obscuring; proof failures never consume a challenge or partially create authority.
- `422`: Canonical Buzz control-plane error. Authorization is existence-obscuring; proof failures never consume a challenge or partially create authority.

---

[API](https://skmtc.dev/run402/apis/run402-api.md) · [All operations](https://skmtc.dev/run402/apis/run402-api/llms.txt) · [OpenAPI document](https://skmtc.dev/run402/apis/run402-api/revisions/893607557f50?raw)