---
title: "Select a milestone version's champion model"
method: POST
path: "/projects/{project_id}/versions/{version_id}/champion"
tags: ["project-versions"]
---

# Select a milestone version's champion model

`POST /projects/{project_id}/versions/{version_id}/champion`

Record a model as the milestone's champion and route traffic to it.

Args:
    project_id: Project the milestone belongs to.
    version_id: Milestone to record the champion on.
    request: Exactly one champion target, plus an optional reason.
    auth: Authenticated caller.

Returns:
    The updated milestone, the deployment record, and the live pointer.

## Path parameters

- `project_id` string, uuid, required
- `version_id` string, uuid, required

## Request body

- ChampionRequest — Request body for selecting a milestone's champion.
  - `training_job_id` string, nullable — Fine-tune to promote.
  - `base_model` string, nullable — Catalog base model to promote.
  - `reason` string, nullable — Why this model was chosen.

## Response `200`

Successful Response

- ChampionResponse — The milestone and routing state after a champion was confirmed.
  - `version` ProjectVersionResponse, required — A single project milestone.
    - `id` string, required
    - `project_id` string, required
    - `team_id` string, required
    - `version_number` integer, required
    - `status` 'current' | 'frozen' | 'abandoned', required — Lifecycle of a project milestone version (EDD section 9.1).
    - `objective` string, nullable, required
    - `carryover_summary` string, required
    - `champion` ChampionRef, required — What a milestone settled on, as exactly one populated target.
      - `training_job_id` string, nullable — Fine-tune chosen as champion.
      - `base_model` string, nullable — Catalog base model chosen as champion.
    - `created_by` string, required
    - `closed_by` string, nullable, required
    - `closed_at` string, date-time, nullable, required
    - `created_at` string, date-time, required
  - `deployment_id` string, required — Deployment history record written by this promotion.
  - `active_model_id` string, required — Project's live routing pointer after promotion.

## Other responses

- `422` — Validation Error

---

[API](https://skmtc.net/pioneer/apis/brain-api.md) · [All operations](https://skmtc.net/pioneer/apis/brain-api/llms.txt) · [OpenAPI document](https://skmtc-service-staging.skmtc.workers.dev/v1/apis/pioneer/brain-api/revisions/b92f75fd3b61/schema)