---
title: "Get Experiment metadata"
method: GET
path: "/v1/experiments/{experiment_id}"
tags: ["experiments"]
---

# Get Experiment metadata

`GET /v1/experiments/{experiment_id}`

## Request

- Base URL: `https://api.pioneer.ai` (the document declares no server; this is the origin it was published from)
- URL: `https://api.pioneer.ai/v1/experiments/{experiment_id}`
- Auth: one of:
  - API key in header `X-API-Key`
  - HTTP bearer
- TypeScript: <https://skmtc.dev/pioneer/apis/brain-api/docs/v1/experiments/:experiment_id/get.ts> (a function with typed inputs; its response is checked against the schema)

Read Experiment metadata as its creator or an Owner/Admin.

Args:
    experiment_id: Experiment identifier.
    auth: Authenticated caller.

Returns:
    Authorized metadata.

## Path parameters

- `experiment_id` string, uuid, required

## Response `200`

Successful Response

- ExperimentResponse: Metadata for one durable Experiment.
  - `id` string, required
  - `project_id` string, required
  - `project_version_id` string, nullable, required
  - `team_id` string, required
  - `session_id` string, nullable: Creator-only transcript session identifier.
  - `created_by` string, required
  - `title` string, nullable, required
  - `mode` 'mle_agent' | 'auto_agent', required: Which agent drives an Experiment's conversation (EDD section 0.2).
  - `stage` 'scoping' | 'preparing_data' | 'training' | 'evaluating' | 'complete' | 'blocked' | 'cancelled', required: Agent-owned workflow stage of an Experiment (EDD section 0.2).
  - `mode_locked_at` string, date-time, nullable, required
  - `last_activity_at` string, date-time, required
  - `completed_at` string, date-time, nullable, required
  - `completion_outcome` 'incumbent_retained' | 'candidate_promoted': Why a COMPLETE Experiment ended (EDD 8.1). A closed set rather than free text because it is the thing that makes "the incumbent is already good enough" a *queryable* success instead of one inferred from the absence of a promoted model -- and an unvalidated string column cannot be counted on for that. Sits beside ``ExperimentStage`` and ``ExperimentMode``, which back the two other lifecycle discriminators on the same table.
  - `cancelled_at` string, date-time, nullable, required
  - `created_at` string, date-time, required
  - `updated_at` string, date-time, required
  - `summary` ExperimentAssetSummary, required: Stable landing counts and display fields for one Experiment.
    - `active_job_count` integer, required
    - `total_job_count` integer, required
    - `failed_job_count` integer, required: Training jobs on this Experiment that ended in failure. Surfaced on the fine-tune landing row so a failed run is visible without expanding the Experiment, which is the only place its assets are loaded.
    - `dataset_count` integer, required
    - `evaluation_count` integer, required
    - `base_models` string[], required
    - `base_models_truncated` boolean, required
    - `last_activity_at` string, date-time, required
    - `category_label` string, nullable: Uppercase domain label derived from the project, title, and base models. Filled for the agent-sessions list only; null on a single-Experiment read, which renders the project and title themselves. Null means not computed for this response, never that the Experiment has no category.
    - `last_agent_message` string, nullable: Creator-only latest agent message, truncated for a list row. Filled for the agent-sessions list only, and only on the caller's own transcripts.
    - `agent_step_count` integer, nullable: Creator-only count of agent turns taken in the transcript. Filled for the agent-sessions list only, and only on the caller's own transcripts.
    - `agent_turn_active` boolean, required: True when the Experiment's chat session has a Fine-Tune agent turn in flight, including scoping turns that have not started training yet. False when idle or when the turn stamp is too old to believe.

## Other responses

- `422`: Validation Error

## Changes

- **2026-09-24** `0e5e86e2bae5`: 1 info
  - endpoint added

[Operation history](https://skmtc.dev/pioneer/apis/brain-api/changes/v1/experiments/:experiment_id/get.md)

---

[API](https://skmtc.dev/pioneer/apis/brain-api.md) - [All operations](https://skmtc.dev/pioneer/apis/brain-api/llms.txt) - [OpenAPI document](https://skmtc.dev/pioneer/apis/brain-api/revisions/0e5e86e2bae5?raw)