Graine AI
API referenceAgent versions

Create an A/B experiment

Create an A/B experiment on this agent.

Create an A/B experiment on this agent.

The agent in the path is the control; variant_agent_id names the challenger. Both must already exist in your organisation, and they must be different agents — sending the same id for both is a 400.

The experiment is created at status draft and routes no traffic until you activate it with PATCH ... {"status": "active"}. Only one experiment per control agent may be ACTIVE at a time; the second activation is a 409.

variant_traffic_pct defaults to 50, i.e. an even split once active.

Create never conflicts. A new experiment is always a draft and no active-count check applies, so 409 is not a possible outcome here — it only appears on PATCH and DELETE.

Rate limit: 1000 requests per minute per organization (bucket default). Exceeding it returns 429 with Retry-After; the X-RateLimit-* response headers report your remaining allowance on every call.

POST
/v2/agents/{agent_id}/versions
/v2/agents/6c6f4cc3-f56c-479d-8422-7f76694daa29/versions

The Authorization access token

Authorization

Authorization
Required
Bearer <token>

Your Graine API key. Create one in the dashboard under Developers, or via POST /v2/api-keys. Send it as Authorization: Bearer <key>.

In: header

Request Body

application/jsonRequired

variant_agent_id
Required
Variant Agent Id

The challenger agent. Must already exist in this organisation and must differ from the control agent.

Minimum length: 1

version_name
Required
Version Name

Experiment name, 1-100 characters.

Minimum length: 1Maximum length: 100

main_agent_idMain Agent Id | null

Optional echo of the control agent in the path. If supplied it must match the path exactly.

descriptionDescription | null

Free-text notes, up to 500 characters.

Maximum length: 500

variable_testedVariable Tested | null

What is being tested, e.g. 'voice', 'script', 'cadence'.

Maximum length: 200

variant_traffic_pctVariant Traffic Pct

Percentage of calls routed to the variant once the experiment is ACTIVE. Defaults to an even 50/50 split.

Default: 50Minimum: 0Maximum: 100

Path Parameters

agent_id
Required
Agent Id

The CONTROL agent. This becomes main_agent_id.

Query Parameters

organization_idOrganization Id

Optional. It must match the organisation the API key belongs to; any other value is rejected.

Response Body

201

The created experiment, at status 'draft'.

version_id
Required
Version Id

Experiment identifier.

main_agent_id
Required
Main Agent Id

The CONTROL agent. Always equal to the agent_id in the path.

variant_agent_id
Required
Variant Agent Id

The CHALLENGER agent that receives the split traffic.

version_name
Required
Version Name

Experiment name.

descriptionDescription | null

Free-text notes about the experiment.

variable_testedVariable Tested | null

What is being tested, e.g. 'voice', 'script', 'cadence'.

variant_traffic_pct
Required
Variant Traffic Pct

Percentage of calls routed to the variant (0-100). The remainder goes to the control agent. 0 pauses the variant in place; 100 promotes it.

status
Required
Status

draft | active | paused | concluded

winnerWinner | null

control | variant. Only ever set on a concluded experiment.

start_dateStart Date | null

ISO-8601 UTC. Informational; it does not gate routing.

end_dateEnd Date | null

ISO-8601 UTC. Informational; it does not gate routing.

created_byCreated By | null

Identifier of whoever created the experiment.

created_atCreated At | null

ISO-8601 UTC.

updated_atUpdated At | null

ISO-8601 UTC.

400

1000 — malformed or contradictory input: an unknown status token, an empty patch body, an explicit null, or a variant agent that does not exist in this organisation.

error
Required
Error

Stable integer code from the /v2 error table. Branch on this.

message
Required
Message

One human-readable sentence. Wording may change; the code will not.

401

1100 — missing, unknown or inactive API key. 1101 — a browser session token was presented.

error
Required
Error

Stable integer code from the /v2 error table. Branch on this.

message
Required
Message

One human-readable sentence. Wording may change; the code will not.

403

1102 — the key is valid but lacks the scope this endpoint requires, or names another organisation. GET /v2/scopes reports which scopes the key holds.

error
Required
Error

Stable integer code from the /v2 error table. Branch on this.

message
Required
Message

One human-readable sentence. Wording may change; the code will not.

404

1200 — no such agent, or no such version for that agent, in this organisation. Cross-tenant reads answer 404, never 403, so ids cannot be probed.

error
Required
Error

Stable integer code from the /v2 error table. Branch on this.

message
Required
Message

One human-readable sentence. Wording may change; the code will not.

422

1001 — the body or query failed validation; the message names the first offending field.

error
Required
integer

Stable integer code from the error table. Branch on this, not on the message.

message
Required
string

One human-readable sentence. Wording may change; the code will not.

429

1300 — per-organisation rate limit exceeded. Carries Retry-After.

error
Required
Error

Stable integer code from the /v2 error table. Branch on this.

message
Required
Message

One human-readable sentence. Wording may change; the code will not.

503

1501 — the agent service is unreachable or returned a 5xx.

error
Required
Error

Stable integer code from the /v2 error table. Branch on this.

message
Required
Message

One human-readable sentence. Wording may change; the code will not.

504

1502 — the agent service did not respond in time.

error
Required
Error

Stable integer code from the /v2 error table. Branch on this.

message
Required
Message

One human-readable sentence. Wording may change; the code will not.

curl -X POST "https://api.graine.ai/v2/agents/6c6f4cc3-f56c-479d-8422-7f76694daa29/versions?organization_id=string" \
  -H "Authorization: Bearer <token>" \
  -H "Content-Type: application/json" \
  -d '{
    "variant_agent_id": "85598652-87ce-4585-93e3-e03a42259796",
    "version_name": "Warmer opening line",
    "main_agent_id": "6c6f4cc3-f56c-479d-8422-7f76694daa29",
    "description": "Testing a warmer opening line against the current script.",
    "variable_tested": "script",
    "variant_traffic_pct": 50
  }'

The created experiment, at status 'draft'.

{
  "version_id": "9f1c0f7e-1f2a-4c3b-8a11-2c6a0a5f8d10",
  "main_agent_id": "6c6f4cc3-f56c-479d-8422-7f76694daa29",
  "variant_agent_id": "85598652-87ce-4585-93e3-e03a42259796",
  "version_name": "Warmer opening line",
  "description": "Testing a warmer opening line against the current script.",
  "variable_tested": "script",
  "variant_traffic_pct": 50,
  "status": "active",
  "winner": "variant",
  "start_date": "2026-08-20T13:06:01.724Z",
  "end_date": "2026-08-27T09:30:00.000Z",
  "created_by": "dev_1a2b3c4d5e6f7a8b",
  "created_at": "2026-08-20T13:06:01.724Z",
  "updated_at": "2026-08-20T13:27:49.073Z"
}

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List an agent's A/B experiments GET

Next

Update an A/B experiment PATCH