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Stop an experiment

POST /v1/agents/{agent_id}/experiments/{experiment_id}/stop

Property	Value
Operation	`stop_experiment`
Group	Prompt evaluations and experiments
Scope	`agents:write`
Route class	`control`
Idempotency	`Idempotency-Key` accepted: a retry with the same key replays the first answer
Audit	Audited `agent.experiment.stop` (mutation)
Released in	1.55.0
Phase 0 host	Served (the hosted api pins 1.65.0)

Stops a running experiment, or discards a draft, with the reason requested and emits experiment.stopped for a running one (1.55.0); new Calls run the active version again. A stopped experiment answers as it stands; a promoted one is 409 experiment_conflict with the reason promoted.

Request

Set VOCAL_API to the base URL of your API and VOCAL_API_KEY to an API key with the agents:write scope (Authentication and keys). Replace each placeholder, such as agt_... or <name>, with your own value.

curl -X POST "$VOCAL_API/v1/agents/agt_.../experiments/exp_.../stop" \
  -H "Authorization: Bearer $VOCAL_API_KEY" \
  -H "Idempotency-Key: $(uuidgen)"

const response = await fetch(`${process.env.VOCAL_API}/v1/agents/agt_.../experiments/exp_.../stop`, {
  method: 'POST',
  headers: {
    Authorization: `Bearer ${process.env.VOCAL_API_KEY}`,
    'Idempotency-Key': crypto.randomUUID(),
  },
});
console.log(response.status, await response.text());

import os
import uuid

import requests

response = requests.post(
    f"{os.environ['VOCAL_API']}/v1/agents/agt_.../experiments/exp_.../stop",
    headers={
        "Authorization": f"Bearer {os.environ['VOCAL_API_KEY']}",
        "Idempotency-Key": str(uuid.uuid4()),
    },
)
print(response.status_code, response.text)

Parameters

Name	In	Type	Required	Description
`agent_id`	path	AgentId	yes	The id of an Agent: `agt_` and the row's UUIDv7 in 26 Crockford base32 characters. Opaque and safe to log.
`experiment_id`	path	ExperimentId	yes	The id of a traffic-split experiment: `exp_` and the row's UUIDv7 in 26 Crockford base32 characters. Opaque and safe to log.
`idempotency-key`	header	string	no	A client-chosen key, kept 24 hours per Organization, environment and route. A replay returns the stored response.

Responses

Status	Content type	Shape	Error codes
`200`	`application/json`	Experiment
`400`	`application/json`	ErrorEnvelope	`invalid_request`
`401`	`application/json`	ErrorEnvelope	`unauthenticated`
`403`	`application/json`	ErrorEnvelope	`forbidden`, `org_suspended`
`404`	`application/json`	ErrorEnvelope	`not_found`
`409`	`application/json`	ErrorEnvelope	`idempotency_in_progress`, `idempotency_key_reused`, `experiment_conflict`
`429`	`application/json`	ErrorEnvelope	`rate_limited`
`500`	`application/json`	ErrorEnvelope	`internal_error`

Fields of the `200` answer

The shape is Experiment.

Field	Type	Required	Description
`agent_id`	AgentId	yes
`arms`	array of ExperimentArm	yes	The control first, then the candidates in the order they were named.
`created_at`	Timestamp	yes
`created_by`	ActorRef	yes
`description`	string or null	yes	For reviewers.
`goal`	ExperimentGoal or null	no	The goal the results report per arm (1.63.0): a slot value at Call end or an Outcome field value. Fixed at create. Null for none; absent from an api before 1.63.0, which a reader treats as null.
`id`	ExperimentId	yes
`name`	string	yes	A display name.
`object`	`"experiment"`	yes
`promoted_arm`	ExperimentCandidateArmKey or null	yes
`started_at`	Timestamp or null	yes
`started_by`	ActorRef or null	yes
`status`	ExperimentStatus	yes
`stop_reason`	ExperimentStopReason or null	yes
`stop_rule`	ExperimentStopRule or null	yes	Set with `stop_rule` only.
`stop_rules`	ExperimentStopRules	yes
`stopped_at`	Timestamp or null	yes
`stopped_by`	ActorRef or null	yes	Who stopped or promoted it; null when a stop rule or a version change did.
`suite_id`	PromptEvalSuiteId or null	yes	A suite whose rubric judges a sample of live Calls, only with `live_call_judging`; refused with `capability_not_available` and `live_call_judging_not_available` until the Compliance profile carries it, and from 1.63.0 while the profile has it `off`.
`unit`	ExperimentUnit	yes
`updated_at`	Timestamp	yes