API reference · CAIN Trajectory

Evaluate Counterfactual

POST /fabric/trajectories/{trajectory_id}/counterfactual

Last reviewed 2026-10-02

POST /fabric/trajectories/{trajectory_id}/counterfactual

Run counterfactual trust simulation on a trajectory: - Omission: What would trust score be if step K never occurred? - Minimum evidence: What is required to permit a blocked action?

Parameters

Name	In	Type	Meaning
`trajectory_id` required	path	string

Request body

CounterfactualRequest (required)

Field	Type	Meaning
`omitted_step`	integer or null
`proposed_action`	string or null
`proposed_resource`	string or null
`proposed_risk`	number or null	default `0.1`

Responses

Status	Meaning	Body
`200`	Successful Response	object
`422`	Validation Error	`HTTPValidationError`
`401`	No key, or a key that is not valid	JSON `detail`
`429`	Rate limit for your plan reached; retry after the Retry-After seconds	JSON `detail`

Try it

Your API key X-API-Key Remember the key in this tab onlytrajectory_id pathRequest body application/json

This call changes data in the account the key belongs to.

The request goes from your browser straight to this site. Your key is not stored unless you tick the box, and then only in this tab's session storage.

Code

curl -sS -X POST 'https://cainstudio.online/fabric/trajectories/<trajectory_id>/counterfactual' \
  -H "X-API-Key: $CAIN_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"proposed_risk": 0.1}'

import json, os, urllib.request

req = urllib.request.Request('https://cainstudio.online/fabric/trajectories/<trajectory_id>/counterfactual', method='POST',
    headers={"X-API-Key": os.environ["CAIN_API_KEY"], "Content-Type": "application/json"},
    data=json.dumps({
      "proposed_risk": 0.1
    }).encode())
with urllib.request.urlopen(req, timeout=60) as r:
    print(r.status, json.load(r))

const res = await fetch("https://cainstudio.online/fabric/trajectories/<trajectory_id>/counterfactual", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.CAIN_API_KEY!,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "proposed_risk": 0.1
  }),
});
console.log(res.status, await res.json());

Schemas used

HTTPValidationError · ValidationError · CounterfactualRequest

← Complete Trajectory · all 22 CAIN Trajectory calls · Make Trajectory Decision →

Try CAIN-42 on your own agents

Create a free account and every new account starts with a 7-day trial of the full platform. Or try the sandbox first, with no account at all.

Create a free account → · Try the sandbox · See the whole ecosystem