API reference · Trust Fabric

Ask the live policy engine about a hypothetical call

POST /fabric/policy/evaluate

Last reviewed 2026-10-03

POST /fabric/policy/evaluate

Preview a policy decision without making the call.

Sends the same input document shape the gateway's own request path sends -- a preview that asks a differently-shaped question would answer a different question and be worse than no preview at all.

Request body

EvaluateRequest (required)

Field	Type	Meaning
`service` required	string	min length `1` · max length `128`
`path`	string	max length `512` · default `"/"`
`method`	string	max length `10` · default `"POST"`
`tier`	string or null
`entitled`	boolean	default `true`

Responses

Status	Meaning	Body
`200`	Successful Response	JSON
`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 onlyRequest 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/policy/evaluate' \
  -H "X-API-Key: $CAIN_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"service": "service", "path": "/", "method": "POST", "entitled": true}'

import json, os, urllib.request

req = urllib.request.Request('https://cainstudio.online/fabric/policy/evaluate', method='POST',
    headers={"X-API-Key": os.environ["CAIN_API_KEY"], "Content-Type": "application/json"},
    data=json.dumps({
      "service": "service",
      "path": "/",
      "method": "POST",
      "entitled": True
    }).encode())
with urllib.request.urlopen(req, timeout=60) as r:
    print(r.status, json.load(r))

const res = await fetch("https://cainstudio.online/fabric/policy/evaluate", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.CAIN_API_KEY!,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "service": "service",
    "path": "/",
    "method": "POST",
    "entitled": true
  }),
});
console.log(res.status, await res.json());

Schemas used

HTTPValidationError · ValidationError · EvaluateRequest

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