API reference · Trust Fabric

Exchange an API key for a short-lived browser session

POST /fabric/identity/sessions

Last reviewed 2026-11-06

POST /fabric/identity/sessions

So a browser never has to hold the raw key.

The workbench used to keep a full-privilege, non-expiring credential in localStorage. This is read-scoped and expires, so an injected script gets something far less useful and for far less long.

Responses

Status	Meaning	Body
`200`	Successful Response	JSON
`401`	The X-API-Key header is missing, or the key is unknown, revoked or replaced.	`Error`
`403`	The key is valid but may not do this (for example an agent key approving its own held action).	`Error`
`422`	Validation Error	`HTTPValidationError`
`429`	Rate limit or monthly quota reached. Wait for the number of seconds in Retry-After when it is sent.	`Error`

Try it

Your API key X-API-Key Remember the key in this tab only

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/identity/sessions' \
  -H "X-API-Key: $CAIN_API_KEY"

import json, os, urllib.request

req = urllib.request.Request('https://cainstudio.online/fabric/identity/sessions', method='POST',
    headers={"X-API-Key": os.environ["CAIN_API_KEY"]})
with urllib.request.urlopen(req, timeout=60) as r:
    print(r.status, json.load(r))

const res = await fetch("https://cainstudio.online/fabric/identity/sessions", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.CAIN_API_KEY!,
  },
});
console.log(res.status, await res.json());

Schemas used

Error · HTTPValidationError · ValidationError

← Verify an Ed25519 signature against a registered principal · all 81 Trust Fabric calls · Inspect the session token in use →

Try CAIN-42 on your own agents

Create a free account and every new account starts with a 30-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