API reference · CAIN Budget

Reserve Budget

POST /fabric/budgets/{budget_id}/reserve

Last reviewed 2026-10-02

POST /fabric/budgets/{budget_id}/reserve

Reserve budget for an action.

Parameters

Name	In	Type	Meaning
`budget_id` required	path	string

Request body

ReserveRequest (required)

Field	Type	Meaning
`amount_cents` required	number	> `0.0`
`action` required	string	min length `1`
`trace_id`	string or null
`decision_id`	string or null
`ttl_seconds`	integer	min `1.0` · max `3600.0` · default `300`
`idempotency_key`	string or null

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 onlybudget_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/budgets/<budget_id>/reserve' \
  -H "X-API-Key: $CAIN_API_KEY" \
  -H 'Content-Type: application/json' \
  -d '{"amount_cents": 1.0, "action": "action", "ttl_seconds": 300}'

import json, os, urllib.request

req = urllib.request.Request('https://cainstudio.online/fabric/budgets/<budget_id>/reserve', method='POST',
    headers={"X-API-Key": os.environ["CAIN_API_KEY"], "Content-Type": "application/json"},
    data=json.dumps({
      "amount_cents": 1.0,
      "action": "action",
      "ttl_seconds": 300
    }).encode())
with urllib.request.urlopen(req, timeout=60) as r:
    print(r.status, json.load(r))

const res = await fetch("https://cainstudio.online/fabric/budgets/<budget_id>/reserve", {
  method: "POST",
  headers: {
    "X-API-Key": process.env.CAIN_API_KEY!,
    "Content-Type": "application/json",
  },
  body: JSON.stringify({
    "amount_cents": 1.0,
    "action": "action",
    "ttl_seconds": 300
  }),
});
console.log(res.status, await res.json());

Schemas used

HTTPValidationError · ReserveRequest · ValidationError

← Release Reservation · all 13 CAIN Budget calls · List Transactions →

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