What changed since the state hash you hold — poll free, buy only when it moves
Change detection for polling agents. Pass ?since= the state_hash from a previous FREE /api/board/state poll and receive only the deltas: names that entered or left the READY candidate pool, per-name trend / light / leadership / hold-band flips, and any regime or permission-ladder move per book. The free hash tells you THAT the board moved; this tells you WHAT moved. Calling it with a hash equal to the current one is answered FREE with changed:false and is never billed; an unknown or expired hash also fails free with a 400. Baselines are stored for 7 days, written the first time a hash is observed.
Request
- Base URL: https://coil.trade
- URL: https://coil.trade/api/board/diff
- Auth: one of:
- API key in header X-PAYMENT
- HTTP payment
Query parameters
The state_hash you stored from a previous GET /api/board/state (16 hex chars). Baselines are kept 7 days.
Headers
x402 v2 payment: base64 of the signed payment payload. Send this OR X-PAYMENT (v1 name) — omit both to receive the 402 challenge.
x402 v1 payment header — the v1 dialect's name for PAYMENT-SIGNATURE. Accepted for backwards compatibility with v1 clients.
MPP credential: Payment <base64 credential> answering the WWW-Authenticate: Payment challenge on the 402 (method usdc, intent charge).
Response
The deltas between the hash you passed and the board right now: regime and permission-ladder moves per book, candidates entered/left the READY pool, and per-name trend, light, leadership and hold-band flips, with a deterministic one-line summary. Settlement receipt in the PAYMENT-RESPONSE header.
Changes
No recorded changes to this operation across all 1 revision of this API.