How the AgentiCoins objects fit together.
Auth
Sandbox keys from Settings → Developers. Prefix sk_sandbox_.
Idempotency
Pass Idempotency-Key on POST /quotes and POST /payment-intents.
Errors
RFC 9457-style problem+json. Codes: policy_blocked, quote_expired, rail_unavailable.
Webhooks
HMAC-SHA256 over the raw body. Events retry with backoff.
Sandbox vs production
Production is request-access. This demo never moves live funds.