Every error response has the shape
{code, message, remediation, docs_url, request_id}. Include the
request_id when reporting problems.
The request body or parameters failed validation. The message lists the offending fields.
Missing, malformed, expired, or revoked credential.
The credential is valid but lacks the required scope.
The SIWE nonce is unknown, already used, or expired. Nonces are single-use.
Signature verification failed, or the SIWE message fields do not match this environment.
The Idempotency-Key was already used with a different payload.
The resource does not exist or does not belong to this account.
Too many requests. Respect Retry-After; unauthenticated endpoints are limited per IP at the edge.
No execution venue answered. Transient; retry shortly.
The request exceeds what the wallet's active policy authorizes. The message names the violated rule.
The spend would exceed a policy budget or velocity limit (see pre-flight POST /v1/checks).
The counterparty is on a screening list (e.g. OFAC SDN) and the policy requires screening.