Error Handling
Stable v1 error envelope and retry guidance.
/v1/invoices errors use { "error": { "code": "...", "message": "..." } }.
Codes are INVALID_AMOUNT, UNSUPPORTED_ASSET, UNSUPPORTED_NETWORK, WALLET_NOT_CONFIGURED, PROJECT_NOT_READY, INVALID_API_KEY, INVOICE_NOT_FOUND, IDEMPOTENCY_CONFLICT, RATE_LIMITED, INVALID_REQUEST, and TEMPORARILY_UNAVAILABLE.
Retry transient failures with the original idempotency key. Correct validation or project-readiness failures before retrying.