# Blockchain provider integration and queues

This package does not include a concrete third-party blockchain provider API. It preserves the `BlockchainGateway` contract so a provider or private node adapter can be added later without changing merchant APIs, ledger logic, payment state transitions, or payout controls.

The default `DisabledBlockchainGateway` fails closed with `BLOCKCHAIN_PROVIDER_NOT_CONFIGURED`. Deposit-address allocation, transaction detection, finality refresh, payout broadcasting, collection, and provider webhook ingestion must remain disabled until a reviewed adapter is supplied.

Merchant-facing authentication and merchant IPN signing continue to use HMAC-SHA256.