A production-grade Ruby client for Nostr Wallet Connect (NIP-47). Handles the Nostr protocol, NIP-04 and NIP-44 v2 encryption, secp256k1 key derivation, Schnorr signing, and — most importantly — a reliable long-running WebSocket connection to the relay with heartbeat pings, forced recycle, exponential backoff, and SIGTERM handling. Developers call `pay_invoice`, `make_invoice`, `lookup_invoice`, etc. and `subscribe_to_notifications { |n| ... }` — the transport reliability is hidden.