A generic token bucket rate limiter keyed by endpoint identifier. Uses a fixed capacity and refill rate, tracks state per key, and can be used in any context requiring per-peer request throttling. Self-contained and testable.

Implements length-prefixed JSON message serialization for the control wire protocol. Defines the ControlMessage enum (Recognition, Invite, InviteResponse, etc.) that carries pairing and recognition data. The framing pattern is reusable for any binary protocol that needs typed messages with a length prefix.

A JSON file-based store with atomic rename (write to tmp then rename), capped record count (500), and explicit mark_interrupted for crash recovery. Generic enough to be extracted for any application needing a simple, durable key-value store with conflict-free replacement.

A pure function that validates relay URLs with a regex pattern, ensuring correct format (ws/wss scheme, host, optional port). Returns a validation state object. No external dependencies, easily portable to other projects.

Generates a short human-readable fingerprint (60-bit base32 encoded) from a public key byte array using BLAKE3 hash. Used for device identification. A self-contained utility that can be reused in any application requiring short unique identifiers from binary keys.