Noise IK pattern name, zero-padded to HASHLEN (32 bytes).
Used on reconnect when the client has a valid cached serverStaticPublic
(from a previous XX handshake). Saves one round trip and ships a 0-RTT
payload. Mirrors WA Web’s w constant.
Noise XX pattern name, zero-padded to HASHLEN (32 bytes) per Noise § 5.2.
Used on the first connect / pairing where the client has no cached server
static key. Mirrors WA Web’s M constant in WAWebOpenChatSocket.
Noise XXfallback pattern name (36 bytes, hashed by Noise spec).
Used to recover gracefully when an in-flight IK handshake is rejected by
the server (server’s static rotated, cached pub key is stale). The client
reuses the ephemeral it already sent in the IK ClientHello and processes
the server’s XX-style ServerHello. Mirrors WA Web’s A constant.