nx_x11_connect.nx

nx_x11_connect.nx -- bits-up X11 wire-protocol connection setup. Opens an AF_UNIX socket to the local X server (typically WSLg's /tmp/.X11-unix/X0 on Windows/WSL2, or an X11/Xorg server on Linux), sends the connection-setup request, and reads the server's reply. Returns the connected fd + parsed server info. X11 protocol reference: X Window System Protocol §8 (Connection Setup), public wire spec (X11 Release 11.0+). Same flavor of bits-up work as TLS/HTTP: we read the spec, write the bytes, no third-party client library. Setup request bytes (12 + auth-name + auth-data, padded to 4): byte 0: byte-order ('l' = 0x6c = little-endian, 'B' = big) byte 1: pad (0) bytes 2-3: major version (11) [u16 LE] bytes 4-5: minor version (0) [u16 LE] bytes 6-7: auth_proto_name_len [u16 LE] bytes 8-9: auth_proto_data_len [u16 LE] bytes 10-11: pad auth_proto_name (padded to 4) auth_proto_data (padded to 4) Server reply byte 0: 1 = success (info follows) 0 = failed (reason string follows) 2 = authenticate (more auth needed) For local WSLg, anonymous auth (zero-length name/data) is accepted when the connecting uid matches the server's owner. If WSLg rejects this, we'll add MIT-MAGIC-COOKIE-1 via ~/.Xauthority parse. Public API: nx_x11_connect_local(display_num) Connects to /tmp/.X11-unix/X<display_num>, performs setup handshake. Returns negative verdict or positive fd. Sealed verdict (negative on failure): NX_X11_OK positive fd returned NX_X11_SOCKET_FAIL socket()/connect() failed