- the ASSOCIATE reply's BND.ADDR/BND.PORT is a relay handle, not a
destination (per-datagram destinations ride the datagram header);
swapping "tell the client about a UDP port" for "tell the client
about the UDP tunnel" preserves every RFC property: one channel per
association, {addr, data} frames in-band, channel EOF = association
lifetime, optional front-door binds on either side
- sentinel-address hunch superseded: no virtualized relay address is
ever needed on the in-band path; BND.ADDR there is pure
RFC-compatibility surface
- producer egress has two variants, both dial-callback policy (OQ-SK-01
shape): local UdpSocket (no flow table, native-only) or composed
per-target alktunnels udp-tunnels (lazy destination->tunnel table;
flow table reborn as channel handles; per-target ACL for free —
dissolves most of OQ-SK-05 for the composed path)
- no upstream ask: alktunnels' connected-udp substrate is correct as-is
for per-target composition; an unconnected-egress resource would be
SOCKS5 again (circular)
- POC #2 baseline settled: sketch both egress variants behind the dial
callback, measure per-destination open cost of the composed variant