After switching the dev harness to `localhost`, the QUIC handshake still
stalled and the relay logged nothing at all — packets weren't reaching
it. `localhost` resolves to ::1 first on most systems, and IPv6 loopback
isn't reliably routable (Docker's IPv6 UDP port-forwarding silently
blackholes), so the UDP socket was connecting into a hole.
QuicWebTransportFactory.connect now resolves the authority host to a
concrete address preferring IPv4 for the UDP socket target, while still
passing the original hostname as the TLS SNI server name — so SNI keeps
matching the server certificate and stays a legal RFC 6066 host_name.
https://claude.ai/code/session_01PoQupfdoKU3ryQwLwTeXeM
Claude
6a60918cc6