Review: the merged `Claimed | Legacy` arm gave a legacy window a hot
transition to a tunnel — every accept re-negotiated, and a peer upgraded
while the window stayed open was promoted underneath live connections.
The product does not need a mode switch inside a window's lifetime, and
the transition was extra state-machine surface for nothing: reopening
the window picks up an upgraded peer.
The two arms are separate again. `Claimed` negotiates once and the
peer's answer fixes the window's mode. `Legacy` logs in for every accept
as before, asks for no tunnel — `LoginConfigHandler::port_forward_mux`
carries the request per login, so the raw pipe never has to talk to a
peer that thinks it agreed to multiplex — and ignores what the peer
reports. Both arms keep skipping a local socket that hung up during
login.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01EZ49AbZJYfm8NTp5yDPMab