The tunnel branch's other half is served for real against published
alktunnels 0.4.1 / alkcall 0.10.1, with POC-3 §C.4 as the template:
- tcpip_forward/streamlocal_forward (+ both cancel forms) map the
vanilla listen request family-ward through TunnelListener::open on
the held ChannelClient (bounded inline dial — the global request's
reply + the &mut u32 bound-port out-param are the hook's); the
wire bind endpoint rides as the resource string verbatim (OpenSSH
client-side normalization parity). A reply without the minted
listen token/bound report declines and reaps its fabric listener.
- the door serves the fabric's inbound tunnel/forwarded opens: the
serve config gains TunnelListenSeam (the seam-config second
course-correction — the shared ServingConfig registry the assembly
wired at from_connection_with_serving); alkssh registers the
forwarded openable (ChannelCore over a clone of the held client's
manager) at SshAdapter::new — a failed registration is a failed
construction (AdapterError::ListenRegistration).
- the forwarded-tcpip data leg: token correlation through the shared
ListenRouter → the in-crate per-session channel cap at the accept
surface (the acceptor vocabulary) → Handle::
channel_open_forwarded_tcpip streaming the listen request's own
args + the actually-bound port (sshd parity) with
TunnelForwardedParams.peer as the originator → pump_bidi(ssh,
fabric). Correlation-miss → teardown-at-birth, never a half-open
SSH channel. Unix arrivals ride forwarded-streamlocal@openssh.com.
- bounded bookkeeping: the per-session listener map packet-loop-only
with a dedicated max_concurrent_channels-ceiling counter; the
route map bounded by construction (mints at accepted listens,
removed at cancels + session teardown — the handler's Drop).
- the harness grew the client-side accept hook
(server_channel_open_forwarded_tcpip/_streamlocal,
acceptor-driven) + a hand-rolled tracing subscriber; 18 contract
rows + both real-tool smokes (ssh -L, ssh -R + curl) green in
tests/tunnel_mapping.rs; the wave-2 stub listen rows migrated per
build (unfeatured / seam-unconfigured).
Verified: cargo test across default/git/session/sftp/tunnel and all
combos + --all-features; clippy -D warnings (default, all-features,
combos); cargo fmt --check; cargo doc --no-deps clean;
taskgraph validate (26 tasks).