The biggest single-row surface of the spine: pty/shell/pipe-exec serve
through the published alktty seam (drive_session_pre_negotiated) over a
translation bridge, re-landing POC-3 stage D as contract:
- src/tty_map.rs (session feature): the bridge (SSH data → Chunk::stdin
through a bounded mpsc + framing task; SSH EOF → the zero-length
stdin sentinel — verified against alktty's pump semantics; stdout →
data; stderr → extended_data(1); exit chunk → the derivation
contract), the locally-built negotiation (OQ-08: shell argv verbatim,
wrapper ++ [cmd], cwd/env session-side, ttymodes → the reserved {}
modes JSON), and the spawned serving path.
- serve_tty_row: driven chunks→SSH inline so the exit report is the
path's final act (status before close, ADR-006 decision 4); two
cancel signals (per-channel watch fired by channel_close, connection
teardown fired by SessionHandler::Drop) abort the alktty session
task — the ADR-056 kill-on-drop contract is the cancelled session's
cleanup.
- Derivation contract rules 1–6 in derive_exit + the crate-local
signum→name table: −N → exit-signal(name), −1 → exit-status(255),
core_dumped never, unmapped negatives → 255, the PTY-path rule-5
fidelity limit documented; wire rows pin the shapes.
- Negotiation-error frames (alktty's 0x00-length-prefixed error
framing) → negotiation-failed serving decline + exit-status(255) +
close — the one could-not-start claim this door makes (nothing ran).
- Control rows: window_change/signal → the per-channel BridgeSurface
(bounded mpsc, try_send, never awaited on the packet loop); signal
names verbatim (no decline shape — fire-and-forget); pre-serve
resizes update the stored pty params (final size wins).
- Unset-declines (OQ-08) keep the git row's serving-path shape
(failure then close, spawned): shell-unconfigured /
wrapper-unconfigured / seam-unconfigured; pipe-less shell SERVES
pipe-mode (the recorded vanilla-sshd posture); env_request decline
unchanged (OQ-09).
- tests: the hand-rolled TtyBackend shim + ownership witness doubles;
serving rows through the harness, the unset-field decline matrix,
derivation rows on the wire, negotiation-failure rows, the identity
ride asserted live at the seam, the kill witness; the real-tool
smoke — OpenSSH -tt against a real PTY via dev-dep alktty local
(test graph only), skip-with-reason posture. Wave-2 stub rows
migrated to the new decline reasons (dispatch_core, observe).
Verification: cargo test (113) / --features session (149) / git (142) /
tunnel (115) / --all-features (161) — all green; cargo clippy
--all-targets -- -D warnings ×5 feature configs; cargo fmt --check;
cargo doc --no-deps ×3 builds clean; taskgraph validate.
glm-5.3-flash
b1e569d1a8