Implement allocate_pty in src/pty.rs: portable_pty openpty + spawn as
session leader (set_controlling_tty(true)), with the three-thread
blocking→async bridge (REQ-TTY-01): reader → mpsc<Bytes> with
zero-length EOF sentinel, writer draining mpsc<StdinCmd> (Bytes/Eof),
waiter → oneshot<i32>. TtyHandle.stdout is ReceiverStream<Bytes>,
stdin is a StdinSink AsyncWrite wrapper over mpsc::Sender<StdinCmd>
(parks a reserve+send future when the channel is full), stderr is None
(PTY merges), exit_code is LocalExitFuture.
PtyControl implements TtyControl: resize via MasterPty::resize; signal
via libc::kill(-pgid, sig) with kill(pid, sig) fallback (Unix, REQ-TTY-02)
using alknet_tty::signal_from_name; unknown names and non-Unix fall back
to ChildKiller::kill (SIGHUP).
LocalExitFuture wraps the oneshot::Receiver<i32> + a ChildKiller kill
guard (ADR-056). poll delegates to the receiver and disarms the guard
on Ready (no-op Drop on happy path); Drop on cancel calls
ChildKiller::kill (SIGHUP) — best-effort; the waiter thread reaps.
Bump portable-pty 0.8 → 0.9 to match the POC API (MasterPty: Send).
Add tokio-stream, serde_json (dev), tempfile (dev) deps.
Tests: happy path (echo), stdin round-trip (cat), resize, signal INT
kills child, signal reaches process group (bash -c "sleep 60"),
cancel cleanup on drop, unknown signal falls back to ChildKiller.
glm-5.2
9f8d07fc25