The single STREAM_CONTROL = 3 was documented as bidirectional but the
adapter had to ignore Exit from the client because the two directions
were indistinguishable on the same stream_type — half-duplex in
disguise. Phase 7 splits it into two halves so the bidirectionality is
literal on the wire.
Changes:
- wire.rs: STREAM_CTRL_IN = 3 (client→server), STREAM_CTRL_OUT = 4
(server→client); InvalidStreamType bound > 3 → > 4; Chunk::control
→ Chunk::ctrl_in/ctrl_out; ChunkWriter::write_control_json →
write_ctrl_in_json/write_ctrl_out_json; tests split accordingly.
- control.rs: ControlMessage doc updated with the stream_type column;
JSON shape unchanged.
- adapter.rs: pump_client_to_backend dispatches on STREAM_CTRL_IN
(Resize/Signal/Eof; Exit on ctrl_in is a protocol violation,
ignored); send_exit_chunk emits on STREAM_CTRL_OUT; STREAM_CTRL_OUT
from the client is a protocol violation, ignored. 3 new tests for
the direction enforcement; existing tests updated to the new
stream_types.
- negotiation.rs: framing-disambiguation doc updated (server-sent
stream_type set is {1, 2, 4}).
- alknet-tty-local/tests: common/mod.rs, pty.rs, pipe.rs updated to
the new constants.
Specs:
- ADR-052 amended (§4a 'Control channel split (Phase 7 amendment)').
- tty-wire.md + tty-adapter.md updated (last_updated 2026-07-18).
Verification:
- cargo test -p alknet-tty: 65 passed (was 61; +4 new tests).
- cargo test -p alknet-tty-local: 19 passed.
- cargo test --workspace --all-features: 1017 passed, 0 failed.
- cargo clippy --workspace --all-features: clean.
- cargo fmt --all: clean.
C1: Box<dyn TtyControl + Clone> does not compile (Clone is not object-safe).
Replace with a TtyControlHandle newtype: #[derive(Clone)] wrapping
Arc<dyn TtyControl + Send + Sync>. The trait stays object-safe; the
newtype carries the Clone-ability. Updated across tty-backend.md,
ADR-053, OQ-43, and the tty README.
W1: 'Drop is the cleanup, threads exit on channel close' was false for
the local PTY waiter thread (blocked in Child::wait(), does not observe
channel close) — a child that ignores stdin EOF would be orphaned on
session cancel. New ADR-056 commits a backend cleanup contract: dropping
the exit_code future MUST kill the session target. The local backend
implements it via a ChildKiller held in the exit_code future's Drop
guard (disarmed on resolve). Corrected the lifecycle section in
tty-adapter.md, added the mechanism + constraint to tty-local.md, and
referenced ADR-056 from tty-backend.md, overview.md, both READMEs.
S1: error-frame < 16 MiB stated as a wire-format invariant (not an
assumption) so the 0x00-first-byte disambiguation trick is sound by
construction.
S2: carriage field validation (MUST be "raw" in v1, else
malformed_negotiation) specified.
S3: NegotiateRequest + TerminalParamsWire Rust structs added with
serde defaults and validation rules.
S4: modes field annotated 'backends MUST ignore content in v1' in both
tty-backend.md and ADR-053.
S5: AsyncWrite/Stream qualified with crate origins (tokio::io,
futures_core) in the TtyHandle struct definitions.
The backpressure chain is complete by construction: QUIC flow control
→ bounded drainer channel → bounded stdout channel → OS pipe/PTY buffer
→ process write() blocks. Every link awaits its producer; no unbounded
buffer breaks the chain. The reversal path (an additive ControlMessage
variant, not a wire-format header change) is noted in ADR-052's
consequences as a two-way door, not the expected path.
Tightened ADR-052 assumption 1 from a hedge ('expected to work; a POC
would confirm') to a decided constraint. Updated all OQ-45 references
across the tty spec docs from 'open (low risk)' to 'resolved'.
Grounded in the alknet-docker POC (seed codec) and the alknet-tty POC
(2026-07-05, validated the control channel, the local-PTY blocking→async
bridge, and the signal-delivery contract).
Four ADRs:
- ADR-052: wire format — alknet/tty ALPN, two-carriage (JSON negotiation
then raw chunks), fixed channel set 0-3, control as JSON, negotiation-
error framing disambiguation
- ADR-053: TtyBackend trait + TtyHandle — the backend inversion point;
exit_code as a Future; REQ-TTY-01 (backends need not be natively async)
- ADR-054: local backend as alknet-tty-local sibling crate behind a
feature re-export; PTY vs pipe per-session; runner pattern preserved
- ADR-055: exit code on a stream_type 3 control chunk; "exit chunk is
last" invariant; adapter owns the ordering
Five component specs (crates/tty/): README, overview, tty-wire, tty-
backend, tty-adapter, tty-local. The docker/SSH backends are future
crates (out of scope); the trait shape is committed so they can be
built against it.
Five OQs (OQ-43…47): two resolved (TtyControl Clone, stdin closure),
two deferred(scope) (terminal modes, runner API surface), one open
low-risk (flow control).
Zero critical issues from a general-subagent architecture review;
warnings addressed (inline rationale trimmed to ADR refs, TtyError and
StdinCmd defined, framing disambiguation documented, missing ADRs added
to index tables).
glm-5.2