ADR-054 prescribes with a re-export
module, but cargo rejects the cyclic dependency (alknet-tty →
alknet-tty-local → alknet-tty) even with an optional dep. The re-export
is deferred to the assembly layer: consumers depend on alknet-tty-local
directly and register LocalTtyBackend in the TtyAdapter backend map.
The feature gate stays declared (empty) for forward compatibility.
Assembly pattern documented in the crate root doc comment.
Implement TtyAdapter (ProtocolHandler on alknet/tty) and the
drive_session three-pump bidirectional driver in adapter.rs.
TtyAdapter holds a HashMap<String, Arc<dyn TtyBackend>> keyed by the
negotiation frame's backend string and an optional OwnershipProvider.
handle() loops accept_bi and spawns drive_session per stream.
drive_session proceeds in three phases:
1. Negotiation — read length-prefixed JSON, parse NegotiateRequest,
validate (carriage == raw, cmd non-empty), look up backend, scope-gate
(tty:open), resource ownership check via backend.resource_id() +
OwnershipProvider::owns(), construct TtyParams. Errors sent as JSON
in negotiation framing, stream closed.
2. Allocation — backend.allocate(¶ms). On failure send
allocate_failed error, close.
3. Raw carriage — three concurrent pumps:
A. stdout/stderr → client (stream_type 1/2), zero-length sentinel on EOF
B. client → backend: stdin chunks → TtyHandle.stdin, control chunks →
Resize/Signal/Eof dispatch (Exit ignored, unknown types ignored)
C. exit → exit chunk: await exit_code; on resolve enqueue exit chunk
Exit-chunk-is-last invariant (ADR-055): adapter waits for BOTH
stdout/stderr pumps to complete AND exit_code to resolve before
enqueueing the exit chunk (tokio::join!). On TtyError → code -1.
Cancel cleanup (ADR-056): on connection drop/stream reset, pump tasks
drop, TtyHandle drops, exit_code future drops without resolve →
backend kill-on-Drop fires. Client write-half close is NOT a cancel —
session runs to completion.
Access control (ADR-050): scope gate at negotiation (tty:open scope,
configurable constant), resource ownership via backend.resource_id() +
OwnershipProvider::owns() when wired.
18 integration tests with a TestBackend fixture over tokio::io::duplex:
happy path, exit-chunk-is-last, stdin EOF, resize/signal control,
unknown control ignored, exit control ignored, unknown_backend,
malformed_negotiation (bad JSON, carriage != raw, empty cmd),
allocate_failed, exit error (-1), cancel cleanup, scope gate forbidden,
ownership check deny/allow, stderr pump, eof control closes stdin.
Also fix two clippy unused_mut warnings in negotiation.rs tests.
Replace placeholder negotiation types with the full Phase 1 wire shape:
- NegotiateRequest/TerminalParamsWire with serde(flatten) capturing
backend-specific fields into backend_params
- NegotiationReader/Writer: self-contained 4-byte BE length-prefixed
framing on tokio AsyncRead/AsyncWrite, bounds-checked against MAX_CHUNK_LEN
- NegotiationError (Io, ConnectionClosed, FrameTooLarge, Json) via thiserror
- error_response_bytes helper for server-side JSON error frames
- into_inner reclaims the stream for raw-chunk use
- Error frames stay under 16 MiB so the high byte of the length prefix is
0x00, making the framing-disambiguation trick sound (ADR-052 §5)
Unit tests cover round-trip, serde(flatten) capture, FrameTooLarge,
ConnectionClosed on truncated header/body, error-response shape, and the
0x00-first-byte framing-disambiguation invariant. backend.rs's
From<NegotiateRequest> for TtyParams still compiles (same field shapes).
backend.rs defines its own BoxFuture type alias
(Pin<Box<dyn Future + Send>>) using std::future::Future + futures_core,
so the futures crate is unused. Removes the dead dependency.
Port the POC's control channel schema (alknet-tty-poc/src/control.rs)
into crates/alknet-tty/src/control.rs: the ControlMessage tagged enum
(Resize/Signal/Eof/Exit) with snake_case type tag, to_json/from_slice
helpers, and the Unix-only signal_from_name mapping the 9 supported
signal names to libc numbers. Unknown type tags return a serde_json
error; the adapter (later task) ignores that error per the wire spec's
extensibility policy. Adds libc as a target.'cfg(unix)' dependency.
Refs: docs/architecture/crates/tty/tty-wire.md §"Control Channel"
Refs: docs/architecture/decisions/055-exit-code-on-control-chunk.md
Create crates/alknet-tty with Cargo.toml (alknet-core path dep, tokio,
bytes, futures-core, tokio-stream, serde, serde_json, async-trait,
tracing, thiserror — no portable_pty/bollard/russh/alknet-call per
ADR-057), the `local` feature gate (dep wiring deferred to
tty/local-feature-reexport), src/lib.rs with the crate doc comment and
module declarations, and skeleton modules (wire, control, negotiation,
backend, adapter) with doc comments and TODO markers. Add the crate to
the workspace members list.
cargo check, clippy -D warnings, and fmt --check all pass.
glm-5.2