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