feat(tty-local): initialize alknet-tty-local sibling crate (ADR-054)

Create crates/alknet-tty-local with Cargo.toml (alknet-tty workspace dep,
portable-pty, libc unix-only, tokio, bytes, futures-core, tracing,
thiserror), src/lib.rs with module declarations and LocalTtyBackend
re-export, and skeleton module files (pty, pipe, backend) with doc
comments and TODO markers. Add the crate to the workspace members list.

Cargo.lock

@@ -147,6 +147,20 @@ dependencies = [
  "tracing",
 ]
 
+[[package]]
+name = "alknet-tty-local"
+version = "0.1.0"
+dependencies = [
+ "alknet-tty",
+ "bytes",
+ "futures-core",
+ "libc",
+ "portable-pty",
+ "thiserror 2.0.18",
+ "tokio",
+ "tracing",
+]
+
 [[package]]
 name = "alknet-vault"
 version = "0.1.0"
@@ -1077,6 +1091,12 @@ dependencies = [
  "litrs",
 ]
 
+[[package]]
+name = "downcast-rs"
+version = "1.2.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "75b325c5dbd37f80359721ad39aca5a29fb04c89279657cffdda8736d0c0b9d2"
+
 [[package]]
 name = "dunce"
 version = "1.0.5"
@@ -1246,6 +1266,17 @@ version = "0.2.9"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "28dea519a9695b9977216879a3ebfddf92f1c08c05d984f8996aecd6ecdc811d"
 
+[[package]]
+name = "filedescriptor"
+version = "0.8.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e40758ed24c9b2eeb76c35fb0aebc66c626084edd827e07e1552279814c6682d"
+dependencies = [
+ "libc",
+ "thiserror 1.0.69",
+ "winapi",
+]
+
 [[package]]
 name = "find-msvc-tools"
 version = "0.1.9"
@@ -1932,6 +1963,15 @@ dependencies = [
  "web-sys",
 ]
 
+[[package]]
+name = "ioctl-rs"
+version = "0.1.6"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f7970510895cee30b3e9128319f2cefd4bde883a39f38baa279567ba3a7eb97d"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "ipconfig"
 version = "0.3.4"
@@ -2377,6 +2417,15 @@ version = "2.8.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "88904434abc2901f197fe8cc55f0445e7ded921dba5911dad2e2b39b48e663c4"
 
+[[package]]
+name = "memoffset"
+version = "0.6.5"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5aa361d4faea93603064a027415f07bd8e1d5c88c9fbf68bf56a285428fd79ce"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "mime"
 version = "0.3.17"
@@ -2621,6 +2670,20 @@ dependencies = [
  "wmi",
 ]
 
+[[package]]
+name = "nix"
+version = "0.25.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f346ff70e7dbfd675fe90590b92d59ef2de15a8779ae305ebcbfd3f0caf59be4"
+dependencies = [
+ "autocfg",
+ "bitflags 1.3.2",
+ "cfg-if",
+ "libc",
+ "memoffset",
+ "pin-utils",
+]
+
 [[package]]
 name = "no-std-net"
 version = "0.6.0"
@@ -3118,6 +3181,27 @@ version = "1.13.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "c33a9471896f1c69cecef8d20cbe2f7accd12527ce60845ff44c153bb2a21b49"
 
+[[package]]
+name = "portable-pty"
+version = "0.8.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "806ee80c2a03dbe1a9fb9534f8d19e4c0546b790cde8fd1fea9d6390644cb0be"
+dependencies = [
+ "anyhow",
+ "bitflags 1.3.2",
+ "downcast-rs",
+ "filedescriptor",
+ "lazy_static",
+ "libc",
+ "log",
+ "nix",
+ "serial",
+ "shared_library",
+ "shell-words",
+ "winapi",
+ "winreg",
+]
+
 [[package]]
 name = "portmapper"
 version = "0.5.0"
@@ -4082,6 +4166,48 @@ dependencies = [
  "serde",
 ]
 
+[[package]]
+name = "serial"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a1237a96570fc377c13baa1b88c7589ab66edced652e43ffb17088f003db3e86"
+dependencies = [
+ "serial-core",
+ "serial-unix",
+ "serial-windows",
+]
+
+[[package]]
+name = "serial-core"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3f46209b345401737ae2125fe5b19a77acce90cd53e1658cda928e4fe9a64581"
+dependencies = [
+ "libc",
+]
+
+[[package]]
+name = "serial-unix"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "f03fbca4c9d866e24a459cbca71283f545a37f8e3e002ad8c70593871453cab7"
+dependencies = [
+ "ioctl-rs",
+ "libc",
+ "serial-core",
+ "termios",
+]
+
+[[package]]
+name = "serial-windows"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "15c6d3b776267a75d31bbdfd5d36c0ca051251caafc285827052bc53bcdc8162"
+dependencies = [
+ "libc",
+ "serial-core",
+]
+
 [[package]]
 name = "sha1"
 version = "0.10.6"
@@ -4119,6 +4245,22 @@ dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "shared_library"
+version = "0.1.9"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "5a9e7e0f2bfae24d8a5b5a66c5b257a83c7412304311512a0c054cd5e619da11"
+dependencies = [
+ "lazy_static",
+ "libc",
+]
+
+[[package]]
+name = "shell-words"
+version = "1.1.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "dc6fe69c597f9c37bfeeeeeb33da3530379845f10be461a66d16d03eca2ded77"
+
 [[package]]
 name = "shlex"
 version = "2.0.1"
@@ -4409,6 +4551,15 @@ dependencies = [
  "windows-sys 0.61.2",
 ]
 
+[[package]]
+name = "termios"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d5d9cf598a6d7ce700a4e6a9199da127e6819a61e64b68609683cc9a01b5683a"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "thiserror"
 version = "1.0.69"
@@ -5509,6 +5660,15 @@ dependencies = [
  "memchr",
 ]
 
+[[package]]
+name = "winreg"
+version = "0.10.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "80d0f4e272c85def139476380b12f9ac60926689dd2e01d4923222f40580869d"
+dependencies = [
+ "winapi",
+]
+
 [[package]]
 name = "wit-bindgen"
 version = "0.57.1"

Cargo.toml

@@ -5,6 +5,7 @@ members = [
     "crates/alknet-call",
     "crates/alknet-http",
     "crates/alknet-tty",
+    "crates/alknet-tty-local",
 ]
 resolver = "2"
 

crates/alknet-tty-local/Cargo.toml

@@ -0,0 +1,22 @@
+[package]
+name = "alknet-tty-local"
+version.workspace = true
+edition.workspace = true
+license.workspace = true
+description = "Local TTY backend for alknet-tty: LocalTtyBackend via portable_pty (PTY mode) and std::process::Command (pipe/runner mode)"
+repository.workspace = true
+
+[lib]
+name = "alknet_tty_local"
+
+[dependencies]
+alknet-tty = { path = "../alknet-tty" }
+portable-pty = "0.8"
+tokio = { version = "1", features = ["full"] }
+bytes = "1"
+futures-core = "0.3"
+tracing = "0.1"
+thiserror = "2"
+
+[target.'cfg(unix)'.dependencies]
+libc = "0.2"

crates/alknet-tty-local/src/backend.rs

@@ -0,0 +1,16 @@
+//! `LocalTtyBackend`: the `TtyBackend` implementation for local processes.
+//!
+//! `allocate()` branches on `TtyParams::terminal`: `Some(TerminalParams)`
+//! selects PTY mode (this crate's `pty` module); `None` selects pipe mode
+//! (the runner case, this crate's `pipe` module). One backend serves both
+//! (ADR-054).
+
+// TODO: implement
+
+/// Local TTY backend: implements `alknet_tty::TtyBackend` for local processes.
+///
+/// `allocate()` branches on `TtyParams::terminal`: `Some(TerminalParams)`
+/// selects PTY mode (this crate's `pty` module); `None` selects pipe mode
+/// (the runner case, this crate's `pipe` module). One backend serves both
+/// (ADR-054).
+pub struct LocalTtyBackend;

crates/alknet-tty-local/src/lib.rs

@@ -0,0 +1,13 @@
+//! alknet-tty-local: Local TTY backend for alknet-tty.
+//!
+//! `LocalTtyBackend` implements `alknet_tty::TtyBackend` via `portable_pty`
+//! (PTY mode, terminal semantics) and `std::process::Command` (pipe mode,
+//! the runner case). The blocking→async bridge for PTY mode uses three
+//! dedicated std threads feeding tokio mpsc/oneshot channels (REQ-TTY-01).
+//! Signal forwarding targets the foreground process group (REQ-TTY-02).
+
+pub mod backend;
+pub mod pipe;
+pub mod pty;
+
+pub use backend::LocalTtyBackend;

crates/alknet-tty-local/src/pipe.rs

@@ -0,0 +1,8 @@
+//! Pipe mode for `LocalTtyBackend`: `tokio::process`-backed runner sessions.
+//!
+//! Spawns the command with `Stdio::piped()` for stdin/stdout/stderr, exposes
+//! tokio-native `AsyncRead`/`AsyncWrite` (no std-thread bridge needed),
+//! `PipeControl` (no-op resize, `libc::kill(pid, sig)` signal), and the
+//! ADR-056 kill guard on the `exit_code` future.
+
+// TODO: implement

crates/alknet-tty-local/src/pty.rs

@@ -0,0 +1,9 @@
+//! PTY mode for `LocalTtyBackend`: `portable_pty`-backed terminal sessions.
+//!
+//! Implements the blocking→async bridge (REQ-TTY-01) via three dedicated
+//! std threads (reader, writer, waiter) feeding tokio mpsc/oneshot channels,
+//! `PtyControl` for resize/signal, REQ-TTY-02 process-group signal
+//! forwarding (`libc::kill(-pgid, sig)`), and the ADR-056 kill guard on the
+//! `exit_code` future.
+
+// TODO: implement