Wrap sidecar in a Job Object/process group via process-wrap

[nedtwigg]

Summary

• Replaces the Rust-side tauri-plugin-shell sidecar API with std::process::Command wrapped by process-wrap, so the Node.js sidecar runs inside a Windows Job Object (with KILL_ON_JOB_CLOSE) or a Unix process group.
• The OS now guarantees the sidecar tree dies with the host regardless of which Tauri lifecycle events fired — fixes the orphan node.exe that was holding target\debug\node.exe open and breaking subsequent cargo builds with PermissionDenied from tauri-build.
• Keeps tauri-plugin-shell registered as a plugin because the frontend uses open() from @tauri-apps/plugin-shell in updater.ts. Only the Rust-side sidecar spawn moves off it.

What changed

• standalone/src-tauri/Cargo.toml — add process-wrap = { version = "9", features = ["std"] }, drop unused libc dep (was only used by the now-deleted kill_process_tree).
• standalone/src-tauri/src/lib.rs:
  • start_sidecar now resolves the bundled node binary via a new resolve_node_binary_path() (looks alongside current_exe() for node-{TAURI_ENV_TARGET_TRIPLE}{ext} then node{ext}), spawns via process_wrap::std::CommandWrap + JobObject/ProcessGroup::leader, and reads stdout/stderr on plain std::threads using BufReader::lines() (replacing the old tauri::async_runtime::spawn + CommandEvent matcher).
  • SidecarState.child_pid: u32 → child: Arc<Mutex<Box<dyn ChildWrapper + Send + Sync>>>.
  • kill_process_tree (taskkill on Windows / libc::kill on Unix) replaced by kill_sidecar which calls start_kill() on the wrapped child. Same exit-time wiring as before — RunEvent::Exit and the shutdown_sidecar command both call it.

Why not just upgrade Tauri?

We're already on the latest stable tauri (2.10.3) and tauri-plugin-shell (2.3.5). The relevant upstream feature request — a sidecar-lifecycle plugin that handles graceful shutdown and crash detection — is open and unimplemented (tauri-apps/plugins-workspace#3062). Job Objects are the industry-standard answer to "kill child when parent dies regardless of how parent dies" (Chromium, VS Code, etc. all use them); process-wrap is the canonical Rust crate that abstracts Job Objects + Unix process groups under one API.

Why not also remove tauri-plugin-shell entirely?

The frontend still uses open() for the changelog/issue links. Swapping that to tauri-plugin-opener is a separate small follow-up — keeping it out of this PR keeps the diff focused.

Test plan

• cargo test -p mouseterm_lib passes (3 new tests cover find_node_binary paths, 5 existing tests unchanged).
• pnpm dev:standalone launches and a terminal pane works (sidecar IPC functions over the new std::process::Command pipes).
• Normal window close: no node.exe orphan remains.
• Force-kill host (Stop-Process -Force on mouseterm.exe): sidecar node.exe disappears immediately. This was the failure mode the refactor exists to fix.
• Manual verification on macOS / Linux (process group path) — I only have Windows locally.

🤖 Generated with Claude Code

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