fix(acp): prevent Windows terminal hangs from pipe orphans and .cmd shims

src-tauri/src/acp/terminal_runtime.rs

@@ -1,6 +1,7 @@
 use std::collections::HashMap;
 use std::process::Stdio;
 use std::sync::Arc;
+use std::time::Duration;
 
 use sacp::schema::{
     CreateTerminalRequest, CreateTerminalResponse, KillTerminalRequest, KillTerminalResponse,
@@ -9,9 +10,16 @@ use sacp::schema::{
 };
 use tokio::io::{AsyncRead, AsyncReadExt};
 use tokio::sync::Mutex;
+use tokio::task::JoinHandle;
 
 type TerminalMap = HashMap<String, Arc<TerminalInstance>>;
 const DEFAULT_OUTPUT_BYTE_LIMIT: u64 = 1_000_000;
+/// After the child process exits, wait up to this long for the stdout/stderr
+/// reader tasks to drain naturally before aborting them. Needed because a
+/// grandchild process (e.g. Node spawned from a `.cmd` shim on Windows) can
+/// inherit the pipe handle and keep it open long after the direct child
+/// exits, turning `wait_for_exit` into a silent hang.
+const READER_DRAIN_GRACE: Duration = Duration::from_millis(200);
 
 #[derive(Debug)]
 pub enum TerminalRuntimeError {
@@ -41,6 +49,7 @@ struct TerminalInstance {
     output_limit: Option<usize>,
     child: Mutex<Option<tokio::process::Child>>,
     snapshot: Mutex<TerminalSnapshot>,
+    reader_handles: Mutex<Vec<JoinHandle<()>>>,
 }
 
 impl TerminalInstance {
@@ -50,6 +59,24 @@ impl TerminalInstance {
             output_limit: output_limit.and_then(|v| usize::try_from(v).ok()),
             child: Mutex::new(Some(child)),
             snapshot: Mutex::new(TerminalSnapshot::default()),
+            reader_handles: Mutex::new(Vec::new()),
+        }
+    }
+
+    /// Wait briefly for stdout/stderr reader tasks to finish; abort any that
+    /// remain. Must be called after the direct child has already exited —
+    /// otherwise we would abort readers that are still making progress.
+    async fn drain_readers(&self) {
+        let handles: Vec<JoinHandle<()>> =
+            std::mem::take(&mut *self.reader_handles.lock().await);
+        for handle in handles {
+            let abort = handle.abort_handle();
+            if tokio::time::timeout(READER_DRAIN_GRACE, handle)
+                .await
+                .is_err()
+            {
+                abort.abort();
+            }
         }
     }
 
@@ -105,11 +132,10 @@ impl TerminalInstance {
 
     async fn wait_for_exit(&self) -> Result<TerminalExitStatus, TerminalRuntimeError> {
         self.refresh_exit_status().await?;
-        {
+        let cached_exit = self.snapshot.lock().await.exit_status.clone();
-            let snapshot = self.snapshot.lock().await;
+        if let Some(exit_status) = cached_exit {
-            if let Some(exit_status) = snapshot.exit_status.clone() {
+            self.drain_readers().await;
-                return Ok(exit_status);
+            return Ok(exit_status);
-            }
         }
 
         let exit_status = {
@@ -128,6 +154,8 @@ impl TerminalInstance {
             map_exit_status(status)
         };
 
+        self.drain_readers().await;
+
         let mut snapshot = self.snapshot.lock().await;
         snapshot.exit_status = Some(exit_status.clone());
         Ok(exit_status)
@@ -135,11 +163,10 @@ impl TerminalInstance {
 
     async fn kill_command(&self) -> Result<(), TerminalRuntimeError> {
         self.refresh_exit_status().await?;
-        {
+        let already_exited = self.snapshot.lock().await.exit_status.is_some();
-            let snapshot = self.snapshot.lock().await;
+        if already_exited {
-            if snapshot.exit_status.is_some() {
+            self.drain_readers().await;
-                return Ok(());
+            return Ok(());
-            }
         }
 
         let exit_status = {
@@ -163,6 +190,8 @@ impl TerminalInstance {
             map_exit_status(status)
         };
 
+        self.drain_readers().await;
+
         let mut snapshot = self.snapshot.lock().await;
         snapshot.exit_status = Some(exit_status);
         Ok(())
@@ -246,18 +275,23 @@ impl TerminalRuntime {
             child,
         ));
 
+        let mut handles: Vec<JoinHandle<()>> = Vec::new();
         if let Some(reader) = stdout {
             let terminal_ref = terminal.clone();
-            tokio::spawn(async move {
+            handles.push(tokio::spawn(async move {
                 read_stream(reader, terminal_ref).await;
-            });
+            }));
         }
 
         if let Some(reader) = stderr {
             let terminal_ref = terminal.clone();
-            tokio::spawn(async move {
+            handles.push(tokio::spawn(async move {
                 read_stream(reader, terminal_ref).await;
-            });
+            }));
+        }
+
+        if !handles.is_empty() {
+            terminal.reader_handles.lock().await.extend(handles);
         }
 
         self.terminals

src-tauri/src/process.rs

@@ -71,25 +71,32 @@ impl SetEnv for tokio::process::Command {
     }
 }
 
+/// On Windows, resolve a bare program name to its concrete file on PATH
+/// by trying `.exe → .cmd → .bat` in order.
+///
+/// Rust's `Command::new("foo")` on Windows relies on `CreateProcessW`'s
+/// implicit extension lookup, which does not locate `.cmd` / `.bat` shims
+/// reliably for many npm-installed tools (`tsc`, `vite`, `eslint`, ...).
+/// Without this helper those agents hang or ENOENT when ACP agents send
+/// bare names. Extension fallback is **purely additive**: if the caller
+/// already supplied a path, extension, or the `.exe` is found, the result
+/// is identical to the previous behavior.
 #[cfg(windows)]
-fn maybe_windows_cmd_shim(program: &OsStr) -> Option<OsString> {
+fn resolve_windows_program(program: &OsStr) -> Option<OsString> {
     let path = Path::new(program);
+    // Only apply fallback for bare names (no path components, no extension).
     if path.components().count() != 1 || path.extension().is_some() {
         return None;
     }
 
     let raw = program.to_string_lossy();
-    let normalized = raw.to_ascii_lowercase();
+    for ext in ["exe", "cmd", "bat"] {
-    let needs_cmd_shim = matches!(
+        let candidate = format!("{raw}.{ext}");
-        normalized.as_str(),
+        if which::which(&candidate).is_ok() {
-        "npm" | "npx" | "pnpm" | "pnpx" | "yarn" | "yarnpkg" | "corepack"
+            return Some(OsString::from(candidate));
-    );
+        }
-
-    if needs_cmd_shim {
-        Some(OsString::from(format!("{raw}.cmd")))
-    } else {
-        None
     }
+    None
 }
 
 pub fn normalized_program<S>(program: S) -> OsString
@@ -98,8 +105,8 @@ where
 {
     #[cfg(windows)]
     {
-        if let Some(shimmed) = maybe_windows_cmd_shim(program.as_ref()) {
+        if let Some(resolved) = resolve_windows_program(program.as_ref()) {
-            return shimmed;
+            return resolved;
         }
     }