Fix sidecar crash recovery and Windows console window

- Fix is_running() to check actual process liveness via try_wait()
  instead of just checking if the handle exists
- Auto-restart sidecar on pipe errors (broken pipe, closed stdout)
  with one retry attempt
- Hide sidecar console window on Windows (CREATE_NO_WINDOW flag)
- Log sidecar stderr to sidecar.log file for crash diagnostics
- Include exit status in error message when sidecar fails to start

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src-tauri/src/sidecar/mod.rs

@@ -6,6 +6,9 @@ use std::path::{Path, PathBuf};
 use std::process::{Child, ChildStdin, Command, Stdio};
 use std::sync::{Mutex, OnceLock};
 
+#[cfg(target_os = "windows")]
+use std::os::windows::process::CommandExt;
+
 use crate::sidecar::messages::IPCMessage;
 
 /// Resource directory set by the Tauri app during setup.
@@ -231,10 +234,28 @@ impl SidecarManager {
         self.stop().ok();
         eprintln!("[sidecar-rs] Starting frozen sidecar: {}", path.display());
 
-        let child = Command::new(path)
+        // Log sidecar stderr to a file for diagnostics
-            .stdin(Stdio::piped())
+        let stderr_cfg = if let Some(data_dir) = DATA_DIR.get() {
+            let log_path = data_dir.join("sidecar.log");
+            eprintln!("[sidecar-rs] Sidecar stderr → {}", log_path.display());
+            match std::fs::File::create(&log_path) {
+                Ok(f) => Stdio::from(f),
+                Err(_) => Stdio::inherit(),
+            }
+        } else {
+            Stdio::inherit()
+        };
+
+        let mut cmd = Command::new(path);
+        cmd.stdin(Stdio::piped())
             .stdout(Stdio::piped())
-            .stderr(Stdio::inherit())
+            .stderr(stderr_cfg);
+
+        // Hide the console window on Windows (CREATE_NO_WINDOW = 0x08000000)
+        #[cfg(target_os = "windows")]
+        cmd.creation_flags(0x08000000);
+
+        let child = cmd
             .spawn()
             .map_err(|e| format!("Failed to start sidecar binary: {e}"))?;
 
@@ -300,7 +321,22 @@ impl SidecarManager {
                     .read_line(&mut line)
                     .map_err(|e| format!("Read error: {e}"))?;
                 if bytes == 0 {
-                    return Err("Sidecar closed stdout before sending ready".to_string());
+                    // Try to get the exit code for diagnostics
+                    let exit_info = {
+                        let mut proc = self.process.lock().map_err(|e| e.to_string())?;
+                        if let Some(ref mut child) = *proc {
+                            match child.try_wait() {
+                                Ok(Some(status)) => format!(" (exit status: {status})"),
+                                _ => String::new(),
+                            }
+                        } else {
+                            String::new()
+                        }
+                    };
+                    return Err(format!(
+                        "Sidecar closed stdout before sending ready{exit_info}. \
+                         The Python sidecar may have crashed on startup — check app logs for details."
+                    ));
                 }
                 let trimmed = line.trim();
                 if trimmed.is_empty() {
@@ -330,11 +366,46 @@ impl SidecarManager {
 
     /// Send a message and receive the response, calling a callback for intermediate messages.
     /// Intermediate messages include progress, pipeline.segment, and pipeline.speaker_update.
+    ///
+    /// If the sidecar has crashed (broken pipe), automatically restarts it and retries once.
     pub fn send_and_receive_with_progress<F>(
         &self,
         msg: &IPCMessage,
         on_intermediate: F,
     ) -> Result<IPCMessage, String>
+    where
+        F: Fn(&IPCMessage),
+    {
+        match self.send_and_receive_inner(msg, &on_intermediate) {
+            Ok(response) => Ok(response),
+            Err(e)
+                if e.contains("Write error")
+                    || e.contains("closed stdout")
+                    || e.contains("not available") =>
+            {
+                eprintln!("[sidecar-rs] Sidecar communication failed ({e}), restarting...");
+                self.cleanup_handles();
+                // Stop any zombie process
+                {
+                    let mut proc = self.process.lock().map_err(|e| e.to_string())?;
+                    if let Some(ref mut child) = proc.take() {
+                        let _ = child.kill();
+                        let _ = child.wait();
+                    }
+                }
+                self.ensure_running()?;
+                self.send_and_receive_inner(msg, &on_intermediate)
+            }
+            Err(e) => Err(e),
+        }
+    }
+
+    /// Inner implementation of send_and_receive.
+    fn send_and_receive_inner<F>(
+        &self,
+        msg: &IPCMessage,
+        on_intermediate: &F,
+    ) -> Result<IPCMessage, String>
     where
         F: Fn(&IPCMessage),
     {
@@ -420,8 +491,39 @@ impl SidecarManager {
     }
 
     pub fn is_running(&self) -> bool {
-        let proc = self.process.lock().ok();
+        let mut proc = match self.process.lock() {
-        proc.map_or(false, |p| p.is_some())
+            Ok(p) => p,
+            Err(_) => return false,
+        };
+        if let Some(ref mut child) = *proc {
+            // Check if the process has exited
+            match child.try_wait() {
+                Ok(Some(_status)) => {
+                    // Process has exited — clean up handles
+                    eprintln!("[sidecar-rs] Sidecar process has exited");
+                    drop(proc);
+                    let _ = self.cleanup_handles();
+                    false
+                }
+                Ok(None) => true, // Still running
+                Err(_) => false,
+            }
+        } else {
+            false
+        }
+    }
+
+    /// Clean up stdin/stdout/process handles after the sidecar has exited.
+    fn cleanup_handles(&self) {
+        if let Ok(mut s) = self.stdin.lock() {
+            *s = None;
+        }
+        if let Ok(mut r) = self.reader.lock() {
+            *r = None;
+        }
+        if let Ok(mut p) = self.process.lock() {
+            *p = None;
+        }
     }
 }