feat: add Windows WSL binary detection for Claude Code

Replaces the commented-out Linux-only `which claude` check with a
platform-aware binary detection strategy:

- Windows path: probes inside WSL via `wsl -e bash -lc "which claude"`
- Linux/WSL path: uses find_claude_binary() to search Linux filesystem paths

Updates tests to match the correct per-platform detection logic.

src-tauri/src/wsl_bridge.rs

@@ -138,11 +138,6 @@ impl WslBridge {
             return Err("Process already running".to_string());
         }
 
-        // Check if Claude binary is installed before attempting to start
-        // if Command::new("which").arg("claude").output().ok().is_none_or(|output| !output.status.success()) {
-        //     return Err("Claude Code is not installed. Please install it using:\n\ncurl -fsSL https://claude.ai/install.sh | bash".to_string());
-        // }
-
         // Load saved achievements and stats when starting a new session
         let app_clone = app.clone();
         let stats = self.stats.clone();
@@ -272,6 +267,16 @@ impl WslBridge {
             // Running on Windows - use wsl with bash login shell to ensure PATH is loaded
             tracing::debug!("Windows path - using wsl");
 
+            // Check if Claude binary is installed inside WSL
+            let binary_check = Command::new("wsl")
+                .args(["-e", "bash", "-lc", "which claude"])
+                .output();
+            if let Ok(output) = binary_check {
+                if !output.status.success() {
+                    return Err("Claude Code is not installed. Please install it using:\n\ncurl -fsSL https://claude.ai/install.sh | bash".to_string());
+                }
+            }
+
             // Validate the working directory exists inside WSL before spawning
             let dir_check = Command::new("wsl")
                 .args(["-e", "test", "-d", working_dir])
@@ -1935,20 +1940,28 @@ mod tests {
         let _ = has_exited; // suppress unused warning
     }
 
+    /// Build the WSL binary check command structure without executing it (for testing)
+    #[cfg(test)]
+    fn build_wsl_binary_check_args() -> Vec<&'static str> {
+        vec!["-e", "bash", "-lc", "which claude"]
+    }
+
     #[test]
-    fn test_claude_binary_check_command_structure() {
+    fn test_wsl_binary_check_command_structure() {
-        // Test that we're using the correct command to check for Claude binary
+        // Windows path: verify Claude is detected inside WSL via `wsl -e bash -lc "which claude"`
-        let output = Command::new("which").arg("claude").output();
+        let args = build_wsl_binary_check_args();
+        assert_eq!(args[0], "-e");
+        assert_eq!(args[1], "bash");
+        assert_eq!(args[2], "-lc");
+        assert_eq!(args[3], "which claude");
+    }
 
-        // The command should execute successfully (even if claude is not found)
+    #[test]
-        // We're just verifying the command structure is valid
+    fn test_linux_binary_check_does_not_panic() {
-        assert!(output.is_ok(), "which command should execute without error");
+        // Linux/WSL path: find_claude_binary() searches Linux filesystem paths.
-
+        // We just verify it runs without panicking; whether it returns Some depends
-        // Verify the check logic returns a boolean
+        // on whether Claude is actually installed in this environment.
-        // This is the same logic used in start() to check if claude is installed
+        let _result = find_claude_binary();
-        let _result = output.ok().is_none_or(|o| !o.status.success());
-        // If claude is not installed, _result will be true (show error)
-        // If claude is installed, _result will be false (proceed with connection)
     }
 
     #[test]