fix: correct WSL detection and binary lookup for GUI context

- detect_wsl() now short-circuits on Windows builds (cfg! compile-time
  check), preventing inherited WSL_DISTRO_NAME from routing a native
  Windows .exe through the Linux code path
- find_claude_binary() no longer early-exits when HOME is unset; falls
  back to bash -lc "which claude" so GUI apps (which don't inherit
  shell PATH) can still locate the binary via the login shell

src-tauri/src/wsl_bridge.rs

@@ -39,6 +39,12 @@ const SEARCH_TOOLS: [&str; 5] = ["Read", "Glob", "Grep", "WebSearch", "WebFetch"
 const CODING_TOOLS: [&str; 3] = ["Edit", "Write", "NotebookEdit"];
 
 fn detect_wsl() -> bool {
+    // A native Windows binary is never running inside WSL, even if launched from a WSL
+    // terminal that has WSL_DISTRO_NAME set in its environment.
+    if cfg!(target_os = "windows") {
+        return false;
+    }
+
     // Check /proc/version for WSL indicators
     if let Ok(version) = std::fs::read_to_string("/proc/version") {
         let version_lower = version.to_lowercase();
@@ -61,23 +67,29 @@ fn detect_wsl() -> bool {
 }
 
 fn find_claude_binary() -> Option<String> {
-    // Check common installation locations for claude
+    // Check common installation locations for claude (when HOME is available)
-    let home = std::env::var("HOME").ok()?;
+    if let Ok(home) = std::env::var("HOME") {
         let paths_to_check = [
             format!("{}/.local/bin/claude", home),
             format!("{}/.claude/local/claude", home),
-        "/usr/local/bin/claude".to_string(),
-        "/usr/bin/claude".to_string(),
         ];
-
         for path in &paths_to_check {
             if std::path::Path::new(path).exists() {
                 return Some(path.clone());
             }
         }
+    }
 
-    // Fall back to checking PATH via which
+    // Check system-wide locations
-    if let Ok(output) = Command::new("which").arg("claude").output() {
+    for path in &["/usr/local/bin/claude", "/usr/bin/claude"] {
+        if std::path::Path::new(path).exists() {
+            return Some((*path).to_string());
+        }
+    }
+
+    // Use a login shell to resolve claude via the user's PATH - GUI apps don't
+    // inherit shell PATH, so bare `which` may miss ~/.local/bin entries
+    if let Ok(output) = Command::new("bash").args(["-lc", "which claude"]).output() {
         if output.status.success() {
             let path = String::from_utf8_lossy(&output.stdout).trim().to_string();
             if !path.is_empty() {