Log PowerShell stderr in Windows tests

apps/desktop/src-tauri/src/agent.rs

@@ -723,6 +723,39 @@ fn collect_windows_extended() -> serde_json::Value {
         serde_json::from_str(trimmed).ok()
     }
 
+    fn decode_powershell_text(bytes: &[u8]) -> Option<String> {
+        if bytes.is_empty() {
+            return None;
+        }
+        if bytes.starts_with(&[0xFF, 0xFE]) {
+            return decode_utf16_le_to_string(&bytes[2..]);
+        }
+        if bytes.len() >= 2 && bytes[1] == 0 {
+            if let Some(s) = decode_utf16_le_to_string(bytes) {
+                return Some(s);
+            }
+        }
+        if bytes.contains(&0) {
+            if let Some(s) = decode_utf16_le_to_string(bytes) {
+                return Some(s);
+            }
+        }
+        std::str::from_utf8(bytes).map(|s| s.to_string()).ok()
+    }
+
+    fn decode_utf16_le_to_string(bytes: &[u8]) -> Option<String> {
+        if bytes.len() % 2 != 0 {
+            return None;
+        }
+        let utf16: Vec<u16> = bytes
+            .chunks_exact(2)
+            .map(|chunk| u16::from_le_bytes([chunk[0], chunk[1]]))
+            .collect();
+        String::from_utf16(&utf16)
+            .ok()
+            .map(|s| s.trim().to_string())
+    }
+
     fn encode_ps_script(script: &str) -> String {
         let mut bytes = Vec::with_capacity(script.len() * 2);
         for unit in script.encode_utf16() {
@@ -749,6 +782,11 @@ fn collect_windows_extended() -> serde_json::Value {
             .output()
             .ok()?;
         if out.stdout.is_empty() {
+            if cfg!(test) && !out.stderr.is_empty() {
+                if let Some(err) = decode_powershell_text(&out.stderr) {
+                    eprintln!("[collect_windows_extended] PowerShell stderr for `{cmd}`: {err}");
+                }
+            }
             return None;
         }
         parse_powershell_json(&out.stdout)