🥇 export from upstream (c220697)

src/docker.rs

@@ -122,8 +122,13 @@ pub fn build_compose_env(workspace: &Path) -> Result<HashMap<String, String>> {
     let home = dirs::home_dir().ok_or(DockerError::NoHomeDir)?;
     let sandcage_home = home.join(".sandcage");
 
-    let uid = id_flag("-u")?;
-    let gid = id_flag("-g")?;
+    // On Windows, UID/GID passthrough is meaningless — use the container's
+    // built-in agent user (1000:1000). On Linux, match the host user.
+    let (uid, gid) = if cfg!(windows) {
+        ("1000".to_string(), "1000".to_string())
+    } else {
+        (id_flag("-u")?, id_flag("-g")?)
+    };
 
     let mut env = HashMap::new();
     env.insert("SANDCAGE_UID".into(), uid);