fix(desktop): preserve inherited KANDEV_SERVER_HOST for embedded backend (#2838)

Co-authored-by: Carlos Florencio <carlosmflorencio@gmail.com>

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

@@ -849,6 +849,36 @@ mod tests {
         assert!(!env.contains_key(OsStr::new("kandev_desktop_native_notifications")));
     }
 
+    #[test]
+    fn desktop_environment_overrides_inherited_server_host_with_loopback() {
+        // Desktop launches must keep the embedded backend on the loopback host.
+        let mut inherited = BTreeMap::new();
+        inherited.insert(
+            OsString::from("KANDEV_SERVER_HOST"),
+            OsString::from("10.0.0.42"),
+        );
+
+        let env = desktop_environment(Path::new("/opt/kandev"), inherited, None);
+
+        assert_eq!(
+            env.get(OsStr::new("KANDEV_SERVER_HOST")),
+            Some(&OsString::from(LOOPBACK_HOST)),
+            "desktop_environment must force the loopback server host",
+        );
+    }
+
+    #[test]
+    fn desktop_environment_falls_back_to_loopback_when_server_host_unset() {
+        // The default production path: no inherited KANDEV_SERVER_HOST,
+        // desktop_environment must inject the loopback default.
+        let env = desktop_environment(Path::new("/opt/kandev"), BTreeMap::new(), None);
+
+        assert_eq!(
+            env.get(OsStr::new("KANDEV_SERVER_HOST")),
+            Some(&OsString::from(LOOPBACK_HOST))
+        );
+    }
+
     #[test]
     fn missing_launcher_returns_readable_error() {
         let dir = temp_root("missing-launcher");