Bring back merge logic

openhands/server/routes/settings.py

@@ -54,7 +54,17 @@ async def store_settings(
         github_token = request.state.github_token
     try:
         settings_store = await SettingsStoreImpl.get_instance(config, github_token)
+        existing_settings = await settings_store.load()
+
+        if existing_settings:
+            # Only update settings that are not None with the new values
+            for key, value in settings.__dict__.items():
+                if value is None:
+                    setattr(settings, key, getattr(existing_settings, key))
+            if settings.llm_api_key is None:
+                settings.llm_api_key = existing_settings.llm_api_key
         await settings_store.store(settings)
+
         return JSONResponse(
             status_code=status.HTTP_200_OK,
             content={'message': 'Settings stored'},