Track if files are writable and disable saving if they are not.

jupyter_server_documents/rooms/yroom_file_api.py

@@ -105,6 +105,7 @@ def __init__(self, *args, **kwargs):
         self._last_path = None
         self._last_modified = None
         self._stopped = False
+        self._is_writable = True
 
         # Initialize content-related primitives
         self._content_loading = False
@@ -199,6 +200,10 @@ async def _load_content(self, jupyter_ydoc: YBaseDoc) -> None:
                 format=self.file_format
             ))
 
+        # The content manager uses this to tell consumers of the API if the file is writable.
+        # We need to save this so we can use it during save.
+        self._is_writable = file_data.get('writable', True)
+
         if self.file_type == "notebook":
             self.log.info(f"Processing outputs for loaded notebook: '{self.room_id}'.")
             file_data = self.outputs_manager.process_loaded_notebook(file_id=self.file_id, file_data=file_data)
@@ -364,6 +369,9 @@ async def save(self, jupyter_ydoc: YBaseDoc):
         instead.
         """
         try:
+            # Return immediately if the content manager has marked this file as non-writable
+            if not self._is_writable:
+                return
             # Build arguments to `CM.save()`
             path = self.get_path()
             content = jupyter_ydoc.source