Fix: prevent remote edits from being silently deleted on concurrent updates

hub-client/src/App.tsx

@@ -373,12 +373,14 @@ function App() {
   }, [navigateToProjectSelector]);
 
   const handleContentChange = useCallback((path: string, content: string) => {
+    // updateFileContent fires handle.change(), which synchronously triggers the
+    // 'change' event on the DocHandle. The registered changeHandler calls
+    // callbacks.onFileChanged with the true merged Automerge document state,
+    // which propagates to setFileContents via onFileContent. Setting fileContents
+    // directly here with the raw editor content would overwrite that merged state,
+    // causing concurrent remote edits to be silently deleted by subsequent
+    // updateText calls that diff against the stale Monaco content.
     updateFileContent(path, content);
-    setFileContents((prev) => {
-      const next = new Map(prev);
-      next.set(path, content);
-      return next;
-    });
   }, []);
 
   const handleProjectCreated = useCallback(async (

ts-packages/quarto-sync-client/src/client.ts

@@ -461,9 +461,11 @@ export function createSyncClient(callbacks: SyncClientCallbacks, astOptions?: AS
       updateText(doc, ['text'], content);
     });
 
-    // Notify callback (local change)
-    callbacks.onFileChanged(path, content, []);
-    tryParseAndNotify(path, content);
+    // onFileChanged and tryParseAndNotify are called by the 'change' event handler
+    // registered in subscribeToFile/subscribeToFileInternal, which passes the true
+    // merged Automerge document state. Calling them again here with the raw editor
+    // content would overwrite the merged state in fileContents, causing concurrent
+    // remote edits to be silently deleted on the next updateFileContent call.
   }
 
   /**