From 567c084092d9a6c9f41364a24226ca6ae8e16118 Mon Sep 17 00:00:00 2001
From: shikokuchuo <53399081+shikokuchuo@users.noreply.github.com>
Date: Mon, 23 Mar 2026 14:05:48 -0700
Subject: [PATCH] Fix: prevent remote edits from being silently deleted on
 concurrent updates

Remove the redundant `setFileContents` call in `handleContentChange` and the duplicate `onFileChanged`/`tryParseAndNotify` calls in `updateFileContent`.

Both were overwriting the true merged Automerge document state with raw editor content, causing concurrent remote edits to be dropped by subsequent `updateText` diffs.
---
 hub-client/src/App.tsx                       | 12 +++++++-----
 ts-packages/quarto-sync-client/src/client.ts |  8 +++++---
 2 files changed, 12 insertions(+), 8 deletions(-)

diff --git a/hub-client/src/App.tsx b/hub-client/src/App.tsx
index 24a1e88b..1dec1e74 100644
--- a/hub-client/src/App.tsx
+++ b/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 (
diff --git a/ts-packages/quarto-sync-client/src/client.ts b/ts-packages/quarto-sync-client/src/client.ts
index 392023b2..b27761f3 100644
--- a/ts-packages/quarto-sync-client/src/client.ts
+++ b/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.
   }
 
   /**