fix: pull-only sync should not push back to cloud — prevents ordering revert

The receiving browser (e.g. Chromium) was pushing bookmarks back to cloud
after pulling updates from the source browser (e.g. Firefox), overwriting
the source browser's ordering changes. This caused a revert cycle:

1. Firefox reorders → syncs to cloud ✅
2. Chromium syncs → pulls new order → but also pushes back with old indices
3. Firefox syncs → pulls Chromium's overwritten order → reverts

Root cause: bookmarksToUpdate (cloud→local updates) was incorrectly counted
as 'local changes to push'. And Step 9 always pushed regardless of whether
there were actual local changes.

Fix:
- Remove bookmarksToUpdate from hasLocalChangesToPush (they're cloud→local)
- Gate Step 9 push behind hasLocalChangesToPush check
- Store cloud checksum on pull-only syncs for future comparison

v0.8.19

Author: ralyodio

apps/extension/__tests__/cross-browser-sync.test.js

@@ -613,3 +613,59 @@ describe('Bookmark Update Detection', () => {
     expect(bookmarkNeedsUpdate(cloud, local)).toBe(false);
   });
 });
+
+describe('Pull-only sync should not push back to cloud', () => {
+  it('should not treat cloud→local updates as local changes to push', () => {
+    // bookmarksToUpdate are updates FROM cloud, not local changes
+    // hasLocalChangesToPush should NOT include bookmarksToUpdate.length
+    const localAdditions = []; // no new local bookmarks
+    const locallyModifiedBookmarkIds = new Set(); // no locally modified bookmarks
+    const localTombstones = [];
+    const cloudTombstones = [];
+    const deletedLocally = 0;
+    const bookmarksToUpdate = [{ cloud: { url: 'a', index: 1 }, local: { url: 'a', index: 0 } }];
+
+    // This is the fixed logic — bookmarksToUpdate should NOT be included
+    const hasLocalChangesToPush =
+      localAdditions.length > 0 ||
+      locallyModifiedBookmarkIds.size > 0 ||
+      localTombstones.length > cloudTombstones.length ||
+      deletedLocally > 0;
+
+    expect(hasLocalChangesToPush).toBe(false);
+    // Even though there are bookmarks to update from cloud, we should NOT push back
+    expect(bookmarksToUpdate.length).toBe(1);
+  });
+
+  it('should push when there are actual local additions', () => {
+    const localAdditions = [{ url: 'https://new-local.com' }];
+    const locallyModifiedBookmarkIds = new Set();
+    const localTombstones = [];
+    const cloudTombstones = [];
+    const deletedLocally = 0;
+
+    const hasLocalChangesToPush =
+      localAdditions.length > 0 ||
+      locallyModifiedBookmarkIds.size > 0 ||
+      localTombstones.length > cloudTombstones.length ||
+      deletedLocally > 0;
+
+    expect(hasLocalChangesToPush).toBe(true);
+  });
+
+  it('should push when there are locally modified bookmarks', () => {
+    const localAdditions = [];
+    const locallyModifiedBookmarkIds = new Set(['bookmark-123']);
+    const localTombstones = [];
+    const cloudTombstones = [];
+    const deletedLocally = 0;
+
+    const hasLocalChangesToPush =
+      localAdditions.length > 0 ||
+      locallyModifiedBookmarkIds.size > 0 ||
+      localTombstones.length > cloudTombstones.length ||
+      deletedLocally > 0;
+
+    expect(hasLocalChangesToPush).toBe(true);
+  });
+});

apps/extension/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@marksyncr/extension",
-  "version": "0.8.18",
+  "version": "0.8.19",
   "private": true,
   "type": "module",
   "scripts": {

apps/extension/src/background/index.js

@@ -1726,13 +1726,12 @@ async function performSync(sourceId) {
       console.log(`[MarkSyncr] Local checksum: ${localChecksum}`);
       console.log(`[MarkSyncr] Cloud checksum: ${cloudChecksum}`);
 
-      // Determine if we have local changes to push to cloud
-      // Local changes = bookmarks that exist locally but not in cloud (before this sync)
-      // OR bookmarks that differ from cloud (local-first model: local changes override cloud)
-      // OR tombstones that need to be synced
+      // Determine if we have LOCAL (user-initiated) changes to push to cloud
+      // NOTE: bookmarksToUpdate are cloud→local updates (received FROM cloud), NOT local changes.
+      // Including them here was causing the receiving browser to re-push cloud data back,
+      // overwriting the original browser's ordering changes.
       const hasLocalChangesToPush =
         localAdditions.length > 0 ||
-        bookmarksToUpdate.length > 0 ||
         locallyModifiedBookmarkIds.size > 0 ||
         localTombstones.length > cloudTombstones.length ||
         deletedLocally > 0;
@@ -1785,15 +1784,28 @@ async function performSync(sourceId) {
       }
 
       // Step 9: Push merged bookmarks and tombstones back to cloud
-      console.log(
-        `[MarkSyncr] Pushing ${mergedFlat.length} merged bookmarks and ${mergedTombstones.length} tombstones to cloud...`
-      );
-      const syncResult = await syncBookmarksToCloud(mergedFlat, detectBrowser(), mergedTombstones);
-      console.log('[MarkSyncr] Cloud sync result:', syncResult);
+      // ONLY push if we have actual local changes. If this was a pull-only sync
+      // (we just received updates from cloud), don't push back — that would overwrite
+      // the source browser's changes with our potentially different index ordering.
+      let syncResult = null;
+      if (hasLocalChangesToPush) {
+        console.log(
+          `[MarkSyncr] Pushing ${mergedFlat.length} merged bookmarks and ${mergedTombstones.length} tombstones to cloud...`
+        );
+        syncResult = await syncBookmarksToCloud(mergedFlat, detectBrowser(), mergedTombstones);
+        console.log('[MarkSyncr] Cloud sync result:', syncResult);
+      } else {
+        console.log(
+          '[MarkSyncr] Pull-only sync — skipping push to cloud (no local changes to push)'
+        );
+      }
 
       // Store the new checksum
-      if (syncResult.checksum) {
+      if (syncResult?.checksum) {
         await storeLastCloudChecksum(syncResult.checksum);
+      } else if (cloudChecksum) {
+        // Pull-only: store the cloud checksum so next sync knows we're in sync
+        await storeLastCloudChecksum(cloudChecksum);
       }
 
       // Step 10: Save version history ONLY when we have local changes being pushed to cloud

apps/web/package.json

@@ -1,6 +1,6 @@
 {
   "name": "@marksyncr/web",
-  "version": "0.8.18",
+  "version": "0.8.19",
   "private": true,
   "type": "module",
   "scripts": {

package.json

@@ -1,6 +1,6 @@
 {
   "name": "marksyncr",
-  "version": "0.8.18",
+  "version": "0.8.19",
   "private": true,
   "description": "Cross-browser bookmark sync extension with cloud storage",
   "type": "module",