fix(grid): append infinite scroll result segments

apps/desktop/src/components/grid/DataGrid.vue

@@ -2269,6 +2269,8 @@ const isInfiniteScrollPaginating = ref(false);
 let lastInfiniteScrollPage = 0;
 let infiniteScrollCheckScheduled = false;
 let infiniteScrollAllLoaded = false;
+let infiniteScrollRequestedOffset: number | undefined;
+let infiniteScrollRequestedLimit: number | undefined;
 // Tracks whether the current loading cycle was triggered by a refresh/rollback
 // (as opposed to a normal paginate). Used to decide whether to auto-redirect
 // when the current page no longer exists after data was deleted.
@@ -2313,9 +2315,19 @@ watch(
     if (prevLoading && !loading && infiniteScrollLoading.value) {
       infiniteScrollLoading.value = false;
       isInfiniteScrollPaginating.value = false;
-      // Detect if the backend returned no new data for this page
-      const expectedRows = currentPage.value * pageSize.value;
-      if (props.result.rows.length < expectedRows) {
+      const requestedOffset = infiniteScrollRequestedOffset;
+      const requestedLimit = infiniteScrollRequestedLimit;
+      infiniteScrollRequestedOffset = undefined;
+      infiniteScrollRequestedLimit = undefined;
+      if (requestedOffset === undefined || props.result.appended_from_row_count !== requestedOffset) {
+        // Failed/stale append requests preserve the old result. Roll back the
+        // optimistic page marker so a later scroll can retry the same segment.
+        currentPage.value = Math.max(1, currentPage.value - 1);
+        lastInfiniteScrollPage = Math.max(0, currentPage.value - 1);
+        return;
+      }
+      const appendedRows = props.result.rows.length - requestedOffset;
+      if (props.result.rows.length >= infiniteScrollMaxRows.value || appendedRows < (requestedLimit ?? pageSize.value)) {
         infiniteScrollAllLoaded = true;
       }
     }
@@ -2489,21 +2501,21 @@ function nextPage() {
 
 function infiniteScrollNextPage() {
   if (infiniteScrollLoading.value || props.loading) return;
+  const nextOffset = props.result.rows.length;
+  const remainingRows = infiniteScrollMaxRows.value - nextOffset;
+  if (remainingRows <= 0) return;
+  const nextLimit = Math.min(pageSize.value, remainingRows);
   const nextPageNum = currentPage.value + 1;
-  const cumulativeLimit = nextPageNum * pageSize.value;
-  if (cumulativeLimit > infiniteScrollMaxRows.value) return;
   // Stop if we already know all data is loaded
   if (infiniteScrollAllLoaded) return;
-  // Skip if we already have this many rows loaded (e.g. cached data)
-  if (props.result.rows.length >= cumulativeLimit) {
-    currentPage.value = nextPageNum;
-    return;
-  }
   infiniteScrollLoading.value = true;
   isInfiniteScrollPaginating.value = true;
+  infiniteScrollRequestedOffset = nextOffset;
+  infiniteScrollRequestedLimit = nextLimit;
   currentPage.value = nextPageNum;
-  // Load cumulative data (all rows up to current page) to append instead of replace
-  emit("paginate", 0, cumulativeLimit, currentWhereInput(), currentOrderBy());
+  // Fetch only the missing segment. Re-reading offset 0 grows transfer and replaces
+  // row identities, which would invalidate pending edits while the user scrolls.
+  emit("paginate", nextOffset, nextLimit, currentWhereInput(), currentOrderBy());
 }
 function checkInfiniteScroll(scroller: HTMLElement) {
   if (!infiniteScrollEnabled.value || infiniteScrollLoading.value || props.loading) return;
@@ -2969,6 +2981,8 @@ function resetInfiniteScrollState() {
   currentPage.value = 1;
   lastInfiniteScrollPage = 0;
   infiniteScrollAllLoaded = false;
+  infiniteScrollRequestedOffset = undefined;
+  infiniteScrollRequestedLimit = undefined;
   isInfiniteScrollPaginating.value = false;
   infiniteScrollLoading.value = false;
   infiniteScrollPositions = new WeakMap();