element-web/patches/@tanstack__virtual-core@3.patch

diff --git a/dist/esm/index.d.ts b/dist/esm/index.d.ts
index 039bff8..39d31ff 100644
--- a/dist/esm/index.d.ts
+++ b/dist/esm/index.d.ts
@@ -78,6 +78,12 @@ export interface VirtualizerOptions<TScrollElement extends Element | Window, TIt
     initialMeasurementsCache?: Array<VirtualItem>;
     lanes?: number;
     anchorTo?: ScrollAnchor;
+    /**
+     * With `anchorTo: "end"`, reject an item as the scroll anchor (e.g. a transient
+     * placeholder/sentinel row whose key does not survive the update); anchoring
+     * steps inward to the nearest accepted item. Element-web patch, pending upstream.
+     */
+    isValidAnchorItem?: (item: VirtualItem) => boolean;
     followOnAppend?: FollowOnAppend;
     scrollEndThreshold?: number;
     isScrollingResetDelay?: number;
diff --git a/dist/esm/index.js b/dist/esm/index.js
index 7032b66..b8140c8 100644
--- a/dist/esm/index.js
+++ b/dist/esm/index.js
@@ -321,7 +321,24 @@ class Virtualizer {
         const didEdgeKeysChange = didCountChange || prevCount > 0 && nextCount > 0 && (merged.getItemKey(0) !== prevFirstKey || merged.getItemKey(nextCount - 1) !== prevLastKey);
         if (didEdgeKeysChange) {
           edgeKeysChanged = true;
-          const item = prevCount > 0 ? this.getVirtualItemForOffset(this.getScrollOffset()) ?? measurements[0] : null;
+          let item = prevCount > 0 ? this.getVirtualItemForOffset(this.getScrollOffset()) ?? measurements[0] : null;
+          // With anchorTo: "end" the scroll is re-pinned by the key of the item
+          // under the current offset. If the consumer rejects that item as an
+          // anchor via isValidAnchorItem — e.g. a transient placeholder/sentinel
+          // row (loading spinner, "load more", skeleton) whose key does not
+          // survive the update — re-pinning by its key would fail and the
+          // prepend would go uncompensated (the list jumps to the edge). Such
+          // rows only sit at the extreme edges, so step one index inward to the
+          // nearest accepted item, whose key persists across the update.
+          const isValidAnchorItem = merged.isValidAnchorItem;
+          if (item && isValidAnchorItem && !isValidAnchorItem(item)) {
+            const step = item.index === 0 ? 1 : -1;
+            let i = item.index;
+            while (i >= 0 && i < measurements.length && measurements[i] && !isValidAnchorItem(measurements[i])) {
+              i += step;
+            }
+            item = measurements[i] ?? item;
+          }
           if (item) {
             anchor = [item.key, this.getScrollOffset() - item.start];
           }
@@ -443,7 +460,23 @@ class Virtualizer {
         });
         this.unsubs.push(
           this.options.observeElementRect(this, (rect) => {
+            var _a2;
+            // With anchorTo: "end", keep an end-pinned viewport pinned when the
+            // scroll element shrinks, as resizeItem does when an item grows. The
+            // browser keeps scrollTop, so the end would otherwise drop below the
+            // fold. Judge "pinned" against the size before this change, and never
+            // scroll past the element's real end, except while a clamped write
+            // waits for the sizer (the DOM end is stale then; the retry lands it).
+            // Element-web patch, pending upstream.
+            const prevSize = this.scrollRect !== null ? this.getSize() : null;
+            const wasAtEnd = prevSize !== null && this.options.anchorTo === "end" && ((_a2 = this.scrollState) == null ? void 0 : _a2.behavior) !== "smooth" && this.getVirtualDistanceFromEnd() <= this.options.scrollEndThreshold;
             this.scrollRect = rect;
+            if (wasAtEnd && prevSize > this.getSize()) {
+              const shrink = prevSize - this.getSize();
+              this.applyScrollAdjustment(
+                this._clampedAdjustment !== null ? shrink : Math.min(shrink, this.getDistanceFromEnd())
+              );
+            }
             this.maybeNotify();
           })
         );
@@ -913,9 +946,19 @@ class Virtualizer {
       const itemSize = this.itemSizeCache.get(key) ?? cachedSize;
       const delta = size - itemSize;
       if (delta !== 0) {
-        const wasAtEnd = this.options.anchorTo === "end" && ((_b = this.scrollState) == null ? void 0 : _b.behavior) !== "smooth" && this.getVirtualDistanceFromEnd() <= this.options.scrollEndThreshold;
+        // `this.scrollOffset` only updates when the async scroll event fires, so
+        // within a frame it can be stale in two ways: (a) an earlier resize in the
+        // same ResizeObserver batch already queued `scrollAdjustments`, and (b) a
+        // programmatic scroll (scrollToOffset / the reconcile loop) wrote scrollTop
+        // this frame — recorded synchronously in `_intendedScrollOffset` but not yet
+        // reflected by getScrollOffset(). Evaluating "was the view at the end?" (or
+        // "is this item above the fold?") against the stale offset makes resizes
+        // during a scroll-to-end land uncompensated, stranding the view above the
+        // bottom. Use the synchronous truth when a write is pending.
+        const effectiveScrollOffset = this._intendedScrollOffset ?? (this.getScrollOffset() + this.scrollAdjustments);
+        const wasAtEnd = this.options.anchorTo === "end" && ((_b = this.scrollState) == null ? void 0 : _b.behavior) !== "smooth" && this.getTotalSize() - this.getSize() - effectiveScrollOffset <= this.options.scrollEndThreshold;
         const prevTotalSize = wasAtEnd ? this.getTotalSize() : 0;
-        const scrollOffsetWithAdj = this.getScrollOffset() + this.scrollAdjustments;
+        const scrollOffsetWithAdj = effectiveScrollOffset;
         const isFirstMeasure = !this.itemSizeCache.has(key);
         const defaultShouldAdjust = isFirstMeasure ? (
           // First measurement: compensate any item whose top sits above the
@@ -928,9 +971,12 @@ class Virtualizer {
           // below — e.g. a streaming chat message growing at its bottom)
           // changes size *below* the anchor point, so shifting scrollTop by the
           // delta would drag the viewport downward on every growth (#1218).
-          // Also skip during backward scroll to avoid the "items jump while
-          // scrolling up" cascade.
-          itemStart + itemSize <= scrollOffsetWithAdj && this.scrollDirection !== "backward"
+          // Upstream also skips this while scrolling backwards, a guard against
+          // corrections firing from a stale scroll offset. The effective-offset
+          // fix above removes the staleness, and keeping the guard meant every
+          // image or link preview that finished loading above the viewport
+          // shoved the view while scrolling up — so the guard is dropped.
+          itemStart + itemSize <= scrollOffsetWithAdj
         );
         const shouldAdjustScroll = ((_c = this.scrollState) == null ? void 0 : _c.behavior) !== "smooth" && (this.shouldAdjustScrollPositionOnItemSizeChange !== void 0 ? this.shouldAdjustScrollPositionOnItemSizeChange(
           // The callback expects a VirtualItem; build one lazily only
@@ -1197,16 +1243,19 @@ class Virtualizer {
       this._iosDeferredAdjustment += delta;
       return false;
     } else {
-      const target = this.getScrollOffset() + this.scrollAdjustments + delta;
+      // A programmatic scroll written this frame is not yet visible through
+      // getScrollOffset(); build the correction on the offset that was written.
+      const base = this._intendedScrollOffset ?? this.getScrollOffset();
+      const target = base + this.scrollAdjustments + delta;
       const el = this.scrollElement;
       const maxAtWrite = el !== null && ("scrollHeight" in el || "document" in el) ? this.getMaxScrollOffset() : null;
       this._clampedAdjustment = maxAtWrite !== null && target > maxAtWrite + 0.5 ? { target, maxAtWrite } : null;
-      this._scrollToOffset(this.getScrollOffset(), {
+      this._scrollToOffset(base, {
         adjustments: this.scrollAdjustments += delta,
         behavior
       });
       if (this.scrollOffset !== null) {
-        this.scrollOffset += this.scrollAdjustments;
+        this.scrollOffset = base + this.scrollAdjustments;
         if (this.scrollOffset < 0) this.scrollOffset = 0;
         this.scrollAdjustments = 0;
       }