fix: repeat disposes wrong rows when from advances from non-zero offset

The front-clear loop indexed the local _nodes array with a global
index, so sliding a window (e.g. 1-3 -> 3-5) disposed rows that stayed
visible and leaked rows that left. Dispose the correct local positions
instead. Fixes #2767.

Co-authored-by: Cursor <cursoragent@cursor.com>

Author: ryansolid

.changeset/fix-repeat-offset-disposal.md

@@ -0,0 +1,5 @@
+---
+"@solidjs/signals": patch
+---
+
+Fix `repeat` (`<Repeat>`) disposing the wrong row owners when `from` advances from a non-zero offset. The front-clear loop indexed the local `_nodes` array with a global index, so a sliding window (e.g. rows 1-3 → 3-5) disposed rows that stayed visible and leaked rows that left. It now disposes the correct local positions.

packages/solid-signals/src/map.ts

@@ -345,12 +345,13 @@ function updateRepeat<MappedItem>(this: RepeatData<MappedItem>): any[] {
     for (let i = to; i < prevTo; i++) this._nodes[i - this._offset].dispose();
 
     if (this._offset < from) {
-      // clear beginning
-      let i = this._offset;
-      while (i < from && i < this._len) this._nodes[i++].dispose();
+      // clear beginning — `_nodes` is local-indexed, so the rows leaving the
+      // front sit at local positions 0..(from - _offset), clamped to old len.
+      const removed = from - this._offset;
+      for (let i = 0; i < removed && i < this._len; i++) this._nodes[i].dispose();
       // shift indexes
-      this._nodes.splice(0, from - this._offset);
-      this._mappings.splice(0, from - this._offset);
+      this._nodes.splice(0, removed);
+      this._mappings.splice(0, removed);
     } else if (this._offset > from) {
       // shift indexes
       let i = prevTo - this._offset - 1;

packages/solid-signals/tests/repeat.test.ts

@@ -4,6 +4,7 @@ import {
   createSignal,
   createStore,
   flush,
+  onCleanup,
   repeat
 } from "../src/index.js";
 
@@ -183,6 +184,31 @@ it("should compute map when key by index", () => {
   expect(computed).toHaveBeenCalledTimes(4);
 });
 
+it("disposes the rows that leave the window when `from` advances from a non-zero offset", () => {
+  const cleanups: number[] = [];
+  const [from, setFrom] = createSignal(1);
+
+  const map = createRoot(() =>
+    repeat(
+      () => 3,
+      index => {
+        onCleanup(() => cleanups.push(index));
+        return index;
+      },
+      { from }
+    )
+  );
+
+  expect(map()).toEqual([1, 2, 3]);
+
+  // slide window 1-3 -> 3-5: rows 1 and 2 leave, row 3 stays
+  setFrom(3);
+  flush();
+
+  expect(map()).toEqual([3, 4, 5]);
+  expect(cleanups.sort((a, b) => a - b)).toEqual([1, 2]);
+});
+
 it("should retain instances when only `offset` changes", () => {
   const [source] = createStore<Array<{ id: string }>>([
     { id: "a" },