diff --git a/docs/superpowers/plans/2026-09-04-frontend.md b/docs/superpowers/plans/2026-09-04-frontend.md
index bd4e07d..18efc1b 100644
--- a/docs/superpowers/plans/2026-09-04-frontend.md
+++ b/docs/superpowers/plans/2026-09-04-frontend.md
@@ -1885,8 +1885,8 @@ export class PageHeights {
   range(scrollTop: number, viewport: number, overscan: number): [number, number] {
     if (this.n === 0) return [0, 0];
     const a = Math.max(0, this.pageAt(scrollTop) - overscan);
-    const b = Math.min(this.n - 1, this.pageAt(scrollTop + viewport) + overscan);
-    return [a, b + 1];
+    const b = Math.min(this.n, this.pageAt(scrollTop + viewport) + overscan); // [start, end)
+    return [a, b];
   }
 }
 ```