From 1223b5338bd8d97c31bf02e60bb6ff65792ad371 Mon Sep 17 00:00:00 2001
From: 2 * r + 2 * t <61896496+soramanew@users.noreply.github.com>
Date: Thu, 9 Apr 2026 19:10:34 +1000
Subject: [PATCH] fix: prevent cacheBuffer from extending viewport over height

---
 plugin/src/Caelestia/Components/lazylistview.cpp | 14 +++++++++++++-
 1 file changed, 13 insertions(+), 1 deletion(-)

diff --git a/plugin/src/Caelestia/Components/lazylistview.cpp b/plugin/src/Caelestia/Components/lazylistview.cpp
index 14fb4bb8..edcef17d 100644
--- a/plugin/src/Caelestia/Components/lazylistview.cpp
+++ b/plugin/src/Caelestia/Components/lazylistview.cpp
@@ -507,7 +507,19 @@ QRectF LazyListView::effectiveViewport() const {
             vp = QRectF(vp.x(), top, vp.width(), bottom - top);
     }
 
-    return vp.adjusted(0, -m_cacheBuffer, 0, m_cacheBuffer);
+    vp.adjust(0, -m_cacheBuffer, 0, m_cacheBuffer);
+
+    // Trim the cache-buffered viewport to [0, layoutHeight]. No items exist outside
+    // those bounds, so extending past them wastes budget and can cause edge thrashing
+    // when a large cache buffer reaches the opposite end of the content.
+    if (m_layoutHeight > 0) {
+        const qreal top = std::max(vp.y(), 0.0);
+        const qreal bottom = std::min(vp.y() + vp.height(), m_layoutHeight);
+        if (top < bottom)
+            vp = QRectF(vp.x(), top, vp.width(), bottom - top);
+    }
+
+    return vp;
 }
 
 std::pair<int, int> LazyListView::computeVisibleRange() const {