From acac784c2b7148d3f749dca9f59a3e4e5ee3fe8e Mon Sep 17 00:00:00 2001
From: tetrisgm <30949000+tetrisgm@users.noreply.github.com>
Date: Thu, 27 Aug 2026 17:51:22 -0700
Subject: [PATCH] runtime: preserve adaptive 4:3 across DPI rounding

(cherry picked from commit b6aedc800a0a7375ba7c31344c03a3b9d401edfd)
---
 runtime/src/main.cpp | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/runtime/src/main.cpp b/runtime/src/main.cpp
index 40d16fcf..d9fade8f 100644
--- a/runtime/src/main.cpp
+++ b/runtime/src/main.cpp
@@ -1658,7 +1658,11 @@ static void update_adaptive_widescreen() {
     if (width <= 0 || height <= 0) return;
 
     int num = width, den = height;
-    if ((int64_t)width * 3 <= (int64_t)height * 4) {
+    /* A nominal 4:3 client can be one physical pixel wider after fractional-DPI
+     * conversion (for example 960x720 -> 2161x1620 at 225%).  Keep that
+     * rounding pixel in the identity fallback instead of engaging an almost-
+     * identity widescreen squash and its cull guard. */
+    if ((int64_t)(width - 1) * 3 <= (int64_t)height * 4) {
         num = 4; den = 3;
     } else if ((int64_t)width * g_ws_adaptive_max_den >=
                (int64_t)height * g_ws_adaptive_max_num) {