terminal is fixed and im not happy about it

src/glyph_shader.wgsl

@@ -459,11 +459,16 @@ fn vs_cell_bg(
     
     // For default background (type 0), use fully transparent so the window's
     // clear color (which has background_opacity applied) shows through.
+    // UNLESS the grid params specify an opaque background (e.g. alternate screen).
     // Only non-default backgrounds should be opaque.
     // But NOT if the cell is selected (selection always has white bg)
     let bg_type = cell.bg & 0xFFu;
     if bg_type == COLOR_TYPE_DEFAULT && !is_reverse && !is_selected {
-        bg.a = 0.0;
+        if grid_params.background_opacity < 1.0 {
+            bg.a = 0.0;
+        } else {
+            bg.a = 1.0;
+        }
     }
     
     // Calculate cursor color