Tone down generated UI surfaces

tools/smoke_visual_assets.gd

@@ -5035,6 +5035,9 @@ func _check_panel_texture_path(failures: Array[String], path: String, context: S
 		failures.append("%s should not keep chroma-key green pixels: %s (%d sampled)" % [context, path, green_fringe_samples])
 	if luma_max - luma_min < 0.10:
 		failures.append("%s should contain visible material contrast: %s" % [context, path])
+	var warm_bias := _image_visible_warm_bias(image, 8)
+	if warm_bias > 0.12:
+		failures.append("%s should avoid a dominant yellow UI cast: %s (warm bias %.3f)" % [context, path, warm_bias])
 
 
 func _check_button_texture_path(failures: Array[String], path: String, context: String) -> void:
@@ -5090,6 +5093,25 @@ func _check_button_texture_path(failures: Array[String], path: String, context:
 		failures.append("%s should not keep chroma-key green pixels: %s (%d sampled)" % [context, path, green_fringe_samples])
 	if luma_max - luma_min < 0.08:
 		failures.append("%s should contain visible material contrast: %s" % [context, path])
+	var warm_bias := _image_visible_warm_bias(image, 8)
+	if warm_bias > 0.12:
+		failures.append("%s should avoid a dominant yellow UI cast: %s (warm bias %.3f)" % [context, path, warm_bias])
+
+
+func _image_visible_warm_bias(image: Image, sample_step: int) -> float:
+	var total_bias := 0.0
+	var visible_samples := 0
+	var step := maxi(1, sample_step)
+	for y in range(0, image.get_height(), step):
+		for x in range(0, image.get_width(), step):
+			var pixel := image.get_pixel(x, y)
+			if pixel.a <= 0.05:
+				continue
+			total_bias += maxf(0.0, ((pixel.r + pixel.g) * 0.5) - pixel.b)
+			visible_samples += 1
+	if visible_samples <= 0:
+		return 0.0
+	return total_bias / float(visible_samples)
 
 
 func _check_tile_marker_texture_path(failures: Array[String], path: String, context: String) -> void: