diff --git a/src/game/engine/scenes/tests/gameplay_arc_proof.gd b/src/game/engine/scenes/tests/gameplay_arc_proof.gd
index 37cf2b8e..5530d6d4 100644
--- a/src/game/engine/scenes/tests/gameplay_arc_proof.gd
+++ b/src/game/engine/scenes/tests/gameplay_arc_proof.gd
@@ -228,9 +228,13 @@ func _capture_step(label: String, mode: String, focus: Vector2i = Vector2i.ZERO)
 		_focus_camera(focus, 5.0 * 384.0)
 	else:
 		_setup_camera_fit()
-	# Multiple frames so the canvas items finish redraw + camera resolves.
-	for _i: int in range(8):
+	# Wait two real frames-rendered to flush the GPU composite. process_frame
+	# fires before draw; frame_post_draw fires AFTER GPU composite, which is
+	# what `get_viewport().get_texture()` actually reads.
+	for _i: int in range(3):
 		await get_tree().process_frame
+	for _j: int in range(2):
+		await RenderingServer.frame_post_draw
 	var image: Image = get_viewport().get_texture().get_image()
 	if image == null:
 		push_error("gameplay_arc: viewport image null at %s" % label)