Record STR-053 closeout hash

docs/modernization/debt.md

@@ -18,6 +18,11 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Recent Reductions
 
+- 2026-06-14: `DEBT-0036` was narrowed again. `execute_canvas_draw_merge_plane_dispatch()`
+  now routes the per-plane framebuffer setup and unbind handling through
+  `execute_canvas_draw_merge_plane_setup(...)` plus
+  `execute_canvas_draw_merge_plane_final_composite(...)`; the per-plane wrapper
+  still owns the plane-selection loop and branch dispatch.
 - 2026-06-14: `DEBT-0036` was narrowed again. `execute_canvas_draw_merge_plane_iteration()`
   now routes the per-plane dispatch wrapper through
   `execute_canvas_draw_merge_plane_dispatch(...)`; the plane loop still owns