Record STR-033 closeout hash

docs/modernization/debt.md

@@ -215,6 +215,10 @@ agent or engineer to remove them without reconstructing context from chat.
   branch orchestration now routes through `draw_merge_branch_orchestration(...)`;
   the retained path still owns the concrete per-branch framebuffer, sampler,
   and texture wiring.
+- 2026-06-13: DEBT-0036 was narrowed again. `Canvas::draw_merge()` final-plane
+  composite now routes through `draw_merge_final_plane_composite(...)`; the
+  retained path still owns the concrete merged-texture copy, checkerboard
+  redraw, and final blend/draw wiring.
 - 2026-06-13: DEBT-0036 was narrowed again. `NodeStrokePreview::draw_stroke_immediate()`
   now routes retained preview feedback/material/composite planning plus stroke
   shader uniform assembly through