Record STR-051 branch dispatch object closeout

docs/modernization/debt.md

@@ -18,6 +18,10 @@ 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_branch_body()`
+  now routes the branch dispatch object assembly through
+  `make_canvas_draw_merge_branch_dispatch(...)`; the branch body still owns the
+  selection guard and dispatch wiring.
 - 2026-06-14: `DEBT-0036` was narrowed again. `Canvas::draw_merge_branch_orchestration()`
   now routes the temporary erase, temporary paint, texture, and blend dispatch
   bodies through retained helpers inside `execute_canvas_draw_merge_branch_body(...)`;