Extract pad stroke copy region helper

docs/modernization/debt.md

@@ -541,6 +541,9 @@ agent or engineer to remove them without reconstructing context from chat.
   brush-tip dispatch now uses a retained helper object, with regression
   coverage proving the helper order; the live path still owns the concrete
   brush-tip texture object and dual-pass branch wiring.
+- 2026-06-13: DEBT-0036 was narrowed again. `Canvas::stroke_draw()` pad copy
+  behavior now uses a retained helper for copy-region wiring; the pad branch
+  still owns the concrete framebuffer and texture-object callbacks.
 - 2026-06-13: DEBT-0036 was narrowed again. `Canvas::draw_merge` checkerboard
   background shader setup and final merged-texture redraw setup now route
   through `legacy_canvas_draw_merge_services.h`. The retained Canvas path still

docs/modernization/tasks.md

@@ -840,7 +840,7 @@ ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_composito
 
 ### STR-029 - Extract Stroke Draw Pad Copy Callback Body
 
-Status: Ready
+Status: Done
 Score: +1 renderer boundary and OpenGL parity
 Debt: `DEBT-0036`
 Scope: `src/canvas.cpp`, `src/legacy_canvas_stroke_execution_services.h`, `tests/paint_renderer/compositor_tests.cpp`
@@ -864,6 +864,12 @@ Validation:
 ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_compositor|pp_paint_renderer_stroke_execution" --output-onfailure
 ```
 
+### Completed Task Log
+
+| Date | Task | Score | Validation | Commit |
+| --- | --- | --- | --- | --- |
+| 2026-06-13 | STR-029 | +1 renderer boundary and OpenGL parity | `ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_compositor|pp_paint_renderer_stroke_execution" --output-onfailure` | `pending` |
+
 Progress Notes:
 
 - 2026-06-13: `NodeStrokePreview::draw_stroke_immediate()` now routes final