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

src/canvas.cpp

@@ -1080,13 +1080,9 @@ void Canvas::stroke_draw()
                     face_index));
         },
         [&](const pp::paint_renderer::CanvasStrokeCopyRegion& copy_region) {
-            copy_framebuffer_to_texture_2d(
-                copy_region.x,
-                copy_region.y,
-                copy_region.x,
-                copy_region.y,
-                copy_region.width,
-                copy_region.height);
+            pp::panopainter::execute_legacy_canvas_stroke_pad_copy_region(
+                copy_region,
+                copy_framebuffer_to_texture_2d);
         },
         [&](int face_index) {
             pp::panopainter::unbind_legacy_canvas_stroke_texture_inputs(

src/legacy_canvas_stroke_execution_services.h

@@ -311,6 +311,19 @@ struct LegacyCanvasStrokePadExecutionResult {
 [[nodiscard]] inline LegacyCanvasStrokePadExecutionResult execute_legacy_canvas_stroke_pad_faces(
     const LegacyCanvasStrokePadExecutionRequest& request);
 
+inline void execute_legacy_canvas_stroke_pad_copy_region(
+    const pp::paint_renderer::CanvasStrokeCopyRegion& copy_region,
+    const std::function<void(int, int, int, int, int, int)>& copy_framebuffer_to_texture_2d)
+{
+    copy_framebuffer_to_texture_2d(
+        copy_region.x,
+        copy_region.y,
+        copy_region.x,
+        copy_region.y,
+        copy_region.width,
+        copy_region.height);
+}
+
 struct LegacyCanvasStrokeMixPassPlane {
     int index = 0;
     bool visible = true;

tests/paint_renderer/compositor_tests.cpp

@@ -1934,6 +1934,32 @@ void legacy_canvas_stroke_dual_pass_brush_tip_dispatch_preserves_order(pp::tests
     PP_EXPECT(h, steps == expected);
 }
 
+void legacy_canvas_stroke_pad_copy_region_preserves_coordinates(pp::tests::Harness& h)
+{
+    std::vector<std::string> steps;
+    pp::panopainter::execute_legacy_canvas_stroke_pad_copy_region(
+        pp::paint_renderer::CanvasStrokeCopyRegion {
+            .x = 7,
+            .y = 11,
+            .width = 13,
+            .height = 17,
+        },
+        [&](int src_x, int src_y, int dst_x, int dst_y, int width, int height) {
+            steps.emplace_back(
+                std::to_string(src_x) + "," +
+                std::to_string(src_y) + "," +
+                std::to_string(dst_x) + "," +
+                std::to_string(dst_y) + "," +
+                std::to_string(width) + "," +
+                std::to_string(height));
+        });
+
+    const std::vector<std::string> expected {
+        "7,11,7,11,13,17",
+    };
+    PP_EXPECT(h, steps == expected);
+}
+
 void plans_canvas_stroke_commit_erase_sequence(pp::tests::Harness& h)
 {
     const auto plan = plan_canvas_stroke_commit_sequence(
@@ -3812,6 +3838,9 @@ int main()
     harness.run(
         "legacy_canvas_stroke_dual_pass_brush_tip_dispatch_preserves_order",
         legacy_canvas_stroke_dual_pass_brush_tip_dispatch_preserves_order);
+    harness.run(
+        "legacy_canvas_stroke_pad_copy_region_preserves_coordinates",
+        legacy_canvas_stroke_pad_copy_region_preserves_coordinates);
     harness.run("plans_canvas_stroke_commit_erase_sequence", plans_canvas_stroke_commit_erase_sequence);
     harness.run("plans_canvas_stroke_commit_composite_sequence", plans_canvas_stroke_commit_composite_sequence);
     harness.run(