Extract pad destination dispatch helper

docs/modernization/debt.md

@@ -547,6 +547,10 @@ agent or engineer to remove them without reconstructing context from chat.
 - 2026-06-13: DEBT-0036 was narrowed again. `Canvas::stroke_draw()` dual-pass
   shader setup now uses a retained wrapper helper; the dual-pass branch still
   owns the concrete shader selection and framebuffer wiring.
+- 2026-06-13: DEBT-0036 was narrowed again. `Canvas::stroke_draw()` pad
+  destination dispatch now reuses a retained helper object, with regression
+  coverage proving the helper order; the pad branch still owns the concrete
+  texture-object wiring and copy timing.
 - 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

@@ -791,7 +791,7 @@ ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_composito
 
 ### STR-027 - Extract Stroke Draw Pad Destination Dispatch
 
-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`
@@ -817,6 +817,12 @@ 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-027 | +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` |
+
 ### STR-028 - Extract Stroke Draw Pad Face Orchestration
 
 Status: Ready

src/canvas.cpp

@@ -1052,6 +1052,18 @@ void Canvas::stroke_draw()
             .slot = 1,
         },
             };
+    const auto pad_destination_texture_dispatch =
+        pp::panopainter::make_legacy_canvas_stroke_pad_destination_texture_dispatch(
+            [&](int texture_slot) {
+                set_active_texture_unit(texture_slot);
+            },
+            [&](int dst_face_index) {
+                m_tex[dst_face_index].bind();
+            },
+            [&](int dst_face_index) {
+                m_tex[dst_face_index].unbind();
+            },
+            0);
     [[maybe_unused]] const auto pad_result = pp::panopainter::execute_legacy_canvas_stroke_pad_face_callbacks(
         pad_faces,
         stroke_extent,
@@ -1067,17 +1079,7 @@ void Canvas::stroke_draw()
         [&](int face_index) {
             pp::panopainter::bind_legacy_canvas_stroke_texture_inputs(
                 pad_destination_texture_binding,
-                pp::panopainter::make_legacy_canvas_stroke_pad_destination_texture_dispatch(
+                pad_destination_texture_dispatch);
-                    [&](int texture_slot) {
-                        set_active_texture_unit(texture_slot);
-                    },
-                    [&](int dst_face_index) {
-                        m_tex[dst_face_index].bind();
-                    },
-                    [&](int dst_face_index) {
-                        m_tex[dst_face_index].unbind();
-                    },
-                    face_index));
         },
         [&](const pp::paint_renderer::CanvasStrokeCopyRegion& copy_region) {
             pp::panopainter::execute_legacy_canvas_stroke_pad_copy_region(
@@ -1087,17 +1089,7 @@ void Canvas::stroke_draw()
         [&](int face_index) {
             pp::panopainter::unbind_legacy_canvas_stroke_texture_inputs(
                 pad_destination_texture_binding,
-                pp::panopainter::make_legacy_canvas_stroke_pad_destination_texture_dispatch(
+                pad_destination_texture_dispatch);
-                    [&](int texture_slot) {
-                        set_active_texture_unit(texture_slot);
-                    },
-                    [&](int dst_face_index) {
-                        m_tex[dst_face_index].bind();
-                    },
-                    [&](int dst_face_index) {
-                        m_tex[dst_face_index].unbind();
-                    },
-                    face_index));
         },
         [&] {
             m_brush_shape.draw_fill();

tests/paint_renderer/compositor_tests.cpp

@@ -1968,6 +1968,47 @@ void legacy_canvas_stroke_dual_shader_wrapper_preserves_setup(pp::tests::Harness
     PP_EXPECT(h, steps.size() == 1U);
 }
 
+void legacy_canvas_stroke_pad_destination_dispatch_preserves_order(pp::tests::Harness& h)
+{
+    std::vector<std::string> steps;
+    const auto dispatch = pp::panopainter::make_legacy_canvas_stroke_pad_destination_texture_dispatch(
+        [&](int slot) {
+            steps.emplace_back("activate:" + std::to_string(slot));
+        },
+        [&](int face_index) {
+            steps.emplace_back("bind:" + std::to_string(face_index));
+        },
+        [&](int face_index) {
+            steps.emplace_back("unbind:" + std::to_string(face_index));
+        },
+        4);
+
+    pp::panopainter::bind_legacy_canvas_stroke_texture_inputs(
+        std::array {
+            pp::panopainter::LegacyCanvasStrokeTextureBinding {
+                .input = pp::panopainter::LegacyCanvasStrokeTextureInput::stroke_destination,
+                .slot = 1,
+            },
+        },
+        dispatch);
+    pp::panopainter::unbind_legacy_canvas_stroke_texture_inputs(
+        std::array {
+            pp::panopainter::LegacyCanvasStrokeTextureBinding {
+                .input = pp::panopainter::LegacyCanvasStrokeTextureInput::stroke_destination,
+                .slot = 1,
+            },
+        },
+        dispatch);
+
+    const std::vector<std::string> expected {
+        "activate:1",
+        "bind:4",
+        "activate:1",
+        "unbind:4",
+    };
+    PP_EXPECT(h, steps == expected);
+}
+
 void plans_canvas_stroke_commit_erase_sequence(pp::tests::Harness& h)
 {
     const auto plan = plan_canvas_stroke_commit_sequence(
@@ -3849,6 +3890,9 @@ int main()
     harness.run(
         "legacy_canvas_stroke_pad_copy_region_preserves_coordinates",
         legacy_canvas_stroke_pad_copy_region_preserves_coordinates);
+    harness.run(
+        "legacy_canvas_stroke_pad_destination_dispatch_preserves_order",
+        legacy_canvas_stroke_pad_destination_dispatch_preserves_order);
     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(