Extract dual brush tip dispatch

docs/modernization/debt.md

@@ -537,6 +537,10 @@ agent or engineer to remove them without reconstructing context from chat.
   sampler dispatch now has regression coverage through
   `make_legacy_canvas_stroke_live_pass_sampler_dispatch(...)`; the live path
   still owns the concrete sampler objects and binding state.
+- 2026-06-13: DEBT-0036 was narrowed again. `Canvas::stroke_draw()` dual-pass
+  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::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

@@ -668,6 +668,12 @@ Validation:
 ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_compositor|pp_paint_renderer_stroke_execution" --output-on-failure
 ```
 
+### Completed Task Log
+
+| Date | Task | Score | Validation | Commit |
+| --- | --- | --- | --- | --- |
+| 2026-06-13 | STR-022 | +1 renderer boundary and OpenGL parity | `ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_compositor|pp_paint_renderer_stroke_execution" --output-on-failure` | `pending` |
+
 Progress Notes:
 
 - 2026-06-13: `NodeStrokePreview::draw_stroke_immediate()` now routes final

src/canvas.cpp

@@ -1121,6 +1121,22 @@ void Canvas::stroke_draw()
                 .slot = 0,
             },
         };
+        const auto dual_pass_brush_tip_dispatch =
+            pp::panopainter::make_legacy_canvas_stroke_brush_tip_texture_dispatch(
+                [&](int texture_slot) {
+                    set_active_texture_unit(texture_slot);
+                },
+                [&](int) {
+                    dual_brush->m_tip_texture ?
+                        dual_brush->m_tip_texture->bind() :
+                        unbind_texture_2d();
+                },
+                [&](int) {
+                    dual_brush->m_tip_texture ?
+                        dual_brush->m_tip_texture->unbind() :
+                        unbind_texture_2d();
+                },
+                0);
         auto frames_dual = stroke_draw_compute(*m_dual_stroke);
         const std::array<bool, 6> include_dual_dirty =
             SIXPLETTE(stroke_material.composite_pass.dual_blend_mode == 0);
@@ -1131,40 +1147,12 @@ void Canvas::stroke_draw()
                     .bind_brush_tip = [&] {
                             pp::panopainter::bind_legacy_canvas_stroke_texture_inputs(
                                 dual_pass_texture_bindings,
-                                pp::panopainter::make_legacy_canvas_stroke_brush_tip_texture_dispatch(
+                                dual_pass_brush_tip_dispatch);
-                                    [&](int texture_slot) {
-                                        set_active_texture_unit(texture_slot);
-                                    },
-                                    [&](int) {
-                                        dual_brush->m_tip_texture ?
-                                            dual_brush->m_tip_texture->bind() :
-                                            unbind_texture_2d();
-                                    },
-                                    [&](int) {
-                                        dual_brush->m_tip_texture ?
-                                            dual_brush->m_tip_texture->unbind() :
-                                            unbind_texture_2d();
-                                    },
-                                    0));
                     },
                     .unbind_brush_tip = [&] {
                         pp::panopainter::unbind_legacy_canvas_stroke_texture_inputs(
                             dual_pass_texture_bindings,
-                            pp::panopainter::make_legacy_canvas_stroke_brush_tip_texture_dispatch(
+                            dual_pass_brush_tip_dispatch);
-                                [&](int texture_slot) {
-                                    set_active_texture_unit(texture_slot);
-                                },
-                                [&](int) {
-                                    dual_brush->m_tip_texture ?
-                                        dual_brush->m_tip_texture->bind() :
-                                        unbind_texture_2d();
-                                },
-                                [&](int) {
-                                    dual_brush->m_tip_texture ?
-                                        dual_brush->m_tip_texture->unbind() :
-                                        unbind_texture_2d();
-                                },
-                                0));
                     },
                     .setup_dual_shader = [&] {
                         pp::panopainter::setup_legacy_stroke_dual_shader(

tests/paint_renderer/compositor_tests.cpp

@@ -1892,6 +1892,48 @@ void legacy_canvas_stroke_live_pass_sampler_dispatch_preserves_order(pp::tests::
     PP_EXPECT(h, steps == expected);
 }
 
+void legacy_canvas_stroke_dual_pass_brush_tip_dispatch_preserves_order(pp::tests::Harness& h)
+{
+    std::vector<std::string> steps;
+    const auto dispatch = pp::panopainter::make_legacy_canvas_stroke_brush_tip_texture_dispatch(
+        [&](int slot) {
+            steps.emplace_back("activate:" + std::to_string(slot));
+        },
+        [&](int) {
+            steps.emplace_back("bind-tip");
+        },
+        [&](int) {
+            steps.emplace_back("unbind-tip");
+        },
+        0);
+
+    pp::panopainter::bind_legacy_canvas_stroke_texture_inputs(
+        std::array {
+            pp::panopainter::LegacyCanvasStrokeTextureBinding {
+                .input = pp::panopainter::LegacyCanvasStrokeTextureInput::brush_tip,
+                .slot = 0,
+            },
+        },
+        dispatch);
+
+    pp::panopainter::unbind_legacy_canvas_stroke_texture_inputs(
+        std::array {
+            pp::panopainter::LegacyCanvasStrokeTextureBinding {
+                .input = pp::panopainter::LegacyCanvasStrokeTextureInput::brush_tip,
+                .slot = 0,
+            },
+        },
+        dispatch);
+
+    const std::vector<std::string> expected {
+        "activate:0",
+        "bind-tip",
+        "activate:0",
+        "unbind-tip",
+    };
+    PP_EXPECT(h, steps == expected);
+}
+
 void plans_canvas_stroke_commit_erase_sequence(pp::tests::Harness& h)
 {
     const auto plan = plan_canvas_stroke_commit_sequence(
@@ -3767,6 +3809,9 @@ int main()
     harness.run(
         "legacy_canvas_stroke_live_pass_sampler_dispatch_preserves_order",
         legacy_canvas_stroke_live_pass_sampler_dispatch_preserves_order);
+    harness.run(
+        "legacy_canvas_stroke_dual_pass_brush_tip_dispatch_preserves_order",
+        legacy_canvas_stroke_dual_pass_brush_tip_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(