Extract dual stroke tip dispatch overload

docs/modernization/debt.md

@@ -18,6 +18,10 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Recent Reductions
 
+- 2026-06-13: `LATER-003` was narrowed again. `Canvas::stroke_draw()` now
+  routes dual-brush tip dispatch through retained helper overloads, so the
+  face-index callback wiring is no longer built inline in the dual-pass
+  branch.
 - 2026-06-13: `LATER-003` was narrowed again. `Canvas::stroke_draw()` now
   routes pad destination texture dispatch through retained helper overloads,
   so the face-index callback wiring is no longer built inline in the pad

docs/modernization/tasks.md

@@ -575,6 +575,9 @@ Done Checks:
 
 Progress Notes:
 
+- 2026-06-13: `Canvas::stroke_draw()` now routes dual-brush tip dispatch
+  through retained helper overloads, so the face-index callback wiring is no
+  longer built inline in the dual-pass branch.
 - 2026-06-13: `Canvas::stroke_draw()` now routes pad destination texture
   dispatch through retained helper overloads, so the face-index callback
   wiring is no longer built inline in the pad branch.

src/canvas.cpp

@@ -946,16 +946,17 @@ void Canvas::stroke_draw()
                                 [&](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(
@@ -964,16 +965,17 @@ void Canvas::stroke_draw()
                                 [&](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(

src/legacy_canvas_stroke_execution_services.h

@@ -116,6 +116,22 @@ struct LegacyCanvasStrokeTextureInputDispatch {
     };
 }
 
+[[nodiscard]] inline LegacyCanvasStrokeTextureInputDispatch make_legacy_canvas_stroke_brush_tip_texture_dispatch(
+    std::function<void(int)> activate_texture_unit,
+    std::function<void(int)> bind_brush_tip,
+    std::function<void(int)> unbind_brush_tip,
+    int face_index)
+{
+    return make_legacy_canvas_stroke_brush_tip_texture_dispatch(
+        std::move(activate_texture_unit),
+        [bind_brush_tip = std::move(bind_brush_tip), face_index]() {
+            bind_brush_tip(face_index);
+        },
+        [unbind_brush_tip = std::move(unbind_brush_tip), face_index]() {
+            unbind_brush_tip(face_index);
+        });
+}
+
 [[nodiscard]] inline LegacyCanvasStrokeTextureInputDispatch make_legacy_canvas_stroke_destination_texture_dispatch(
     std::function<void(int)> activate_texture_unit,
     std::function<void()> bind_stroke_destination,

tests/paint_renderer/stroke_execution_tests.cpp

@@ -309,6 +309,27 @@ void retained_stroke_brush_tip_texture_dispatch_helper_builds_expected_callback_
     PP_EXPECT(h, events == expected_events);
 }
 
+void retained_stroke_brush_tip_texture_dispatch_helper_builds_expected_face_wiring(pp::tests::Harness& h)
+{
+    std::vector<std::string> events;
+    const auto dispatch = pp::panopainter::make_legacy_canvas_stroke_brush_tip_texture_dispatch(
+        [&](int slot) { events.emplace_back("activate:" + std::to_string(slot)); },
+        [&](int face_index) { events.emplace_back("bind:" + std::to_string(face_index)); },
+        [&](int face_index) { events.emplace_back("unbind:" + std::to_string(face_index)); },
+        2);
+
+    dispatch.activate_texture_unit(0);
+    dispatch.bind_brush_tip();
+    dispatch.unbind_brush_tip();
+
+    const std::vector<std::string> expected_events {
+        "activate:0",
+        "bind:2",
+        "unbind:2",
+    };
+    PP_EXPECT(h, events == expected_events);
+}
+
 void retained_stroke_live_pass_sampler_dispatch_helper_builds_expected_callback_wiring(pp::tests::Harness& h)
 {
     std::vector<std::string> events;
@@ -1818,6 +1839,9 @@ int main()
     harness.run(
         "retained_stroke_brush_tip_texture_dispatch_helper_builds_expected_callback_wiring",
         retained_stroke_brush_tip_texture_dispatch_helper_builds_expected_callback_wiring);
+    harness.run(
+        "retained_stroke_brush_tip_texture_dispatch_helper_builds_expected_face_wiring",
+        retained_stroke_brush_tip_texture_dispatch_helper_builds_expected_face_wiring);
     harness.run(
         "retained_stroke_destination_texture_dispatch_helper_builds_expected_callback_wiring",
         retained_stroke_destination_texture_dispatch_helper_builds_expected_callback_wiring);