Extract stroke commit history mutation helpers

docs/modernization/debt.md

@@ -182,6 +182,10 @@ agent or engineer to remove them without reconstructing context from chat.
   routes the remaining service wiring through `make_canvas_stroke_commit_request(...)`;
   the retained path still owns the concrete history mutation and layer dirty
   box updates.
+- 2026-06-13: DEBT-0036 was narrowed again. `Canvas::stroke_commit()` now
+  routes action bookkeeping and dirty-box capture/mutation through helper
+  functions; the retained callback builder now only forwards concrete canvas
+  state.
 - 2026-06-13: DEBT-0036 was narrowed again. `Canvas::stroke_commit()` now
   builds its retained callback table through
   `make_legacy_canvas_stroke_commit_callbacks(...)`; the legacy executor still

docs/modernization/tasks.md

@@ -1839,7 +1839,7 @@ ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_stroke_ex
 
 ### STR-040 - Extract Stroke Commit Local History And Dirty Mutation
 
-Status: Ready
+Status: Done
 Score: +1 renderer boundary and OpenGL parity
 Debt: `DEBT-0036`
 Scope: `src/canvas.cpp`, `tests/paint_renderer/stroke_execution_tests.cpp`
@@ -1850,6 +1850,8 @@ Move the remaining local history and dirty-mutation work inside
 `make_canvas_stroke_commit_callbacks()` into a retained helper so the callback
 builder only forwards concrete canvas state.
 
+Closeout: `aa53a5f9`
+
 Done Checks:
 
 - `make_canvas_stroke_commit_callbacks()` no longer owns the history/dirty

src/canvas.cpp

@@ -606,48 +606,13 @@ static auto make_canvas_stroke_commit_callbacks(
             canvas.apply_canvas_clear_color(cc);
             set_active_texture_unit(0);
         },
-        [&]() {
+        [&]() { stamp_canvas_stroke_commit_action(canvas, action); },
-            action->m_layer_idx = canvas.m_current_layer_idx;
-            action->m_frame_idx = canvas.layer().m_frame_index;
-            action->m_canvas = &canvas;
-            ActionManager::add(action);
-        },
         [&]() {
             canvas.stroke_commit_timelapse();
         },
-        [&](int i) {
+        [&](int i) { capture_canvas_stroke_commit_layer_state(canvas, action, i); },
-            canvas.m_layers[canvas.m_current_layer_idx]->rtt(i).bindFramebuffer();
+        [&](int i) { apply_canvas_stroke_commit_dirty_mutation(canvas, i); },
-        },
+        [&](int i) { copy_canvas_stroke_commit_layer_image(canvas, i); },
-        [&](int i) {
-            glm::vec2 box_sz = zw(canvas.m_dirty_box[i]) - xy(canvas.m_dirty_box[i]);
-            action->m_image[i] = std::make_unique<uint8_t[]>(
-                static_cast<std::size_t>(box_sz.x * box_sz.y * 4));
-            canvas.m_layers[canvas.m_current_layer_idx]->rtt(i).readPixelsRgba8(
-                static_cast<int>(canvas.m_dirty_box[i].x),
-                static_cast<int>(canvas.m_dirty_box[i].y),
-                static_cast<int>(box_sz.x),
-                static_cast<int>(box_sz.y),
-                action->m_image[i].get());
-
-            action->m_box[i] = canvas.m_dirty_box[i];
-            action->m_old_box[i] = canvas.m_layers[canvas.m_current_layer_idx]->box(i);
-            action->m_old_dirty[i] = canvas.m_layers[canvas.m_current_layer_idx]->face(i);
-        },
-        [&](int i) {
-            if (!canvas.m_layers[canvas.m_current_layer_idx]->m_alpha_locked) {
-                auto& lbox = canvas.m_layers[canvas.m_current_layer_idx]->box(i);
-                lbox = glm::vec4(
-                    glm::min(xy(canvas.m_dirty_box[i]), xy(lbox)),
-                    glm::max(zw(canvas.m_dirty_box[i]), zw(lbox)));
-            }
-            canvas.m_layers[canvas.m_current_layer_idx]->face(i) = true;
-        },
-        [&](int i) {
-            set_active_texture_unit(0);
-            canvas.m_tex2[i].bind();
-            copy_framebuffer_to_texture_2d(0, 0, 0, 0, canvas.m_width, canvas.m_height);
-            canvas.m_tex2[i].unbind();
-        },
         [&](int i) {
             bind_commit_inputs(i);
         },
@@ -848,6 +813,61 @@ static auto make_canvas_stroke_commit_request(
     return pp::panopainter::make_legacy_canvas_stroke_commit_request(faces, sequence, commit_callbacks);
 }
 
+static void stamp_canvas_stroke_commit_action(
+    Canvas& canvas,
+    ActionStroke* action)
+{
+    action->m_layer_idx = canvas.m_current_layer_idx;
+    action->m_frame_idx = canvas.layer().m_frame_index;
+    action->m_canvas = &canvas;
+    ActionManager::add(action);
+}
+
+static void capture_canvas_stroke_commit_layer_state(
+    Canvas& canvas,
+    ActionStroke* action,
+    int i)
+{
+    canvas.m_layers[canvas.m_current_layer_idx]->rtt(i).bindFramebuffer();
+
+    glm::vec2 box_sz = zw(canvas.m_dirty_box[i]) - xy(canvas.m_dirty_box[i]);
+    action->m_image[i] = std::make_unique<uint8_t[]>(
+        static_cast<std::size_t>(box_sz.x * box_sz.y * 4));
+    canvas.m_layers[canvas.m_current_layer_idx]->rtt(i).readPixelsRgba8(
+        static_cast<int>(canvas.m_dirty_box[i].x),
+        static_cast<int>(canvas.m_dirty_box[i].y),
+        static_cast<int>(box_sz.x),
+        static_cast<int>(box_sz.y),
+        action->m_image[i].get());
+
+    action->m_box[i] = canvas.m_dirty_box[i];
+    action->m_old_box[i] = canvas.m_layers[canvas.m_current_layer_idx]->box(i);
+    action->m_old_dirty[i] = canvas.m_layers[canvas.m_current_layer_idx]->face(i);
+}
+
+static void apply_canvas_stroke_commit_dirty_mutation(
+    Canvas& canvas,
+    int i)
+{
+    if (!canvas.m_layers[canvas.m_current_layer_idx]->m_alpha_locked) {
+        auto& lbox = canvas.m_layers[canvas.m_current_layer_idx]->box(i);
+        lbox = glm::vec4(
+            glm::min(xy(canvas.m_dirty_box[i]), xy(lbox)),
+            glm::max(zw(canvas.m_dirty_box[i]), zw(lbox)));
+    }
+    canvas.m_layers[canvas.m_current_layer_idx]->face(i) = true;
+}
+
+static void copy_canvas_stroke_commit_layer_image(
+    Canvas& canvas,
+    int i)
+{
+    set_active_texture_unit(0);
+    canvas.m_tex2[i].bind();
+    copy_framebuffer_to_texture_2d(0, 0, 0, 0, canvas.m_width, canvas.m_height);
+    canvas.m_tex2[i].unbind();
+}
+
 std::vector<Canvas::StrokeFrame> Canvas::stroke_draw_compute(Stroke& stroke) const
 {
     auto samples = stroke.compute_samples();