Promote stroke commit sequence invocation task

docs/modernization/tasks.md

@@ -1257,6 +1257,33 @@ ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_stroke_ex
   assembly through `make_legacy_canvas_stroke_commit_request(...)`, so the
   callsite only supplies concrete faces, sequence, and callbacks.
 
+### STR-015 - Extract Stroke Commit Sequence Invocation
+
+Status: Ready
+Score: +1 renderer boundary and OpenGL parity
+Debt: `DEBT-0036`
+Scope: `src/canvas.cpp`, `tests/paint_renderer/compositor_tests.cpp`
+
+Goal:
+
+Move the remaining `execute_legacy_canvas_stroke_commit_sequence(...)`
+invocation shape out of `Canvas::stroke_commit()` so the callsite only passes
+already-built retained commit state.
+
+Done Checks:
+
+- `Canvas::stroke_commit()` no longer spells the retained commit request
+  invocation inline.
+- Regression coverage proves the helper preserves the retained request shape.
+- `docs/modernization/debt.md` records the reduced stroke-commit invocation
+  surface.
+
+Validation:
+
+```powershell
+ctest --preset desktop-fast --build-config Debug -R "pp_paint_renderer_stroke_execution|pp_paint_renderer_compositor" --output-on-failure
+```
+
 ### STR-011 - Extract Preview Main Pass Orchestration
 
 Status: Done