Extend retained stroke preview helper tests

docs/modernization/roadmap.md

@@ -3136,6 +3136,10 @@ Results:
   input binding order, sample execution destination-copy behavior, live-pass
   face-framebuffer dirty tracking, and pad-face destination-copy behavior
   without depending on the broader compositor test translation unit.
+- `pp_paint_renderer_stroke_execution_tests` now also covers retained preview
+  background capture ordering, final composite ordering, and preview
+  texture-copy bind-before-copy behavior through
+  `legacy_canvas_stroke_preview_services.h`.
 - `pp_paint_renderer_stroke_execution_tests` now also covers retained texture
   dispatch activation order and sampler-dispatch routing across brush tip,
   destination, pattern, and mixer helper inputs.

docs/modernization/tasks.md

@@ -509,6 +509,12 @@ Done Checks:
 
 Progress Notes:
 
+- 2026-06-13: `pp_paint_renderer_stroke_execution_tests` now also covers
+  retained preview background capture ordering, final composite ordering, and
+  preview texture-copy bind-before-copy behavior via
+  `legacy_canvas_stroke_preview_services.h`. Next test slice should target the
+  next header-level preview live sample or mix-pass ordering surface without
+  reopening production files.
 - 2026-06-13: `Canvas::stroke_draw_samples()` now routes polygon
   triangulation, sample-point assembly, and the retained destination-copy /
   upload / draw helper handoff through