Share retained stroke face sample dispatch

docs/modernization/debt.md

@@ -33,6 +33,11 @@ agent or engineer to remove them without reconstructing context from chat.
   final plane draw ordering through `execute_legacy_canvas_stroke_mix_pass(...)`;
   mixer framebuffer/state setup and per-plane shader material/MVP preparation
   remain retained in `Canvas`.
+- 2026-06-13: DEBT-0036 was narrowed again. `Canvas::stroke_draw_samples()`
+  now routes face-indexed destination bind/copy/unbind and brush upload/draw
+  through `execute_legacy_canvas_stroke_face_sample_polygon(...)`; the
+  retained sample executor owns the face-aware dispatch contract while
+  `Canvas` keeps only concrete GL object callbacks.
 - 2026-06-13: DEBT-0036 was narrowed again. `NodeStrokePreview::stroke_draw_mix()`
   now routes mixer framebuffer bind/unbind, viewport/scissor/blend state,
   texture-slot binding, and final plane draw through one local helper;

docs/modernization/roadmap.md

@@ -3133,6 +3133,10 @@ Results:
   retained sampler/texture-slot binding, and final plane draw ordering, while
   mixer framebuffer/state setup and per-plane shader material/MVP preparation
   remain in the legacy Canvas path.
+- `Canvas::stroke_draw_samples()` now shares
+  `execute_legacy_canvas_stroke_face_sample_polygon(...)` for face-indexed
+  destination bind/copy/unbind and brush upload/draw dispatch, while concrete
+  GL object callbacks remain in the legacy Canvas path.
 - `NodeStrokePreview::stroke_draw_mix()` now shares one local helper for mixer
   framebuffer bind/unbind, viewport/scissor/blend state, texture-slot
   binding, and final plane draw, while material planning and shader uniform

docs/modernization/tasks.md

@@ -509,6 +509,13 @@ Done Checks:
 
 Progress Notes:
 
+- 2026-06-13: `Canvas::stroke_draw_samples()` now routes face-indexed
+  destination bind/copy/unbind and brush upload/draw through
+  `execute_legacy_canvas_stroke_face_sample_polygon(...)`; the retained sample
+  executor now owns the face-aware dispatch contract while `Canvas` keeps only
+  the concrete GL object callbacks. Next slice should target any remaining
+  final temporary-texture composite setup without reopening landed sample,
+  mix, sampler, dirty, face, or pad helpers.
 - 2026-06-13: `pp_paint_renderer_stroke_execution_tests` now also covers
   direct retained frame-sample callback ordering plus
   `execute_legacy_canvas_stroke_frame_samples_with_dirty_tracking(...)`