Isolate legacy stroke composite shader setup

docs/modernization/debt.md

@@ -18,6 +18,12 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Recent Reductions
 
+- 2026-06-12: DEBT-0036 was narrowed again. Canvas live draw-merge and
+  `NodeStrokePreview` final stroke composite `kShader::CompDraw` setup now
+  share `legacy_canvas_stroke_composite_services.h` for retained shader binding
+  and composite/pattern/dual uniform writes. Texture/RTT binding, samplers,
+  draw calls, commit-time compositing, and non-stroke `CompDraw` callers remain
+  retained legacy execution.
 - 2026-06-12: DEBT-0036 was narrowed again. Canvas and `NodeStrokePreview`
   live stroke passes now route retained `kShader::Stroke` binding plus setup,
   blend, pattern, and per-sample uniform writes through

docs/modernization/roadmap.md

@@ -1348,9 +1348,11 @@ destination copy, brush vertex upload, brush-shape draw, and destination unbind
 through `execute_legacy_canvas_stroke_sample`, creating the first retained
 OpenGL stroke execution service seam. Live stroke `kShader::Stroke` binding,
 setup, blend, pattern, and per-sample uniform writes now pass through
-`legacy_canvas_stroke_shader_services.h`, leaving RTT/texture ownership,
-dirty-box policy, composite/pad/checkerboard shaders, and retained callback
-execution under `DEBT-0036`.
+`legacy_canvas_stroke_shader_services.h`. Live draw-merge and preview final
+stroke composite `kShader::CompDraw` setup now pass through
+`legacy_canvas_stroke_composite_services.h`, leaving RTT/texture ownership,
+dirty-box policy, pad/checkerboard/commit composite shaders, and retained
+callback execution under `DEBT-0036`.
 It also owns renderer API texture-format to
 OpenGL internal/pixel/component token mapping, including depth-stencil formats,
 for future backend texture objects. `Texture2D` 2D texture binding, upload,