Route canvas clear state through GL backend

docs/modernization/roadmap.md

@@ -1121,9 +1121,11 @@ Retained `Canvas` stroke/thumbnail/object/export paths and `NodeCanvas`
 panorama rendering use the same tested active-texture dispatch for their
 texture-unit switches, and their live viewport, scissor, and generic
 depth/blend/scissor capability changes now route through the same backend
-dispatch contracts. `NodeCanvas` saved viewport/clear-color query, density
-target color clear, and clear-color restore paths also use tested
-`pp_renderer_gl` dispatch helpers.
+dispatch contracts. Retained `Canvas` stroke draw/commit, thumbnail
+generation, object drawing, and `LayerFrame::clear` saved viewport/clear-color
+query plus clear-color restore paths also use tested `pp_renderer_gl` dispatch
+helpers. `NodeCanvas` saved viewport/clear-color query, density target color
+clear, and clear-color restore paths use the same helpers.
 Desktop HMD eye rendering now routes eye framebuffer viewport changes through
 the tested `pp_renderer_gl` viewport dispatch while platform VR SDK bridges
 remain isolated for later platform-shell extraction.
@@ -2075,6 +2077,10 @@ Results:
   query, clear-color query, clear-color restore, and color-buffer clear helpers
   in `NodeCanvas` and `NodeStrokePreview`, removing direct query/clear calls
   from those draw bodies while keeping their legacy compositing order.
+- Retained Canvas stroke draw/commit, thumbnail, object-render, and
+  `LayerFrame::clear` paths now use the same tested backend viewport query,
+  clear-color query, and clear-color restore helpers, removing direct
+  viewport/clear-state queries from `src/canvas.cpp` and the frame clear path.
 - Canvas draw-merge shader-blend selection now consumes the extracted
   `pp_paint_renderer` stroke composite planner for current layer and primary
   brush blend modes, while preserving legacy OpenGL compositing execution under