Plan canvas stroke feedback copies

docs/modernization/roadmap.md

@@ -888,6 +888,12 @@ The OpenGL shader initialization path now stores a renderer-neutral
 `RenderDeviceFeatures` snapshot converted by `pp_renderer_gl`, and those live
 canvas gates consume that snapshot instead of rebuilding feature flags from
 individual `ShaderManager` extension booleans.
+`pp_paint_renderer::plan_canvas_stroke_feedback` now models the current stroke
+shader's required destination feedback without changing the legacy shader math.
+Live `Canvas::stroke_draw` consumes that plan for main-brush, dual-brush, and
+stroke-pad destination-copy versus framebuffer-fetch decisions; thumbnail layer
+blending is the remaining direct canvas feedback branch before a fuller live
+paint-renderer execution boundary can take over.
 The existing renderer classes are not yet fully
 behind the renderer interfaces.
 
@@ -1623,6 +1629,10 @@ Results:
   shared canvas blend-gate plan to decide whether they can read destination
   color through framebuffer fetch or must copy the destination texture before
   the legacy OpenGL blend draw.
+- Canvas main-brush, dual-brush, and stroke-pad draw paths now use the tested
+  `pp_paint_renderer` stroke-feedback plan to decide whether framebuffer fetch
+  supplies destination color or the legacy OpenGL path must copy the target
+  texture before drawing.
 - Canvas equirectangular import drawing and depth export rendering now route
   depth/blend state and active texture units through the renderer GL backend
   mapping.