Route retained readbacks through GL backend

docs/modernization/roadmap.md

@@ -1105,7 +1105,10 @@ formats to `pp_renderer_gl`, and its CPU lightmap row dispatch now uses the
 shared legacy `parallel_for` helper rather than platform-specific worker APIs.
 Its live heightmap draw and bake paths now execute depth/blend state changes,
 depth clears, color-write-mask toggles, active texture selection, and bake
-viewport changes through tested `pp_renderer_gl` dispatch adapters.
+viewport changes through tested `pp_renderer_gl` dispatch adapters. Its desktop
+texture-resize path now reuses `Texture2D::get_image()`, so grid texture
+readback also goes through the tested framebuffer-backed texture readback
+dispatch instead of direct `glGetTexImage`.
 Legacy `util.cpp` OpenGL error naming and `gl_state` save/restore now delegate
 error codes, state queries, framebuffer targets, texture binding targets, and
 active texture units to `pp_renderer_gl`.
@@ -2029,8 +2032,9 @@ Results:
   blend/depth state execution, active texture unit switches, transform/cut
   viewport execution, 2D framebuffer-to-texture copy dispatch, RGBA8 readback
   formats, and RTT-backed transform history region readbacks through the
-  renderer GL backend mapping. The retained canvas-tip pick readback remains
-  direct legacy OpenGL until the readback boundary is finished under DEBT-0036.
+  renderer GL backend mapping. Canvas-tip pick readback now routes through the
+  tested framebuffer readback dispatch using the active read framebuffer, with
+  only a local OpenGL adapter endpoint retained in `src/canvas_modes.cpp`.
 - `NodeCanvas` panorama UI rendering now routes sampler defaults, saved
   viewport/clear/blend/depth/scissor state, tested viewport and clear-color
   query dispatch, color clears, clear-color restore, active texture units,
@@ -2066,7 +2070,9 @@ Results:
 - `NodePanelGrid` live heightmap drawing and bake setup now route depth/blend
   state, depth clears, color-write-mask toggles, active texture selection, and
   bake viewport execution through tested renderer GL backend dispatch
-  contracts.
+  contracts. Its desktop texture-resize readback now uses the retained
+  `Texture2D::get_image()` helper, so it consumes the same tested
+  framebuffer-backed texture readback dispatch instead of `glGetTexImage`.
 - Retained simple UI draw paths now share `legacy_ui_gl_dispatch` for
   blend-state execution, fallback 2D texture unbinds, `NodeViewport` viewport
   query/restore, color-buffer clear, and clear-color restore. This covers