Share retained renderbuffer dispatch bridge

docs/modernization/roadmap.md

@@ -1152,7 +1152,8 @@ status used by `RTT::create`/`RTT::destroy` and framebuffer bind/restore paths,
 also live in `pp_renderer_gl`. Depth renderbuffer allocation/storage/delete and
 framebuffer depth attach/detach sequences used by retained `RTT` and canvas
 object-drawing helpers now execute through tested `pp_renderer_gl` dispatch
-contracts. 2D framebuffer-to-texture
+contracts and share the retained `legacy_gl_renderbuffer_dispatch` raw callback
+bridge. 2D framebuffer-to-texture
 copies used by canvas, transform, layer-conversion, panorama UI, brush preview,
 and CanvasLayer cube-face generation paths now route through a tested
 `pp_renderer_gl` copy dispatch via the retained target-aware framebuffer-copy
@@ -1271,8 +1272,9 @@ query plus clear-color restore paths also use tested `pp_renderer_gl` dispatch
 helpers. The retained `Canvas` active-texture, fallback texture unbind,
 viewport/scissor execution, viewport and clear-color query, clear-color
 restore, and capability query/apply adapter endpoints now share
-`legacy_ui_gl_dispatch`; Canvas depth renderbuffer allocation/attachment/delete
-remains a separate retained renderer-resource bridge under DEBT-0036.
+`legacy_ui_gl_dispatch`; Canvas and RTT depth renderbuffer
+allocation/attachment/delete now share `legacy_gl_renderbuffer_dispatch` while
+resource lifetime ownership remains retained under DEBT-0036.
 `NodeCanvas` saved viewport/clear-color query, density target color clear, and
 clear-color restore paths use the same helpers. `NodeCanvas` and
 `NodeStrokePreview` now share that retained UI GL dispatch bridge for
@@ -2539,9 +2541,12 @@ Results:
   viewport/clear-state queries from `src/canvas.cpp` and the frame clear path.
   Their active-texture selection, fallback 2D texture unbind, viewport/scissor
   execution, clear-color restore, and capability query/apply adapter endpoints
-  now share `legacy_ui_gl_dispatch`; retained Canvas depth renderbuffer
-  allocation/attachment/delete remains open as a renderer-resource bridge under
-  DEBT-0036.
+  now share `legacy_ui_gl_dispatch`.
+- Retained Canvas and RTT depth renderbuffer allocation, framebuffer depth
+  attachment, and renderbuffer deletion now share
+  `legacy_gl_renderbuffer_dispatch`, removing duplicated raw renderbuffer
+  callbacks from `src/canvas.cpp` and `src/rtt.cpp` while resource lifetime
+  ownership remains open under DEBT-0036.
 - 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
@@ -2571,7 +2576,7 @@ Results:
   viewport/clear/blend state, active texture units, readback format/type,
   framebuffer copy targets, and depth renderbuffer allocation plus framebuffer
   depth attach/detach through tested renderer GL backend dispatch contracts;
-  `src/canvas.cpp` no longer contains raw `GL_*` constants.
+  `src/canvas.cpp` no longer owns raw renderbuffer callbacks.
 - Retained Canvas, NodeCanvas, NodeStrokePreview, and HMD viewport/scissor/
   capability execution now compiles through the renderer GL backend dispatch
   adapters with `pp_legacy_paint_document`, `pp_panopainter_ui`, and