Extract brush refresh and thin unmerged NodeCanvas pass

docs/modernization/roadmap.md

@@ -80,13 +80,13 @@ What is still carrying too much live ownership:
 Current hotspot files:
 
 - `src/canvas.cpp`: 2645 lines
-- `src/app_layout.cpp`: 285 lines
+- `src/app_layout.cpp`: 229 lines
 - `src/canvas_modes.cpp`: 1798 lines
 - `src/node.cpp`: 1594 lines
-- `src/main.cpp`: 434 lines
+- `src/main.cpp`: 390 lines
 - `src/node_panel_brush.cpp`: 1197 lines
 - `src/node_stroke_preview.cpp`: 890 lines
-- `src/node_canvas.cpp`: 881 lines
+- `src/node_canvas.cpp`: 831 lines
 - `src/app.cpp`: 502 lines
 - `src/app_dialogs.cpp`: 142 lines
 
@@ -132,7 +132,10 @@ Current architecture mismatches that must be treated as real blockers:
   routes through `execute_node_canvas_draw_merge_tail(...)`, while the
   unmerged-path onion-range planning, plane filtering, per-layer visit
   handling, and per-visit layer-path execution now also route through
-  `execute_legacy_canvas_draw_unmerged_node_canvas_shell(...)`.
+  `execute_legacy_canvas_draw_unmerged_node_canvas_shell(...)`, while the
+  broader unmerged cache/viewport/background/composite pass setup now also
+  routes through
+  `execute_legacy_canvas_draw_unmerged_node_canvas_pass(...)`.
 - `app_layout.cpp` and `app_dialogs.cpp` are still mixed shell/controller files
   rather than thin composition/binding surfaces, even though tools-menu binding
   plus nested panels/options submenu wiring now live in
@@ -150,8 +153,9 @@ Current architecture mismatches that must be treated as real blockers:
   `App::init_menu_edit()` is now a thin call-through, while UI-direction and
   persisted floating/docked panel-state ownership now also live in
   `src/app_layout_ui_state.cpp`, while draw-toolbar binding now also lives in
-  `src/app_layout_draw_toolbar.cpp`, and `src/app_layout.cpp` is now mostly
-  brush-refresh and layout/bootstrap composition, while the
+  `src/app_layout_draw_toolbar.cpp`, while brush-refresh now also lives in
+  `src/app_layout_brush.cpp`, and `src/app_layout.cpp` is now mostly
+  layout/bootstrap composition, while the
   informational overlay opener family now also lives in
   `src/app_dialogs_info_openers.cpp` and the corresponding `App::dialog_*`
   entrypoints are thinner, while the export/video/PPBR dialog family now also
@@ -175,9 +179,9 @@ Current architecture mismatches that must be treated as real blockers:
   retained local state object instead of separate process-wide globals, the
   Win32 async GL/context lock state now lives under
   `src/platform_windows/windows_platform_services.cpp` instead of `main.cpp`
-  retained state, the main-thread queued task state now sits behind a narrow
-  retained helper instead of `RetainedState.main_tasklist` /
-  `main_task_mutex`, the canvas async worker now sits behind a named retained
+  retained state, the main-thread queued task state now lives under
+  `src/platform_windows/windows_platform_services.cpp` instead of staying in
+  `src/main.cpp`, the canvas async worker now sits behind a named retained
   local worker-state helper instead of a bare static accessor, the
   prepared-file worker and the canvas async import/export/save/open worker now
   live under `AppRuntime` instead of retained static app-events/canvas