Extract app frame and export dialog helpers

docs/modernization/roadmap.md

@@ -86,9 +86,9 @@ Current hotspot files:
 - `src/main.cpp`: 1117 lines
 - `src/node_panel_brush.cpp`: 1197 lines
 - `src/node_stroke_preview.cpp`: 933 lines
-- `src/node_canvas.cpp`: 953 lines
-- `src/app.cpp`: 950 lines
-- `src/app_dialogs.cpp`: 789 lines
+- `src/node_canvas.cpp`: 897 lines
+- `src/app.cpp`: 502 lines
+- `src/app_dialogs.cpp`: 441 lines
 
 Current architecture mismatches that must be treated as real blockers:
 
@@ -139,7 +139,10 @@ Current architecture mismatches that must be treated as real blockers:
   `src/app_layout_about_layer_menu.cpp` and `App::init_menu_about()` plus
   `App::init_menu_layer()` are now thin call-throughs, while the informational
   overlay opener family now also lives in `src/app_dialogs_info_openers.cpp`
-  and the corresponding `App::dialog_*` entrypoints are thinner.
+  and the corresponding `App::dialog_*` entrypoints are thinner, while the
+  export/video/PPBR dialog family now also lives in
+  `src/app_dialogs_export.cpp` and those `App::dialog_*` entrypoints are
+  thinner too.
 - `App`, `Canvas`, `Node`, retained workers, and platform entrypoints still use
   global singleton reach, raw observer pointers, retained static worker
   ownership in several app families, and ad hoc mutex/condition-variable
@@ -172,7 +175,12 @@ Current architecture mismatches that must be treated as real blockers:
   while `App::rec_loop()` now delegates worker-iteration orchestration into
   the retained recording bridge, `App::update_rec_frames()` now delegates
   recording label refresh through that same retained recording path, and the
-  canvas state-management cluster for picking, clear/clear-all, layer
+  UI observer math, repeated UI child traversal, and canvas toolbar refresh
+  now live in `src/legacy_app_frame_services.cpp` instead of staying inline in
+  `src/app.cpp`, while the larger document/export/save/open/thumbnail
+  document-IO cluster now lives in `src/legacy_canvas_document_io_services.cpp`
+  and `src/app.cpp` is materially thinner,
+  while the canvas state-management cluster for picking, clear/clear-all, layer
   add/remove/order/lookups, animation frame control, resize, and snapshot
   save/restore now lives in `src/legacy_canvas_state_services.cpp` instead of
   `src/canvas.cpp`, while the larger import/export/save/open/thumbnail

docs/modernization/tasks.md

@@ -199,7 +199,12 @@ Current slice:
 - `NodeCanvas` non-`draw_merged` per-layer temporary erase/paint, layer-texture,
   and blend setup now also route through
   `make_legacy_canvas_draw_merge_layer_path_gl_execution(...)`, but the node
-  still owns the remaining draw lambdas and broader renderer-state shell.
+  still owned the remaining draw lambdas and broader renderer-state shell.
+- `NodeCanvas` now routes that remaining non-`draw_merged` per-layer blend,
+  composite, debug-outline, and frame callback assembly through the local
+  `make_node_canvas_layer_path_execution(...)` helper, which materially thins
+  `NodeCanvas::draw()` even though the broader draw loop still lives in
+  `src/node_canvas.cpp`.
 
 Write scope:
 - `src/node_stroke_preview.cpp`
@@ -322,7 +327,7 @@ Mini-model packet:
 
 #### ARC-APP-002 - Split `app_dialogs.cpp` Into Workflow Adapters And Widget Openers
 
-Status: Ready
+Status: In Progress
 
 Why now:
 `src/app_dialogs.cpp` still mixes document workflow decisions, export routing,
@@ -334,6 +339,10 @@ Current slice:
   and the corresponding `App::dialog_*` entrypoints are now thin call-throughs,
   but document/export workflow and retained dialog execution are still inline in
   `src/app_dialogs.cpp`.
+- Export, video-export, and PPBR export entrypoints now also live in
+  `src/app_dialogs_export.cpp`, and the corresponding `App::dialog_*`
+  entrypoints are now thin call-throughs, but new/open/save/browse/resize and
+  retained dialog execution are still inline in `src/app_dialogs.cpp`.
 
 Write scope:
 - `src/app_dialogs.cpp`
@@ -364,11 +373,19 @@ Mini-model packet:
 
 #### ARC-APP-003 - Reduce `app.cpp` To Frame, Queue, And Composition Shell
 
-Status: Ready
+Status: In Progress
 
 Why now:
 `src/app.cpp` still carries startup, frame flow, queue draining, recording,
-observer math, and composition logic in one 950-line file.
+and composition logic in one 502-line file.
+
+Current slice:
+- UI observer math now routes through `src/legacy_app_frame_services.cpp`
+  instead of staying inline in `src/app.cpp`.
+- The repeated UI child traversal in `App::draw()` now routes through the same
+  retained helper.
+- Canvas toolbar refresh in `App::update()` now also routes through that helper
+  file, materially shrinking `src/app.cpp`.
 
 Write scope:
 - `src/app.cpp`