Thin canvas draw seams and own grid worker

docs/modernization/debt.md

@@ -18,6 +18,22 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Reductions
 
+- 2026-06-16: `DEBT-0036` was narrowed again. `NodeCanvas` smoothing-mask
+  overlay draw, smoothing-mask face pass, grid keepalive draw, heightmap draw,
+  and current-mode draw now route through
+  `execute_legacy_canvas_draw_merge_post_draw(...)` in
+  `src/legacy_canvas_draw_merge_services.h` instead of living inline in
+  `NodeCanvas::draw()`; broader canvas draw orchestration and retained GL
+  resource ownership remain.
+- 2026-06-16: `DEBT-0036` was narrowed again. The retained
+  `NodePanelGrid::bake_uvs()` worker now uses scoped `std::jthread` ownership
+  instead of a raw local `std::thread`; retained bake execution, progress-loop
+  polling, and grid rendering ownership remain.
+- 2026-06-16: `DEBT-0017` was narrowed again.
+  `LegacyPlatformServices::prepare_storage_paths()` now routes Apple storage
+  path setup through a local helper instead of reading `App::I` directly in
+  the method body; the retained Apple fallback adapter and broader
+  platform-to-app singleton reach remain.
 - 2026-06-16: `DEBT-0036` was narrowed again. `NodeStrokePreview` background
   preview execution now owns its worker as `std::jthread` with explicit stop,
   unblock, and join semantics instead of a raw `std::thread`; retained queue

docs/modernization/roadmap.md

@@ -102,13 +102,16 @@ Current architecture mismatches that must be treated as real blockers:
   app shell.
 - `pp_panopainter_ui` still depends on `pp_legacy_app`.
 - `Canvas`, `NodeCanvas`, and `NodeStrokePreview` still own too much live
-  OpenGL execution around the renderer boundary.
+  OpenGL execution around the renderer boundary, even though `NodeCanvas`
+  display resolve, cache-to-screen composite, and post-draw mask/grid/current-
+  mode sequencing now route through retained draw-merge helpers.
 - `app_layout.cpp` and `app_dialogs.cpp` are still mixed shell/controller files
   rather than thin composition/binding surfaces.
 - `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
-  ownership.
+  ownership, even though most previously detached or raw app-facing worker
+  launches now use owned `std::jthread` or service-owned worker queues.
 - Modern C++23 usage exists in extracted components, especially `std::span`,
   explicit result/status objects, and a few concepts, but the live app still
   does not consistently express ownership, thread affinity, or renderer

docs/modernization/tasks.md

@@ -132,8 +132,11 @@ Current slice:
   through `legacy_node_stroke_preview_execution_services.h`, but the preview
   node still owns most live-pass and retained GL resource execution.
 - `NodeCanvas` display resolve plus cache-to-screen checkerboard/cache-texture
-  composite now route through `legacy_canvas_draw_merge_services.h`, but
-  broader canvas draw orchestration is still inline.
+  composite now route through `legacy_canvas_draw_merge_services.h`.
+- `NodeCanvas` smoothing-mask overlay, smoothing-mask face pass, grid keepalive
+  draw, heightmap draw, and current-mode draw now also route through
+  `execute_legacy_canvas_draw_merge_post_draw(...)`, but broader canvas draw
+  orchestration is still inline.
 
 Write scope:
 - `src/node_stroke_preview.cpp`
@@ -348,9 +351,9 @@ Mini-model packet:
 Status: In Progress
 
 Why now:
-Canvas imports/exports/saves, cloud transfer, brush import/export, grid
-lightmap work, stroke preview, and event persistence still launch detached
-threads. That is not a safe modernization foundation.
+The biggest app-facing async families have been moved off detached launches,
+but retained worker ownership and ad hoc runtime control are still not a safe
+modernization foundation.
 
 Current slice:
 - app-owned render/UI runtime queues and cloud worker ownership are already
@@ -361,8 +364,9 @@ Current slice:
   workers with explicit UI-thread handoff
 - canvas async import/export/save/open and timelapse export now also use owned
   worker queues instead of detached threads
-- preview background rendering and recording thread ownership now also use
-  `std::jthread`, but their retained loop/control flow is still open
+- preview background rendering, recording, and the retained
+  `NodePanelGrid::bake_uvs()` worker now also use `std::jthread`, but their
+  retained loop/control flow is still open
 
 Write scope:
 - `src/canvas.cpp`
@@ -563,6 +567,9 @@ Current slice:
   `App::set_platform_services()`
 - `platform_apple` clipboard, display/share, cursor, and save-ui-state calls
   now route through injected Apple bridge callbacks instead of `App::I`
+- `LegacyPlatformServices::prepare_storage_paths()` now routes Apple path
+  preparation through a narrow local helper instead of reading `App::I`
+  directly in that method body
 - retained Apple callback injection and broader `platform_legacy` singleton
   reach are still open