Own grid workers and thin Apple platform bridge

docs/modernization/debt.md

@@ -18,6 +18,27 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Reductions
 
+- 2026-06-16: `DEBT-0051`/`DEBT-0052`/`DEBT-0055` were narrowed again.
+  `src/platform_apple/apple_platform_services.*` no longer reaches `App::I`
+  for clipboard, display/share, cursor-visibility, or save-ui-state behavior;
+  those calls now flow through narrow injected Apple bridge callbacks from
+  `src/platform_legacy/legacy_platform_services.cpp`, while retained Apple
+  bridge construction and broader platform singleton reach remain.
+- 2026-06-16: `DEBT-0036` was narrowed again. `NodeCanvas` density-resolve
+  display execution now routes through
+  `legacy_canvas_draw_merge_services.h` instead of living inline in
+  `NodeCanvas::draw()`; the cache-to-screen composite block and broader canvas
+  draw orchestration remain retained.
+- 2026-06-16: `DEBT-0053` was narrowed again. `App::pick_file_save(...)` no
+  longer launches a detached worker for background prepared-file writes; it
+  now uses a service-owned `std::jthread` queue and posts prepared-file save
+  completion back to the UI thread, while retained platform save/download
+  handoff execution remains.
+- 2026-06-16: `DEBT-0036` was narrowed again. The retained grid lightmap
+  launch in `src/legacy_grid_ui_services.cpp` no longer uses a detached
+  worker thread; it now uses a service-owned `std::jthread` queue with
+  UI-thread state handoff, while retained bake execution and grid rendering
+  ownership remain.
 - 2026-06-16: `DEBT-0048` was narrowed again. The retained ABR/PPBR import
   bridge in `src/legacy_brush_package_import_services.cpp` no longer launches
   detached worker threads; it now uses a service-owned `std::jthread` queue,