Trim recording loop and retain async worker state

docs/modernization/debt.md

@@ -18,6 +18,17 @@ agent or engineer to remove them without reconstructing context from chat.
 
 ## Reductions
 
+- 2026-06-16: `DEBT-0037` was narrowed again. `App::rec_loop()` in
+  `src/app.cpp` now routes its coherent frame encode/update chunk through a
+  local helper instead of carrying dirty-stroke clearing, equirect PBO
+  creation, the worker-side `yield`, `ImageRef` creation, encode, and frame
+  label refresh inline; retained recording loop control, readback call sites,
+  and MP4 execution remain.
+- 2026-06-16: `DEBT-0003` was narrowed again. The prepared-file worker in
+  `src/app_events.cpp` and the canvas async worker in `src/canvas.cpp` now sit
+  behind named retained local worker-state helpers instead of bare static
+  worker accessors; retained app/canvas singleton reach and broader runtime
+  ownership remain.
 - 2026-06-16: `DEBT-0003` was narrowed again. `src/main.cpp` now keeps Win32
   window handles, GL/task mutex state, stylus timers, splash-dialog state, and
   VR worker state behind one retained local state object instead of separate