diff --git a/TODO.md b/TODO.md
index e409aa7..e79ef41 100644
--- a/TODO.md
+++ b/TODO.md
@@ -9,3 +9,8 @@
 - [ ] `POST /room` and `generate_room_code` are removed from `backend/src/main.rs`; rooms are only created via `?room=`.
 - [ ] Baseball scoreboard is gone (`frontend/src/scoreboard.ts`, `#scoreboard-baseball`); HUD keeps stones-left chips and running totals only.
 - [ ] README no longer claims a continuous m/s slider, a local friction scalar, or live `jasonlooked`/`pr2-features` branches; e2e `throwFor` no longer sends `friction`.
+
+## Algorithm 2026-09-03
+
+- [ ] Backend `#[cfg(test)]` module in `backend/src/physics.rs` is gone, and test-only `PhysicsWorld::new_open` is gone with it.
+- [ ] Unused Vite leftover `frontend/public/icons.svg` is deleted; nothing in HTML/CSS/TS references it (favicon.svg stays).