katgpt-rs: Skill for Claude Code

Rust Optimization

Optimize *.rs files in the target scope using the checklist below. This is a LOOP. You keep optimizing until you cannot find anything to optimize.

Termination

After each turn, end your response with exactly one of:

• Continue optimizing remaining files. — you made code changes this turn
• No optimizations this pass. — you read files but changed nothing

If you only summarized what you read without changing code, say "no optimizations this pass".

Checklist

1. Complexity: O(n) scan → O(1) lookup, merge HashMap lookups, merge loops, boundary-vs-volume (Stokes/divergence theorem: integrate boundary O(n^{(d-1)/d}) instead of interior O(n) for low-dim d≤3 region mass queries — curse-of-dim caps it at d≤3)
2. Allocations: String → &'static str, pre-allocate, eliminate .to_string()
3. Layout: field reorder (u64→u32→u8), #[repr(u8)] enums, remove #[repr(C)]
4. Arithmetic: f32 counters → u32/u64
5. Iterators: fix double chunks_exact(), use index arithmetic
6. Concurrency: Arc<RwLock<HashMap>> → papaya, Mutex<u32> → AtomicU32
7. SIMD: chunked loops, branch-free inner loops
8. Caching: pre-compute lookup tables, compute once not N×M
9. Errors: unwrap() → ?, let _ = → .log_err()
10. Bevy / Real-time loop (see § Bevy / Real-time Loop for details):
    • Event loop spin: WinitSettings::default() (Continuous) pegs CPU at 100% even idle — switch to UpdateMode::reactive_low_power(max_wait) matching tick rate
    • Vsync ≠ event loop: PresentMode::Fifo controls GPU only, independent of CPU loop spin
    • Static geometry: bake to LineList / TriangleList mesh once, NEVER redraw via gizmos.line() per-frame (each call is CPU + per-frame buffer grow)
    • Asset lifecycle: despawning a Bevy Entity does NOT release its Assets<Mesh> / Assets<StandardMaterial> handles — call meshes.remove(handle.0.id()) + materials.remove(...) on despawn or leak indefinitely (regrow-on-new-EntityId patterns leak ~N assets per cycle)
    • GUI repaint storms: bevy_egui sets set_request_repaint_callback that fires bevy_winit::WakeUp on delay.is_zero() — bypasses reactive max_wait and spins the loop. Diagnose via in-process perf overlay before assuming the engine itself is the hog.
    • Frame-rate cap fallback: a Last-schedule std::thread::sleep system capped at e.g. 60 FPS is a belt-and-suspenders defense when vsync + reactive mode somehow don't throttle
11. Perf diagnosis: ship an in-process perf overlay (sysinfo for CPU/RAM + Bevy's Time::delta() for FPS) inside the GUI itself — external ps sampling misses focused-window swings and requires keeping a terminal attached
12. Sorted indexes & scans (see § Sorted Indexes & Scans for details): seek to a prefix (never skip-walk), visitor/borrowing scans (0 alloc), bulk insert via sorted merge, order maintained at mutation not per-read, sort keys computed once, early-exit bounded scans