The standard library. Utilities are ours and generic; vendors are the sanctioned boundary around someone else's code.
- Scheduling primitives — why boot never blocks the main thread.
- Global observers — shared, multiplexed Resize/Intersection observers.
- Limiters — Debouncer, Throttler, Sleep.
- The vendor boundary — how third-party libraries are wrapped.
- Maps: the engine adapter — the reference for a complex swappable subsystem.