@tryonit/core: Zero-Dependency Core of the TryOnIt SDK

@tryonit/core is the foundation of TryOnIt, the open-source SDK I built so shoppers can see makeup, glasses, jewellery, watches, hair colour and clothing on themselves through their camera. The core holds everything that does not depend on a browser, so the web, React and React Native packages share one implementation of the rules instead of three.

It is pure TypeScript with zero runtime dependencies and no DOM. It compiles without DOM types, takes an injectable fetch, never touches window, document or navigator, and a test imports the entire public API in a Node environment without DOM globals. That discipline is what let the React Native package reuse it unchanged.

Inside are a small schema builder that validates product manifests for 15 asset types with readable, path-based errors and ships a JSON Schema kept in sync by a unit test; an immutable store with a finite state machine for the camera session; the anchor math that turns MediaPipe landmarks into poses for the nose bridge, ear lobes, wrist and fingers, with iris-based metric scale; One Euro smoothing filters; and a homography warp for clothing. It also ships tryonit-validate, a CLI that checks manifests and their GLB and PNG files in CI. A typical import is about 5.9 KB min+gzip.