four

Umbrella package and application composition root. Part of fourJS.

Implements §45 and §98 of docs/SPECIFICATION.md. import * as Four from "fourJS" exposes every workspace package as a namespace (Four.scene, Four.physics, Four.animation, …).

What's here

• Application — the §45 composition root and the only API this package owns rather than re-exports: it wires the §10 fixed-step scheduler, the §39 system registry, world-transform resolution, and the fixedUpdate / update / render events (ApplicationEventMap), with an optional injected renderer.
• createPickProvider — RFC 0005's four-line adapter: a @fourjs/render PickingService presented as @fourjs/input's PickProvider. Import from "fourJS" (the umbrella root), not fourJS/input. Never referenced by Application; tree-shakes when unused. Pair with registerPickingPipeline() from @fourjs/render-webgl or @fourjs/render-webgpu.
• Namespace re-exports — one namespace per package (core, math, scene, geometry, materials, assets, motion, input, serialization, diagnostics, particles, text, render, animation, physics, the render backends, ui, and the physics solver packages).
• A renderer-free headless composition path via the four/application subpath.

Notes and deviations

• ApplicationOptions.renderer takes a Renderer instance, not §45's string union — string/"auto" backend selection is deferred to a §62 registry so this package never imports backends at runtime (recorded spec §45 departure).

Unit tests are colocated in tests/ per §92.

Workspace name four; publishes as @danielsimonjr/fourjs.