shadcn ui : Registry + components.json (Deep)

The shadcn registry is a code-distribution protocol, not a package index. A registry serves JSON descriptions of items (components, blocks, hooks, themes) ; the CLI fetches those descriptions and writes the embedded files into the consumer project. Every project carries a components.json that describes WHERE to write those files and WHICH registries to read from.

This skill covers the SCHEMA and the HOSTING model. The CLI command surface (init, add, view, search, build, migrate) lives in shadcn-core-cli. Do not duplicate command syntax here ; link out.

Quick Reference : Which Registry For Which Need

Q1. Are you installing PUBLIC shadcn components only?
    yes  → default `@shadcn` registry, no `registries` field needed
    no   → Q2