# Extension points — shadcn-ui/ui

> Canonical page: https://codevetter.com/unpack/ui/extension-points

# Extension points — shadcn-ui/ui

Scanned commit 98a1fe67b439324ddc857f47fbdce056600a4329 (2026-09-21). Generated by codevetter codevetter 1.12.0 on 2026-09-22.

Primary plug-in surfaces: the templates registry + createTemplate factory for new frameworks; the ordered transformer array for content rewrites; the updaters pipeline for new install concerns; registry item types + FILE_TYPE_TO_CONFIG_KEY for new artifact kinds; the components.json registries map for third-party registries; migrations registry for codemods; commander command table and MCP tools array for new CLI/MCP surface; presets and the /init URL contract for create flows; directory.json + validation for the public registry index.
- New framework templates: add a templates/<name>-app (+ -monorepo) dir and a createTemplate entry in src/templates (fields: scaffold/create/init/postInit/files/monorepo overrides, frameworks list for getTemplateForFramework inference). — [packages/shadcn/src/templates/index.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/templates/index.ts) [packages/shadcn/src/templates/create-template.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/templates/create-template.ts)
- Content transforms: add a Transformer module under utils/transformers and append it to the ordered transform() array in update-files.ts (position matters — e.g. transformCleanup runs last, transformNext is conditional). — [packages/shadcn/src/utils/updaters/update-files.ts#L164-198](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/utils/updaters/update-files.ts#L164-L198) [packages/shadcn/src/utils/transformers/index.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/utils/transformers/index.ts)
- Install concerns plug in as updaters under utils/updaters invoked from addProjectComponents/addWorkspaceComponents in a fixed order (deps → tailwind config → env vars → fonts → files → css). — [packages/shadcn/src/utils/add-components.ts#L104-147](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/utils/add-components.ts#L104-L147)
- New registry item types require extending registryItemTypeSchema/registryItemSchema (discriminated union on type) plus the FILE_TYPE_TO_CONFIG_KEY map that routes files to workspace targets, with parity on the site schema. — [packages/shadcn/src/registry/schema.ts#L81-193](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/registry/schema.ts#L81-L193) [packages/shadcn/src/utils/add-components.ts#L227-246](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/utils/add-components.ts#L227-L246)
- Third-party registries: users add entries to components.json `registries` with {name}/{style}/${ENV} templated URLs (+ optional headers/params); `shadcn registry add` writes them and ensureRegistriesInConfig auto-discovers @namespaces from item addresses and the registries index. — [packages/shadcn/src/registry/schema.ts#L6-26](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/registry/schema.ts#L6-L26) [packages/shadcn/src/registry/builder.ts#L22-56](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/registry/builder.ts#L22-L56) [packages/shadcn/src/commands/registry/add.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/commands/registry/add.ts) [packages/shadcn/src/utils/registries.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/utils/registries.ts)
- New CLI command: create a commander Command module under src/commands and addCommand it in index.ts; subcommand groups follow the commands/registry pattern (parent Command + .command children). — [packages/shadcn/src/index.ts#L33-47](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/index.ts#L33-L47) [packages/shadcn/src/commands/registry/index.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/commands/registry/index.ts)
- New codemods: add a module under src/migrations and register it in commands/migrate.ts (existing: migrate-radix, migrate-icons, migrate-base-color, migrate-rtl, migrate-cn). — [packages/shadcn/src/commands/migrate.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/commands/migrate.ts) [packages/shadcn/src/migrations/migrate-radix.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/migrations/migrate-radix.ts)
- New MCP tool: append to the tools[] literal in the ListToolsRequestSchema handler and add a case in handleCallTool (zod-parse args, return {content:[{type:'text',text}]}; RegistryError gets formatted with code/suggestion/context). — [packages/shadcn/src/mcp/index.ts#L55-187](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/mcp/index.ts#L55-L187) [packages/shadcn/src/mcp/index.ts#L545-598](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/mcp/index.ts#L545-L598)
- Presets: DEFAULT_PRESETS in src/preset + encode/decode preset codes (isPresetCode/decodePreset) resolve to site /init URLs; the site's parseDesignSystemConfig + buildRegistryBase define the server half of the contract. — [packages/shadcn/src/preset/presets.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/preset/presets.ts) [packages/shadcn/src/preset/preset.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/preset/preset.ts) [apps/v4/app/(app)/(create)/lib/parse-config.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/apps/v4/app/(app)/(create)/lib/parse-config.ts) [apps/v4/registry/config.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/apps/v4/registry/config.ts)
- Public registry directory: community registries are listed in apps/v4/registry/directory.json, validated by scripts/validate-registries.mts, and gated by the validate-registries workflow (reserved-namespace blocklist). — [apps/v4/registry/directory.json](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/apps/v4/registry/directory.json) [apps/v4/scripts/validate-registries.mts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/apps/v4/scripts/validate-registries.mts) [.github/workflows/validate-registries.yml](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/.github/workflows/validate-registries.yml)
- Icon libraries are pluggable via src/icons (exported as shadcn/icons) + transform-icons + the iconLibrary config field; styles/themes/fonts/base-colors are data registries under apps/v4/registry consumed by both site and build. — [packages/shadcn/src/icons/index.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/icons/index.ts) [packages/shadcn/src/utils/transformers/transform-icons.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/packages/shadcn/src/utils/transformers/transform-icons.ts) [apps/v4/registry/themes.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/apps/v4/registry/themes.ts) [apps/v4/registry/fonts.ts](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/apps/v4/registry/fonts.ts)
- Agent-facing extension: skills/*/SKILL.md bundles (with rules/ and evals/) encode usage rules for AI tools — adding a skill is a docs-only change, separate from CLI code. — [skills/shadcn/SKILL.md](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/skills/shadcn/SKILL.md) [skills/migrate-radix-to-base/SKILL.md](https://github.com/shadcn-ui/ui/blob/98a1fe67b439324ddc857f47fbdce056600a4329/skills/migrate-radix-to-base/SKILL.md)

Every claim links to its cited files at the pinned commit. Citations identify source evidence; they do not establish runtime correctness. Independent CodeVetter scan — not reviewed by upstream maintainers.

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