Base UI Migrator

Automated workflow that converts bespoke React UI primitives and other component libraries to Base UI (@base-ui/react).

Base UI is the unstyled successor to Radix UI, maintained by the Material UI team and Radix authors. It exposes the same composition model (Root + parts) but with a single canonical API, modern data attributes for state styling, and built-in transitions. This skill knows the full catalog (37 components, snapshotted) and how to map common bespoke patterns to it.

When to Apply

Use this skill when:

• The user explicitly asks to migrate to Base UI, or to a specific Base UI component.
• You spot a React file with bespoke overlays — manual modals, dropdown menus built from useState + click-outside hooks, floating UI compositions — that have a Base UI equivalent.
• The codebase uses Radix UI, Headless UI, Reach UI, or react-aria components — these are 1:1 mappable to Base UI.
• The user wants to consolidate a fragmented set of UI primitives behind one library.
• The user wants to scan a directory for migration opportunities.

Do NOT trigger when:

• The user is starting a fresh project and asks for a UI library recommendation (suggest they install Base UI directly, no migration needed).
• The user is migrating away from Base UI (out of scope).

Workflow Overview

┌─────────────────────────────────────────────────────────────┐
│ 0. Stale check — is assets/data/llms.txt > 7 days old?      │
│    └─ if yes → scripts/refresh-catalog.sh                   │
├─────────────────────────────────────────────────────────────┤
│ 1. Scan target — scripts/scan-candidates.sh <path>          │
│    Output: JSON {file, line, pattern, suggested_component}  │
├─────────────────────────────────────────────────────────────┤
│ 2. Triage — present candidates to the user, confirm scope   │
│    (write-risk gate: never migrate silently)                │
├─────────────────────────────────────────────────────────────┤
│ 3. Install @base-ui/react if missing                        │
│    └─ Use the project's package manager (autodetected)      │
├─────────────────────────────────────────────────────────────┤
│ 4. Per candidate:                                           │
│    a. Look up references/catalog.md → get component name    │
│    b. Read references/migration-patterns.md (top tier) OR   │
│       fetch-component-doc.sh <component> (cached on disk)   │
│    c. Edit source — replace bespoke with Base UI parts      │
│    d. Preserve existing styling (Tailwind / CSS Modules)    │
├─────────────────────────────────────────────────────────────┤
│ 5. Verify — scripts/verify-migration.sh                     │
│    Runs typecheck + build + flags leftover bespoke patterns │
├─────────────────────────────────────────────────────────────┤
│ 6. Cleanup — uninstall replaced libraries (optional)        │
└─────────────────────────────────────────────────────────────┘

Risk level: Write. The skill edits source files. It never force-pushes, deletes branches, or runs irreversible commands. Always commit (or stash) before starting so git diff shows the migration cleanly.

Tool Requirements

scripts/scan-candidates.sh falls back to grep if rg is missing, but is much slower.

Quick Reference

Scripts

References

Cached Catalog Data

Setup

On first use, the skill reads config.json for project-specific settings. If empty, ask the user:

• project_root — where to scan and apply edits (default: current working directory)
• package_manager — pnpm / npm / yarn / bun (autodetect from lockfile, confirm)
• styling — tailwind / css-modules / styled-components / emotion / vanilla-extract / other (so migrations preserve the project's idiom)
• target_paths — directories to scan (default: src/)

Save responses back to config.json before proceeding.

Triggers Worth Acting On (Even When Phrased Casually)

• "Swap this modal for Base UI" → run scan on one file
• "We're moving off Radix" → run scan on whole repo, expect 1:1 mappings
• "Replace <dialog> with something accessible" → migrate to Dialog
• "Build a popover" (in an existing codebase) → check catalog before scaffolding bespoke

Gotchas

See gotchas.md. Highlights:

• Package was renamed: @base-ui-components/react → @base-ui/react. Old imports still resolve in some snapshots; always migrate to the new name.
• Portals are required for overlays: Dialog, Popover, Menu, Select, Tooltip, AlertDialog all need <Component.Portal> between Root and Backdrop/Positioner/Popup. Forgetting this is the #1 cause of "it renders but doesn't appear."
• State is styled via data attributes: data-[state=open], data-[starting-style], data-[ending-style]. Don't reach for JS-driven enter/exit animations — the data attributes drive CSS transitions.
• Controlled vs uncontrolled: every interactive component has both modes. Match the source code — if the bespoke version used useState for open, port to <Dialog.Root open={...} onOpenChange={...}>.

Related Skills

• react-19-component-scaffolder — generate new Base UI components from templates after migration
• tailwind-refactor — clean up the styling once the structure is on Base UI
• react-optimise — re-check rendering performance after the migration