Shadcn Tailwind V4 Primitives

shadcn/ui + Radix Primitives on Tailwind v4

Overview

This skill scaffolds a real, accessible component layer — shadcn/ui-style wrappers over Radix primitives — that looks like it was written by the team, not pasted from the docs. The output is a set of new files under components/ui/ (select, combobox, switch, tooltip, drawer, form, …) that every route can adopt in place of native <select>s, title= tooltips, hand-rolled dropdowns, and DIY meters.

Two disciplines make it work and both are non-optional. First: a semantic-token layer must already exist — stock shadcn code references CSS variables like bg-background, border-input, bg-popover; without them every primitive renders unstyled (see dark-mode-token-migration). Second: one shared house-rules contract (templates/house-rules.md) governs color, focus, animation, touch-targets, radius, and types, so a fleet of authoring agents produces one coherent style instead of twenty. Primitives authored this way are dark-ready from birth (tokens), keyboard/AT-accessible (Radix), and touch-correct (44px targets, 16px inputs). This method comes from a real shipped Next.js / Tailwind v4 redesign — every rule below earned its place fixing something that silently broke.

When to use

• "The app is full of native <select>s / title= tooltips / custom dropdowns — give it a real component library."
• "Stand up shadcn/ui on this Tailwind v4 project."
• "We're faking a progress bar / toggle / combobox by hand — replace it with an accessible primitive."
• Before a per-route migration: build the primitive layer once, then swap call-sites onto it (with parallel-agent-refactor).

When NOT to use this skill

• The app already has a mature component system (Radix already wrapped, MUI, Chakra, Mantine, an in-house kit). Don't fork a second one — extend what's there.
• No semantic-token layer and you're not willing to build one first. Every primitive here assumes tokens. Do dark-mode-token-migration first, or the whole set ships dead styles.
• You need one control, once. Adding cmdk + vaul + react-hook-form for a single dropdown is overkill — style one Radix component inline.
• Pure visual redesign / taste work → frontend-design. This skill builds the plumbing; it doesn't pick the aesthetic.

What to build (the faked-control census)

Grep the app for the anti-patterns in the right column, then author the matching primitive as a new file. Authoring new files means a parallel fan-out has zero write conflicts (nobody edits the same file).

Dependencies

State these explicitly — never assume they're installed. Install only the packages for the primitives you're actually building.

npm i @radix-ui/react-select @radix-ui/react-switch @radix-ui/react-checkbox \
  @radix-ui/react-radio-group @radix-ui/react-tooltip @radix-ui/react-dropdown-menu \
  @radix-ui/react-popover @radix-ui/react-tabs @radix-ui/react-toggle \
  @radix-ui/react-toggle-group @radix-ui/react-progress @radix-ui/react-slider \
  @radix-ui/react-separator @radix-ui/react-label \
  cmdk vaul react-hook-form @hookform/resolvers zod

# optional
npm i lucide-react   # icons — OR keep inline SVG if that's the house style; don't mix
npm i tldts          # ONLY if you build smart domain inputs (public-suffix parsing)

Prereq that is not an npm package: the semantic-token layer (the CSS-var definitions for --background, --popover, --primary, --border, --input, --accent, --muted, --destructive, … and their -foreground pairs). If bg-popover and border-input don't resolve, stop and build the token layer first — see dark-mode-token-migration.

Authoring discipline (the six house rules)

These are the whole point — hand the full contract in templates/house-rules.md to every authoring agent. The rules, and the why so you generalize past the listed cases:

1. Read the existing button (and input) FIRST. They are the style reference — copy their "use client" placement, their cn import path, their React.forwardRef + displayName shape, and their formatting. Every new primitive mirrors them exactly.
2. Color = semantic tokens ONLY. Use bg-popover/text-popover-foreground, border-border, border-input, bg-primary/text-primary-foreground, bg-accent/text-accent-foreground, text-muted-foreground, bg-muted, bg-destructive. Never a raw palette shade (bg-gray-100, #1e293b, text-white) for chrome. Tokens are why the set is dark-ready with zero extra work — a raw shade breaks in the other theme.
3. Focus = rely on the global ring. If the app has a global :focus-visible ring, do not add per-component focus-visible:ring-* / outline-*. Per-component rings drift and fight the global one; one source of truth keeps focus consistent.
4. Animation = transitions + built-in motion, never animate-*. Tailwind v4 ships no tailwindcss-animate. animate-in, animate-out, fade-in-*, zoom-in-*, slide-in-from-*, and data-[state=…]:animate-* silently render nothing — no error, no warning. Radix exposes data-[state] attributes you drive with transition-*/CSS keyframes (it does not animate itself); vaul self-animates. The one blessed state-motion is a chevron: data-[state=open]:rotate-180 transition-transform.
5. Touch targets. Interactive triggers and menu-items (SelectTrigger, DropdownMenuItem, CommandItem row, TabsTrigger, CopyButton) get pointer-coarse:min-h-11. Text-entry controls (command input, combobox input, textarea) use text-sm … pointer-coarse:text-base — 16px on touch, which prevents the iOS focus-zoom trap. Do not balloon checkbox/switch themselves (they'd look wrong); enlarge their hit-area by pairing them with a label instead.
6. Radius, border, types. rounded-md for controls, rounded-lg/rounded-xl for surfaces (popover/menu/sheet), hairline border widths. Type the ref with React.ComponentRef<…> and React.ComponentPropsWithoutRef<…> — React.ElementRef is @deprecated in @types/react 19.

A reference primitive (annotated)

Every primitive is the canonical shadcn wrapper with the house rules applied. Switch shows all of them in ~20 lines — clone this shape for the rest.

"use client"                                   // rule 1 — like the button

import * as React from "react"
import * as SwitchPrimitive from "@radix-ui/react-switch"
import { cn } from "@/lib/utils"               // rule 1 — the PROJECT's util; match the button's import

const Switch = React.forwardRef<
  React.ComponentRef<typeof SwitchPrimitive.Root>,          // rule 6 — ComponentRef, not ElementRef
  React.ComponentPropsWithoutRef<typeof SwitchPrimitive.Root>
>(({ className, ...props }, ref) => (
  <SwitchPrimitive.Root
    ref={ref}
    className={cn(
      "peer inline-flex h-6 w-11 shrink-0 cursor-pointer items-center rounded-full",
      "border-2 border-transparent transition-colors",       // rule 4 — transition, NOT animate-*
      "data-[state=checked]:bg-primary data-[state=unchecked]:bg-input",   // rule 2 — tokens only
      "disabled:cursor-not-allowed disabled:opacity-50",     // rule 3 — no focus-visible ring; global handles it
      className,                                             // don't balloon size (rule 5) — pair with a <Label>
    )}
    {...props}
  >
    <SwitchPrimitive.Thumb
      className={cn(
        "pointer-events-none block h-5 w-5 rounded-full bg-background shadow-lg ring-0 transition-transform",
        "data-[state=checked]:translate-x-5 data-[state=unchecked]:translate-x-0",
      )}
    />
  </SwitchPrimitive.Root>
))
Switch.displayName = SwitchPrimitive.Root.displayName        // rule 1 — like the button

export { Switch }

Every other primitive is the same shape with rules 2/4/5/6 applied to its parts:

• Triggers (SelectTrigger, DropdownMenuItem, …) add pointer-coarse:min-h-11, and for a chevron the one blessed motion data-[state=open]:rotate-180 transition-transform.
• Surfaces (popover / menu / sheet content) use rounded-lg border bg-popover text-popover-foreground shadow-md — popover tokens, hairline border.
• CopyButton is fully house-original (no Radix) yet obeys the same rules: token colors, no per-component focus ring, pointer-coarse:min-h-11.

Full authoring contract + call-site API table: templates/house-rules.md. It carries the file-header/forwardRef boilerplate, the per-part patterns, and the Radix→native mapping — hand it to every author verbatim.

Radix API notes for call-sites (hand these to the migrator)

The primitives are NOT drop-in for the native DOM API — e.g. Select gives you onValueChange(value) (not an onChange event), a SelectItem needs a sentinel value like "all" (empty string throws at runtime), Switch/Checkbox use onCheckedChange(boolean), CommandItem uses onSelect. The full call-site mapping is the table in templates/house-rules.md §7 — put it in the migration spec when a parallel-agent-refactor migrator rewires call-sites.

Fan-out authorship (parallel, one barrier)

Because every primitive is a new file, you can author the whole set concurrently. Give every author agent the identical templates/house-rules.md + one reference file (the existing button) + a disjoint list of files to create. Group interdependent primitives under a single owner so a cross-file import lands from one hand; the few remaining cross-file imports resolve when all files land together at the end.

Barrier discipline: the orchestrator runs verification ONCE, at the end — never let agents run build concurrently. Cross-file imports (form→label, combobox→popover/command, CommandDialog→Dialog) are unresolved within the wave and resolve only when every file exists at the barrier. parallel-agent-refactor owns the orchestration mechanics (fan-out, structured returns, the barrier); this skill supplies which files and how each one is written.

Output

The deliverable is a coherent primitive layer plus proof it isn't silently dead:

components/ui/
  select.tsx  combobox.tsx  command.tsx  switch.tsx  checkbox.tsx
  radio-group.tsx  tooltip.tsx  dropdown-menu.tsx  popover.tsx  tabs.tsx
  toggle.tsx  toggle-group.tsx  progress.tsx  slider.tsx  separator.tsx
  label.tsx  textarea.tsx  form.tsx  drawer.tsx  copy-button.tsx

Because unknown Tailwind utilities no-op instead of erroring, a green typecheck+build does not prove the styles exist. Run these greps at the barrier — the first two must return nothing, the third gets eyeballed — then verify:

# forbidden v4 animation classes (silently render nothing) — MUST be empty
rg -n 'animate-in|animate-out|fade-in|fade-out|zoom-in|zoom-out|slide-in-from|data-\[state=[^]]*\]:animate-' components/ui
# per-component focus rings fighting the global ring — MUST be empty if you rely on the global ring
rg -n 'focus-visible:ring|focus-visible:outline' components/ui
# raw palette shades / hex used for chrome instead of tokens — inspect every hit
rg -n 'bg-(gray|slate|zinc|neutral)-|text-(gray|slate|zinc)-|#[0-9a-fA-F]{6}' components/ui
# only now: ONE typecheck + ONE build (never run concurrently across agents)
npx tsc --noEmit && npm run build

Barrier checklist (copy into your notes and tick):

[ ] Semantic token layer exists (bg-popover / border-input / bg-primary resolve) — verified BEFORE authoring
[ ] Every primitive mirrors the existing button (use client, cn import, forwardRef + displayName)
[ ] Color grep clean — only semantic tokens, no raw palette / hex for chrome
[ ] Animation grep clean — no animate-*/fade-in-*/data-[state]:animate-* anywhere
[ ] Focus grep clean — no per-component rings (global ring relied on)
[ ] Triggers/menu-items have pointer-coarse:min-h-11; text inputs are 16px on touch
[ ] CommandDialog strips the base Dialog's own chrome; checkbox/switch paired with a label
[ ] ONE typecheck + ONE build, green, at the barrier

Pitfalls

• Authoring before the token layer exists. Stock shadcn code assumes bg-background/border-input/bg-popover CSS vars are defined. Skip that layer and every primitive is unstyled — and the build stays green, so nothing tells you. Build the token layer first (dark-mode-token-migration).
• Unknown Tailwind utilities don't error — they no-op. A misspelled or non-existent token (bg-poopver, a class from a plugin you don't have) produces no style and no warning. A green build is not proof; grep the output and eyeball a render.
• tailwindcss-animate isn't in v4. animate-in / fade-in-* / data-[state=open]:animate-* copied from stock shadcn silently do nothing. Drive Radix's data-[state] attributes with transition-*/CSS keyframes (Radix doesn't animate itself; vaul does); grep to confirm none leaked in.
• The base Dialog's own chrome flows into CommandDialog. CommandDialog wraps Dialog, so the dialog's padding/border/shadow layer onto the command palette. Strip or override the inherited chrome so the palette isn't double-framed.
• Ballooning checkbox/switch to hit 44px. Their hit-area is small, but forcing min-h-11 on the control itself looks wrong. Pair them with a Label and let the label extend the clickable area — that's the accessible fix anyway.
• React.ElementRef. @deprecated in @types/react 19; use React.ComponentRef. Stock snippets predating v19 still use ElementRef — swap it.
• Mixing icon strategies. Pick lucide-react or inline SVG to match the house style — don't ship half and half.

Combining with other skills

• dark-mode-token-migration — the hard prerequisite. It defines the semantic tokens every primitive here depends on, and once they're tokens the whole set gets dark mode for free. Do it first, always.
• parallel-agent-refactor — the orchestration engine: author this set as its wave A (new files, disjoint owners, one barrier), then run wave C to swap call-sites onto the primitives using the Radix API notes above.
• ux-decision-rubrics — decide which primitive each job actually needs (select vs combobox vs dropdown-menu; switch vs checkbox) before wiring anything, so you don't build the wrong control.
• empirical-responsive-audit — after building, render and measure to prove the 44px targets, 16px inputs, and safe-area rules actually hold — the primitive layer is where those mobile-correctness rules get baked in once.
• ui-ux-audit — sources the backlog: it's the review that finds the faked <select>s, title= tooltips, and DIY meters this skill replaces; run it again after to confirm the swap landed.
• frontend-design — for the visual/aesthetic layer on top; this skill builds accessible plumbing, not the look.
• production-agent-audit, godaddy-api, other platform-ops skills — orthogonal; unrelated to building a UI primitive layer.