Form

A composition primitive over `@base-ui/react/field`. The form ecosystem owns a long tail of subtle a11y wiring — label/control association via generated ids, `aria-describedby` for description + error, `aria-invalid` flipping on validity, focus management…

form & inputserver320pxuiv1.1.0

Preview

Form — live renderprimitives-form--default

Rendered from the story the storybook (a11y) CI gate runs axe against — the preview can't show something that hasn't been verified.

Install

Two equivalent paths — the URL works in any shadcn-CLI setup; the alias works once you've registered @interlace in your components.json.

Via shadcn URL
npx shadcn@latest add https://ds.interlace.tools/r/form.json
With the @interlace alias
npx shadcn@latest add @interlace/form

Behavior

What this component does — the keyboard path, the measured colour, the text equivalent and the states it can be in. Every figure below is read out of the test or the source that enforces it by scripts/build-behavior-map.mjs, so nothing here can outlive the gate that keeps it true.

Every semantic colour pair this component's own source uses, measured against the shipped hexes in all 4 theme × scheme combinations. The tightest is destructive on background at 7.60:1 (harbor · light), against a floor of 3:1.

Measured WCAG contrast ratios per token pair and theme
PairinterlacelightinterlacedarkharborlightharbordarkFloor
destructive on backgrounddestructive tint on the page surface8.31:110.43:17.60:110.03:13.0:1SC 1.4.11
muted-foreground on backgroundsecondary copy9.41:111.32:17.82:19.52:14.5:1SC 1.4.3
destructive on carddestructive tint inside a card8.31:19.66:18.02:19.09:13.0:1SC 1.4.11
muted-foreground on cardsecondary copy in a card9.41:110.48:18.25:18.64:14.5:1SC 1.4.3

Text pairs are held to 4.5:1 (WCAG 2.2 SC 1.4.3); borders, rings and chart axes to 3:1 (SC 1.4.11 non-text). Bold is the worst cell in the row — the one a brand fork has to keep an eye on.

Where it renders, how narrow it survives, and whether its lines are inside the coverage gate — three answers a consumer needs before the paste, not after the bug.

Render boundary
server component

Renders during SSR / RSC with no hydration cost. It can be imported from a server component without pulling the page into the client.

Minimum viewport
MIN_VIEWPORT = 320

Declared, not assumed. Below 320 CSS px the preflight contract draws a dev-mode outline — how to switch it on.

Coverage gate
not in the gate

The 100% gate currently covers src/charts/**/*.{ts,tsx} and src/lib/**/*.{ts,tsx} and src/primitives/{button-variants,data-state-model,meter-scale,skeleton-variants}.ts and src/primitives/{alert,aspect-ratio,avatar,badge,box,breadcrumb,button,callout,card,checkbox,code-editor,container,data-state,focus-ring,grade-badge,grid,input,label,meter,pagination,published-date,reading-time,section,section-boundary,separator,skip-link,stack,stat-strip,tag,textarea,typography,visually-hidden}.tsx and src/patterns/lint-playground.tsx. This file is outside it — the glob widens in phase 7.2.

History

This component is at v1.1.0, first shipped in @interlace/ui 1.0.0. The version is stamped as a banner into the file the install writes, so the copy in your tree says which one you have — compare it with the number above before deciding whether to re-run the install.

Import

8 named exports — pull the parts you need.

Public API
import { Field, FieldControl, FieldDescription, FieldError, FieldLabel, FieldValidity, Form, MIN_VIEWPORT } from '@/components/ui/form';

Anatomy

Extracted from the primitive's JSDoc header. The source is the only documentation that can't drift.

<Form action={serverAction}>
    <Field name="email">
      <FieldLabel>Email</FieldLabel>
      <FieldControl render={<Input type="email" required />} />
      <FieldDescription>We'll never share it.</FieldDescription>
      <FieldError />
    </Field>
    <Button type="submit">Sign in</Button>
  </Form>

API reference

Parsed from the type declarations in the source — the same file the install writes into your tree, so this table can't drift from the component you get.

FormProps

Also accepts every <form> attribute.

PropTypeDescription
asChildbooleanRender as the passed child element (e.g. a framework-specific `<Form>` from `react-router` / `remix-run`). Server-safe slot: when set and a single React element child is provided, we `cloneElement` and merge our `data-slot` / `data-min-viewport` / `className` onto it. Not Base UI `useRender` (which would flip this tree to a client boundary).

Accessibility

Every story for this component is rendered headlessly and checked with axe-core (wcag2aa, wcag22aa, best-practice, ACT) on every PR. That gate has no continue-on-error, so what ships has zero known violations.

What follows is what static analysis can see. Axe cannot press a key and never sees an overlay open, so the operable-without-a-mouse claim lives in Behavior instead, where the keyboard path is replayed step by step.

Focus + keyboard behaviour
Owned by @base-ui/react/field — focus trapping, dismissal and typeahead come from the headless primitive, not from us.
Focus ring (WCAG 2.2 SC 2.4.13)
Not focusable — no focus indicator required.
Reduced motion
No animation to gate.
ARIA in the source
None — semantics come from the element or the Base UI primitive rather than hand-written ARIA.

Examples

3 more states from the same story file.

R-rule compliance

Every primitive in @interlace/ui models to the portable 26-rule floor enforced by the componentApi ESLint preset. The cells below pin exactly where each rule applies in this file.

RuleConceptWhere
R4Extends native el`Form` extends `React.ComponentProps<'form'>`
R6data-slot on every part`data-slot="form"` + Base UI parts emit their own slot attrs
R7className merged + ...rest`cn(className)` + `{...props}` on every part
R9Native onSubmit stays native`onSubmit` / `action` / `method` pass through `{...props}`
R10Composition seam`Form` accepts `asChild` via a server-safe React.cloneElement slot
R13Ecosystem firstBase UI `Field.*` owns id wiring + ARIA + validity state
R14Declares min viewport`data-min-viewport={String(MIN_VIEWPORT)}` + exported const
R18Tailwind onlyZero inline `style`; classes only
R19Tokens only`text-ui` / `text-ui-sm` / `text-muted-foreground` / `text-destructive`
R20AA contrastmeasured composites — see the table below
R25Server componentNo hooks, no `'use client'`; Base UI `Field.*` is the client part
R26A11y from native el + headlessNative `<form>` + Base UI `Field.*` ARIA wiring

Minimum viewport

This primitive declares MIN_VIEWPORT = 320 CSS px (DESIGN_PRINCIPLES #14). When mounted in a container narrower than this, the preflight contract draws a dev-mode outline so the regression is visible during local development.

Opt-in to the dev-mode warning
<body data-interlace-dev>...</body>

Add the data-interlace-dev attribute to the body in development builds only — preflight then outlines any primitive whose container is below its declared data-min-viewport.

Dependencies

Base UI primitive
@base-ui/react/field
Lucide icons
none
NPM dependencies
  • @base-ui/react
Registry dependencies

Source

The full implementation — components/ui/form.tsx once installed.

247 lines · TypeScript
import * as React from 'react';

// @interlace/form v1.1.0 — Interlace design system.
// Docs, props and live preview: https://ds.interlace.tools/c/form
// What changed since: https://ds.interlace.tools/c/form#history
// Generated banner — keep it, the upgrade diff reads this version.

/**
 * @interlace/ui — Form
 *
 * A composition primitive over `@base-ui/react/field`. The form ecosystem owns
 * a long tail of subtle a11y wiring — label/control association via generated
 * ids, `aria-describedby` for description + error, `aria-invalid` flipping on
 * validity, focus management when validation fails. Base UI's `Field.*` parts
 * already encode that contract; this file is the DS skin (R13: ecosystem
 * first — wrap, never re-implement).
 *
 * Two layers ship here:
 *
 *   1. `Form` — a server-component `<form>` wrapper with a server-safe

…227 more lines…

Registry JSON

The raw registry record — what the shadcn CLI fetches.