Radio

Source

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1. Title and support strip

Choose exactly one value from a visible set. Stable ID: SWC-radio; source IDs: P19, P22, S20, L8, B. Maturity: proposed; availability: documented reference, not a published component package. Owner: Space Works design-system owner, Shaan Shoukath; product maintainers own app integration. Documentation introduced/updated for v2.1.0, planned under decision 397. Last source verification: 2026-11-13. Web implementation is described below; Compose/SwiftUI are starter mappings with no verified component parity.

2. Use it for / choose something else

Use for one-of-many form choices where seeing alternatives matters. Checkbox supports multiple choices; SegmentedControl switches two or three views of the same object; Select suits a longer list.

Extracted source contract: P19 — P19. Form card with checkbox cards and developer reference (R6) · P22 — P22. Auth split screen (R11) · S20 — S20. Staff sign-in (LoginPanel) ← R11 · L8 — L8. AuthLayout (R11) and CenteredCardLayout (R12–R15) · B — B. Interaction states. The purpose, anatomy, variants and dimensions below condense those sections without moving their IDs or anchors. Source P rules describe observed reference boards; B/C and later decisions resolve brand adaptations.

Authority and implementation status gives precedence. Source inventory preserves headings, table cells, code and links for publication checks.

3. Live example and complete code

Full-page runnable example: start node examples/web/server.mjs from the repository root, then open http://localhost:4174/examples/web/component-gallery.html#radio. Choose Light/Dark, preview width and an applicable state; exercise hover, pressed and focus-visible with real input. Complete source: HTML, behaviour, styles. No app module, network API or build step is required. These are portable reference compositions, not replicas of app exports.

<fieldset><legend>Layout</legend><label class="choice"><input type="radio" name="layout" value="list" checked>List</label><label class="choice"><input type="radio" name="layout" value="cards">Cards</label></fieldset>

The linked shell supplies CSS/tokens and any data-* behaviour. Static text/native controls remain without JavaScript; modal content has an inline fallback. Copy the complete source for enhancements, not this fragment alone. First-screen setup shows the whole document.

4. Anatomy

Numbered reading-order diagram: [1] → [2] → [3] → [4]. Slots and name ownership:

1. Fieldset and legend: name the decision.
2. Native radios sharing one group name.
3. Visible label for every option.
4. Optional hint/error linked to the group and affected inputs.

5. Variants

Unselected and selected; default optional group or required explicit choice. Reference WordFeedback renders one radio per word. No generic Radio export or asynchronous radio group is supplied.

Variant	Choose it for
Native group	One mutually exclusive choice with legend.
Required group	Explicit choice required before submit; preserve after error.

Native products use platform controls with mapped roles/settings. A web keyboard model does not establish native parity. Gallery variants/states are reference compositions, not undocumented app props.

6. States

State handling belongs either to this primitive or the containing task explicitly named below. N/A records a semantic or API limitation, not an omitted requirement.

State	Presentation / copy	Action, focus, announcement and data
Default	Required visible name, correct role and truthful current value/context.	Enabled actions follow §8; no automatic announcement for static content.
Hover	Use B hover roles without hiding the label or necessary boundary.	No hover-exclusive instructions; child controls retain their own contracts.
Pressed	Use B active colours during activation; do not mutate on pointer-down.	Native click/release activates once; optional child actions use Button.
Focus-visible	Visible 2 px ring plus offset; ≥3:1 against actual adjacent colour.	Keep focused actions visible above sticky chrome and the software keyboard.
Selected	Checked/current semantics and a non-colour selection mark.	Caller controls selection; keep values stable through failed persistence.
Disabled	Explicit surface/muted/line colours and an understandable prerequisite.	Use native disabled where supported; aria-disabled requires event guards. Consult §11 for unsupported props.
Read-only	N/A — no read-only component mode; noneditable information already reads as text.	No read-only API is claimed. For a locked choice, present a labelled static value; native checkbox/radio/select do not honour readOnly.
Loading / pending	Keep context; use task-specific pending copy such as “Saving…”.	Disable only the mutation in progress, announce once and preserve drafts. Fetch state is product-owned unless §11 says otherwise.
Empty	Show absence only after a successful load, with a useful next step.	Never confuse no records with pending, denied access or failure.
Filtered-empty	N/A — this primitive does not filter results; the affected result region owns this state.	Preserve query and scope, offer Clear filters and announce the result once.
Error / retry	“Couldn’t save/load. Try again.” plus persistent explanation and specific recovery.	Keep the user’s value/context, relate field errors by ID and retry only the failed operation.
Offline	Keep clearly labelled last-known values and unsent drafts; explain network-only limitations.	Local navigation/editing/Close can remain available. Product owns safe retry/idempotency; queued is not completed.
Success	Show the completed effect and truthful updated value; use precise confirmation.	Announce once without taking focus; visible in-place changes need no redundant toast or invented success prop.
Interrupted work	Retain safe drafts/context and say whether completion is known or still unresolved.	Reconcile server/session state before repeating a mutation; never automatically replay irreversible work.

7. Specifications and tokens

Keep a 44 px minimum label hit area; allow options to stack at 320 px and enlarged text. Use ink/brand-boundary for the necessary ring and selected dot. Never communicate selection through hue alone.

Load tokens CSS once. Theme pairs: bg/surface/panel with ink or muted; fills use matching on-*; standalone links/essential accent marks use accent-ink or brand-boundary. line is decorative. No alpha text or opacity-based disabled state. outline on hover and raw dark accent on panel need special contrast care; use the tested functional boundary role. Geometry described here is a source contract, not a claim that new CSS variables exist. Wrap translation and enlarged text; use min-inline-size:0 and 320 CSS px reflow rather than clipping.

8. Interaction / accessibility

Tab enters/leaves the native group; arrows move/select among enabled choices; Space chooses the focused option. Browser entry for an entirely unchecked group can vary by direction. Preserve one shared name; do not require a separate Tab stop for every custom option.

Key / input	Behaviour
Tab / Space	Native checkbox or switch traversal / toggle; native radio group enters at chosen option.
Arrows for radio only	Move/select within a same-name native radio group; not checkbox/switch navigation.

Test name/role/value and reading order with a screen reader. The name contains the visible label. Associate errors with unique description IDs and announce status once without moving focus. Test both themes, 400% zoom, forced colours and reduced motion. Use system colours/visible borders in forced colours; do not suppress adaptation by default. Keep focus clear of sticky chrome. The house target is 44 px; WCAG minimum is 24×24 CSS px with exceptions. Provide click/tap alternatives to dragging. Native integrations test TalkBack/VoiceOver, large type and platform focus. These are required checks, not claims of completed AT tests. Accessibility maps criteria, system contracts and product responsibilities.

9. Content

The legend asks a decision (“Layout”); labels are parallel (“List”, “Cards”). State “Choose one” if the task is unfamiliar. Never use a radio to submit or navigate on focus.

Sentence case; translated labels and locale-aware plurals/numbers/dates/currency. Never expose raw error codes or invent a count. Money/evidence outcomes require actual confirmed completion and precise auditable consequences.

10. Do / don’t

Do	Don’t / why
Group related choices with a legend and preserve the chosen value after a save error.	Do not use separate names for mutually exclusive options or auto-submit when focus enters.
Use semantic role tokens and complete visible copy.	Do not copy reference hex colours, alpha text or paid Gilroy weights: they bypass the current theme/type contract.

11. Implementation

Observed API: Native type='radio', shared name, distinct value, checked/defaultChecked, required, disabled and onChange. WordFeedback is a task-specific implementation, not a reusable Radio API; use native controls for a new product.

App source, reference only: frontend/src/components/delight/WordFeedback.tsx. Inspected in the supplied int-stage-r2final worktree; uncommitted content may differ from upstream main. Implementation snapshot records exact file hashes. Neighbours: shared types, desk CSS and motion modules.

<fieldset><legend>View</legend>
  {['List', 'Cards'].map(view => <label key={view}>
    <input type='radio' name='view' value={view} checked={value === view}
      onChange={() => setValue(view)} />{view}</label>)}
</fieldset>

The snippet assumes the source app’s imports/state handlers. It is not a standalone install. Observed app dependencies include React 19.2, React Router 7.18, Tailwind 4.3, Lingui 6.10.1 and local motion/session modules. The separate React starter avoids these app dependencies. Preserve controlled values separately from fetched data. Only validated public/member brand roles take tenant overrides; staff chrome remains Space Works.

Known limitations: Read-only is not supported by native radio. Show a labelled static value for locked choices. A product must own draft value, save validation and server errors; no source claims a universal Radio component.

The standalone gallery uses local sample data/simulated outcomes. Without JS, ordinary content/controls and inline explanations remain; async/modal enhancements require JS. Native source is starter-only, not compiled here.

12. Related and maintenance

Checkbox · Select · SegmentedControl. Named patterns/layouts retain P1–P30/L1–L10 and screen backlinks. Fonts/licences, portable logo master and design-resource availability connect the assets; no public editable library or native component download is asserted.

Evidence: source inspection/captured hashes, not an app/site AT certificate. History: first dedicated contract for planned v2.1.0; no API removal introduced here. Release policy, migrations and contribution route govern maintenance.