LedKey

A molded pill key with an indicator LED that breathes while lit. The latching sibling of HardwareButton: use it when the key's own state is part of the answer (armed, monitoring, recording), not for a command that fires and forgets.

Feel A molded key with an indicator LED that breathes while it is lit.

every state →

Or let the agent fetch it: get_component("led-key") on the Echo MCP server.

Installation

npx echo-ui-cli add led-key

First time? Run npx echo-ui-cli init once — it sets the project up, and add refuses to run before it.

At a glance

Version: 0.3.0
Weight: 525 B · 30.0 KB with what it imports · 1.1 KB of CSS (minified and gzipped; React not counted)
Needs: gsap, size (Echo, brought with it)
Keyboard: A native <button>: Enter and Space press it, with the same travel and sound as a pointer.
Reduced motion: The key does not travel, and the lit LED stops breathing and holds steady.
Sound: press as the key lands on its seam, release as it tops out on the way home, brighter the longer it was held.

Usage

tsx

import { LedKey } from "@/echo/led-key";

<LedKey lit={armed} aria-pressed={armed} onClick={() => setArmed(!armed)}>
  Arm
</LedKey>

Composition

LedKey

Examples

Latching key

A key that toggles its own state says so with aria-pressed — the LED is then the visual half of the same fact.

tsx

<LedKey lit={armed} aria-pressed={armed} onClick={() => setArmed(!armed)}>Arm</LedKey>

Reporting something else

When the LED reports what the device is doing rather than the key's own state, litLabel is what carries it to a screen reader.

tsx

<LedKey lit={recording} litLabel="Recording">Rec</LedKey>

Idle

Unlit is dead plastic — the same two-state LED as StatusDot.

tsx

<LedKey>Snooze +5</LedKey>

A row of keys

Keys read as one transport when they share a well row.

tsx

<div style={{ display: "flex", gap: 12 }}><LedKey lit litLabel="Recording">Rec</LedKey><LedKey>Play</LedKey></div>

Accessibility

A native <button>: Enter and Space press it, with the same travel and sound as a pointer.
For an on/off key, pass aria-pressed alongside lit so the state is announced.
litLabel adds visually hidden text for what the lit LED means (“Recording”) — the LED alone is only colour.

Tested against WCAG 2.2 AA on every release:

axe — No axe violations, in the component's own gallery and on its page.
keyboard — Every action is reachable and operable from the keyboard alone.
focus-visible — Focus is visible on every focusable part, in normal and forced-colors mode.
forced-colors — State stays visible when the look's colours are replaced by the system's.
target-size — Every target's real hit area is at least 24×24px, at every density.
reflow — Content reflows into 320px and survives a doubled text size.

Not covered: screen-reader: not yet verified by a person. Everything above is a machine check; a person has not yet driven this component with a screen reader.

Motion & sound

Motion tokens: lift, light
Reduced motion: The key does not travel, and the lit LED stops breathing and holds steady.
Sound: press as the key lands on its seam, release as it tops out on the way home, brighter the longer it was held.

Props

LedKey props
Prop	Type	Default
`id`The element's id, so a <label for> or an aria-describedby can reach it.	`string`
`name`The field's name in a form submission, and the key react-hook-form registers.	`string`
`disabled`	`boolean`
`required`	`boolean`
`readOnly`	`boolean`
`autoFocus`Focus this control when it mounts. One per page, at most.	`boolean`
`onBlur`Fired on focus loss. react-hook-form validates onTouched and onBlur with it.	`function`
`onFocus`Fired when the control takes focus.	`function`
`onKeyDown`Keyboard handling you own — Enter to send, Escape to clear. Runs before Echo's.	`function`
`onClick`	`function`
`type`"button" (default), "submit" or "reset".	`string`
`form`The id of the form this button submits, when it sits outside it.	`string`
`value`Submitted with the form when this button is the one pressed.	`string`
`title`The browser's own hover tooltip. Never the accessible name.	`string`
`onPointerDown`Runs before Echo's own tactile handler, so the sound lands with the finger.	`function`
`onPointerUp`	`function`
`children` requiredThe key's legend — machine-cased in the skin.	`string`
`lit`Light the LED and breathe it. False is dead plastic.	`boolean`	`false`
`litLabel`What the lit LED means, announced as visually hidden text. For a key that toggles its own state, use aria-pressed instead.	`string`
`size`Height on the control scale: sm 32px, md 44px, lg 60px, the same as a HardwareButton or Field of that size, so they line up in a row. Defaults to the nearest SizeProvider's size.	`"sm" \| "md" \| "lg"`	`"md"`

Anti-patterns

Never let the LED be the only carrier of state — pass litLabel (or aria-pressed when the key toggles itself) so the lit key announces what it means; a colour is not a message.
Never pass both aria-pressed and litLabel — one says the key is on, the other says the device is; using both leaves a screen reader with two answers to one question.
Never use LedKey for a fire-and-forget command (Save, Send, Delete). An LED promises a state that persists after the press; HardwareButton is the cap for actions.
Never render more than one lit key to mean one exclusive choice — that is a Segmented or a RadioGroup, which say so structurally.

Changelog

v0.3.0 · 2026-10-12 · AddedThe drawn device (echo-ui-core, echo-ui-cli, every component that draws its own material). A seed's new render setting is molded (Echo as it has always been: plastic lit by one key light) or drawn: the same parts drawn in the ink, the way a spec sheet draws a key. Every part is outlined at one weight (--echo-line, --echo-line-width), hollow on the body; a raised part stands on a hard ink edge as deep as it rises and travels down it when pressed; a recess is an outline drawn inside; something floating stands on a deeper edge. There's no light, so no gloss, no soft shadow and no glow: what a molded device lights (an LED, the rail, a readout, the focus ring, a fader's knob, a radio's pip) is solid ink, and a low-emphasis action is its label underlined. In black and white (the accent the ink) "on" is solid ink and what's drawn on it inverts: a switch's thumb turns paper, a fader's knob is knocked out with a paper ring. The primary key is the paper key that stands highest, on an ink edge twice as deep as a neutral one's, the way a spec sheet draws its CTA. The accent stays the seed's own colour as a flat fill for what's on (a chosen segment, a checked box, a slider's travel, a switch that's on), so an acid highlighter is acid, not the olive a molded device holds it to; what's drawn on it is the ink, or the body when the accent is too deep for the ink. Pressing, travel, sound, what each material is for and every contrast guarantee are unchanged. npx echo-ui-cli style set render drawn turns it on; a style sets it in its seed; the published style and config schemas describe it, and DESIGN.md says how a drawn device builds. A molded device renders exactly as before: every line is 0px wide there, and each drawn value a component reads (--echo-drawn-fill, -on-fill, -ink, -rule, -glass, -hollow, -decoration) is initial, so it falls back to what the component always drew. HardwareButton's bed is the one new hand-tuned shadow: a drawn key stands on its own edge instead of being drawn in a recess.
v0.3.0 · 2026-10-12 · ChangedEvery item needs echo-ui-core 0.3.0 (all components). The drawn device, readability past AA and the design tests live in core, and the components that use them are built against it, so each item now declares echo-ui-core >=0.3.0 <0.4.0. Update core with the items: npm install echo-ui-core@^0.3.0 (or your package manager's), then npx echo-ui-cli update. An item whose files didn't change is the same code under a new version; the 0.2.0 files stay published.
v0.2.0 · 2026-10-04 · AddedThe light device (echo-ui-core, echo-ui-cli). Echo can be light: a pale chassis makes a device molded in light plastic, like a white calculator or a cream radio, and a dark one makes the device Echo has always been. There's no setting and no mode to switch; the chassis decides (devicePolarity, and values.polarity on the theme). On a light device the page is light: its ground, the well, is the body barely set in. Caps get their own ladder, a step lighter than the body with a lit rim that stops short of white, so they keep their bevel; undersides and seams are shaded darker; dim text moves toward the ground by the same step as on a dark device, and reads about 6:1 on it. Screens are paper glass printed in ink, because a glow on a pale body is a smudge. What's lit (an LED, the current rail) is still the accent, held to 3:1 on every ground, so on is brighter than off; the text it prints (a readout, a count, a current tab) and the focus ring are the accent's ink, a step deeper and held to AA, in the new accent-ink role. The primary cap is the same cap as a dark device's, the accent with a light label: its label is the new primary-cap-ink role, and progress cells, loader dots and a meter's fill, the same plastic, read 3:1 on the page. A neutral cap or a slider that fills with it under its own dark label fills with the new pour-* roles, the accent's pale stops. Shadows are drawn at half their weight, in a deep colour of the body's own hue (--echo-cast-ink) instead of black. Every guarantee holds as it does on a dark device, and the contrast sweep now runs on light bodies too. A dark seed makes exactly the theme it did before, and the new roles equal the ones they stand for there. The components that mixed a recess toward black, painted paper in the text colour or lit a pillow of light with it read the theme's new --echo-shade-ink, --echo-paper-stock and --echo-paper-ink instead, with the old value as the fallback, and a reflective screen reads --echo-screen-*; the components that print a lit label read --echo-primary-cap-ink and --echo-accent-ink the same way; every rail is drawn in the glow, and every focus ring, the ring recipes included, in the ink. style use wears a light style now, and style check says which device a style makes. A dark screen tint on a light body is still refused: one text colour can't serve both, and the theme says so.
v0.2.0 · 2026-10-04 · ChangedBreaking: HardwareButton's sizes are the control heights, so a button lines up with a field. A button's outer height, well included, is now sm 32px, md 44px, lg 60px, the same as a Field, Select, NumberField or OtpField of that size. Before, the default button was 60px beside a 44px field, and no size of button lined up with any input, so a search bar, a filter row or an inline "invite" form never looked right.
v0.2.0 · 2026-10-04 · ChangedComments only, no behaviour change. Comments in the component source used to cite documents, milestones and ticket numbers from Echo's own planning, none of which exist in your project. The citations are gone and the sentences around them stay. Where a comment was only a citation, it now says what it meant. Three development warnings (HardwareButton's engraved/caption checks and StatusDot's missing-label check) also dropped the ticket code at the end of the message. echo-ui diff will show changes in most items; none of them are to code.
v0.2.0 · 2026-10-04 · ChangedAn item's version is now a function of declared data, not of how the changelog is formatted. The version an item ships under is published once and never rewritten, and it used to be inferred from prose: a regex for a bolded "Breaking" run across the whole unreleased section, and attribution by "does a bullet mention this name in backticks". One breaking entry therefore moved every item that changed that cycle, and an entry explaining that "Menu and Sheet are unchanged here" filed itself as a change to Menu and Sheet — which it really had.
v0.2.0 · 2026-10-04 · ChangedBreaking: every control takes a ref, an onBlur and an onFocus — and the two that were wide open are now closed. Four of 49 components could receive a ref, and onBlur appeared in zero public prop types, so react-hook-form's uncontrolled register() — which needs exactly ref, onBlur and name — could not work with any Echo control.
v0.2.0 · 2026-10-04 · ChangedThe agent brief says Echo has not shipped. llms.txt and the MCP server's instructions led with npx echo-ui-cli init, and that name on npm is a reserved stub with no executable — so a model following the brief wrote an install step that fails with npx's own error. The brief now opens with the caveat, and the docs carry it on every surface that shows a command. One switch (CLI_RELEASED) silences all of them at launch, and a test refuses to let one move without the others. Affects all components only in what the brief says about installing them; no item's props, CSS or rendered semantics change.
v0.2.0 · 2026-10-04 · ChangedEcho's home is echo-ui.com. The registry, the docs and the packages all move to it from echo.nawwara.studio. Nothing was published under the old host, so no echo.json anywhere points at it and there is nothing to migrate — this is the last release where that is true.
v0.2.0 · 2026-10-04 · ChangedWeights, line heights, letter-spacing, z-index, border widths and icon sizes come from the theme scales in all components, with the old value as a fallback, so components keep working with echo-ui-core@0.0.1. Strays moved to the nearest step: most by under a pixel; HardwareButton icons are 14/16/20px (were 15/17/19).
v0.2.0 · 2026-10-04 · FixedA light device's recesses keep the body's hue in Chromium (echo-ui-core, BUG-166). Chromium drops the hue of a colour under 0.02 chroma when it mixes in oklch, and draws the mix at hue 0, a rose. A light device's plastic is that grey, so on a lilac body every field, track and rail was pink. A mix made only of greys is made in oklab now, which has no hue to lose; a mix with an accent in it stays in oklch. On a dark device nothing you can see changes.
v0.2.0 · 2026-10-04 · FixedContent now reflows into a 320px screen (400% zoom) and survives a doubled browser text size (WCAG 1.4.10, 1.4.4), across all components. Select's 180px floor, NumberField's readout, Segmented and Steps as flex items, EmptyState's grid columns, and Avatar's fixed-pixel disc all gave way; Panel counts its padding inside a width you set (box-sizing: border-box), so a <Panel style={{ width: 220 }}> is now 220px wide overall rather than 260px.

Preview