design-component

Skill: Design Component

Step 0 — is the kit here? This skill reads files from the kit. Check once: ls ${CLAUDE_SKILL_DIR}/../../../tokens >/dev/null 2>&1 && echo KIT_OK || echo KIT_MISSING On KIT_MISSING only the skill folders were installed, which is what npx skills add does. Say so plainly, point the user at npx ux-ui-agent-skills init or the plugin install, and stop. Do not guess the contents of a file you could not open.

Produce a complete component specification matching the project format.

Steps

1. Read .claude/rules/components.md → "Component Quality Bar" (the 8-state table) and "Atomic Design"; the always-on 8-state table is in CLAUDE.md → Non-Negotiables.
2. Check if it already exists: ${CLAUDE_SKILL_DIR}/../../../components/atoms.md, molecules.md, organisms.md, templates.md, navigation.md, feedback.md, forms-advanced.md, overlays.md. Match the existing spec format.
3. Pull the ARIA pattern from ${CLAUDE_SKILL_DIR}/../../../accessibility/aria-patterns.md and contrast/target rules from ${CLAUDE_SKILL_DIR}/../../../accessibility/wcag-checklist.md.
4. Map every value to tokens (${CLAUDE_SKILL_DIR}/../../../tokens/*.json) — sizes via sizing.json, states via states.json.
5. Apply visual judgment from ${CLAUDE_SKILL_DIR}/../../../taste/design-taste.md (states, focus, no slop).
6. Optional fast start: python3 ${CLAUDE_SKILL_DIR}/../../../scripts/scaffold_component.py "<Name>" to emit a stub, then fill it in.

Output

Spec with: anatomy diagram, variants table, sizes table, all 8 applicable states, token mapping, accessibility (role/keyboard/SR), and a note to render via ${CLAUDE_SKILL_DIR}/../../../frameworks/adapter-protocol.md.

Accuracy — verify every state, don't assume (mandatory when code is produced)

A component is only "correct" when every variant × state renders right — not just the resting default. Build a states harness: render the component in each applicable state (default, hover, focus, active, disabled, loading aria-busy, error aria-invalid, selected aria-pressed/aria-selected) × each variant in one HTML file (see ${CLAUDE_SKILL_DIR}/../../../examples/component-states/button.html). Then RUN the gates and report their real output (CLAUDE.md → Verification Protocol):

• node ${CLAUDE_SKILL_DIR}/../../../scripts/verify_states.mjs <harness> [--dark] — contrast of every element in default/hover/focus
• node ${CLAUDE_SKILL_DIR}/../../../scripts/axe_audit.mjs <harness> [--dark] — ARIA/role/name/label correctness
• node ${CLAUDE_SKILL_DIR}/../../../scripts/measure_render.mjs <harness> [--dark] — every text element AA
• overlays/modals also: node ${CLAUDE_SKILL_DIR}/../../../scripts/verify_focustrap.mjs <harness> --open=<trigger> Every state must pass in light AND dark before the component is "done". Never claim a state is correct without a gate proving it.

Gates prove contrast/a11y — they do NOT prove pixels. RENDER AND LOOK.

The contrast/axe gates pass while the UI is still visibly broken: a checkbox that doesn't toggle, a dash sitting at the bottom of its box, a checkmark and an indeterminate dash with mismatched stroke weight, a control that's too heavy. You must screenshot the harness and inspect it before claiming done — for every state, and after interaction. Playwright + system Chrome:

const b = await chromium.launch({channel:'chrome'});
const p = await b.newPage({deviceScaleFactor:4});
await p.goto('file://'+abs); await p.addStyleTag({content:'*{transition:none!important}'});
await p.mouse.move(2000,2000);                 // park pointer OFF the component
await p.locator('.stack').first().screenshot({path:'/tmp/x.png'});

Read the PNG. Then look for, specifically:

• Functional: click each interactive element and assert the state actually changed (await loc.click(); expect(await loc.isChecked())). A custom control whose overlay box covers the real <input> will not toggle unless the box has pointer-events:none (or an enclosing <label> forwards the click).
• Geometry: glyphs centered, not stacked/offset. If a display:grid box holds an opacity:0 sibling plus a ::after, the pseudo lands in row 2 → use display:none on the hidden sibling, or one container child.
• Stroke consistency: a checkmark and its indeterminate dash must use the same rendering method (one <svg>, two <path> toggled by state — same stroke-width), never an svg check vs a CSS ::after rect (they read as different weights).
• Transition artifact: screenshot WITHOUT disabling transitions and a just-clicked control looks half-faded mid-animation — that is not a bug. Always disable transitions and park the pointer before judging a state.

Consistency across files is non-negotiable. The same component (e.g. checkbox) must use byte-identical CSS + markup in every harness/page. A checkbox that looks thin in form-controls and heavy (native accent-color) in data-table is a bug. Factor one pattern, reuse it verbatim.

Verified custom checkbox/radio pattern (thin, token-driven, gated + eyeballed)

Real <input> underneath (keeps native a11y + keyboard); a drawn .box overlay with pointer-events:none; check + dash as two <path> in one <svg> toggled by :checked / :indeterminate; 1.5px border-strong, .25rem radius, .62rem glyph, stroke-width:2 round caps. Reference: ${CLAUDE_SKILL_DIR}/../../../examples/component-states/form-controls.html and data-table.html (select-all uses indeterminate). Native accent-color renders too heavy — do not use it when the house look is "thin".

Responsive — every component, no sideways scroll (gated)

Build mobile-first; a fixed-px width that can't shrink is a bug. Run node ${CLAUDE_SKILL_DIR}/../../../scripts/verify_responsive.mjs <file|dir> — it loads each harness at 280/320/414px and fails on any horizontal overflow. The four recurring causes and their fixes:

• fixed inline-size:Npx → inline-size:100%;max-inline-size:Npx (cap, don't pin).
• <ul>/<ol> default 40px inline-start padding (a *{margin:0} reset does NOT clear padding) → padding:0;margin:0 on every list. This also silently mis-aligns a list's edge vs a sibling block (looks like unequal widths) — same fix.
• non-wrapping flex rows (breadcrumb, stepper, tabs) → flex-wrap:wrap, or for tabs overflow-x:auto + .tab{flex:none}.
• grid minmax(Npx,1fr) min larger than viewport → minmax(min(Npx,100%),1fr).

Motion — tokenized, real easing, animate the thing that moves

Timing/easing are tokens (--duration-fast|normal|slow, --ease-out|in|in-out|emphasized in the theme; --transition-micro = fast ease-out). Never hardcode ms/curves. A component that toggles open/closed must animate its height, not just rotate a chevron — collapse via hidden/display:none alone reads as "rigid, no transition". Smooth-height pattern (no JS measuring): wrap content in an inner that clips overflow, animate the grid track:

.panel{display:grid;grid-template-rows:0fr;transition:grid-template-rows var(--duration-normal) var(--ease-emphasized)}
.panel.open{grid-template-rows:1fr}
.panel > .inner{overflow:hidden;min-block-size:0}

Keep a11y: expand = remove hidden then add .open next frame; collapse = remove .open, set hidden on transitionend. Reference: accordion in ${CLAUDE_SKILL_DIR}/../../../examples/component-states/overlays.html. Always honor @media(prefers-reduced-motion:reduce){…transition:none}.

Layout — fill the space, don't ship AI-empty filler

• auto-fit, never auto-fill for card grids. auto-fill keeps empty phantom tracks so 3 cards cluster left with a void on the right; auto-fit collapses empties so cards stretch to fill the row. Always repeat(auto-fit,minmax(min(Npx,100%),1fr)).
• Equal-height panels in a row: align-items:stretch on the grid, AND make the shorter panel's body fill — .panel{display:flex;flex-direction:column} + the inner region flex:1. A child sized with block-size:% (e.g. chart bars) needs a definite-height ancestor (a flex:1 box or explicit height), or the % resolves to 0 and the element collapses. Wrap the bar in a flex:1 .barbox and give the bar block-size:% of that.
• A main region that's 80% whitespace reads as machine-generated. Fill a dashboard with real, plausible content (stats row + activity list + a chart), not one lonely widget. Intentional density is the difference between "designed" and "AI slop".
• Trailing gap in a toolbar/header: a flex item with flex:1 capped by max-inline-size stops growing and leaves empty space after the last item. Push the right-hand cluster with margin-inline-start:auto on its first element.
• Mobile nav must not overlap. Putting the sidebar and main in the same grid area makes an opened sidebar paint over content. On mobile switch the shell to display:block so opening the sidebar pushes main down. Reference: ${CLAUDE_SKILL_DIR}/../../../examples/component-states/app-shell.html.

Icons — real lucide, referenced by name (never hand-draw paths)

Hand-approximated SVG path data renders as broken glyphs (a help "?" became a dot; settings became a hamburger). Use verbatim lucide paths, referenced by name via an injected <symbol> sprite — ${CLAUDE_SKILL_DIR}/../../../examples/component-states/icons.js defines each icon once and <svg class="ico" aria-hidden="true"><use href="#i-NAME"/></svg> uses it. No per-use path duplication, no network, offline + gate-safe. Add a new icon to icons.js once; never paste raw paths into markup. (Inline lucide is acceptable only if the path is copied verbatim from lucide.) .ico{stroke:currentColor;fill:none;stroke-width:2} — color via currentColor.

Graphical / icon-only controls (3:1, theme-stable)

A no-text control (carousel dot, kebab, icon button) is held to 3:1 (WCAG 1.4.11), not 4.5 — verify_states applies this automatically when an element has no direct text node. Two traps it catches:

• An empty <button> keeps the UA color:buttontext (≈black) regardless of theme → set its color to the actual indicator color and drive the visual via currentColor (e.g. dot is a ::before{background:currentColor}), so the gate measures the real thing.
• Theme-flipping tokens (--color-chart-N, --color-surface-brand) invert between light/dark; white text or a teal indicator on them passes in one mode and fails the other. Use dark-aware values (override in [data-theme="dark"]) or stable tokens (--color-action-primary, --color-text-link which adapts) for avatars, active dots, and selected states.