Skill Frontend Excellence

Frontend Excellence

Use this as the process layer for product UI. It does not own design-system tokens or application brand.

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Design system  = source of truth (components, tokens, themes, patterns)
This skill     = process (intent, creativity, preserve vs redesign, DoD)
Application    = product context (configured Design Profile)
Visual QA      = smoke evidence
Maestro        = orchestration / retries
Router         = discovery / invocation

Do not copy design-system documentation into this skill. Locate live metadata via adapters/design-system.md or the project's configured adapter.

This skill is for product surfaces (admin, authentication, portals, forms, tables). For cinematic marketing sites use skill-premium-web-experience. For a single visual polish pass use skill-impeccable. This skill coordinates those instead of replacing them.

Composition and precedence

Use one owner for each concern:

When more than one downstream skill applies, load at most two for a standard task. The top-level intent and Definition of Done remain owned here.

When to load

Natural-language requests such as:

• modernize esta tela
• migre MUI, Bootstrap ou outro design system para o sistema adotado pelo projeto
• melhore este formulário
• corrija o mobile
• refatore este frontend
• crie uma tela nova

Also load when the user asks for Visual QA, Design Profile, or frontend Definition of Done.

Step 0 — Classify intent (mandatory)

Derive, do not ask unless two intents are equally likely:

Posture:

Creativity (NONE|LOW|MEDIUM|HIGH) comes from the request and the application Design Profile. The stricter of the two wins.

Gold rule: refactor is not redesign. MIGRATE, REFACTOR, library upgrades, and React/router/TypeScript work default to PRESERVE + NONE.

Run scripts/classify-intent.mjs when available. Read only the matching workflow:

• CREATE
• REDESIGN
• IMPROVE
• MIGRATE / REFACTOR
• FIX
• REVIEW

Step 1 — Resolve the design system (mandatory)

Run node scripts/discover-design-system.mjs <project-root> and persist its structured result. Only status: resolved with confidence >= 0.80 permits new visual implementation. For ambiguous or unresolved, stop with BLOCKED_REQUIRES_USER_DECISION; ask whether to preserve local components, use a named project system, or explicitly propose a new visual base. Never choose by package popularity or model preference.

Step 2 — Load context

1. Application Design Profile: use the project's configured file, package export, or the bundled neutral fallback. Do not assume a repository layout.
2. Design-system metadata via the adapter. Never invent components.
3. Existing routes, tokens, i18n, tests, and startup commands from the app.
4. If PRESERVE: capture baseline screenshots before editing.

Step 3 — Implement under the right workflow

• CREATE → workflows/create.md
• REDESIGN + HIGH → workflows/redesign.md (directions before code)
• IMPROVE → workflows/improve.md
• MIGRATE / REFACTOR + PRESERVE → workflows/migrate.md
• FIX → workflows/fix.md
• REVIEW → workflows/review.md

Engineering, visual, accessibility, responsive, and maintainability rules are in standards.

Step 4 — Visual QA is part of the work

Build passing is not done. Run the checklist in validation/definition-of-done.md, with smoke details in validation/visual.md and validation/accessibility.md.

Preferred command (the path is relative to this skill package):

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node scripts/visual-qa.mjs --url <app-url> --out .frontend-excellence/visual-qa/

Viewports default to the shared smoke widths: 390, 768, 1280, 1440.

Hard failures (any one fails the task):

• console / page errors
• contrast below WCAG AA for normal text (4.5:1) except a documented design-system exception
• missing accessible name on controls
• page-level overflow on required viewports
• PRESERVE: unintended visual delta vs baseline

This is a smoke harness, not a complete WCAG audit. Score (validation/visual.md) never overrides a hard failure; use the project's accessibility tooling for certification.

Step 5 — Independent visual review

Produce structured findings even if the same agent implements:

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id: UI-001
severity: high
viewport: 390x844
component: LoginPanel
problem: Insufficient text contrast.
expected: WCAG AA 4.5:1
actual: measured or approximated ratio
action: Use a semantic text token that meets AA.

Do not conclude with “ficou bonito” or “ficou profissional”.

Guardrails

• Never force every app to look the same. A design system is vocabulary; the Design Profile is identity.
• Never recreate a design-system component. Search metadata first.
• Never start REDESIGN+HIGH by writing components. Produce 2–3 genuinely different directions first.
• Never mark frontend complete from compile/lint alone.
• Never overwrite uncommitted human work.
• Prefer the project's documented package subpath imports when the app already does; do not introduce a barrel that the tree-shaking contract forbids.
• Delegate visual craft to skill-open-design-ui, interaction states to skill-modern-ui-patterns, UX gate to skill-frontend-ux-guardrails, E2E to skill-webapp-testing.

Related Skills

• skill-open-design-ui
• skill-modern-ui-patterns
• skill-frontend-ux-guardrails
• skill-webapp-testing
• skill-impeccable
• skill-premium-web-experience
• skill-verification-before-completion
• skill-browser-agent

Verification

• Intent, posture, and creativity are written down before the first UI edit.
• Design-system metadata was consulted (or the adapter recorded that no supported system was found).
• Design Profile was loaded or explicitly recorded as missing.
• Visual QA artifacts exist under the project's configured output directory or the skill fixture run.
• Definition of Done checklist is complete for the intent.