Product Design

Product Design

Decide what the interface should do, then route who builds and verifies it: pick the right interaction, make scope and consequence clear, cover reality beyond the happy path.

• IS: the decision layer. From a brief, spec, mockup, intent, or existing UI: choose the interaction and control, name the object, scope, and consequence of each action, settle reversibility and the safeguard it implies, enumerate every reachable state, set resilience expectations, and require accessibility as task completion. It decides, then routes build, verification, and wording out.
• IS NOT:
  • whether a feature deserves investment or fits the product: out of scope; state it as an open product question.
  • building or styling UI, visual direction, palettes, type: ui-design.
  • auditing the built result (rendered quality, a11y markup, keyboard, layout, performance, React or Next code-level UX with a ship verdict): ui-design Audit mode.
  • copy wording, persuasion, or AI-ism removal: ghostwriter.
  • motion, gesture physics, or deep typography: ui-animation, typography-audit.
  • whether an agentic feature earns trust: ax-audit.

Routing boundary

product-design owns action semantics, scope, reversibility, and contested state choices. ui-design builds and styles those states. ui-animation owns timing, gestures, and measured motion. A routine missing loading or error state stays with the UI build; a gesture replacing a control needs a product decision and an accessible alternative before its physics.

Request modes

Resolve one mode from the user's verb and artifact before acting, then load that mode's references. references/rules.md loads in every mode: every finding cites a rule ID from it, and you cannot conclude that no rule governs a decision without the registry in front of you.

Review mode is about a flow, not an artifact. "Audit this component", "check my UI", and "design QA this page" point at built markup and belong to ui-design Audit mode. This skill's review asks whether the decisions behind a flow are right, and stops at decision altitude.

Modes chain: shape leads into spec; review leads into harden. When intent is ambiguous, use the narrowest mode the verb supports. A URL, screenshot, route, or component identifies scope; it does not authorize edits.

Whether a standard belongs in the consuming project's linter rather than in this skill is codebase-architecture's enforcement ladder. evals/evals.json never loads during a user task; it is the regression set for anyone changing this skill.

Workflow

Product design pass:
- [ ] Step 1: Classify the request into one mode
- [ ] Step 2: Locate authority (user constraints, project design system, AGENTS.md)
- [ ] Step 3: Load rules.md plus that mode's reference files
- [ ] Step 4: Write the internal brief (shape, spec, harden); stop and ask if job, outcome, or consequence is unfillable
- [ ] Step 5: Name object, scope, consequence, and reversibility for each action in scope (spec, action, review)
- [ ] Step 6: Enumerate reachable states and check coverage (shape, spec, harden)
- [ ] Step 7: Emit output with a rule ID or labeled coverage gap per finding or decision; route follow-on work to siblings
- [ ] Step 8: List unresolved product decisions

Steps 5 and 6 are mode-scoped because their references are: a pure action pass has no state matrix to enumerate, and a shape pass has no built actions to name yet.

Output length follows the work, not the template. A single settled decision is a short answer; drop the sections a pass did not need rather than filling them.

Decision authority

Conflict order, highest first:

1. The user's explicit goal and constraints.
2. Verified user and product evidence, and what the system actually does.
3. Project-canonical guidance: AGENTS.md or CLAUDE.md, the project's design system, routed sibling skills.
4. Sibling-skill ownership: route, do not duplicate.
5. This skill's standards (below).
6. General interface and platform conventions (WCAG 2.2, NN/g, Apple HIG, Material, GOV.UK), which references/rules.md cites per rule.

When a request spans authorities, name the owning skill and hand off.

Product design standards

Five pillars, each naming its rule IDs in references/rules.md and the reference that details it.

• Right interaction. Pick the control from the choice's shape; keep options visible and reversible; prefer inline disclosure over a modal; every gesture has a control alternative; choose the smallest coherent intervention. rule/control-matches-cardinality, rule/navigation-vs-action, rule/inline-before-modal, rule/no-nested-modals, rule/gesture-has-control-alternative, rule/smallest-intervention. Detail: references/product-judgment.md.
• Action naming and consequence. Name the object, scope, and consequence; settle reversibility first, then the pattern; an irreversible action gets review, check, or named confirmation; undo appears only when honest. rule/name-object-scope-consequence, rule/destructive-names-action, rule/destructive-proportional, rule/irreversible-action-safeguard, rule/undo-only-when-honest, rule/preserve-user-input. Detail: references/naming-and-copy.md.
• State coverage. Design every reachable state, not just the populated one: empty states name the object and a first action; errors explain and offer recovery; timers warn before they discard. rule/cover-reachable-states, rule/empty-state-action, rule/error-states-recovery, rule/loading-stable-labels, rule/time-limit-adjustable. Detail: references/surfaces.md.
• Resilience. Overflow, extreme data, localization and RTL, offline, and network failure are designed states; every fetch lands in one. Shares rule/cover-reachable-states: it is the same requirement pointed at adverse inputs. Detail: references/surfaces.md > Resilience. Whether the built UI renders them is ui-design Audit mode's check.
• Accessibility as task completion. Every control has a name; the primary flow completes by keyboard with visible focus; nothing already entered is retyped; authentication allows assistance; state and consequence are understandable, not just labeled. rule/accessible-name-required, rule/keyboard-complete-flow, rule/no-custom-focus-bypass, rule/no-redundant-entry, rule/auth-allows-assistance. Detail: references/interface-quality.md. Markup and target-size checks route to ui-design Audit mode.