Interface Design

Turn an approved experience model into a concrete, product-specific interface direction. Own interface decisions and non-production design specimens; never write durable product code.

Task: $ARGUMENTS (if empty, infer the desired interface outcome)

Routing Precedence

1. PR, diff, or review feedback → code-review; stop this skill.
2. Confirmation of a completed feature → verify; stop this skill.
3. Read-only composition, visual-system, or UI-craft critique → run audit here.
4. New or materially changed product surface → product-craft owns orchestration; require READY FOR INTERFACE before interface planning.
5. A change limited to interface-owned sections of an approved contract → run delta here.
6. Whenever design independently triggers, finish the required surface gates before technical planning; no durable write occurs here.

Parallel sub-agents may assist only below this owner after boundaries are approved. They never own interface direction.

Modes

Default behavior is verb-free: infer the smallest applicable path.

• audit — inspect the existing interface against its job, contract, captured system, and quality floor. Read-only.
• redesign — propose a materially different composition or art direction while preserving approved experience scope. Any job, IA, state, recovery, or microcopy change emits EXPERIENCE DELTA REQUIRED.
• study — extract structural design principles from a user-supplied screenshot or URL, diagnose what makes them work, and ask for acceptance before applying them. Borrow logic, not costume.
• delta — propose changes only to named interface-owned sections; preserve all unaffected contract sections.
• Default — produce the Seed or Full interface direction requested by product-craft.

Owned Contract Sections

• Surface Type & Craft Profile
• Visual System
• Component Rules
• Responsive & Accessibility
• Performance & Formatting
• Do / Don't

Composition, macrostructure, and hierarchy are expressed through these sections and constrained by the approved UX Model. references/interface-contract.md explains the concreteness bar; it is not another schema.

Required Context

1. The approved Experience gate and its affected experience-owned contract sections.
2. Nearest applicable design-contract.md, captured product system, representative screens, theme/tokens, and used component primitives.
3. ../product-craft/references/contract-schema.md, ../product-craft/references/quality-floor.md, and ../product-craft/references/output-formats.md.
4. The one applicable profile in references/medium-profiles.md for the declared medium, and references/surface-profiles.md.
5. references/reference-study.md before drawing candidates for any new direction. Study how this job has already been solved well; candidates drawn without it converge on defaults.
6. references/concept-stage.md when direction is being chosen or materially changed, or when redesign/study runs.
7. references/interface-contract.md for Full work or a contract delta that changes system/component rules.

Workflow

1. Confirm Experience Authority

For new/material work, require Experience gate: READY FOR INTERFACE, the approved experience-stage obligations, and experience_approved recorded from explicit user evidence. Preserve every row verbatim. Treat jobs, IA, screen inventory, content priority, flows, states, recovery, navigation intent, and microcopy intent as constraints. If interface exploration exposes a needed change, mark the affected interface obligation GAP, emit EXPERIENCE DELTA REQUIRED, and stop that path.

Audits may inspect an existing surface without a gate because they are read-only. Findings do not authorize edits.

2. Classify the Surface

Select the primary surface profile before choosing craft rules. Mixed surfaces may use multiple profiles only when scope boundaries are explicit. The quality floor outranks profiles; the approved contract outranks profile defaults.

3. Commit Composition and Direction

Macrostructure follows the approved information and flow model. Study references first, then use the concept method to draw candidates that differ in structure rather than in coat. Choose structural relationships, hierarchy, density, and component voice together instead of assembling independently fashionable defaults.

Candidates are single self-contained artifacts in the declared medium's own substrate with realistic content, compared on the same screen and the same data — see references/medium-profiles.md for what that file is. Render and inspect each at both extremes of that medium's adaptation axis, or at what its profile names instead, before showing it.

The user picks. Present the candidates with a recommendation and stop; taste is theirs to supply. Where there is no owner to ask — an external product surface — commit the sharpest direction that serves the job and survives every floor, and say that you did. A mixed or unclear audience is a gate.

The selected artifact becomes durable reference, not a discarded specimen. Record it in the contract's ## Artifact Ledger with its revision, selection coordinate, coverage, and the states and adaptation extremes actually reviewed; implementation reads it directly. Keep artifacts under .agents/, never in product source paths, and never wire APIs, persistence, production routing, or durable application state into them. Unselected candidates stay in the ledger as exploratory.

4. Make the Interface Contract Concrete

Specify only used dimensions and components. Name token/value/rule, component state, adaptation behavior, accessibility value, formatting behavior, design tension, and signature moment or justified N/A. A naked adjective is not a contract value.

Seed covers touched presentation decisions. Focused Delta covers approved changed sections only. Full covers all used dimensions, component families mapped to workflows, invariants with rationale, and known gaps.

5. Hand Off

Emit Surface Obligations rows for this stage using ../product-craft/references/output-formats.md: Stage: interface, each row deriving from the experience obligations it serves, evidence shaped as artifact:<ART-NNN>#<state>@<adaptation extreme>, and GAP where a required interface decision is missing or contradictory.

Record the selected artifact in ## Artifact Ledger. This stage's approval token is direction_selected, recorded only from the user's own words together with the chosen ART-NNN — never on their behalf.

Every applicable experience obligation needs at least one interface obligation deriving from it. Each interface row names one implementable requirement and cites inspected artifact evidence — artifact or render, state, adaptation extreme, and what was actually observed. Generating an artifact without looking at it is missing, not evidence.

Full work, changed macrostructure, and changed adaptation behavior need inspected evidence at both extremes the medium has. One representative screen per affected macrostructure is enough; do not multiply screens per row. A fixed canvas or genuinely unaffected presentation may use N/A:<concrete reason>.

Emit the exact Interface gate record. READY FOR BUILD requires concrete composition, direction, component presentation, adaptation behavior, and accessibility values, no open material interface question, every applicable experience obligation covered, every interface obligation at PASS with its evidence inspected, and direction_selected recorded from the user's own words. Implementation obligations stay PENDING until ui-engineering produces them. An unresolved or Focused interface delta stays owned by interface-design; a Full READY FOR BUILD handoff moves to design when its independent trigger applies. Do not name ui-engineering merely because it could implement next.

If design independently triggers, pass READY FOR BUILD to the general design workflow. UI engineering may start durable implementation only after the technical plan is persisted/active and the user has authorized build.

Do not edit the canonical contract unless the user authorized the file change and the applicable Interface gate is approved. Product-craft coordinates the canonical update and Decision Log.

Audit

An audit is read-only and identity-preserving.

1. Establish the lens: accessibility floor → approved contract or captured product system → selected surface profile.
2. Inspect the rendered surface and key states when feasible; name uninspected scope.
3. Report findings by severity (blocks the job, slows the job, polish) with observation, evidence, user-job impact, and concrete correction.
4. Separate strengths from friction. Test hierarchy, density, macrostructure, component consistency, adaptation behavior, and product specificity.
5. If changes are requested later, convert only accepted findings into Focused Delta or redesign.

Routed Stops

Emit EXPERIENCE DELTA REQUIRED for changes to Product Context, UX Model, Data & State Model, Interaction Model, or Microcopy. Emit CONTRACT GAP and mark the affected INT row GAP when required interface intent is missing or contradictory. An ownership-unclear gap routes to product-craft. Stop only the affected path and return ownership through product-craft.