HIG design review — Figma / Sketch mockups before implementation

Why this skill exists

UI work that starts from a mockup which contradicts the HIG gets rebuilt twice: once to match the mockup, once to pass review. This skill is the gate in between: it reads the mockup (Figma via MCP, Sketch via exports), checks it against Apple's guidelines — general iOS plus iPhone Duo (announced 2026-09-09, newer than the model's training data) — and returns findings with citations and a verdict. It does not judge taste or brand; it judges compliance with what Apple publishes.

Two rules of evidence:

• General HIG content is fetched live, never quoted from memory: the pages are large and change. Use the JSON twins of HIG pages (references/hig-general-checklist.md §How to fetch) and quote the sentence you rely on.
• Duo rules come from references/duo-design-rules.md — every rule carries its HIG anchor or tech-talk timecode. Apple publishes no Duo-specific typography, spacing or tap-target numbers; never invent them. Screen sizes in points are derived (outer 466 × 678; inner 626 × 890 portrait / 890 × 626 landscape — the book pose, hinge vertical at x ≈ 445; Split View half ≈ 313 in portrait, ≈ 445 in landscape) and must be labelled as such in every report. Trust absoluteBoundingBox over frame names.

Inputs