Audit UI layouts with deterministic spatial measurements

deterministic-design is a reusable skill that catches AI-generated UI failures by rendering interfaces and measuring them with deterministic metrics rather than trusting a model's visual judgment. It provides two sub-skills: design-spatial performs layout audits using 8-pt grid spacing and computes centroid, optical-center, and pixel-oracle balance with annotated screenshots, while design-ux scores rendered UI against Nielsen's 10 heuristics plus interaction principles using a separate fresh-eyes judge that outputs a prioritized fix list.

Use this skill when AI-generated UI "looks off", appears misaligned or centered-mush, or fails usability checks - when you need to prove a layout is balanced and usable instead of trusting the model's eye. Compose it with any taste or token design skill before reporting design "done". The workflow requires a rendered UI or screenshot; it cannot validate components that have not been built or captured. Do NOT use this as a substitute for product judgment or user testing - automated scoring can miss brand nuance, copy tone, accessibility needs, and domain-specific user expectations.

You provide a rendered UI or screenshot of an interface. The design-spatial sub-skill returns layout audit data including centroid, optical-center, and pixel-oracle balance calculations, plus an annotated screenshot showing spatial measurements against an 8-pt grid. The design-ux sub-skill returns a usability score based on Nielsen's 10 heuristics and interaction principles, delivered as a prioritized list of fixes from a separate vision-based judge.

This skill is composable with any existing design skill, including the default Anthropic design skill. It lives as a subdir of ckw-design in the central repository and publishes separately as deterministic-design-skill. Load the two sub-skills as needed: design-spatial for layout audits and design-ux for usability audits.

This skill is for teams and developers who need to validate AI-generated UI with objective measurements rather than subjective visual assessment. It improves existing design skills by adding a measurement and judgment layer they lack - it doesn't just advise on taste, it renders, measures, and judges the output. It represents the determinism narrative in the skill ecosystem, with a sibling skill focused on human-in-the-loop workflows (lookdev).