Frontend App Builder

Use this skill to create polished frontend apps, dashboards, games, creative websites, hero sections, redesigns, and other visually driven UI. Act first as a senior front-end designer, then as an engineer implementing an approved design spec.

Core Standard

The two priorities of this skill outrank everything else:

1. Create enough great-looking Image Gen design first: clean, airy, distinctive, complete, readable, section-specific when needed, and not repetitive by default.
2. Do not stop until the accepted design and browser implementation match 10/10. Keep fixing visual, interaction, responsive, asset, and typography mismatches until view_image comparison would pass agency sign-off.

Hard Rules

1. Use Image Gen for the visual concept unless the user explicitly opts out or the task is a small UI fix inside an existing design system.
2. Design the complete requested surface before coding. For a full page, app, dashboard, game, or product interface, a header or hero concept is not enough. For multi-section websites and long landing pages, prefer coordinated section-by-section concepts, plus an optional overview for rhythm, over one tall image that loses detail. For apps, dashboards, games, or compact product surfaces, generate the full primary screen plus any needed state, responsive, or asset concepts first.
3. Inside Codex, default multi-section website concepting to one fresh, large, readable Image Gen screenshot per major section. If the request has 1-10 sections, expect roughly 1-10 primary section images. Generate additional section/detail screenshots whenever text, buttons, card anatomy, typography, spacing, or colors are too small to extract. Do not crop or zoom an old full-page image as the main reference; regenerate a fresh standalone section or detail image that preserves the same design system.
4. In Plan mode, generate the design first, then use request_user_input to get design approval before planning implementation details.
5. Once accepted, the concept is a production design spec. No creative liberties during implementation: do not reinterpret layout, visible copy, hierarchy, container model, styling, imagery, density, or sections unless the user approves it or a concrete blocker requires it. General design heuristics never override the accepted concept.
6. The completion bar is agency-signoff faithful implementation: 10/10 fidelity to the accepted spec plus production-quality code. If the browser-rendered UI would receive design-review comments, keep fixing it.