penpot-build-screen — brief to on-system screen

1. Title + How it works

penpot-build-screen turns a brief into a crafted, on-system screen; every mutation goes through execute_code; validate visually with export_shape; read structure with penpotUtils.shapeStructure (full tool surface: shared/penpot-mcp-tool-reference.md). It first discovers the existing design system (tokens + components via penpot-foundations / the local library), then builds the screen section by section inside flex Boards, binding tokens and reusing components — never generating an entire screen in one call.

2. The One Rule That Matters Most

Reuse the system; build incrementally. Prefer existing components and semantic tokens over raw shapes. Build one section, checkpoint with an export_shape, then continue. If no system exists, bootstrap only a minimal one (hand off to penpot-foundations for anything substantial).

3. Penpot MCP Tool Reference

Full surface: shared/penpot-mcp-tool-reference.md. Key calls: penpot.createBoard()/addFlexLayout() for the screen and sections; penpot.library.local.components + comp.instance() to reuse components; shape.applyToken for token binding; export_shape('selection'|'page') at checkpoints.