What problem does it solve? Users often want a quick personal tool — a dashboard, tracker, calculator, chart, or slide deck — without setting up a real project, build pipeline, or deployment. This Skill creates persistent, single-user visual apps inside the assistant sandbox and iterates on them over time, while routing complex or shippable products to a proper project folder with a coding agent. ## Core Features & Use Cases - Sandboxed app creation: Scaffolds multi-file Preact + TSX apps (formatVersion 2) via app_create, compiles with esbuild through app_refresh, and surfaces a preview card with app_open. - Design system and widgets: Auto-injected --v-* design tokens, .v-* utility classes, and window.vellum.widgets.* chart/formatting utilities with automatic light/dark mode and responsive mobile-to-desktop baselines. - Server-side persistence: Custom route handlers in routes/*.ts served at /v1/x/... give apps JSON-file CRUD storage, full Node API access, and event publishing to connected clients. - Use Case: A user says "make me a habit tracker." The Skill loads the frontend-design skill, scaffolds the app, writes a routes/habits.ts CRUD handler, compiles once, and shows a preview card — then iterates live when the user asks for changes. ## Quick Start Ask the assistant to build a personal dashboard, tracker, calculator, chart, or slide deck for your own use and it will create and preview a persistent sandbox app.
