Core Concepts

Note

We assume that you are already familiar with ChatGPT Apps, MCP Apps, and MCP Servers. If you’re not, read Fundamentals first.

Five concepts power frac:

shuffle Write Once, Run Everywhere

Write once, run anywhere - ChatGPT, Claude, Goose, VSCode, etc.

arrows-rotate Data Flow

How data moves between server, host, and view

brain LLM Context Sync

Keep the model aware of view state via data-llm

bolt Fast Iteration

Local development with instant feedback

shield-check Type Safety

End-to-end TypeScript types from server to view

Tip

Start with Write Once, Run Everywhere — it explains how frac abstracts runtime differences so you can focus on your app.