name: chatgpt-app-builder
description: |
Guide developers through creating ChatGPT apps.
Covers the full lifecycle: brainstorming ideas against UX guidelines, bootstrapping projects, implementing tools/widgets, debugging, running dev servers, deploying and connecting apps to ChatGPT.
Use when a user wants to create or update a ChatGPT app / MCP server for ChatGPT, or use the Skybridge framework.

Creating ChatGPT Apps

ChatGPT apps are conversational experiences that extend ChatGPT through tools and custom UI widgets. They're built as MCP servers invoked during conversations.

⚠️ The app is consumed by two users at once: the human and the ChatGPT LLM. They collaborate through the widget—the human interacts with it, the LLM sees its state. Internalize this before writing code: the widget is your shared surface.

SPEC.md keeps track of the app's requirements and design decisions. Keep it up to date as you work on the app.

Setup

1. Discover → discover.md: when user has an idea but no SPEC.md yet
2. Copy template → copy-template.md: when starting a new project with ready SPEC.md
3. Run locally → run-locally.md: when ready to test, need dev server or ChatGPT connection

Architecture

Design or evolve UX flows and API shape → architecture.md

Implementation

• Fetch and render data → fetch-and-render-data.md: when implementing server handlers and widget data fetching
• State and context → state-and-context.md: when persisting widget UI state and updating LLM context
• Prompt LLM → prompt-llm.md: when widget needs to trigger LLM response
• UI guidelines → ui-guidelines.md: display modes, layout constraints, theme, device, and locale
• External links → open-external-links.md: when redirecting to external URLs or setting "open in app" target
• OAuth → oauth.md: when tools need user authentication to access user-specific data
• CSP → csp.md: when declaring allowed domains for fetch, assets, redirects, or iframes

Deploy

• Ship to production → deploy.md: when ready to deploy via Alpic
• Publish to ChatGPT Directory → publish.md: when ready to submit for review

Full API docs: https://docs.skybridge.tech/api-reference.md