Creating Apps For LLMs

Creating Apps For LLMs

ChatGPT apps are conversational experiences that extend ChatGPT through tools and custom UI views. 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 view—the human interacts with it, the LLM sees its state. Internalize this before writing code: the view 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.

Building an ecommerce app? → Read ecommerce.md first.

No SPEC.md? → Read discover.md first. Nothing else until SPEC.md exists.

SPEC.md exists? → Read SPEC.md, then follow architecture.md to design the change. Update SPEC.md, then read the relevant Implementation references below before writing code.

Migrating from Skybridge < 0.36.x? → Read migrate-to-v1.md first. Users may reference skybridge >= 0.36.x as v1.

Migrating from Skybridge 1.x to 2.x? → Fetch the v2.0.0 release notes first and follow them.

Setup

1. Copy template → copy-template.md: when starting a new project with ready SPEC.md
2. Run locally → run-locally.md: when ready to test, need dev server or ChatGPT connection
3. Evals → evals.md: when checking that a real model reaches the right tools from natural prompts, in a test

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 view data fetching
• State and context → state-and-context.md: when persisting view UI state and updating LLM context
• Prompt LLM → prompt-llm.md: when view 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