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If you pay for ChatGPT (Plus, Pro or Business), you can use that plan to build inside AI Sync. No API key, no extra AI bill. You connect Codex, OpenAI’s assistant that runs on your ChatGPT plan, to your AI Sync account once. After that you type what you want, and it does the work in your account.
Codex only sees your account, and only after you sign in and approve it. It can do what your AI Sync login can do, nothing more.

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🧭 Set it up (about 5 minutes, once)

1

Install or update Codex and sign in with ChatGPT

Open the Terminal app and run:
Choose Sign in with ChatGPT when asked. If you already have Codex, still run this: an older Codex can refuse your plan’s newest model.
2

Add your AI Sync account

Your browser opens an AI Sync sign-in page. Sign in with your normal AI Sync login and approve.
3

If no sign-in page opened

Then sign in and approve in the browser.
4

Check it worked

ai-sync should show OAuth in the Auth column.
You can also copy these commands in AI Sync: click your profile (top right) → Settings → Integration → MCP → Connect → Codex tab.

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💬 Three things to ask first

Open Codex (type codex in Terminal) and try:

Write a voice agent prompt

“Create a new inbound agent called Front Desk and write and save a prompt for a friendly medspa receptionist who answers Botox pricing questions and offers to book a consultation.”

Build a workflow

“Create a draft workflow: when a contact gets the tag no-show, wait one day, then send them a text asking to rebook. Leave it off so I can review it.”

Ask about your numbers

“How many calls did my reps make this week, and what was each rep’s connect rate?”
Ask for workflows as drafts and turn them on yourself after a look. Codex will do exactly what you ask, including turning things on.

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❓ Good to know

  • It uses your ChatGPT plan’s limits. Heavy use can hit your plan’s usage cap; it resets on ChatGPT’s schedule.
  • Prefer an API key? You can still paste an OpenAI key under Settings → Integration → OpenAI for workflow AI steps.
  • Disconnect any time: codex mcp logout ai-sync.
See also Connect your AI assistant (MCP) and Asking about your data.