Functions and their kinds
What a function is, the four kinds (Code, Ask AI, Sort into categories, Agent), what each may do, and what it costs.
Try, test, publish, disable
The life of a function version, from a draft you try, through tests, to a published version callers pin, and how to switch one off without breaking anyone.
Use functions in apps
Import a published function or workflow into a hand-built app, call it from a button with the app SDK, show progress and reuse results, and handle errors.