Can a prompt replace Rows?

Build a spreadsheet with a formula function that fetches an HTTP API and parses its JSON response into cells — Rows' actual core trick, treating any API as a live data source. Use Next.js/TypeScript with a spreadsheet-grid library or a simple custom grid implementation. Implement a formula function, usable in a cell, that takes a URL and an optional header set for an API key or bearer token, entered once and stored encrypted, referenced by name in the formula rather than pasted in plaintext, fetches it server-side, never from the browser, to keep credentials off the client, and maps a JSON path from the response into a target range of cells. Support standard spreadsheet formulas referencing the fetched data. Cache each fetch's result until manually refreshed, since automatic scheduled refresh is real additional infrastructure. Add clear error display in-cell when a fetch fails, such as a wrong URL, auth error, or unparseable response, rather than a blank cell. Do not build pre-built integrations with authentication already handled for specific named services, a multiplayer collaborative engine, or publishing a sheet as an interactive web app — those are out of scope; this is a generic fetch-and-parse formula against any API you point it at. Requires hosting; no specific external API required, since it works against whatever URL you give it.