A neighborhood marketplace with messaging, built by Claude Code on Elements

Swapmeadow is a full-stack app built with Claude Code on Elements.

Photo listings, priced or free, neighborhood search, buyer-seller threads, live pending and sold, and saved search email alerts.

Run this app on your machine. Use this demo as inspiration, or as the starting point for your own app. Your agent creates a new app with this one as the scaffold, and you prompt it to add whatever features you want.

How it's built

Swapmeadow needed photo uploads, listings kept to each neighborhood, buyer and seller threads, pending and sold that change on every open page, and email when a new listing matches a saved search. Each of those is a part of Elements, so the agent spent its 25 minutes on the marketplace itself.

• Live listings. Listings are a LiveTable opened per neighborhood and per seller. When a seller marks an item pending or sold, every neighbor's browse page updates with it.

• Live threads and an inbox. Messages and conversations are LiveTables. A database trigger copies each new message onto its conversation, so the header badge and the inbox fill in as a reply arrives.

• Photo uploads as function calls. The sell page sends up to six photos to an @rpc as File values, which stores the listing and its photos in one transaction, and a route serves each photo under its content hash.

• Saved searches by email. Posting a listing schedules a background job that finds the neighbors whose saved searches match and sends each one a single email, however many of their searches it matches.

• Data from SQL files. Four migrations define the schema, add four neighborhoods, and seed eight neighbors with 30 listings, buyer and seller threads, saved items and saved searches, plus 34 credited listing photos.

• Sessions. Every write checks the signed-in user: the seller sets a listing's status, the two people in a thread post to it, and saves stay in your own neighborhood.

Why Elements

Elements is an integrated full-stack app framework and a project server. The project server checks the agent's work as it builds: it type-checks the server and browser code, analyzes the program, applies migrations and runs the tests, then reports the results to the agent. A security mistake, such as calling a server-only function from the browser, is a compile error. The agent reads the report and fixes its own mistakes before it tells you a feature is done. The same checks run on every feature you ask for next.