Deploy Fullstack to Vercel

Deploy Fullstack to Vercel

Deploy a full-stack app with a React/Vite frontend and Python/FastAPI backend to Vercel as a serverless demo, OR deploy a Vellum-built app from the library. No auth required - meant for demos, portfolio pieces, and quick showcases.

When to Use

• User says "deploy this to Vercel", "host this", "publish this"
• User has a project with a frontend + backend they want live
• User wants to deploy a Vellum app that uses backend features (data store, custom routes)
• User wants a quick demo deployment (no persistent database needed)

Authentication

Vellum App Publishing

For publishing Vellum apps from the library, use the built-in publish_page tool. This is the preferred path — it uses the stored Vercel API token (vercel/api_token) via the brokered publish flow without exposing the token to shell commands.

The stored Vercel API token is reserved for brokered publish_page and unpublish_page actions only. Do not pass it to bash, curl, Vercel CLI commands, or proxy credential injection. Do not use network_mode: "proxied" with credential_ids for Vercel deployments.

Custom Full-Stack Deployments

For custom projects that need Vercel deployment (not Vellum app publishing):

1. Install the Vercel CLI with bun install -g vercel (not npm — npm is not available in the sandbox).
2. Use vercel login to authenticate interactively (opens browser for the user).
3. If the user does not want to use CLI auth, stop and ask them for an approved deployment path. Do not extract, inject, or shell with the stored API token.

Deploying a Vellum App

When the user asks to deploy a Vellum app from their library (from /workspace/data/apps/<app-name>/):

1. Detect Vellum Bridge Usage

Check the compiled app for Vellum bridge API usage:

grep -l "window\.vellum\.\|vellum\.fetch\|vellum\.data\|vellum\.sendAction" /workspace/data/apps/<app-name>/dist/*.js /workspace/data/apps/<app-name>/dist/*.html 2>/dev/null

If found, the app depends on the Vellum bridge and needs a shim to work standalone.