Jev x AI SDK Form Router

Three forms use Jev to route submissions by context, with openai/gpt-5.6-luna-fast handling uncertain or failed evaluations. Includes editable samples, routing details, and optional email delivery.

Tech Stack

Getting Started

Prerequisites

• Node.js 22+
• pnpm package manager

1. Clone and install

git clone https://github.com/vercel-labs/jev-ai-sdk-form-router.git
cd jev-ai-sdk-form-router
pnpm install

2. Configure AI Gateway

Routing a submission, including a sample, makes live model calls and requires AI Gateway access to both typesafe-ai/jev and openai/gpt-5.6-luna-fast. Choose one of the authentication options below, or skip this step to explore the forms and load sample inputs without generating routing results.

API Key

Copy the environment example:

cp .env.example .env.local

Create a Vercel AI Gateway key and set AI_GATEWAY_API_KEY in .env.local.

Vercel OIDC

Vercel deployments use automatic OIDC authentication through the SDK, without an API key. To use OIDC locally, install the Vercel CLI if needed, then link the project and pull its environment variables:

npm install --global vercel
vercel link
vercel env pull .env.local

3. Start the app

pnpm dev

Open localhost:3000. The home page redirects to /leads.

How Routing Works

1. Zod validates the submission against the fields in lib/examples.ts.
2. Jev evaluates the complete submission using AI SDK’s experimental_evaluate and selects an allowed team/specialty combination.
3. The app accepts Jev’s choice when its confidence is at least 95%.
4. If confidence is lower, missing, or invalid, or Jev fails, openai/gpt-5.6-luna-fast independently evaluates the same submission and criteria using generateText and Output.object. Its choice becomes final.
5. The result includes the destination, deciding model, Jev statistics, model timings, and an email preview.

Confidence and selected-option probability are separate metrics. The threshold uses the unrounded value of providerMetadata.typesafe.confidence.destination. Jev’s displayed statistics remain attached to its original evaluation when the fallback model makes the final decision.

Provider calls have bounded timeouts and one transient retry. If both models fail, the app returns a retryable error and sends no email.

Optional email delivery

Set up Resend through Vercel Marketplace

The Resend Marketplace integration creates a Resend account and connects it to your Vercel project. During setup, you can select an existing Vercel domain or purchase one.

1. If you haven't already, install the Vercel CLI and link the project:

   npm install --global vercel
   vercel link
   

2. Start the integration setup:

   vercel i resend
   

3. Select an existing domain or purchase one through Vercel, then choose a plan and connect your project. Complete onboarding in Resend, choose Auto configure to add the DNS records, and wait for domain verification.

4. Pull the integration's environment variables for local development:

   vercel env pull .env.local
   

5. Confirm RESEND_API_KEY is present and set RESEND_FROM in .env.local to a sender address on your verified domain.

If you already have a Resend account, you can instead set RESEND_API_KEY and RESEND_FROM directly using your existing API key and a verified domain.

Configure receiving inboxes

In lib/recipients.ts, replace null with a valid inbox for every destination on the form you want to enable. Multiple destinations can share an inbox.

An unchecked Email the receiving team checkbox appears on configured forms.

Recipient keys are derived from the destination registry and checked by TypeScript. Addresses stay server-side. The validated submitter email becomes replyTo. Forms with unconfigured inboxes continue to provide previews.

Email failures preserve the routing result. Resend acceptance does not confirm inbox delivery. If a connection drops after an opted-in submission, check Resend before resubmitting.

Customization

Keep the experimental AI SDK version pinned and rerun the checks when upgrading it.

Checks

pnpm fix       # Format and apply lint fixes
pnpm validate  # Lint, type check, Knip, and tests
pnpm build     # Production build

Tests mock the model providers and Resend. They make no external calls. Coverage includes confidence thresholds, fallback decisions, validation, recipient configuration, and delivery retries.

Resources

• Jev documentation
• Jev and AI SDK guide
• AI SDK evaluation
• React Email