# Next.js

URL: https://tailrace.dev/docs/integrations/nextjs

> Run Tailrace with the Vercel AI SDK in a Next.js App Router route - block secrets, tokenize PII, restore at egress.



Enforce data policy on AI SDK model calls in Next.js. Scan prompts before they reach a provider, scan completions on the way back, and restore tokenized PII at egress for your UI.

## Quickstart [#quickstart]

```ts
// app/api/chat/route.ts
import { createTailrace, PolicyViolationError } from "@tailrace/core";
import { withAiSdk } from "@tailrace/ai-sdk";
import { openai } from "@ai-sdk/openai";
import { generateText } from "ai";

const tailrace = withAiSdk(createTailrace());

export async function POST(req: Request) {
  const { prompt } = await req.json();
  const workflowId = req.headers.get("x-workflow-id") ?? crypto.randomUUID();

  const model = tailrace.model(openai("gpt-4o"), { workflowId, agent: "chat" });

  try {
    const result = await generateText({ model, prompt });
    const restored = await tailrace.restore(result.text, {
      boundary: { kind: "egress", sink: "ui" },
      identity: { agent: "chat" },
      workflowId,
    });
    return Response.json({ text: restored.output });
  } catch (err) {
    if (err instanceof PolicyViolationError) {
      return Response.json(
        { error: { type: "policy_violation", message: err.message } },
        { status: 422 },
      );
    }
    throw err;
  }
}
```

## Boundaries covered [#boundaries-covered]

| Location                | Tailrace boundary                              | Direction                         |
| ----------------------- | ---------------------------------------------- | --------------------------------- |
| Request prompt → model  | `{ kind: "model", provider: "openai/gpt-4o" }` | Outbound to provider              |
| Model completion → app  | Same model boundary                            | Inbound from provider             |
| HTTP response → browser | `{ kind: "egress", sink: "ui" }`               | Restore (explicit `restore` call) |
| Tool args / results     | `{ kind: "tool", name, direction }`            | Out / in (with `wrapTools`)       |

Provider strings use `${providerId}/${modelId}`. Policy globs like `openai/*` match accordingly.

## Runnable example [#runnable-example]

```bash
git clone <repo>
cd tailrace
pnpm install
pnpm --filter example-nextjs-ai-sdk dev
```

Open [http://localhost:3000](http://localhost:3000).

| Button                     | Expected outcome                                     |
| -------------------------- | ---------------------------------------------------- |
| Run A - block secret       | 422, `entity: api_key`, secret never hits mock model |
| Run B - tokenize + restore | 200, UI shows real email, `modelSaw` shows token     |

Source: [`examples/nextjs-ai-sdk`](https://github.com/tailrace/tailrace/tree/main/examples/nextjs-ai-sdk) in the monorepo.

## Edge vs Node [#edge-vs-node]

The example sets `export const runtime = "nodejs"`. `@tailrace/core` and `@tailrace/ai-sdk` also run on Edge when your provider and AI SDK usage are Edge-compatible. Keep vault keys in environment variables (`TAILRACE_VAULT_KEY` or `createTailrace({ vault: { key } })`).

## Guides [#guides]

* [Protect PII in the AI SDK](/docs/guides/protect-pii-in-ai-sdk)
* [Quickstart](/docs/get-started/quickstart)

## Reference [#reference]

* [AI SDK package](/docs/reference/ai-sdk)