Vercel AI SDK

The Vercel AI SDK supports language-model middleware. Benchspan ships an asMiddleware() helper that scans the prompt before the model is invoked.

TypeScript only. The Vercel AI SDK has no official Python equivalent.

Install

npm install @benchspan/sdk ai @ai-sdk/openai

Usage

route.ts

import { BenchGuard, InjectionDetectedError } from "@benchspan/sdk";
import { wrapLanguageModel, generateText } from "ai";
import { openai } from "@ai-sdk/openai";

const guard = new BenchGuard({ apiKey: "ag_live_...", agent: "vercel-app" });

const model = wrapLanguageModel({
  model: openai("gpt-5"),
  middleware: guard.asMiddleware(),
});

try {
  const { text } = await generateText({
    model,
    prompt: userInput,
  });
  return Response.json({ text });
} catch (e) {
  if (e instanceof InjectionDetectedError) {
    return Response.json(
      { error: "Suspicious content detected" },
      { status: 400 },
    );
  }
  throw e;
}

With streaming

Works identically with streamText:

import { streamText } from "ai";

const result = streamText({
  model,   // wrapped model from above
  prompt: userInput,
});

return result.toDataStreamResponse();

If an injection is detected, the middleware throws before the stream is created, so your error handler fires normally.

With tool calls

When tools are involved, the middleware scans tool outputs as they flow back into the prompt:

const result = await generateText({
  model,
  prompt: "Summarize my latest email",
  tools: {
    read_email: tool({
      description: "Read an email by ID",
      parameters: z.object({ id: z.string() }),
      execute: async ({ id }) => mailClient.get(id).body,
    }),
  },
  maxSteps: 5,
});

Each time read_email returns and its output is added to the prompt, BenchGuard scans it. An injection in the email body aborts the run before the next model call.

What gets scanned

Every user and tool message in params.prompt before the model call. system and assistant messages are skipped.

Getting Started

Concepts

SDKs

Framework Integrations

Install

Usage

With streaming

With tool calls

What gets scanned

​Install

​Usage

​With streaming

​With tool calls

​What gets scanned

Install

Usage

With streaming

With tool calls

What gets scanned