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cascadeflow integrates with the Vercel AI SDK as middleware, providing cascade routing for server-side AI applications with streaming support. The goal is still runtime intelligence inside the application loop: maintain streaming UX, keep tool execution server-side, and avoid a proxy hop on every model step.

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Install

npm install @cascadeflow/vercel-ai

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Quick Start

import { createChatHandler } from '@cascadeflow/vercel-ai';
import { CascadeAgent } from '@cascadeflow/core';

const agent = new CascadeAgent({
  models: [
    { name: 'gpt-4o-mini', provider: 'openai', cost: 0.000375 },
    { name: 'gpt-4o', provider: 'openai', cost: 0.00625 },
  ],
});

const handler = createChatHandler(agent, {
  protocol: 'data',           // AI SDK v4 data stream
  tools,                       // Tool definitions
  toolHandlers,                // Server-side tool execution
  maxSteps: 5,                 // Multi-step tool loops
});

// Use in Next.js API route, Express, or any Node.js server
export const POST = handler;

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Features

  • AI SDK v4 data stream and AI SDK v5/v6 UI streams
  • useChat multi-turn support — conversation history preserved
  • parts message format (AI SDK v6)
  • Tool call streaming visibility — see tool calls as they happen
  • Server-side tool execution via toolExecutor or toolHandlers
  • Multi-step controls: maxSteps, forceDirect
  • Cascade decision stream parts — optional metadata in the stream
  • Request-level overrides with allowlist + shared-secret guard

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Why This Integration Matters

  • Preserves fast real-time UX while adding runtime control
  • Keeps governance logic close to tool loops and streaming responses
  • Avoids the compounded latency cost of external proxy mediation

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Multi-Turn Chat

import { useChat } from 'ai/react';

export default function Chat() {
  const { messages, input, handleSubmit, handleInputChange } = useChat({
    api: '/api/chat',
  });

  return (
    <div>
      {messages.map((m) => (
        <div key={m.id}>{m.content}</div>
      ))}
      <form onSubmit={handleSubmit}>
        <input value={input} onChange={handleInputChange} />
      </form>
    </div>
  );
}

​
Request Overrides

Override cascade behavior per request (protected by shared secret): 
const handler = createChatHandler(agent, {
  protocol: 'data',
  allowOverrides: ['forceDirect', 'maxSteps'],
  overrideSecret: process.env.OVERRIDE_SECRET,
});

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Result

40-85% cost savings for Vercel AI SDK applications with streaming support and zero client-side changes.
Examples on GitHub: packages/core/examples/nodejs/vercel-edge.ts | vercel-ai-nextjs/