AI SDK 7 implementation and migration

Apply this skill to ai@7; use ai-sdk to resolve unknown versions and ai-sdk-6 for v6 maintenance. Match provider and UI package versions to the project. AI SDK 7 requires Node.js 22+ and AI SDK packages are ESM-only.

Read the resolved ai/docs/, provider docs and installed source/types first; each ai-sdk.dev/docs/... link in this skill has an offline copy under ai/docs/ (path mapping in ai-sdk). Harness, WorkflowAgent and migration guides live in ai/docs/03-ai-sdk-harnesses/, 03-agents/07-workflow-agent.mdx and 08-migration-guides/23-migration-guide-7-0.mdx; the companion packages ship only types. Use official docs or the matching repository tag when local docs are unavailable. Experimental package APIs need a fresh check before adding long-lived wrappers.

Important boundaries

• Text functions and ToolLoopAgent use instructions; loop limits use isStepCount. Core, agent and server UI-stream helpers use onEnd/onStepEnd (onFinish remains a deprecated alias); client useChat/Chat keeps onFinish.
• prepareStep instruction/message overrides carry forward. Results such as usage and tool arrays aggregate all steps; finalStep preserves final-step access, and is awaited for streams.
• Use runtimeContext for server loop state and schema-validated toolsContext for per-tool state. Neither is model-visible merely by being context.
• Approval, persistence and lifecycle differ across ToolLoopAgent, WorkflowAgent, HarnessAgent and provider-executed tools. Choose the runtime for the actual durability/permission requirements.
• Resolve model IDs and capabilities from the configured provider. Avoid overlapping reasoning settings: provider options can override top-level reasoning.

Core shape

Checked with ai@7.0.124, @ai-sdk/react@4.0.127, zod@4.6.5, React 19 and TypeScript 5.9: tsc --noEmit, plus a mock-model run through one tool step and the follow-up answer. A string model resolves through the AI Gateway.

// app/api/chat/route.ts
import { convertToModelMessages, createUIMessageStreamResponse, isStepCount, streamText, tool,
  toUIMessageStream, validateUIMessages, type InferUITools, type UIDataTypes, type UIMessage } from 'ai';
import { z } from 'zod';

const tools = {
  weather: tool({
    inputSchema: z.object({ city: z.string() }),
    execute: async ({ city }) => ({ city, celsius: 21 }),
  }),
};
export type ChatMessage = UIMessage<never, UIDataTypes, InferUITools<typeof tools>>;

export async function POST(req: Request) {
  const { messages } = await req.json();
  const uiMessages = await validateUIMessages<ChatMessage>({ messages, tools });
  const result = streamText({
    model: 'provider/model-id', // configured gateway ID, or a provider instance
    instructions: 'Answer briefly.',
    messages: await convertToModelMessages(uiMessages),
    tools,
    stopWhen: isStepCount(5),
  });
  return createUIMessageStreamResponse({ stream: toUIMessageStream({ stream: result.stream }) });
}

// app/page.tsx
'use client';
import { useChat } from '@ai-sdk/react';
import { DefaultChatTransport } from 'ai';
import type { ChatMessage } from './api/chat/route';

const transport = new DefaultChatTransport<ChatMessage>({ api: '/api/chat' });

export default function Chat() {
  const { messages, sendMessage, status } = useChat<ChatMessage>({ transport });
  return (
    <form action={(form) => void sendMessage({ text: String(form.get('text')) })}>
      {messages.map((m) => <div key={m.id}>{m.parts.map((part, i) =>
        part.type === 'text' ? <p key={i}>{part.text}</p>
        : part.type === 'tool-weather' && part.state === 'output-available'
          ? <p key={i}>{part.output.city}: {part.output.celsius} °C</p> : null)}</div>)}
      <input name="text" disabled={status === 'submitted' || status === 'streaming'} />
    </form>
  );
}

The v6 spellings (system, stepCountIs, result.toUIMessageStreamResponse()) still compile in 7.0.124; system and the response method are deprecated.

Read for the feature

• Agents: in-memory/durable execution and context.
• Harnesses: runtime-owned sessions and permissions.
• Core functions: output, stream and result contracts.
• Tools: approval boundaries, MCP Apps and sandbox handles.
• UI hooks: UI streams, approval and resumption.
• Migration: semantic changes and codemods.
• Telemetry: registration and data controls.
• Media/files: provider references and capability gates.
• Examples: current official implementations.

Typecheck and exercise the changed multi-turn, tool, stream or resume path. A successful compile does not prove approval policy or persistence behavior.