TypeScript SDK V2 session API (removed) changed

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# TypeScript SDK V2 session API (removed)

> Reference for the removed V2 TypeScript Agent SDK session API, with session-based send/stream patterns for multi-turn conversations.

<Warning>
  The V2 session API is no longer supported. TypeScript Agent SDK 0.3.142 removes `unstable_v2_createSession`, `unstable_v2_resumeSession`, `unstable_v2_prompt`, and the `SDKSession` and `SDKSessionOptions` types.

  To migrate, use the [`query()` API](/docs/en/agent-sdk/typescript) and the [session options](/docs/en/agent-sdk/sessions) it accepts. Pass an `AsyncIterable<SDKUserMessage>` for multi-turn conversations, or `options.resume` to continue a saved session. This page is kept for reference if you maintain code on Agent SDK 0.2.x or earlier.
</Warning>

V2 was an experimental session API that removed the need for async generators and yield coordination. Instead of managing generator state across turns, each turn was a separate `send()`/`stream()` cycle. The API surface reduced to three concepts:

* `createSession()` / `resumeSession()`: Start or continue a conversation
* `session.send()`: Send a message
* `session.stream()`: Get the response

## Installation

Agent SDK 0.2.x is the last version that includes the V2 interface. The package version jumped from 0.2.x directly to 0.3.142, so the removal version above and the install pin below describe the same boundary. To install the last V2-compatible release, pin the major and minor version:

```bash theme={null}
npm install @anthropic-ai/[email protected]
```

<Note>
  The SDK bundles a native Claude Code binary for your platform as an optional dependency, so most installs need no separate Claude Code install. See the [quickstart's install note](/docs/en/agent-sdk/quickstart) for the installs that need one.
</Note>

## Quick start

### One-shot prompt

For simple single-turn queries where you don't need to maintain a session, use `unstable_v2_prompt()`. This example sends a math question and logs the answer:

```typescript theme={null}
import { unstable_v2_prompt } from "@anthropic-ai/claude-agent-sdk";

const result = await unstable_v2_prompt("What is 2 + 2?", {
  model: "claude-opus-4-7"
});
if (result.subtype === "success") {
  console.log(result.result);
}
```

<details>
  <summary>See the same operation in V1</summary>

  ```typescript theme={null}
  import { query } from "@anthropic-ai/claude-agent-sdk";

  const q = query({
    prompt: "What is 2 + 2?",
    options: { model: "claude-opus-4-7" }
  });

  for await (const msg of q) {
    if (msg.type === "result" && msg.subtype === "success") {
      console.log(msg.result);
    }
  }
  ```
</details>

### Basic session

For interactions beyond a single prompt, create a session. V2 separates sending and streaming into distinct steps:

* `send()` dispatches your message
* `stream()` streams back the response

This explicit separation makes it easier to add logic between turns (like processing responses before sending follow-ups).

The example below creates a session, sends "Hello!" to Claude, and prints the text response. It uses [`await using`](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-5-2.html#using-declarations-and-explicit-resource-management) (TypeScript 5.2+) to automatically close the session when the block exits. You can also call `session.close()` manually.

```typescript theme={null}
import { unstable_v2_createSession } from "@anthropic-ai/claude-agent-sdk";

await using session = unstable_v2_createSession({
  model: "claude-opus-4-7"
});

await session.send("Hello!");
for await (const msg of session.stream()) {
  // Filter for assistant messages to get human-readable output
  if (msg.type === "assistant") {
    const text = msg.message.content
      .filter((block) => block.type === "text")
      .map((block) => block.text)
      .join("");
    console.log(text);
  }
}
```

<details>
  <summary>See the same operation in V1</summary>

  In V1, both input and output flow through a single async generator. For a basic prompt this looks similar, but adding multi-turn logic requires restructuring to use an input generator.

  ```typescript theme={null}
  import { query } from "@anthropic-ai/claude-agent-sdk";

  const q = query({
    prompt: "Hello!",
    options: { model: "claude-opus-4-7" }
  });

  for await (const msg of q) {
    if (msg.type === "assistant") {
      const text = msg.message.content
        .filter((block) => block.type === "text")
        .map((block) => block.text)
        .join("");
      console.log(text);
    }
  }
  ```
</details>

### Multi-turn conversation

Sessions persist context across multiple exchanges. To continue a conversation, call `send()` again on the same session. Claude remembers the previous turns.

This example asks a math question, then asks a follow-up that references the previous answer:

```typescript theme={null}
import { unstable_v2_createSession } from "@anthropic-ai/claude-agent-sdk";

await using session = unstable_v2_createSession({
  model: "claude-opus-4-7"
});

// Turn 1
await session.send("What is 5 + 3?");
for await (const msg of session.stream()) {
  // Filter for assistant messages to get human-readable output
  if (msg.type === "assistant") {
    const text = msg.message.content
      .filter((block) => block.type === "text")
      .map((block) => block.text)
      .join("");
    console.log(text);
  }
}

// Turn 2
await session.send("Multiply that by 2");
for await (const msg of session.stream()) {
  if (msg.type === "assistant") {
    const text = msg.message.content
      .filter((block) => block.type === "text")
      .map((block) => block.text)
      .join("");
    console.log(text);
  }
}
```

<details>
  <summary>See the same operation in V1</summary>

  ```typescript theme={null}
  import { query } from "@anthropic-ai/claude-agent-sdk";

  // Must create an async iterable to feed messages
  async function* createInputStream() {
    yield {
      type: "user",
      session_id: "",
      message: { role: "user", content: [{ type: "text", text: "What is 5 + 3?" }] },
      parent_tool_use_id: null
    };
    // Must coordinate when to yield next message
    yield {
      type: "user",
      session_id: "",
      message: { role: "user", content: [{ type: "text", text: "Multiply by 2" }] },
      parent_tool_use_id: null
    };
  }

  const q = query({
    prompt: createInputStream(),
    options: { model: "claude-opus-4-7" }
  });

  for await (const msg of q) {
    if (msg.type === "assistant") {
      const text = msg.message.content
        .filter((block) => block.type === "text")
        .map((block) => block.text)
        .join("");
      console.log(text);
    }
  }
  ```
</details>

### Session resume

If you have a session ID from a previous interaction, you can resume it later. This is useful for long-running workflows or when you need to persist conversations across application restarts.

This example creates a session, stores its ID, closes it, then resumes the conversation:

```typescript theme={null}
import {
  unstable_v2_createSession,
  unstable_v2_resumeSession,
  type SDKMessage
} from "@anthropic-ai/claude-agent-sdk";

// Helper to extract text from assistant messages
function getAssistantText(msg: SDKMessage): string | null {
  if (msg.type !== "assistant") return null;
  return msg.message.content
    .filter((block) => block.type === "text")
    .map((block) => block.text)
    .join("");
}

// Create initial session and have a conversation
const session = unstable_v2_createSession({
  model: "claude-opus-4-7"
});

await session.send("Remember this number: 42");

// Get the session ID from any received message
let sessionId: string | undefined;
for await (const msg of session.stream()) {
  sessionId = msg.session_id;
  const text = getAssistantText(msg);
  if (text) console.log("Initial response:", text);
}

console.log("Session ID:", sessionId);
session.close();

// Later: resume the session using the stored ID
await using resumedSession = unstable_v2_resumeSession(sessionId!, {
  model: "claude-opus-4-7"
});

await resumedSession.send("What number did I ask you to remember?");
for await (const msg of resumedSession.stream()) {
  const text = getAssistantText(msg);
  if (text) console.log("Resumed response:", text);
}
```

<details>
  <summary>See the same operation in V1</summary>

  ```typescript theme={null}
  import { query } from "@anthropic-ai/claude-agent-sdk";

  // Create initial session
  const initialQuery = query({
    prompt: "Remember this number: 42",
    options: { model: "claude-opus-4-7" }
  });

  // Get session ID from any message
  let sessionId: string | undefined;
  for await (const msg of initialQuery) {
    sessionId = msg.session_id;
    if (msg.type === "assistant") {
      const text = msg.message.content
        .filter((block) => block.type === "text")
        .map((block) => block.text)
        .join("");
      console.log("Initial response:", text);
    }
  }

  console.log("Session ID:", sessionId);

  // Later: resume the session
  const resumedQuery = query({
    prompt: "What number did I ask you to remember?",
    options: {
      model: "claude-opus-4-7",
      resume: sessionId
    }
  });

  for await (const msg of resumedQuery) {
    if (msg.type === "assistant") {
      const text = msg.message.content
        .filter((block) => block.type === "text")
        .map((block) => block.text)
        .join("");
      console.log("Resumed response:", text);
    }
  }
  ```
</details>

### Cleanup

Cut at 300 lines. The page has the rest.