---
title: メッセージのストリーミング
url: https://platform.claude.com/docs/ja/build-with-claude/streaming
description: テキスト、ツール使用、思考のデルタを含むMessages APIのレスポンスを、server-sent eventsを使用して段階的にストリーミングします。
---

Messageを作成する際に、`"stream": true`を設定すると、[server-sent events](https://developer.mozilla.org/en-US/Web/API/Server-sent%5Fevents/Using%5Fserver-sent%5Fevents)（サーバー送信イベント）、すなわちSSEを使用してレスポンスを段階的にストリーミングできます。

## SDKを使用したストリーミング

[Python SDK](https://github.com/anthropics/anthropic-sdk-python)と[TypeScript SDK](https://github.com/anthropics/anthropic-sdk-typescript)は、複数の「streaming」（ストリーミング）方法を提供しています。[PHP SDK](https://github.com/anthropics/anthropic-sdk-php)は`createStream()`を通じてストリーミングを提供します。Python SDKでは同期ストリームと非同期ストリームの両方が利用できます。詳細については各SDKのドキュメントを参照してください。

<CodeGroup exclude="shell:cURL">
  ```bash CLI
  ant messages create --stream --format jsonl \
    --model claude-opus-5-5 \
    --max-tokens 1024 \
    --message '{role: user, content: "Hello"}' \
    | jq -rj 'select(.delta.type? == "text_delta") | .delta.text'
  ```

  ```python Python
  client = anthropic.Anthropic()

  with client.messages.stream(
      max_tokens=1024,
      messages=[{"role": "user", "content": "Hello"}],
      model="claude-opus-5-5",
  ) as stream:
      for text in stream.text_stream:
          print(text, end="", flush=True)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  await client.messages
    .stream({
      messages: [{ role: "user", content: "Hello" }],
      model: "claude-opus-5-5",
      max_tokens: 1024
    })
    .on("text", (text) => {
      console.log(text);
    });
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Messages = [new() { Role = Role.User, Content = "Hello" }]
  };

  await foreach (var msg in client.Messages.CreateStreaming(parameters))
  {
      Console.Write(msg);
  }
  ```

  ```go Go
  client := anthropic.NewClient()

  stream := client.Messages.NewStreaming(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("Hello")),
  	},
  })

  for stream.Next() {
  	event := stream.Current()
  	switch eventVariant := event.AsAny().(type) {
  	case anthropic.ContentBlockDeltaEvent:
  		switch deltaVariant := eventVariant.Delta.AsAny().(type) {
  		case anthropic.TextDelta:
  			fmt.Print(deltaVariant.Text)
  		}
  	}
  }
  if err := stream.Err(); err != nil {
  	log.Fatal(err)
  }
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(1024L)
      .addUserMessage("Hello")
      .build();

  try (var streamResponse = client.messages().createStreaming(params)) {
      streamResponse.stream().forEach(event -> {
          event.contentBlockDelta().ifPresent(deltaEvent ->
              deltaEvent.delta().text().ifPresent(td ->
                  System.out.print(td.text())
              )
          );
      });
  }
  ```

  ```php PHP
  $client = new Client();

  $stream = $client->messages->createStream(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => 'Hello']
      ],
      model: 'claude-opus-5-5',
  );

  foreach ($stream as $message) {
      echo $message;
  }
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  stream = client.messages.stream(
    model: "claude-opus-5-5",
    max_tokens: 1024,
    messages: [{ role: "user", content: "Hello" }]
  )

  stream.text.each { |text| print(text) }
  ```
</CodeGroup>

## イベントを処理せずに最終メッセージを取得する

テキストが到着するたびに処理する必要がない場合、SDKは内部でストリーミングを使用しつつ、`client.messages.create()` (go: `client.Messages.New()`; java: `client.messages().create()`; csharp: `client.Messages.Create()`; php: `$client->messages->create()`)が返すものと同一の完全な`Message`オブジェクトを返す方法を提供しています。これは、HTTPタイムアウトを回避するためにSDKがストリーミングを必要とする、大きな`max_tokens`値を持つリクエストで特に便利です。

<CodeGroup exclude="shell:cURL">
  ```bash CLI
  # ant CLI の --stream フラグは 1 行につき 1 イベントを出力し、
  # 最終的な Message には集約されません。長い生成の場合は、
  # 生のイベントをストリーミングしてください：
  ant messages create --stream --format jsonl <<'YAML'
  model: claude-opus-5-5
  max_tokens: 128000
  messages:
    - role: user
      content: Write a detailed analysis...
  YAML
  ```

  ```python Python
  client = anthropic.Anthropic()

  with client.messages.stream(
      max_tokens=128000,
      messages=[{"role": "user", "content": "Write a detailed analysis..."}],
      model="claude-opus-5-5",
  ) as stream:
      message = stream.get_final_message()

  for block in message.content:
      if block.type == "text":
          print(block.text)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  const stream = client.messages.stream({
    max_tokens: 128000,
    messages: [{ role: "user", content: "Write a detailed analysis..." }],
    model: "claude-opus-5-5"
  });

  const message = await stream.finalMessage();
  const textBlock = message.content.find((block) => block.type === "text");
  if (textBlock && textBlock.type === "text") {
    console.log(textBlock.text);
  }
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 128000,
      Messages = [new() { Role = Role.User, Content = "Write a detailed analysis..." }]
  };

  // 到着したイベントを逐次処理したい場合は、代わりに MessageContentAggregator を CollectAsync() に渡してください。
  var message = await client.Messages.CreateStreaming(parameters).Aggregate();
  Console.WriteLine(message);
  ```

  ```go Go
  client := anthropic.NewClient()

  stream := client.Messages.NewStreaming(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 128000,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("Write a detailed analysis...")),
  	},
  })

  message := anthropic.Message{}
  for stream.Next() {
  	event := stream.Current()
  	if err := message.Accumulate(event); err != nil {
  		log.Fatal(err)
  	}
  }
  if err := stream.Err(); err != nil {
  	log.Fatal(err)
  }

  for _, block := range message.Content {
  	if textBlock, ok := block.AsAny().(anthropic.TextBlock); ok {
  		fmt.Println(textBlock.Text)
  	}
  }
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(128000L)
      .addUserMessage("Write a detailed analysis...")
      .build();

  MessageAccumulator accumulator = MessageAccumulator.create();
  try (var streamResponse = client.messages().createStreaming(params)) {
      streamResponse.stream().forEach(accumulator::accumulate);
  }

  Message message = accumulator.message();
  message.content().stream()
      .flatMap(block -> block.text().stream())
      .forEach(textBlock -> System.out.println(textBlock.text()));
  ```

  ```php PHP
  use Anthropic\Lib\Streaming\MessageAccumulator;

  $client = new Client();

  $stream = $client->messages->createStream(
      maxTokens: 128000,
      messages: [
          ['role' => 'user', 'content' => 'Write a detailed analysis...']
      ],
      model: 'claude-opus-5-5',
  );

  $accumulator = MessageAccumulator::forMessages();
  foreach ($stream as $event) {
      $accumulator->accumulate($event);
  }

  echo array_find($accumulator->message()->content, static fn ($block): bool => $block->type === 'text')->text;
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  message = client.messages.stream(
    model: "claude-opus-5-5",
    max_tokens: 128000,
    messages: [{ role: "user", content: "Write a detailed analysis..." }]
  ).accumulated_message

  message.content.each do |block|
    puts block.text if block.type == :text
  end
  ```
</CodeGroup>

`.stream()` (java: `.createStreaming()`; csharp: `.CreateStreaming()`; go: `.NewStreaming()`; php: `->createStream()`)呼び出しはserver-sent eventsでHTTP接続を維持し、その後SDKのメッセージ蓄積ヘルパーである`stream.get_final_message()` (typescript: `stream.finalMessage()`; ruby: `stream.accumulated_message`; csharp: `.Aggregate()`; go: `message.Accumulate(event)`; java, php: `MessageAccumulator`)が、すべてのイベントを完全な`Message`オブジェクトに収集します。

## イベントタイプ

各server-sent eventには、名前付きのイベントタイプと関連するJSONデータが含まれます。各イベントはSSEイベント名（例：`event: message_stop`）を使用し、データ内に対応するイベント`type`を含みます。

各ストリームは次のイベントフローを使用します。

1. `message_start`：空の`content`を持つ`Message`オブジェクトを含みます。[`thinking-binding-controls-2026-08-01`](https://platform.claude.com/docs/ja/build-with-claude/thinking#preserved-thinking-controls)ベータヘッダーを使用している場合、この`Message`オブジェクトには`input_transformations`配列も含まれます。ストリーム途中での[サーバーサイドフォールバック](https://platform.claude.com/docs/ja/build-with-claude/refusals-and-fallback#server-side-fallback)の後、最後の`message_delta`イベントには、実際に応答したモデルのエントリを含む配列が再度含まれます。
2. 一連のコンテンツブロック。それぞれに`content_block_start`、1つ以上の`content_block_delta`イベント、および`content_block_stop`イベントがあります。各コンテンツブロックには、最終的なMessageの`content`配列内のインデックスに対応する`index`があります。例外が1つあります。[サーバーサイドフォールバック](https://platform.claude.com/docs/ja/build-with-claude/refusals-and-fallback#server-side-fallback)レスポンス中は、各モデル境界で`fallback`コンテンツブロックが、間にデルタを挟まない`content_block_start`と`content_block_stop`のペアとして到着します。
3. 1つ以上の`message_delta`イベント。最終的な`Message`オブジェクトに対するトップレベルの変更を示します。
4. 最後の`message_stop`イベント。

<Warning>
  `message_delta`イベントの`usage`フィールドに表示されるトークン数は*累積値*です。
</Warning>

### Pingイベント

イベントストリームには、任意の数の`ping`イベントが含まれる場合もあります。

### エラーイベント

APIはイベントストリーム内で[エラー](https://platform.claude.com/docs/ja/api/errors)を送信することがあります。例えば、使用量が多い期間には`overloaded_error`を受け取ることがあります。これは非ストリーミングのコンテキストでは通常HTTP 529に相当します。

```sse Example error
event: error
data: {"type": "error", "error": {"type": "overloaded_error", "message": "Overloaded"}}
```

### その他のイベント

[バージョニングポリシー](https://platform.claude.com/docs/ja/api/versioning)に従い、新しいイベントタイプが追加される可能性があるため、コードは未知のイベントタイプを適切に処理できるようにしておく必要があります。

## コンテンツブロックデルタのタイプ

各`content_block_delta`イベントには、指定された`index`の`content`ブロックを更新するタイプの`delta`が含まれます。

### テキストデルタ

`text`コンテンツブロックのデルタは次のようになります。

```sse Text delta
event: content_block_delta
data: {"type": "content_block_delta","index": 0,"delta": {"type": "text_delta", "text": "ello frien"}}
```

### 入力JSONデルタ

`tool_use`コンテンツブロックのデルタは、ブロックの`input`フィールドの更新に対応します。最大限の粒度をサポートするため、デルタは*部分的なJSON文字列*ですが、最終的な`tool_use.input`は常に*オブジェクト*です。

文字列のデルタを蓄積し、`content_block_stop`イベントを受信した時点でJSONを解析できます。その際、[Pydantic](https://docs.pydantic.dev/latest/concepts/json/#partial-json-parsing)のようなライブラリを使用して部分的なJSON解析を行うか、SDKの[ストリーミングヘルパー](https://platform.claude.com/docs/ja/build-with-claude/streaming#streaming-with-sdks)を使用します。PythonおよびTypeScript SDKでは、これらのヘルパーにより、ストリーミング中に解析済みの`input`へ段階的にアクセスすることもできます。

`tool_use`コンテンツブロックのデルタは次のようになります。

```sse Input JSON delta
event: content_block_delta
data: {"type": "content_block_delta","index": 1,"delta": {"type": "input_json_delta","partial_json": "{\"location\": \"San Fra"}}}
```

注：現在のモデルは、`input`から一度に1つの完全なキーと値のプロパティを出力することのみをサポートしています。そのため、ツールを使用する際、モデルが処理している間はストリーミングイベント間に遅延が生じる場合があります。`input`のキーと値が蓄積されると、将来のモデルでより細かい粒度を自動的にサポートできる形式とするため、チャンク化された部分的なJSONを含む複数の`content_block_delta`イベントとして出力されます。

### 思考デルタ

ストリーミングを有効にして[思考](https://platform.claude.com/docs/ja/build-with-claude/thinking#streaming-thinking)を使用する場合、`thinking_delta`イベントを通じて思考コンテンツを受け取ります。これらのデルタは`thinking`コンテンツブロックの`thinking`フィールドに対応します。

思考コンテンツの場合、`content_block_stop`イベントの直前に特別な`signature_delta`イベントが送信されます。この署名は思考ブロックの整合性を検証するために使用されます。

思考の設定で`display: "omitted"`が設定されている場合、思考テキストはストリーミングされません。思考ブロックが開き、空の`thinking`文字列を持つ`thinking_delta`を受け取り、続いて単一の`signature_delta`を受け取ってから閉じます。`display: "updates"`（ベータ）では、推論ブロックは同じ方法でストリーミングされ、一部のモデルがツール呼び出しの間に書き込む[進捗更新](https://platform.claude.com/docs/ja/build-with-claude/thinking#progress-updates)のみが、テキストを含む`thinking_delta`イベントをストリーミングします。[思考表示の制御](https://platform.claude.com/docs/ja/build-with-claude/thinking#controlling-thinking-display)を参照してください。

典型的な思考デルタは次のようになります。

```sse Thinking delta
event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "I need to find the GCD of 1071 and 462 using the Euclidean algorithm.\n\n1071 = 2 × 462 + 147"}}
```

署名デルタは次のようになります。

```sse Signature delta
event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "signature_delta", "signature": "EqQBCgIYAhIM1gbcDa9GJwZA2b3hGgxBdjrkzLoky3dl1pkiMOYds..."}}
```

## 完全なHTTPストリームレスポンス

ストリーミングモードを使用する際は[クライアントSDK](https://platform.claude.com/docs/ja/cli-sdks-libraries/overview)を使用してください。ただし、直接APIと統合する場合は、これらのイベントを自分で処理する必要があります。

ストリームレスポンスは次の要素で構成されます。

1. `message_start`イベント

2. 複数になる可能性のあるコンテンツブロック。それぞれに以下が含まれます。

   * `content_block_start`イベント
   * 複数になる可能性のある`content_block_delta`イベント
   * `content_block_stop`イベント

3. 1つ以上の`message_delta`イベント

4. `message_stop`イベント

レスポンス全体に`ping`イベントが散在する場合もあります。形式の詳細については[イベントタイプ](https://platform.claude.com/docs/ja/build-with-claude/streaming#event-types)を参照してください。

### 基本的なストリーミングリクエスト

<CodeGroup>
  ```bash cURL
  curl https://api.anthropic.com/v1/messages \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -d '{
      "model": "claude-opus-5-5",
      "messages": [{"role": "user", "content": "Hello"}],
      "max_tokens": 256,
      "stream": true
    }'
  ```

  ```bash CLI
  ant messages create --stream --format jsonl \
    --model claude-opus-5-5 \
    --max-tokens 256 \
    --message '{role: user, content: Hello}'
  ```

  ```python Python
  client = anthropic.Anthropic()

  with client.messages.stream(
      model="claude-opus-5-5",
      messages=[{"role": "user", "content": "Hello"}],
      max_tokens=256,
  ) as stream:
      for text in stream.text_stream:
          print(text, end="", flush=True)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  const stream = client.messages.stream({
    model: "claude-opus-5-5",
    messages: [{ role: "user", content: "Hello" }],
    max_tokens: 256
  });

  for await (const event of stream) {
    if (event.type === "content_block_delta" && event.delta.type === "text_delta") {
      process.stdout.write(event.delta.text);
    }
  }
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 256,
      Messages = [new() { Role = Role.User, Content = "Hello" }]
  };

  await foreach (var msg in client.Messages.CreateStreaming(parameters))
  {
      Console.Write(msg);
  }
  ```

  ```go Go
  client := anthropic.NewClient()

  stream := client.Messages.NewStreaming(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 256,
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("Hello")),
  	},
  })

  for stream.Next() {
  	event := stream.Current()
  	switch eventVariant := event.AsAny().(type) {
  	case anthropic.ContentBlockDeltaEvent:
  		switch deltaVariant := eventVariant.Delta.AsAny().(type) {
  		case anthropic.TextDelta:
  			fmt.Print(deltaVariant.Text)
  		}
  	}
  }
  if err := stream.Err(); err != nil {
  	log.Fatal(err)
  }
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(256L)
      .addUserMessage("Hello")
      .build();

  try (var streamResponse = client.messages().createStreaming(params)) {
      streamResponse.stream().forEach(event -> {
          event.contentBlockDelta().ifPresent(deltaEvent ->
              deltaEvent.delta().text().ifPresent(td ->
                  System.out.print(td.text())
              )
          );
      });
  }
  ```

  ```php PHP
  $client = new Client();

  $stream = $client->messages->createStream(
      maxTokens: 256,
      messages: [
          ['role' => 'user', 'content' => 'Hello']
      ],
      model: 'claude-opus-5-5',
  );

  foreach ($stream as $message) {
      echo $message;
  }
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  stream = client.messages.stream(
    model: "claude-opus-5-5",
    messages: [{ role: "user", content: "Hello" }],
    max_tokens: 256
  )

  stream.text.each { |text| print(text) }
  ```
</CodeGroup>

```sse Response
event: message_start
data: {"type": "message_start", "message": {"id": "msg_1nZdL29xx5MUA1yADyHTEsnR8uuvGzszyY", "type": "message", "role": "assistant", "content": [], "model": "claude-opus-5-5", "stop_reason": null, "stop_sequence": null, "usage": {"input_tokens": 25, "output_tokens": 1}}}

event: content_block_start
data: {"type": "content_block_start", "index": 0, "content_block": {"type": "text", "text": ""}}

event: ping
data: {"type": "ping"}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": "Hello"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "text_delta", "text": "!"}}

event: content_block_stop
data: {"type": "content_block_stop", "index": 0}

event: message_delta
data: {"type": "message_delta", "delta": {"stop_reason": "end_turn", "stop_sequence":null}, "usage": {"output_tokens": 15}}

event: message_stop
data: {"type": "message_stop"}

```

### ツール使用を伴うストリーミングリクエスト

<Tip>
  ツール使用は、パラメータ値の[きめ細かいストリーミング](https://platform.claude.com/docs/ja/agents-and-tools/tool-use/fine-grained-tool-streaming)をサポートしています。`eager_input_streaming`を使用してツールごとに有効にできます。
</Tip>

このリクエストは、Claudeにツールを使用して天気を報告するよう求めます。

<CodeGroup>
  ```bash cURL
    curl https://api.anthropic.com/v1/messages \
      -H "content-type: application/json" \
      -H "x-api-key: $ANTHROPIC_API_KEY" \
      -H "anthropic-version: 2023-06-01" \
      -d '{
        "model": "claude-opus-5",
        "max_tokens": 1024,
        "tools": [
          {
            "name": "get_weather",
            "description": "Get the current weather in a given location",
            "input_schema": {
              "type": "object",
              "properties": {
                "location": {
                  "type": "string",
                  "description": "The city and state, e.g. San Francisco, CA"
                }
              },
              "required": ["location"]
            }
          }
        ],
        "tool_choice": {"type": "any"},
        "messages": [
          {
            "role": "user",
            "content": "What is the weather like in San Francisco?"
          }
        ],
        "stream": true
      }'
  ```

  ```bash CLI
  ant messages create --stream --format jsonl <<'YAML'
  model: claude-opus-5
  max_tokens: 1024
  tools:
    - name: get_weather
      description: Get the current weather in a given location
      input_schema:
        type: object
        properties:
          location:
            type: string
            description: The city and state, e.g. San Francisco, CA
        required:
          - location
  tool_choice:
    type: any
  messages:
    - role: user
      content: What is the weather like in San Francisco?
  YAML
  ```

  ```python Python
  client = anthropic.Anthropic()

  tools = [
      {
          "name": "get_weather",
          "description": "Get the current weather in a given location",
          "input_schema": {
              "type": "object",
              "properties": {
                  "location": {
                      "type": "string",
                      "description": "The city and state, e.g. San Francisco, CA",
                  }
              },
              "required": ["location"],
          },
      }
  ]

  with client.messages.stream(
      model="claude-opus-5",
      max_tokens=1024,
      tools=tools,
      tool_choice={"type": "any"},
      messages=[
          {"role": "user", "content": "What is the weather like in San Francisco?"}
      ],
  ) as stream:
      for text in stream.text_stream:
          print(text, end="", flush=True)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  const tools: Anthropic.Tool[] = [
    {
      name: "get_weather",
      description: "Get the current weather in a given location",
      input_schema: {
        type: "object",
        properties: {
          location: {
            type: "string",
            description: "The city and state, e.g. San Francisco, CA"
          }
        },
        required: ["location"]
      }
    }
  ];

  const stream = client.messages.stream({
    model: "claude-opus-5",
    max_tokens: 1024,
    tools: tools,
    tool_choice: { type: "any" },
    messages: [
      {
        role: "user",
        content: "What is the weather like in San Francisco?"
      }
    ]
  });

  for await (const event of stream) {
    if (event.type === "content_block_delta" && event.delta.type === "text_delta") {
      process.stdout.write(event.delta.text);
    }
  }
  ```

  ```csharp C#
  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5,
      MaxTokens = 1024,
      Tools = [
          new ToolUnion(new Tool()
          {
              Name = "get_weather",
              Description = "Get the current weather in a given location",
              InputSchema = new InputSchema()
              {
                  Properties = new Dictionary<string, JsonElement>
                  {
                      ["location"] = JsonSerializer.SerializeToElement(new { type = "string", description = "The city and state, e.g. San Francisco, CA" }),
                  },
                  Required = ["location"],
              },
          }),
      ],
      ToolChoice = new ToolChoiceAny(),
      Messages = [
          new() { Role = Role.User, Content = "What is the weather like in San Francisco?" }
      ]
  };

  await foreach (var msg in client.Messages.CreateStreaming(parameters))
  {
      Console.Write(msg);
  }
  ```

  ```go Go
  client := anthropic.NewClient()

  stream := client.Messages.NewStreaming(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5,
  	MaxTokens: 1024,
  	Tools: []anthropic.ToolUnionParam{
  		{OfTool: &anthropic.ToolParam{
  			Name:        "get_weather",
  			Description: anthropic.String("Get the current weather in a given location"),
  			InputSchema: anthropic.ToolInputSchemaParam{
  				Properties: map[string]any{
  					"location": map[string]any{
  						"type":        "string",
  						"description": "The city and state, e.g. San Francisco, CA",
  					},
  				},
  				Required: []string{"location"},
  			},
  		}},
  	},
  	ToolChoice: anthropic.ToolChoiceUnionParam{OfAny: &anthropic.ToolChoiceAnyParam{}},
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What is the weather like in San Francisco?")),
  	},
  })

  for stream.Next() {
  	event := stream.Current()
  	switch eventVariant := event.AsAny().(type) {
  	case anthropic.ContentBlockDeltaEvent:
  		switch deltaVariant := eventVariant.Delta.AsAny().(type) {
  		case anthropic.TextDelta:
  			fmt.Print(deltaVariant.Text)
  		}
  	}
  }
  if err := stream.Err(); err != nil {
  	log.Fatal(err)
  }
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5)
      .maxTokens(1024L)
      .addTool(Tool.builder()
          .name("get_weather")
          .description("Get the current weather in a given location")
          .inputSchema(Tool.InputSchema.builder()
              .properties(JsonValue.from(Map.of(
                  "location", Map.of(
                      "type", "string",
                      "description", "The city and state, e.g. San Francisco, CA"
                  )
              )))
              .putAdditionalProperty("required", JsonValue.from(List.of("location")))
              .build())
          .build())
      .toolChoice(ToolChoice.ofAny(ToolChoiceAny.builder().build()))
      .addUserMessage("What is the weather like in San Francisco?")
      .build();

  try (var streamResponse = client.messages().createStreaming(params)) {
      streamResponse.stream().forEach(event -> {
          event.contentBlockDelta().ifPresent(deltaEvent ->
              deltaEvent.delta().text().ifPresent(td ->
                  System.out.print(td.text())
              )
          );
      });
  }
  ```

  ```php PHP
  $client = new Client();

  $stream = $client->messages->createStream(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => 'What is the weather like in San Francisco?']
      ],
      model: 'claude-opus-5',
      toolChoice: ['type' => 'any'],
      tools: [
          [
              'name' => 'get_weather',
              'description' => 'Get the current weather in a given location',
              'input_schema' => [
                  'type' => 'object',
                  'properties' => [
                      'location' => [
                          'type' => 'string',
                          'description' => 'The city and state, e.g. San Francisco, CA'
                      ]
                  ],
                  'required' => ['location']
              ]
          ]
      ],
  );

  foreach ($stream as $message) {
      echo $message;
  }
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  tools = [
    {
      name: "get_weather",
      description: "Get the current weather in a given location",
      input_schema: {
        type: "object",
        properties: {
          location: {
            type: "string",
            description: "The city and state, e.g. San Francisco, CA"
          }
        },
        required: ["location"]
      }
    }
  ]

  stream = client.messages.stream(
    model: "claude-opus-5",
    max_tokens: 1024,
    tools: tools,
    tool_choice: { type: "any" },
    messages: [
      { role: "user", content: "What is the weather like in San Francisco?" }
    ]
  )

  stream.text.each { |text| print(text) }
  ```
</CodeGroup>

```sse Response
event: message_start
data: {"type":"message_start","message":{"id":"msg_014p7gG3wDgGV9EUtLvnow3U","type":"message","role":"assistant","model":"claude-opus-5","stop_sequence":null,"usage":{"input_tokens":472,"output_tokens":2},"content":[],"stop_reason":null}}

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}

event: ping
data: {"type": "ping"}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"Okay"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":","}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" let"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"'s"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" check"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" the"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" weather"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" for"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" San"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" Francisco"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":","}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" CA"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":":"}}

event: content_block_stop
data: {"type":"content_block_stop","index":0}

event: content_block_start
data: {"type":"content_block_start","index":1,"content_block":{"type":"tool_use","id":"toolu_01T1x1fJ34qAmk2tNTrN7Up6","name":"get_weather","input":{}}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"{\"location\":"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":" \"San"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":" Francisc"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"o,"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":" CA\"}"}}

event: content_block_stop
data: {"type":"content_block_stop","index":1}

event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"tool_use","stop_sequence":null},"usage":{"output_tokens":89}}

event: message_stop
data: {"type":"message_stop"}
```

### 思考を伴うストリーミングリクエスト

このリクエストはストリーミングで思考を有効にします。`display: "summarized"`設定は、完全な思考の連鎖ではなく、Claudeの推論の要約版をストリーミングします。

<CodeGroup>
  ```bash cURL
  curl https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d '{
      "model": "claude-opus-5-5",
      "max_tokens": 20000,
      "stream": true,
      "thinking": {
        "type": "adaptive",
        "display": "summarized"
      },
      "messages": [
        {
          "role": "user",
          "content": "What is the greatest common divisor of 1071 and 462?"
        }
      ]
    }'
  ```

  ```bash CLI
  ant messages create --stream --format jsonl \
    --model claude-opus-5-5 \
    --max-tokens 20000 \
    --thinking '{type: adaptive, display: summarized}' \
    --message '{role: user, content: What is the greatest common divisor of 1071 and 462?}'
  ```

  ```python Python
  client = anthropic.Anthropic()

  with client.messages.stream(
      model="claude-opus-5-5",
      max_tokens=20000,
      thinking={"type": "adaptive", "display": "summarized"},
      messages=[
          {
              "role": "user",
              "content": "What is the greatest common divisor of 1071 and 462?",
          }
      ],
  ) as stream:
      for event in stream:
          if event.type == "content_block_delta":
              delta = event.delta
              match delta.type:
                  case "thinking_delta":
                      print(delta.thinking, end="", flush=True)
                  case "text_delta":
                      print(delta.text, end="", flush=True)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  const stream = client.messages.stream({
    model: "claude-opus-5-5",
    max_tokens: 20000,
    thinking: { type: "adaptive", display: "summarized" },
    messages: [
      {
        role: "user",
        content: "What is the greatest common divisor of 1071 and 462?"
      }
    ]
  });

  for await (const event of stream) {
    if (event.type === "content_block_delta") {
      switch (event.delta.type) {
        case "thinking_delta":
          process.stdout.write(event.delta.thinking);
          break;
        case "text_delta":
          process.stdout.write(event.delta.text);
          break;
      }
    }
  }
  ```

  ```csharp C#
  using Anthropic;
  using Anthropic.Models.Messages;

  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 20000,
      Thinking = new ThinkingConfigAdaptive { Display = Display.Summarized },
      Messages = [new() { Role = Role.User, Content = "What is the greatest common divisor of 1071 and 462?" }]
  };

  await foreach (var msg in client.Messages.CreateStreaming(parameters))
  {
      Console.Write(msg);
  }
  ```

  ```go Go
  client := anthropic.NewClient()

  stream := client.Messages.NewStreaming(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 20000,
  	Thinking: anthropic.ThinkingConfigParamUnion{
  		OfAdaptive: &anthropic.ThinkingConfigAdaptiveParam{
  			Display: anthropic.ThinkingConfigAdaptiveDisplaySummarized,
  		},
  	},
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What is the greatest common divisor of 1071 and 462?")),
  	},
  })

  for stream.Next() {
  	event := stream.Current()
  	switch eventVariant := event.AsAny().(type) {
  	case anthropic.ContentBlockDeltaEvent:
  		switch deltaVariant := eventVariant.Delta.AsAny().(type) {
  		case anthropic.ThinkingDelta:
  			fmt.Print(deltaVariant.Thinking)
  		case anthropic.TextDelta:
  			fmt.Print(deltaVariant.Text)
  		}
  	}
  }
  if err := stream.Err(); err != nil {
  	log.Fatal(err)
  }
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(20000L)
      .thinking(ThinkingConfigAdaptive.builder()
          .display(ThinkingConfigAdaptive.Display.SUMMARIZED)
          .build())
      .addUserMessage("What is the greatest common divisor of 1071 and 462?")
      .build();

  try (var streamResponse = client.messages().createStreaming(params)) {
      streamResponse.stream().forEach(event -> {
          event.contentBlockDelta().ifPresent(deltaEvent -> {
              deltaEvent.delta().thinking().ifPresent(td ->
                  IO.print(td.thinking())
              );
              deltaEvent.delta().text().ifPresent(td ->
                  IO.print(td.text())
              );
          });
      });
  }
  ```

  ```php PHP
  $client = new Client();

  $stream = $client->messages->createStream(
      maxTokens: 20000,
      messages: [
          ['role' => 'user', 'content' => 'What is the greatest common divisor of 1071 and 462?']
      ],
      model: 'claude-opus-5-5',
      thinking: ['type' => 'adaptive', 'display' => 'summarized'],
  );

  foreach ($stream as $message) {
      echo $message;
  }
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  stream = client.messages.stream(
    model: "claude-opus-5-5",
    max_tokens: 20000,
    thinking: { type: "adaptive", display: "summarized" },
    messages: [
      { role: "user", content: "What is the greatest common divisor of 1071 and 462?" }
    ]
  )

  stream.each do |event|
    if event.is_a?(Anthropic::Models::RawContentBlockDeltaEvent)
      delta = event.delta
      case delta
      when Anthropic::Models::ThinkingDelta
        print(delta.thinking)
      when Anthropic::Models::TextDelta
        print(delta.text)
      end
    end
  end
  ```
</CodeGroup>

```sse Response
event: message_start
data: {"type": "message_start", "message": {"id": "msg_01...", "type": "message", "role": "assistant", "content": [], "model": "claude-opus-5-5", "stop_reason": null, "stop_sequence": null}}

event: content_block_start
data: {"type": "content_block_start", "index": 0, "content_block": {"type": "thinking", "thinking": "", "signature": ""}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "I need to find the GCD of 1071 and 462 using the Euclidean algorithm.\n\n1071 = 2 × 462 + 147"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\n462 = 3 × 147 + 21"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\n147 = 7 × 21 + 0"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\nThe remainder is 0, so GCD(1071, 462) = 21."}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "signature_delta", "signature": "EqQBCgIYAhIM1gbcDa9GJwZA2b3hGgxBdjrkzLoky3dl1pkiMOYds..."}}

event: content_block_stop
data: {"type": "content_block_stop", "index": 0}

event: content_block_start
data: {"type": "content_block_start", "index": 1, "content_block": {"type": "text", "text": ""}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 1, "delta": {"type": "text_delta", "text": "The greatest common divisor of 1071 and 462 is **21**."}}

event: content_block_stop
data: {"type": "content_block_stop", "index": 1}

event: message_delta
data: {"type": "message_delta", "delta": {"stop_reason": "end_turn", "stop_sequence": null}}

event: message_stop
data: {"type": "message_stop"}
```

### Web検索ツール使用を伴うストリーミングリクエスト

このリクエストは、Claudeに現在の天気情報をWebで検索するよう求めます。

<CodeGroup>
  ```bash cURL
  curl https://api.anthropic.com/v1/messages \
    -H "x-api-key: $ANTHROPIC_API_KEY" \
    -H "anthropic-version: 2023-06-01" \
    -H "content-type: application/json" \
    -d '{
      "model": "claude-opus-5-5",
      "max_tokens": 1024,
      "stream": true,
      "tools": [
        {
          "type": "web_search_20250305",
          "name": "web_search",
          "max_uses": 5
        }
      ],
      "messages": [
        {
          "role": "user",
          "content": "What is the weather like in New York City today?"
        }
      ]
    }'
  ```

  ```bash CLI
  ant messages create --stream --format jsonl \
    --model claude-opus-5-5 \
    --max-tokens 1024 \
    --tool '{type: web_search_20250305, name: web_search, max_uses: 5}' \
    --message '{role: user, content: What is the weather like in New York City today?}'
  ```

  ```python Python
  client = anthropic.Anthropic()

  with client.messages.stream(
      model="claude-opus-5-5",
      max_tokens=1024,
      tools=[{"type": "web_search_20250305", "name": "web_search", "max_uses": 5}],
      messages=[
          {"role": "user", "content": "What is the weather like in New York City today?"}
      ],
  ) as stream:
      for text in stream.text_stream:
          print(text, end="", flush=True)
  ```

  ```typescript TypeScript
  const client = new Anthropic();

  const stream = client.messages.stream({
    model: "claude-opus-5-5",
    max_tokens: 1024,
    tools: [{ type: "web_search_20250305", name: "web_search", max_uses: 5 }],
    messages: [{ role: "user", content: "What is the weather like in New York City today?" }]
  });

  for await (const event of stream) {
    if (event.type === "content_block_delta" && event.delta.type === "text_delta") {
      process.stdout.write(event.delta.text);
    }
  }
  ```

  ```csharp C#
  using Anthropic;
  using Anthropic.Models.Messages;

  AnthropicClient client = new();

  var parameters = new MessageCreateParams
  {
      Model = Model.ClaudeOpus5_5,
      MaxTokens = 1024,
      Tools = [new ToolUnion(new WebSearchTool20250305() { MaxUses = 5 })],
      Messages = [new() { Role = Role.User, Content = "What is the weather like in New York City today?" }]
  };

  await foreach (var msg in client.Messages.CreateStreaming(parameters))
  {
      Console.Write(msg);
  }
  ```

  ```go Go
  client := anthropic.NewClient()

  stream := client.Messages.NewStreaming(context.TODO(), anthropic.MessageNewParams{
  	Model:     anthropic.ModelClaudeOpus5_5,
  	MaxTokens: 1024,
  	Tools: []anthropic.ToolUnionParam{
  		{
  			OfWebSearchTool20250305: &anthropic.WebSearchTool20250305Param{
  				MaxUses: anthropic.Int(5),
  			},
  		},
  	},
  	Messages: []anthropic.MessageParam{
  		anthropic.NewUserMessage(anthropic.NewTextBlock("What is the weather like in New York City today?")),
  	},
  })

  for stream.Next() {
  	event := stream.Current()
  	switch eventVariant := event.AsAny().(type) {
  	case anthropic.ContentBlockDeltaEvent:
  		switch deltaVariant := eventVariant.Delta.AsAny().(type) {
  		case anthropic.TextDelta:
  			fmt.Print(deltaVariant.Text)
  		}
  	}
  }
  if err := stream.Err(); err != nil {
  	log.Fatal(err)
  }
  ```

  ```java Java
  AnthropicClient client = AnthropicOkHttpClient.fromEnv();

  MessageCreateParams params = MessageCreateParams.builder()
      .model(Model.CLAUDE_OPUS_5_5)
      .maxTokens(1024L)
      .addTool(WebSearchTool20250305.builder()
          .maxUses(5L)
          .build())
      .addUserMessage("What is the weather like in New York City today?")
      .build();

  try (var streamResponse = client.messages().createStreaming(params)) {
      streamResponse.stream().forEach(event -> {
          event.contentBlockDelta().ifPresent(deltaEvent ->
              deltaEvent.delta().text().ifPresent(td ->
                  System.out.print(td.text())
              )
          );
      });
  }
  ```

  ```php PHP
  $client = new Client();

  $stream = $client->messages->createStream(
      maxTokens: 1024,
      messages: [
          ['role' => 'user', 'content' => 'What is the weather like in New York City today?']
      ],
      model: 'claude-opus-5-5',
      tools: [
          ['type' => 'web_search_20250305', 'name' => 'web_search', 'max_uses' => 5]
      ],
  );

  foreach ($stream as $message) {
      echo $message;
  }
  ```

  ```ruby Ruby
  client = Anthropic::Client.new

  stream = client.messages.stream(
    model: :"claude-opus-5-5",
    max_tokens: 1024,
    tools: [
      {
        type: "web_search_20250305",
        name: "web_search",
        max_uses: 5
      }
    ],
    messages: [
      {
        role: "user",
        content: "What is the weather like in New York City today?"
      }
    ]
  )

  stream.text.each { |text| print(text) }
  ```
</CodeGroup>

```sse Response
event: message_start
data: {"type":"message_start","message":{"id":"msg_01G...","type":"message","role":"assistant","model":"claude-opus-5-5","content":[],"stop_reason":null,"stop_sequence":null,"usage":{"input_tokens":2679,"cache_creation_input_tokens":0,"cache_read_input_tokens":0,"output_tokens":3}}}

event: content_block_start
data: {"type":"content_block_start","index":0,"content_block":{"type":"text","text":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"I'll check"}}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":" the current weather in New York City for you"}}

event: ping
data: {"type": "ping"}

event: content_block_delta
data: {"type":"content_block_delta","index":0,"delta":{"type":"text_delta","text":"."}}

event: content_block_stop
data: {"type":"content_block_stop","index":0}

event: content_block_start
data: {"type":"content_block_start","index":1,"content_block":{"type":"server_tool_use","id":"srvtoolu_014hJH82Qum7Td6UV8gDXThB","name":"web_search","input":{}}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"{\"query"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"\":"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":" \"weather"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":" NY"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"C to"}}

event: content_block_delta
data: {"type":"content_block_delta","index":1,"delta":{"type":"input_json_delta","partial_json":"day\"}"}}

event: content_block_stop
data: {"type":"content_block_stop","index":1 }

event: content_block_start
data: {"type":"content_block_start","index":2,"content_block":{"type":"web_search_tool_result","tool_use_id":"srvtoolu_014hJH82Qum7Td6UV8gDXThB","content":[{"type":"web_search_result","title":"Weather in New York City in May 2025 (New York) - detailed Weather Forecast for a month","url":"https://world-weather.info/forecast/usa/new_york/may-2025/","encrypted_content":"Ev0DCioIAxgCIiQ3NmU4ZmI4OC1k...","page_age":null},...]}}

event: content_block_stop
data: {"type":"content_block_stop","index":2}

event: content_block_start
data: {"type":"content_block_start","index":3,"content_block":{"type":"text","text":""}}

event: content_block_delta
data: {"type":"content_block_delta","index":3,"delta":{"type":"text_delta","text":"Here's the current weather information for New York"}}

event: content_block_delta
data: {"type":"content_block_delta","index":3,"delta":{"type":"text_delta","text":" City:\n\n# Weather"}}

event: content_block_delta
data: {"type":"content_block_delta","index":3,"delta":{"type":"text_delta","text":" in New York City"}}

event: content_block_delta
data: {"type":"content_block_delta","index":3,"delta":{"type":"text_delta","text":"\n\n"}}

...

event: content_block_stop
data: {"type":"content_block_stop","index":17}

event: message_delta
data: {"type":"message_delta","delta":{"stop_reason":"end_turn","stop_sequence":null},"usage":{"input_tokens":10682,"cache_creation_input_tokens":0,"cache_read_input_tokens":0,"output_tokens":510,"server_tool_use":{"web_search_requests":1}}}

event: message_stop
data: {"type":"message_stop"}
```

## エラーからの回復

### Claude 4.5以前

Claude 4.5以前のモデルでは、ネットワークの問題、タイムアウト、その他のエラーによって中断されたストリーミングリクエストを、ストリームが中断された箇所から再開することで回復できます。このアプローチにより、レスポンス全体を再処理する必要がなくなります。

基本的な回復戦略は次のとおりです。

1. **部分的なレスポンスを取得する：** エラーが発生する前に正常に受信されたすべてのコンテンツを保存します。
2. **継続リクエストを構築する：** 部分的なアシスタントレスポンスを新しいアシスタントメッセージの冒頭として含む、新しいAPIリクエストを作成します。
3. **ストリーミングを再開する：** 中断された箇所からレスポンスの残りを引き続き受信します。

### Claude 4.6以降

Claude 4.6以降のモデルでも、同じ取得と再開の戦略が適用されますが、ステップ2が変わります。部分的なレスポンスをアシスタントメッセージに配置する代わりに、中断した箇所から続けるようモデルに指示するユーザーメッセージを追加します。

1. **部分的なレスポンスを取得する：** エラーが発生する前に正常に受信されたすべてのコンテンツを保存します。
2. **継続リクエストを構築する：** 部分的なレスポンスと続行の指示を含むユーザーメッセージを持つ新しいAPIリクエストを作成します。例：
   ```text Sample prompt wrap
   Your previous response was interrupted and ended with [previous_response]. Continue from where you left off.
   ```
3. **ストリーミングを再開する：** 中断された箇所からレスポンスの残りを引き続き受信します。

### エラー回復のベストプラクティス

1. **SDKの機能を使用する：** SDKに組み込まれたメッセージ蓄積機能とエラー処理機能を活用します。
2. **コンテンツタイプを処理する：** メッセージには複数のコンテンツブロック（`text`、`tool_use`、`thinking`）が含まれる可能性があることに注意してください。ツール使用ブロックと思考ブロックは部分的に回復することはできません。最新のテキストブロックからストリーミングを再開できます。

## 次のステップ

<CardGroup cols={2}>
  <Card title="停止理由とフォールバック" icon="list" href="https://platform.claude.com/docs/ja/build-with-claude/handling-stop-reasons">
    ストリームが完了したら、各`stop_reason`値を処理します。
  </Card>

  <Card title="きめ細かいツールストリーミング" icon="wrench" href="https://platform.claude.com/docs/ja/agents-and-tools/tool-use/fine-grained-tool-streaming">
    サーバーサイドのバッファリングなしでツール入力JSONをストリーミングし、レイテンシを低減します。
  </Card>

  <Card title="思考" icon="brain" href="https://platform.claude.com/docs/ja/build-with-claude/thinking">
    `thinking_delta`および`signature_delta`イベントで思考出力をストリーミングします。
  </Card>

  <Card title="クライアントSDK" icon="code" href="https://platform.claude.com/docs/ja/cli-sdks-libraries/overview">
    ストリーミング、蓄積、再接続を処理してくれる公式SDKを使用します。
  </Card>

  <Card title="バッチ処理" icon="stack" href="https://platform.claude.com/docs/ja/build-with-claude/batch-processing">
    リアルタイムのレスポンスが不要な場合に、大量のリクエストを非同期で処理します。
  </Card>
</CardGroup>