在建立訊息時，您可以設定 "stream": true 來使用伺服器發送事件 (SSE) 進行增量式串流回應。

​
使用 SDK 進行串流

我們的 Python 和 TypeScript SDK 提供多種串流方式。Python SDK 同時支援同步和非同步串流。詳情請參閱各 SDK 的文件。

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事件類型

每個伺服器發送事件都包含一個命名的事件類型和相關的 JSON 資料。每個事件都會使用 SSE 事件名稱（例如 event: message_stop），並在其資料中包含相對應的事件 type。

每個串流使用以下事件流程：

  1. message_start：包含一個帶有空 content 的 Message 物件。
  2. 一系列內容區塊，每個區塊都有一個 content_block_start、一個或多個 content_block_delta 事件，以及一個 content_block_stop 事件。每個內容區塊都有一個 index，對應於最終 Message content 陣列中的索引。
  3. 一個或多個 message_delta 事件，表示最終 Message 物件的頂層變更。
  4. 最後的 message_stop 事件。

​
Ping 事件

事件串流中可能還包含任意數量的 ping 事件。

​
錯誤事件

我們可能偶爾會在事件串流中發送錯誤。例如，在高使用量期間，您可能會收到 overloaded_error，這在非串流環境中通常對應於 HTTP 529：

錯誤範例
event: error
data: {"type": "error", "error": {"type": "overloaded_error", "message": "Overloaded"}}

​
其他事件

根據我們的版本控制政策，我們可能會添加新的事件類型，您的程式碼應該能夠優雅地處理未知的事件類型。

​
Delta 類型

每個 content_block_delta 事件都包含一個 delta，用於更新給定 index 處的 content 區塊。

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文字 delta

文字內容區塊 delta 看起來像這樣：

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

​
輸入 JSON delta

tool_use 內容區塊的 delta 對應於區塊的 input 欄位的更新。為了支援最大的粒度，delta 是 部分 JSON 字串，而最終的 tool_use.input 始終是一個 物件。

您可以累積字串 delta，並在收到 content_block_stop 事件後解析 JSON，方法是使用像 Pydantic 這樣的函式庫進行部分 JSON 解析，或使用我們的 SDK，它們提供了訪問已解析增量值的輔助工具。

tool_use 內容區塊 delta 看起來像這樣：

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

注意：我們目前的模型只支援一次從 input 中發出一個完整的鍵值屬性。因此，在使用工具時，模型工作時可能會在串流事件之間出現延遲。一旦累積了 input 鍵和值，我們會將它們作為多個帶有分塊部分 json 的 content_block_delta 事件發出，這樣格式就可以自動支援未來模型中的更細粒度。

​
思考 delta

當啟用延伸思考並開啟串流時，您會通過 thinking_delta 事件接收思考內容。這些 delta 對應於 thinking 內容區塊的 thinking 欄位。

對於思考內容，在 content_block_stop 事件之前會發送一個特殊的 signature_delta 事件。此簽名用於驗證思考區塊的完整性。

典型的思考 delta 看起來像這樣：

思考 delta
event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "Let me solve this step by step:\n\n1. First break down 27 * 453"}}

簽名 delta 看起來像這樣：

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

​
原始 HTTP 串流回應

我們強烈建議在使用串流模式時使用我們的客戶端 SDK。但是，如果您正在建立直接的 API 整合，您需要自行處理這些事件。

串流回應由以下部分組成：

  1. 一個 message_start 事件
  2. 可能有多個內容區塊，每個區塊包含： a. 一個 content_block_start 事件 b. 可能有多個 content_block_delta 事件 c. 一個 content_block_stop 事件
  3. 一個 message_delta 事件
  4. 一個 message_stop 事件

整個回應中可能會分散有 ping 事件。有關格式的更多詳細信息，請參見事件類型。

​
基本串流請求

請求
curl https://api.anthropic.com/v1/messages \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --data \
'{
  "model": "claude-3-7-sonnet-20250219",
  "messages": [{"role": "user", "content": "Hello"}],
  "max_tokens": 256,
  "stream": true
}'
回應
event: message_start
data: {"type": "message_start", "message": {"id": "msg_1nZdL29xx5MUA1yADyHTEsnR8uuvGzszyY", "type": "message", "role": "assistant", "content": [], "model": "claude-3-7-sonnet-20250219", "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"}

​
使用工具的串流請求

在這個請求中，我們要求 Claude 使用工具來告訴我們天氣。

請求
  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-3-7-sonnet-20250219",
      "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
    }'
回應
event: message_start
data: {"type":"message_start","message":{"id":"msg_014p7gG3wDgGV9EUtLvnow3U","type":"message","role":"assistant","model":"claude-3-haiku-20240307","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_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":"\"unit\": \"fah"}}

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

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"}

​
延伸思考的串流請求

在這個請求中，我們啟用延伸思考並開啟串流，以查看 Claude 的逐步推理過程。

請求
curl https://api.anthropic.com/v1/messages \
     --header "x-api-key: $ANTHROPIC_API_KEY" \
     --header "anthropic-version: 2023-06-01" \
     --header "content-type: application/json" \
     --data \
'{
    "model": "claude-3-7-sonnet-20250219",
    "max_tokens": 20000,
    "stream": true,
    "thinking": {
        "type": "enabled",
        "budget_tokens": 16000
    },
    "messages": [
        {
            "role": "user",
            "content": "What is 27 * 453?"
        }
    ]
}'
回應
event: message_start
data: {"type": "message_start", "message": {"id": "msg_01...", "type": "message", "role": "assistant", "content": [], "model": "claude-3-7-sonnet-20250219", "stop_reason": null, "stop_sequence": null}}

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

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "讓我一步一步解決這個問題：\n\n1. 首先分解 27 * 453"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\n2. 453 = 400 + 50 + 3"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\n3. 27 * 400 = 10,800"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\n4. 27 * 50 = 1,350"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\n5. 27 * 3 = 81"}}

event: content_block_delta
data: {"type": "content_block_delta", "index": 0, "delta": {"type": "thinking_delta", "thinking": "\n6. 10,800 + 1,350 + 81 = 12,231"}}

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": "27 * 453 = 12,231"}}

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"}

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