API 使用指南
流式输出
三种协议的 SSE 事件格式、结束标志、心跳和流中错误。
在请求体中设置 "stream": true,网关会用 SSE(Server-Sent Events)逐段返回结果。三种协议的事件格式不同。
通用规则
- 响应头为
Content-Type: text/event-stream。 - 认证失败、请求 JSON 无法解析、模型不在密钥的允许列表中时,网关直接返回 JSON 错误和对应的 HTTP 状态码。
- 通过这些检查后,网关立即返回 HTTP
200并开始推送。之后发生的错误(例如模型不存在、没有可用上游、上游断开)以错误事件的形式出现在流中。客户端必须检查流中的错误事件,不能只看 HTTP 状态码。 - 长时间没有数据时,网关每 15 秒发送一次心跳,防止代理或负载均衡断开连接。
Chat Completions
每个事件只有 data: 行,没有 event: 行。流以 data: [DONE] 结束。
data: {"id":"chatcmpl_...","object":"chat.completion.chunk","created":1791730171,"model":"deepseek-v4-pro","choices":[{"index":0,"delta":{"role":"assistant"},"finish_reason":null}]}
data: {"id":"chatcmpl_...","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"reasoning_details":[{"type":"reasoning.text","text":"用户在打招呼。"}]},"finish_reason":null}]}
data: {"id":"chatcmpl_...","object":"chat.completion.chunk","choices":[{"index":0,"delta":{"content":"你好"},"finish_reason":null}]}
data: {"id":"chatcmpl_...","object":"chat.completion.chunk","choices":[{"index":0,"delta":{},"finish_reason":"stop"}]}
data: {"id":"chatcmpl_...","object":"chat.completion.chunk","choices":[],"usage":{"prompt_tokens":12,"completion_tokens":20,"total_tokens":32}}
data: [DONE]- 文本在
choices[0].delta.content中。 - 推理在
choices[0].delta.reasoning_details[]中。见思维链(推理)。 - 工具调用在
choices[0].delta.tool_calls[]中,参数按片段拼接。见工具调用。 - 结束块的
delta为空,finish_reason为stop、length、tool_calls或content_filter。 - 上游报告用量时,网关在结束块之后、
[DONE]之前发送一个choices为空数组的用量块。你不需要设置stream_options.include_usage。 - 心跳是 SSE 注释行
: heartbeat。标准 SSE 解析器会忽略它。
用 OpenAI SDK 读取流:
stream = client.chat.completions.create(
model="deepseek-v4-pro",
messages=[{"role": "user", "content": "写一首两行的诗。"}],
stream=True,
)
for chunk in stream:
if chunk.choices and chunk.choices[0].delta.content:
print(chunk.choices[0].delta.content, end="", flush=True)
if chunk.usage:
print("\n用量:", chunk.usage.total_tokens)流中的错误事件:
data: {"error":{"code":"model_not_found","message":"Model not found: no-such","param":null,"type":"invalid_request_error"}}
data: [DONE]Responses
每个事件有 event: 行和 data: 行,data 中的 type 与事件名相同。流以 data: [DONE] 结束。
常见事件顺序:
response.created、response.in_progressresponse.output_item.added:开始一个输出项(推理、消息或函数调用)。- 内容事件:
response.output_text.delta:回复文本片段。response.reasoning_summary_text.delta:推理摘要片段。response.reasoning_text.delta:原始推理文本片段。response.function_call_arguments.delta:函数参数片段。
- 对应的
.done事件和response.output_item.done。 - 终止事件:
response.completed、response.incomplete或response.failed。 data: [DONE]
event: response.output_text.delta
data: {"type":"response.output_text.delta","item_id":"msg_...","output_index":1,"content_index":0,"delta":"你好","sequence_number":7}用 OpenAI SDK 读取流:
stream = client.responses.create(model="gpt-5.5", input="写一首两行的诗。", stream=True)
for event in stream:
if event.type == "response.output_text.delta":
print(event.delta, end="", flush=True)
elif event.type == "response.completed":
print("\n用量:", event.response.usage.total_tokens)
elif event.type in ("response.failed", "error"):
print("\n失败:", event)流中的错误先发送 event: error,再发送 event: response.failed,最后是 data: [DONE]:
event: error
data: {"type":"error","code":"model_not_found","message":"Model not found: no-such","param":null,"sequence_number":1}
event: response.failed
data: {"type":"response.failed","response":{"status":"failed","error":{"code":"model_not_found","message":"Model not found: no-such"}}}
data: [DONE]客户端应以 response.failed 作为失败的终止信号。
Messages
事件格式与 Anthropic 官方相同。每个事件有 event: 行,流以 message_stop 结束,没有 [DONE]。
event: message_start
data: {"type":"message_start","message":{"id":"msg_...","role":"assistant","content":[],"usage":{"input_tokens":12,"output_tokens":1}}}
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":"你好"}}
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":20}}
event: message_stop
data: {"type":"message_stop"}content_block_delta的delta.type可以是text_delta、thinking_delta、signature_delta或input_json_delta。- 块按
index从 0 开始依次出现,一个块结束后才开始下一个块。 - 心跳是
event: ping事件,数据为{"type":"ping"}。 - 流中的错误是
event: error事件,之后连接关闭。
用 Anthropic SDK 读取流:
with client.messages.stream(
model="claude-sonnet-5",
max_tokens=1024,
messages=[{"role": "user", "content": "写一首两行的诗。"}],
) as stream:
for text in stream.text_stream:
print(text, end="", flush=True)连接中断
- 流已经开始后,网关不会切换到另一个上游。上游中途失败时,你会收到错误事件。
- 上游长时间不发数据时,网关按超时处理,并发送错误终止事件。网关不会把截断的回复报告为成功。
- 客户端断开连接不会取消上游请求。上游正常完成时,网关照常计费,日志中的状态为
client_gone。需要停止生成时,不要依赖断开连接来节省费用。