feat(api): add streaming chat endpoint proxying upstream SSE

api/main.py

@@ -1,7 +1,9 @@
 from contextlib import asynccontextmanager
-from fastapi import FastAPI, HTTPException
+from fastapi import FastAPI, HTTPException, Request
+from fastapi.responses import StreamingResponse
 from pydantic import BaseModel
 from typing import Optional
+import httpx
 import uvicorn
 import os
 import sys
@@ -10,6 +12,7 @@ import sys
 sys.path.append(os.path.dirname(os.path.dirname(os.path.abspath(__file__))))
 
 from chat_service import ChatService
+from config import OPENAI_API_BASE_URL_CONFIG, OPENAI_API_KEY_FROM_CONFIG, OPENAI_LLM_MODEL
 from logging_config import setup_logging, get_logger
 
 # 设置日志
@@ -101,6 +104,82 @@ async def chat_endpoint(request: ChatRequest):
         raise HTTPException(status_code=500, detail=f"Internal server error: {str(e)}")
 
 
+@app.post("/chat/stream")
+async def chat_stream_endpoint(request: Request):
+    """
+    纯转发豆包 SSE 流式输出的接口（OpenAI 格式兼容）。
+
+    允许传入 OpenAI 标准的 messages，也兼容单一 message 字段。
+    """
+    try:
+        payload = await request.json()
+    except Exception:
+        raise HTTPException(status_code=400, detail="Invalid JSON body")
+
+    if not isinstance(payload, dict):
+        raise HTTPException(status_code=400, detail="Request body must be a JSON object")
+
+    messages = payload.get("messages")
+    if messages is None:
+        message = payload.get("message")
+        if not message:
+            raise HTTPException(status_code=400, detail="Missing 'message' or 'messages'")
+        messages = [{"role": "user", "content": message}]
+        payload.pop("message", None)
+
+    payload["messages"] = messages
+    payload.pop("user_id", None)
+    payload.pop("include_audio", None)
+    if not payload.get("model"):
+        payload["model"] = OPENAI_LLM_MODEL
+    payload["stream"] = True
+
+    base_url = OPENAI_API_BASE_URL_CONFIG or ""
+    if not base_url:
+        raise HTTPException(status_code=500, detail="Upstream base URL is not configured")
+
+    api_key = OPENAI_API_KEY_FROM_CONFIG or ""
+    if not api_key or api_key.startswith("YOUR_API_KEY_PLACEHOLDER"):
+        raise HTTPException(status_code=500, detail="Upstream API key is not configured")
+
+    upstream_url = f"{base_url.rstrip('/')}/chat/completions"
+    headers = {
+        "Authorization": f"Bearer {api_key}",
+        "Content-Type": "application/json",
+        "Accept": "text/event-stream",
+    }
+
+    client = httpx.AsyncClient(timeout=None)
+    req = client.build_request("POST", upstream_url, headers=headers, json=payload)
+    resp = await client.send(req, stream=True)
+
+    if resp.status_code != 200:
+        detail_bytes = await resp.aread()
+        await resp.aclose()
+        await client.aclose()
+        detail = detail_bytes.decode("utf-8", "ignore") if detail_bytes else "Upstream error"
+        raise HTTPException(status_code=resp.status_code, detail=detail)
+
+    async def event_stream():
+        try:
+            async for chunk in resp.aiter_raw():
+                if chunk:
+                    yield chunk
+        finally:
+            await resp.aclose()
+            await client.aclose()
+
+    return StreamingResponse(
+        event_stream(),
+        media_type="text/event-stream",
+        headers={
+            "Cache-Control": "no-cache",
+            "Connection": "keep-alive",
+            "X-Accel-Buffering": "no",
+        },
+    )
+
+
 if __name__ == "__main__":
     uvicorn.run(
         "main:app",