feat: 支持 LiteLLM 客户端的 application/octet-stream 请求

修改 Ollama API 路由处理程序，使 /chat 和 /generate 端点能够接受 Content-Type 为 application/octet-stream 的请求。通过绕过 FastAPI 的自动请求验证机制，手动解析请求体，解决了 LiteLLM 客户端连接时出现的 422 错误。此更改保持了对现有 application/json 请求的向后兼容性。

lightrag/api/routers/ollama_api.py

@@ -1,6 +1,6 @@
 from fastapi import APIRouter, HTTPException, Request
 from pydantic import BaseModel
-from typing import List, Dict, Any, Optional
+from typing import List, Dict, Any, Optional, Type
 from lightrag.utils import logger
 import time
 import json
@@ -95,6 +95,47 @@ class OllamaTagResponse(BaseModel):
     models: List[OllamaModel]
 
 
+async def parse_request_body(request: Request, model_class: Type[BaseModel]) -> BaseModel:
+    """
+    Parse request body based on Content-Type header.
+    Supports both application/json and application/octet-stream.
+    
+    Args:
+        request: The FastAPI Request object
+        model_class: The Pydantic model class to parse the request into
+        
+    Returns:
+        An instance of the provided model_class
+    """
+    content_type = request.headers.get("content-type", "").lower()
+    
+    try:
+        if content_type.startswith("application/json"):
+            # FastAPI already handles JSON parsing for us
+            body = await request.json()
+        elif content_type.startswith("application/octet-stream"):
+            # Manually parse octet-stream as JSON
+            body_bytes = await request.body()
+            body = json.loads(body_bytes.decode('utf-8'))
+        else:
+            # Try to parse as JSON for any other content type
+            body_bytes = await request.body()
+            body = json.loads(body_bytes.decode('utf-8'))
+        
+        # Create an instance of the model
+        return model_class(**body)
+    except json.JSONDecodeError:
+        raise HTTPException(
+            status_code=400, 
+            detail="Invalid JSON in request body"
+        )
+    except Exception as e:
+        raise HTTPException(
+            status_code=400,
+            detail=f"Error parsing request body: {str(e)}"
+        )
+
+
 def estimate_tokens(text: str) -> int:
     """Estimate the number of tokens in text using tiktoken"""
     tokens = TiktokenTokenizer().encode(text)
@@ -197,13 +238,17 @@ class OllamaAPI:
                 ]
             )
 
-        @self.router.post("/generate", dependencies=[Depends(combined_auth)])
-        async def generate(raw_request: Request, request: OllamaGenerateRequest):
+        @self.router.post("/generate", dependencies=[Depends(combined_auth)], include_in_schema=True)
+        async def generate(raw_request: Request):
             """Handle generate completion requests acting as an Ollama model
             For compatibility purpose, the request is not processed by LightRAG,
             and will be handled by underlying LLM model.
+            Supports both application/json and application/octet-stream Content-Types.
             """
             try:
+                # Parse the request body manually
+                request = await parse_request_body(raw_request, OllamaGenerateRequest)
+                
                 query = request.prompt
                 start_time = time.time_ns()
                 prompt_tokens = estimate_tokens(query)
@@ -363,13 +408,17 @@ class OllamaAPI:
                 trace_exception(e)
                 raise HTTPException(status_code=500, detail=str(e))
 
-        @self.router.post("/chat", dependencies=[Depends(combined_auth)])
-        async def chat(raw_request: Request, request: OllamaChatRequest):
+        @self.router.post("/chat", dependencies=[Depends(combined_auth)], include_in_schema=True)
+        async def chat(raw_request: Request):
             """Process chat completion requests acting as an Ollama model
             Routes user queries through LightRAG by selecting query mode based on prefix indicators.
             Detects and forwards OpenWebUI session-related requests (for meta data generation task) directly to LLM.
+            Supports both application/json and application/octet-stream Content-Types.
             """
             try:
+                # Parse the request body manually
+                request = await parse_request_body(raw_request, OllamaChatRequest)
+                
                 # Get all messages
                 messages = request.messages
                 if not messages: