add llm service

app/services/llm.py

@@ -0,0 +1,51 @@
+import httpx
+import orjson
+from typing import AsyncGenerator, Optional
+
+
+class StreamLLMService:
+    def __init__(self, base_url: str = "http://localhost:11434/v1"):
+        self.base_url = base_url
+        self.model = "llama3.2"
+
+    async def stream_chat(self, prompt: str) -> AsyncGenerator[bytes, None]:
+        """Stream chat completion responses from LLM."""
+        # Send user message first
+        user_msg = {
+            'role': 'user',
+            'content': prompt,
+        }
+        yield orjson.dumps(user_msg) + b'\n'
+
+        # Open client as context manager and stream responses
+        async with httpx.AsyncClient(base_url=self.base_url) as client:
+            async with client.stream(
+                    "POST",
+                    "/chat/completions",
+                    json={
+                        "model": self.model,
+                        "messages": [{"role": "user", "content": prompt}],
+                        "stream": True
+                    },
+                    timeout=60.0
+            ) as response:
+                async for line in response.aiter_lines():
+                    print(line)
+                    if line.startswith("data: ") and line != "data: [DONE]":
+                        try:
+                            json_line = line[6:]  # Remove "data: " prefix
+                            data = orjson.loads(json_line)
+                            content = data.get("choices", [{}])[0].get("delta", {}).get("content", "")
+                            if content:
+                                model_msg = {
+                                    'role': 'model',
+                                    'content': content
+                                }
+                                yield orjson.dumps(model_msg) + b'\n'
+                        except Exception:
+                            pass
+
+
+# FastAPI dependency
+def get_llm_service(base_url: Optional[str] = None) -> StreamLLMService:
+    return StreamLLMService(base_url=base_url)