switched to openrouter model

app/config/config.yaml

@@ -8,6 +8,9 @@ llm:
   gemini_lite:
     provider: "gemini_lite"
     model_name: "gemini-2.5-flash-lite"
+  openrouter:
+    provider: "openrouter"
+    model_name: "google/gemma-3-27b-it:free"
 
 embedding_model: 
   openai: 

app/services/RAG_service.py

@@ -42,8 +42,8 @@ class RAGService:
 
     def _init_models(self):
         """Initialize LLM and embedding Models"""
-        print("[RAGService] Loading LLM model (gemini)...")
-        self.model_loader = ModelLoader(model_provider="gemini")
+        print("[RAGService] Loading LLM model (openrouter)...")
+        self.model_loader = ModelLoader(model_provider="openrouter")
         self.llm = self.model_loader.load_llm()
         print("[RAGService] LLM model loaded.")
         print("[RAGService] Loading embedding model (huggingface)...")

app/utils/model_loader.py

@@ -10,6 +10,8 @@ from dotenv import load_dotenv
 from langchain_huggingface import HuggingFaceEmbeddings
 # from langchain_openai import OpenAIEmbeddings
 from langchain_community.embeddings import OpenAIEmbeddings
+from langchain.chat_models import init_chat_model
+
 class ConfigLoader:
     def __init__(self):
         print(f"Loading config....")
@@ -20,7 +22,7 @@ class ConfigLoader:
     
 
 class ModelLoader(BaseModel):
-    model_provider: Literal["groq", "gemini", "openai","gemini_lite", "huggingface"] = "gemini" 
+    model_provider: Literal["groq", "gemini", "openai","gemini_lite", "huggingface","openrouter"] = "openrouter" 
     config: Optional[ConfigLoader] = Field(default = None, exclude = True) # either the config is ConfigLoader object or None
 
     def model_post_init(self, __context: Any)->None:
@@ -65,6 +67,16 @@ class ModelLoader(BaseModel):
             api_key = os.getenv("OPENAI_API_KEY")
             model_name = self.config["embedding_model"]["openai"]["model_name"]
             llm = OpenAIEmbeddings(model=model_name, api_key = api_key)
+        elif self.model_provider == "operouter":
+            load_dotenv()
+            api_key = os.getenv("OPENROUTER_API_KEY")
+            model_name = self.config["llm"]["openrouter"]["model_name"]
+            llm = init_chat_model(
+                model=model_name,
+                model_provider="openai",
+                base_url="https://openrouter.ai/api/v1",
+                api_key=api_key
+            )
         elif self.model_provider =="huggingface":
             load_dotenv()
             print("Loading model from huggingface:")