From d66c7fb8b01bd498c75497b4a53f7dc2f6db083f Mon Sep 17 00:00:00 2001
From: Ishaan Jaff <ishaanjaffer0324@gmail.com>
Date: Thu, 24 Jul 2025 13:15:28 -0700
Subject: [PATCH] async_pre_routing_hook

---
 litellm/router_strategy/auto_router.py | 66 ++++++++++++++++++++++++++
 1 file changed, 66 insertions(+)
 create mode 100644 litellm/router_strategy/auto_router.py

diff --git a/litellm/router_strategy/auto_router.py b/litellm/router_strategy/auto_router.py
new file mode 100644
index 00000000000..641ff8bf3cb
--- /dev/null
+++ b/litellm/router_strategy/auto_router.py
@@ -0,0 +1,66 @@
+"""
+Auto-Routing Strategy that works with a Semantic Router Config
+"""
+
+import json
+import os
+from typing import List, Literal, Optional, Union
+
+from semantic_router.schema import RouteChoice
+
+import litellm
+from litellm.integrations.custom_logger import CustomLogger
+from litellm.proxy.proxy_server import DualCache, UserAPIKeyAuth
+
+
+class AutoRouter(CustomLogger):
+    DEFAULT_AUTO_SYNC_VALUE = "local"
+    def __init__(
+        self,
+        router_config_path: str,
+        default_model: str
+    ):  
+        from semantic_router import Route
+        from semantic_router.encoders import OpenAIEncoder
+        from semantic_router.routers import SemanticRouter
+        self.router_config_path = router_config_path
+        self.auto_sync_value = self.DEFAULT_AUTO_SYNC_VALUE
+        loaded_router: SemanticRouter = SemanticRouter.from_json(self.router_config_path)
+        self.routelayer: SemanticRouter = SemanticRouter(
+                routes=loaded_router.routes,
+                encoder=loaded_router.encoder,
+                auto_sync=self.auto_sync_value
+            )
+        self.default_model = default_model
+        pass
+
+
+    async def async_pre_routing_hook(
+        self, 
+        data: dict, call_type: Literal[
+            "completion",
+            "text_completion",
+            "embeddings",
+            "image_generation",
+            "moderation",
+            "audio_transcription",
+        ]):
+        from semantic_router.schema import RouteChoice
+
+        #self.routelayer.to_json("./config/router.json")
+        # If the call type is embeddings, do not modify the model.
+        if call_type in ["embeddings", "image_generation"]:
+           #print("Call type is 'embeddings', using default behavior.")
+           return data  # Return without modifying the data
+        
+        msg = data['messages'][-1]['content']
+        route_choice: Optional[Union[RouteChoice, List[RouteChoice]]] = self.routelayer(text=msg)
+        if isinstance(route_choice, RouteChoice):
+            data["model"] = route_choice.name
+        elif isinstance(route_choice, list):
+            data["model"] = route_choice[0].name
+        else:
+            data["model"] = self.default_model
+
+        return data
+