[Fix] Add validation for served model name to reserve : for LoRA adapter syntax (#12912)

Co-authored-by: neelabhsinha <neelabhsinha97@gmail.com>

python/sglang/srt/server_args.py

@@ -3678,6 +3678,13 @@ class ServerArgs:
             None,
         }, "moe_dense_tp_size only support 1 and None currently"
 
+        # Check served model name to not have colon as it is reserved for LoRA adapter syntax
+        assert ":" not in self.served_model_name, (
+            "served_model_name cannot contain a colon (':') character. "
+            "The colon is reserved for the 'model:adapter' syntax used in LoRA adapter specification. "
+            f"Invalid value: '{self.served_model_name}'"
+        )
+
         # Check LoRA
         self.check_lora_server_args()