fix: fail fast for CP HiCache storage args

python/sglang/srt/server_args.py

@@ -751,6 +751,9 @@ class ServerArgs:
         # Validate SSL arguments early (before dummy-model short-circuit).
         self._handle_ssl_validation()
 
+        # Validate CP shared KV constraints early (before dummy-model short-circuit).
+        self._handle_cp_shared_kv_validation()
+
         if self.model_path.lower() in ["none", "dummy"]:
             # Skip for dummy models
             return
@@ -904,6 +907,16 @@ class ServerArgs:
                 "to be specified."
             )
 
+    def _handle_cp_shared_kv_validation(self):
+        assert not (
+            self.enable_nsa_prefill_cp_shared_kv
+            and self.hicache_storage_backend is not None
+        ), (
+            "enable_nsa_prefill_cp_shared_kv does not support "
+            "hicache_storage_backend in the host-only CP HiCache stage. "
+            "Disable hicache_storage_backend or disable CP shared KV."
+        )
+
     def _handle_deprecated_args(self):
         # Handle deprecated tool call parsers
         deprecated_tool_call_parsers = {"qwen25": "qwen", "glm45": "glm"}
@@ -1457,15 +1470,6 @@ class ServerArgs:
     def _handle_model_specific_adjustments(self):
         from sglang.srt.configs.model_config import is_deepseek_nsa
 
-        assert not (
-            self.enable_nsa_prefill_cp_shared_kv
-            and self.hicache_storage_backend is not None
-        ), (
-            "enable_nsa_prefill_cp_shared_kv does not support "
-            "hicache_storage_backend in the host-only CP HiCache stage. "
-            "Disable hicache_storage_backend or disable CP shared KV."
-        )
-
         if parse_connector_type(self.model_path) == ConnectorType.INSTANCE:
             return