diff --git a/enterprise/litellm_enterprise/proxy/hooks/managed_files.py b/enterprise/litellm_enterprise/proxy/hooks/managed_files.py
index cbd17845c5f..674db49a259 100644
--- a/enterprise/litellm_enterprise/proxy/hooks/managed_files.py
+++ b/enterprise/litellm_enterprise/proxy/hooks/managed_files.py
@@ -504,7 +504,7 @@ class _PROXY_LiteLLMManagedFiles(CustomLogger, BaseFileEndpoints):
                 if retrieve_file_id
                 else False
             )
-            if potential_file_id:
+            if potential_file_id and "llm_output_file_id," in potential_file_id:
                 model_id = self.get_model_id_from_unified_file_id(potential_file_id)
                 if model_id:
                     data["model"] = model_id
@@ -1058,7 +1058,12 @@ class _PROXY_LiteLLMManagedFiles(CustomLogger, BaseFileEndpoints):
         return file_id.split("llm_output_file_model_id,")[1].split(";")[0]
 
     def get_output_file_id_from_unified_file_id(self, file_id: str) -> str:
-        return file_id.split("llm_output_file_id,")[1].split(";")[0]
+        marker = "llm_output_file_id,"
+        if marker not in file_id:
+            raise ValueError(
+                f"Unified id does not contain {marker!r}: {file_id[:80]!r}"
+            )
+        return file_id.split(marker, 1)[1].split(";")[0]
 
     async def async_post_call_success_hook(
         self, data: Dict, user_api_key_dict: UserAPIKeyAuth, response: LLMResponseTypes
@@ -1102,13 +1107,22 @@ class _PROXY_LiteLLMManagedFiles(CustomLogger, BaseFileEndpoints):
                         decoded_unified_file_id = _is_base64_encoded_unified_file_id(
                             file_id_value
                         )
-                        if decoded_unified_file_id:
+                        if (
+                            decoded_unified_file_id
+                            and "llm_output_file_id," in decoded_unified_file_id
+                        ):
                             provider_file_id = (
                                 self.get_output_file_id_from_unified_file_id(
                                     decoded_unified_file_id
                                 )
                             )
                             unified_file_id = file_id_value
+                        elif decoded_unified_file_id:
+                            verbose_logger.warning(
+                                f"Skipping {file_attr}={file_id_value!r}: "
+                                "unified id is not a managed file output id"
+                            )
+                            continue
                         else:
                             provider_file_id = file_id_value
                             unified_file_id = self.get_unified_output_file_id(
diff --git a/tests/test_litellm/enterprise/proxy/test_managed_files_hook.py b/tests/test_litellm/enterprise/proxy/test_managed_files_hook.py
index 7ca86d24494..1336490a344 100644
--- a/tests/test_litellm/enterprise/proxy/test_managed_files_hook.py
+++ b/tests/test_litellm/enterprise/proxy/test_managed_files_hook.py
@@ -222,3 +222,36 @@ async def test_should_not_double_wrap_already_unified_output_file_id():
         already_unified + "=" * (-len(already_unified) % 4)
     ).decode()
     assert decoded.count(f"llm_output_file_id,{provider_file_id}") == 1
+
+
+@pytest.mark.asyncio
+async def test_should_skip_non_file_unified_id_on_output_file_id():
+    """Batch-style unified ids lack llm_output_file_id; must not IndexError or re-wrap."""
+    import base64
+
+    managed_files = _make_managed_files_instance()
+    batch_unified = (
+        base64.urlsafe_b64encode(
+            b"litellm_proxy;model_id:openai/openai/gpt-5.5-batch;llm_batch_id:batch_abc"
+        )
+        .decode()
+        .rstrip("=")
+    )
+
+    batch_response = _make_batch_response(
+        model_id="openai/openai/gpt-5.5-batch",
+        model_name="openai/openai/gpt-5.5-batch",
+        output_file_id=batch_unified,
+    )
+    user_api_key_dict = _make_user_api_key_dict()
+
+    with patch("litellm.afile_retrieve", AsyncMock()) as mock_afile_retrieve:
+        await managed_files.async_post_call_success_hook(
+            data={},
+            user_api_key_dict=user_api_key_dict,
+            response=batch_response,
+        )
+
+    assert batch_response.output_file_id == batch_unified
+    mock_afile_retrieve.assert_not_called()
+    managed_files.store_unified_file_id.assert_not_awaited()