fix(batches): keep managed files on owner

Managed files and batches are provider-owned. Cross-model fallbacks can dispatch creation with credentials that cannot access the input file and replace the owning provider's validation error.\n\nCloses #35359

litellm/proxy/batches_endpoints/endpoints.py

@@ -262,7 +262,10 @@ async def create_batch(
                     detail={"error": "LLM Router not initialized. Ensure models added to proxy."},
                 )
 
-            response = await llm_router.acreate_batch(**_create_batch_data)
+            response = await llm_router.acreate_batch(
+                **_create_batch_data,
+                disable_fallbacks=True,
+            )
             response.input_file_id = input_file_id
             response._hidden_params["unified_file_id"] = unified_file_id
         else:

tests/test_litellm/proxy/batches_endpoints/test_endpoints.py

@@ -469,7 +469,7 @@ async def test_create__fallback_body_custom_llm_provider(harness):
 
 
 @pytest.mark.asyncio
-async def test_create__unified_file_id_single_model(harness):
+async def test_create__unified_file_id_single_model_disables_cross_model_fallbacks(harness):
     set_body(
         harness,
         {
@@ -489,6 +489,7 @@ async def test_create__unified_file_id_single_model(harness):
     harness.litellm_acreate.assert_not_called()
     # model injected from the unified id, input_file_id restored, hidden param set
     assert harness.router_kwargs()["model"] == "gpt-4o-mini"
+    assert harness.router_kwargs()["disable_fallbacks"] is True
     assert resp.input_file_id == "litellm_proxy_unified_id"
     assert resp._hidden_params["unified_file_id"] == "unified-xyz"
 

tests/test_litellm/test_router.py

@@ -6054,6 +6054,51 @@ def test_get_configured_token_limits_coerces_numeric_strings():
     assert router.get_configured_token_limits("quoted-limits-model") == (32000, 8000)
 
 
+@pytest.mark.asyncio
+async def test_acreate_batch_disable_fallbacks_surfaces_owning_provider_error():
+    router = litellm.Router(
+        model_list=[
+            {
+                "model_name": "owning-model",
+                "litellm_params": {
+                    "model": "openai/gpt-4o-mini",
+                    "api_key": "sk-owning",
+                },
+            },
+            {
+                "model_name": "fallback-model",
+                "litellm_params": {
+                    "model": "azure/gpt-4o-mini",
+                    "api_key": "sk-fallback",
+                    "api_base": "https://fallback.openai.azure.com",
+                    "api_version": "2024-08-01-preview",
+                },
+            },
+        ],
+        fallbacks=[{"owning-model": ["fallback-model"]}],
+        num_retries=0,
+    )
+    owning_provider_error = litellm.BadRequestError(
+        message="completion_window must be one of: 24h",
+        model="openai/gpt-4o-mini",
+        llm_provider="openai",
+    )
+    mock_create = AsyncMock(side_effect=owning_provider_error)
+
+    with patch.object(router, "_acreate_batch", mock_create):
+        with pytest.raises(litellm.BadRequestError, match="24h"):
+            await router.acreate_batch(
+                model="owning-model",
+                input_file_id="file-owned-by-openai",
+                endpoint="/v1/chat/completions",
+                completion_window="5m",
+                disable_fallbacks=True,
+            )
+
+    mock_create.assert_awaited_once()
+    assert mock_create.call_args.kwargs["model"] == "owning-model"
+
+
 @pytest.mark.asyncio
 async def test_acreate_batch_request_bedrock_tags_override_deployment_tags():
     import httpx