Merge pull request #20516 from Chesars/fix/openrouter-native-model-double-strip

fix(adapter): double-stripping of model names with provider-matching prefixes

litellm/litellm_core_utils/get_llm_provider_logic.py

@@ -3,6 +3,7 @@ from typing import Optional, Tuple
 import litellm
 from litellm.constants import REPLICATE_MODEL_NAME_WITH_ID_LENGTH
 from litellm.llms.openai_like.json_loader import JSONProviderRegistry
+from litellm.llms.openrouter.common_utils import NATIVE_OPENROUTER_MODELS
 from litellm.secret_managers.main import get_secret, get_secret_str
 
 from ..types.router import LiteLLM_Params
@@ -171,6 +172,12 @@ def get_llm_provider(  # noqa: PLR0915
                 dynamic_api_key=dynamic_api_key,
             )
 
+        # Check native OpenRouter models before provider_list stripping.
+        # These models have IDs like "openrouter/free" which would be
+        # incorrectly stripped to just "free" by the logic below.
+        if model in NATIVE_OPENROUTER_MODELS:
+            return model, "openrouter", dynamic_api_key, api_base
+
         # check if llm provider part of model name
 
         if (

litellm/llms/openrouter/common_utils.py

@@ -1,5 +1,15 @@
 from litellm.llms.base_llm.chat.transformation import BaseLLMException
 
+# Native OpenRouter models whose IDs start with "openrouter/".
+# When used via LiteLLM (openrouter/openrouter/free), get_llm_provider()
+# must not strip the inner "openrouter/" prefix on its second invocation.
+# See: https://github.com/BerriAI/litellm/issues/16353
+NATIVE_OPENROUTER_MODELS = {
+    "openrouter/auto",
+    "openrouter/free",
+    "openrouter/bodybuilder",
+}
+
 
 class OpenRouterException(BaseLLMException):
     pass

tests/litellm/llms/openrouter/test_openrouter_native_models.py

@@ -0,0 +1,75 @@
+"""
+Tests for native OpenRouter model name handling in get_llm_provider.
+
+OpenRouter's native models (openrouter/auto, openrouter/free,
+openrouter/bodybuilder) should not have their "openrouter/" prefix
+stripped when passed to get_llm_provider(), since that prefix is part
+of the actual model ID on OpenRouter's API.
+
+"""
+
+import pytest
+
+import litellm
+
+
+class TestNativeOpenRouterModelsNotStripped:
+    """get_llm_provider must preserve native OpenRouter model names."""
+
+    @pytest.mark.parametrize(
+        "model",
+        [
+            "openrouter/auto",
+            "openrouter/free",
+            "openrouter/bodybuilder",
+        ],
+    )
+    def test_native_model_not_stripped(self, model):
+        """Native OpenRouter model IDs are returned as-is."""
+        result_model, provider, _, _ = litellm.get_llm_provider(model=model)
+        assert result_model == model
+        assert provider == "openrouter"
+
+    @pytest.mark.parametrize(
+        "model,expected_model",
+        [
+            ("openrouter/openrouter/free", "openrouter/free"),
+            ("openrouter/openrouter/auto", "openrouter/auto"),
+            ("openrouter/openrouter/bodybuilder", "openrouter/bodybuilder"),
+        ],
+    )
+    def test_double_prefixed_model_strips_once_to_native(self, model, expected_model):
+        """openrouter/openrouter/free strips to openrouter/free (not further)."""
+        result_model, provider, _, _ = litellm.get_llm_provider(model=model)
+        assert result_model == expected_model
+        assert provider == "openrouter"
+
+    @pytest.mark.parametrize(
+        "model,expected_model",
+        [
+            ("openrouter/openrouter/free", "openrouter/free"),
+            ("openrouter/openrouter/auto", "openrouter/auto"),
+        ],
+    )
+    def test_full_round_trip_no_double_strip(self, model, expected_model):
+        """Simulates the bridge flow: two consecutive get_llm_provider calls."""
+        # First call (in adapter/handler)
+        model_after_first, provider, _, _ = litellm.get_llm_provider(model=model)
+        assert model_after_first == expected_model
+
+        # Second call (inside litellm.completion)
+        model_after_second, provider2, _, _ = litellm.get_llm_provider(
+            model=model_after_first
+        )
+        # Should stay as native model, not stripped further
+        assert model_after_second == expected_model
+        assert provider2 == "openrouter"
+
+    def test_regular_openrouter_model_still_strips_normally(self):
+        """Non-native models like openrouter/anthropic/claude-3-haiku still strip normally."""
+        model, provider, _, _ = litellm.get_llm_provider(
+            model="openrouter/anthropic/claude-3-haiku"
+        )
+        assert provider == "openrouter"
+        # Should strip the openrouter/ prefix
+        assert model == "anthropic/claude-3-haiku"