fix(gemini): simplify model version check (#42465)

litellm/llms/gemini/chat/transformation.py

@@ -102,7 +102,7 @@ class GoogleAIStudioGeminiConfig(VertexGeminiConfig):
             "include_server_side_tool_invocations",
             "service_tier",
         ]
-        if supports_reasoning(model, custom_llm_provider="gemini"):
+        if supports_reasoning(model, custom_llm_provider="gemini") or self._is_gemini_3_or_newer(model):
             supported_params.append("reasoning_effort")
             supported_params.append("thinking")
         if self.is_model_gemini_audio_model(model):

litellm/llms/vertex_ai/gemini/vertex_and_google_ai_studio_gemini.py

@@ -2,6 +2,7 @@
 ## httpx client for vertex ai calls
 ## Initial implementation - covers gemini + image gen calls
 import json
+import re
 import time
 from collections.abc import Callable, Mapping, Sequence
 from copy import deepcopy
@@ -283,20 +284,15 @@ class VertexGeminiConfig(VertexAIBaseConfig, BaseConfig):
     @staticmethod
     def _is_gemini_3_or_newer(model: str) -> bool:
         """
-        Check if the model is Gemini 3 Pro or newer.
-
-        Gemini 3 models include:
-        - gemini-3-pro-preview
-        - gemini-3-flash
-        - gemini-3-flash-preview (Gemini 3 Flash)
-        - gemini-3.1-pro-preview, gemini-3.1-flash, gemini-3.1-flash-lite-preview
-        - gemini-3.5-flash
-        - Any future Gemini 3.x models
+        Check if the model is Gemini 3 or newer.
         """
-        # Check for Gemini 3 models
-        if "gemini-3" in model:
-            return True
-        return False
+        model_name = model.split("/")[-1].lower()
+        if not model_name:
+            return False
+        # Pre-Gemini 3 models: gemini-1.x, gemini-2.x, gemini-pro, gemini-flash, gemini-exp
+        if re.match(r"^gemini-(?:[12](?:\.\d+)?|exp|(?:pro|flash)(?!-(?:lite-)?latest$))(?:-|$)", model_name):
+            return False
+        return True
 
     @staticmethod
     def _forward_gemini_function_call_id(model: str) -> bool:
@@ -347,9 +343,10 @@ class VertexGeminiConfig(VertexAIBaseConfig, BaseConfig):
         if self._supports_penalty_parameters(model):
             supported_params.extend(["frequency_penalty", "presence_penalty"])
 
-        if supports_reasoning(model):
+        if supports_reasoning(model) or self._is_gemini_3_or_newer(model):
             supported_params.append("reasoning_effort")
             supported_params.append("thinking")
+
         return supported_params
 
     def map_tool_choice_values(self, model: str, tool_choice: str | dict) -> ToolConfig | None:
@@ -871,8 +868,8 @@ class VertexGeminiConfig(VertexAIBaseConfig, BaseConfig):
     @staticmethod
     def _supports_minimal_thinking_level(model: str) -> bool:
         lowered: Final = model.lower()
-        is_gemini3flash: Final = "gemini-3" in lowered and "flash" in lowered
-        return is_gemini3flash and not is_explicitly_disabled_factory(
+        is_gemini3_or_newer_flash: Final = VertexGeminiConfig._is_gemini_3_or_newer(model) and "flash" in lowered
+        return is_gemini3_or_newer_flash and not is_explicitly_disabled_factory(
             model=model, custom_llm_provider=None, key="supports_minimal_reasoning_effort"
         )
 
@@ -890,9 +887,7 @@ class VertexGeminiConfig(VertexAIBaseConfig, BaseConfig):
         Returns:
             GeminiThinkingConfig with thinkingLevel and includeThoughts
         """
-        is_gemini3flash: Final = model and ("flash" in model.lower() and "gemini-3" in model.lower())
         supports_minimal: Final = bool(model) and VertexGeminiConfig._supports_minimal_thinking_level(model)
-        is_gemini31pro: Final = model and ("gemini-3.1-pro-preview" in model.lower())
         if reasoning_effort == "minimal":
             if supports_minimal:
                 return {"thinkingLevel": "minimal", "includeThoughts": True}
@@ -901,10 +896,7 @@ class VertexGeminiConfig(VertexAIBaseConfig, BaseConfig):
         elif reasoning_effort == "low":
             return {"thinkingLevel": "low", "includeThoughts": True}
         elif reasoning_effort == "medium":
-            if is_gemini31pro or is_gemini3flash:
-                return {"thinkingLevel": "medium", "includeThoughts": True}
-            else:
-                return {"thinkingLevel": "high", "includeThoughts": True}
+            return {"thinkingLevel": "medium", "includeThoughts": True}
         elif reasoning_effort == "high":
             return {"thinkingLevel": "high", "includeThoughts": True}
         elif reasoning_effort in ("disable", "none"):

tests/test_litellm/litellm_core_utils/test_fallback_generalizations.py

@@ -517,7 +517,7 @@ def test_shipped_gemini_chat_baseline_keeps_reasoning_effort_on_unmapped_model(s
         drop_params=False,
     )
     assert isinstance(optional_params, dict)
-    assert optional_params["thinkingConfig"]["thinkingBudget"] > 0
+    assert optional_params["thinkingConfig"]["thinkingLevel"] == "medium"
     assert optional_params["thinkingConfig"]["includeThoughts"] is True
 
 

tests/test_litellm/llms/vertex_ai/gemini/test_vertex_and_google_ai_studio_gemini.py

@@ -2435,10 +2435,16 @@ def test_is_gemini_3_or_newer():
         VertexGeminiConfig,
     )
 
-    # Gemini 3 models
+    # Gemini 3+ models
     assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-3-pro-preview") == True
     assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-3-flash") == True
     assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-3-pro") == True
+    assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-3.1-pro-preview") == True
+    assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-test-id-bla") == True
+    assert VertexGeminiConfig._is_gemini_3_or_newer("test-id-bla") == True
+    assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-flash-latest") == True
+    assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-flash-lite-latest") == True
+    assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-pro-latest") == True
     assert (
         VertexGeminiConfig._is_gemini_3_or_newer("vertex_ai/gemini-3-pro-preview")
         == True
@@ -2453,11 +2459,53 @@ def test_is_gemini_3_or_newer():
     assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-2.0-flash") == False
     assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-1.5-pro") == False
     assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-pro") == False
+    assert VertexGeminiConfig._is_gemini_3_or_newer("gemini-flash") == False
 
     # Edge cases
     assert VertexGeminiConfig._is_gemini_3_or_newer("") == False
 
 
+@pytest.mark.parametrize(
+    "model",
+    [
+        "gemini-3.1-pro-preview",
+        "gemini-3-flash",
+        "gemini-test-id-bla",
+        "test-id-bla",
+    ],
+)
+def test_gemini_3_reasoning_effort_maps_to_thinking_level(model: str):
+    """Test that reasoning_effort maps to thinkingLevel and default temperature=1.0"""
+    from litellm.llms.gemini.chat.transformation import GoogleAIStudioGeminiConfig
+    from litellm.llms.vertex_ai.gemini.vertex_and_google_ai_studio_gemini import (
+        VertexGeminiConfig,
+    )
+
+    vertex_cfg = VertexGeminiConfig()
+    studio_cfg = GoogleAIStudioGeminiConfig()
+
+    for cfg in (vertex_cfg, studio_cfg):
+        supported = cfg.get_supported_openai_params(model)
+        assert "reasoning_effort" in supported
+        assert "thinking" in supported
+
+    for effort in ("low", "medium", "high"):
+        mapped = vertex_cfg.map_openai_params(
+            non_default_params={"reasoning_effort": effort},
+            optional_params={},
+            model=model,
+            drop_params=False,
+        )
+        assert mapped["thinkingConfig"] == {
+            "thinkingLevel": effort,
+            "includeThoughts": True,
+        }
+        assert mapped["temperature"] == 1.0
+        assert "thinkingBudget" not in mapped["thinkingConfig"]
+
+
+
+
 def _tool_call_messages(tool_call_id: str):
     return [
         {"role": "user", "content": "hi"},
@@ -2643,7 +2691,7 @@ def test_reasoning_effort_maps_to_thinking_level_gemini_3():
     assert result["thinkingConfig"]["thinkingLevel"] == "low"
     assert result["thinkingConfig"]["includeThoughts"] is True
 
-    # Test medium -> high + includeThoughts=True (medium not available yet)
+    # Test medium -> medium + includeThoughts=True
     optional_params = {}
     non_default_params = {"reasoning_effort": "medium"}
     result = v.map_openai_params(
@@ -2652,7 +2700,7 @@ def test_reasoning_effort_maps_to_thinking_level_gemini_3():
         model=model,
         drop_params=False,
     )
-    assert result["thinkingConfig"]["thinkingLevel"] == "high"
+    assert result["thinkingConfig"]["thinkingLevel"] == "medium"
     assert result["thinkingConfig"]["includeThoughts"] is True
 
     # Test high -> high + includeThoughts=True
@@ -2853,7 +2901,7 @@ def test_reasoning_effort_dict_format_gemini_3():
         model=model,
         drop_params=False,
     )
-    assert result["thinkingConfig"]["thinkingLevel"] == "high"
+    assert result["thinkingConfig"]["thinkingLevel"] == "medium"
     assert result["thinkingConfig"]["includeThoughts"] is True
 
     # Test dict format without effort key - no thinkingConfig should be set