fix(gemini): add presence_penalty support for Google AI Studio (#18154)

Fixes #14753

Co-authored-by: Krish Dholakia <krrishdholakia@gmail.com>

litellm/llms/gemini/chat/transformation.py

@@ -87,6 +87,7 @@ class GoogleAIStudioGeminiConfig(VertexGeminiConfig):
             "stop",
             "logprobs",
             "frequency_penalty",
+            "presence_penalty",
             "modalities",
             "parallel_tool_calls",
             "web_search_options",

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

@@ -14,6 +14,7 @@ from litellm.llms.vertex_ai.common_utils import VertexAIError
 from litellm.llms.vertex_ai.gemini.vertex_and_google_ai_studio_gemini import (
     VertexGeminiConfig,
 )
+from litellm.llms.gemini.chat.transformation import GoogleAIStudioGeminiConfig
 from litellm.types.llms.vertex_ai import UsageMetadata
 from litellm.types.utils import ChoiceLogprobs, Usage
 from litellm.utils import CustomStreamWrapper
@@ -2315,6 +2316,17 @@ def test_partial_json_chunk_on_first_chunk():
     assert iterator.chunk_type == "accumulated_json", "Should switch to accumulated_json mode"
 
 
+
+def test_google_ai_studio_presence_penalty_supported():
+    """
+    Test that presence_penalty is supported for Google AI Studio Gemini.
+
+    Regression test for https://github.com/BerriAI/litellm/issues/14753
+    """
+    config = GoogleAIStudioGeminiConfig()
+    supported_params = config.get_supported_openai_params(model="gemini-2.0-flash")
+
+    assert "presence_penalty" in supported_params
 # ==================== Tool Type Separation Tests ====================
 # These tests verify that each Tool object contains exactly one type per Vertex AI API spec
 # Ref: https://cloud.google.com/vertex-ai/generative-ai/docs/reference/rest/v1beta1/Tool