From 3b45b170fe486489e46db2960eb9331d8925b763 Mon Sep 17 00:00:00 2001
From: Julian von der Goltz <julian@vdgoltz.net>
Date: Wed, 20 May 2026 15:00:38 +0200
Subject: [PATCH] Address Gemini thought signature review feedback

---
 .../llms/vertex_ai/gemini/transformation.py   |  4 --
 litellm/types/llms/vertex_ai.py               |  1 +
 .../test_vertex_ai_gemini_transformation.py   | 49 +++++++++++++++++++
 3 files changed, 50 insertions(+), 4 deletions(-)

diff --git a/litellm/llms/vertex_ai/gemini/transformation.py b/litellm/llms/vertex_ai/gemini/transformation.py
index 3a4e52997de..65cdddd6c01 100644
--- a/litellm/llms/vertex_ai/gemini/transformation.py
+++ b/litellm/llms/vertex_ai/gemini/transformation.py
@@ -994,10 +994,6 @@ def _gemini_convert_messages_with_history(  # noqa: PLR0915
                         if (
                             isinstance(existing_part, dict)
                             and existing_part.get("thoughtSignature")
-                            and (
-                                existing_part.get("functionCall") is not None
-                                or existing_part.get("function_call") is not None
-                            )
                         ):
                             turn_thought_signature = existing_part.get(
                                 "thoughtSignature"
diff --git a/litellm/types/llms/vertex_ai.py b/litellm/types/llms/vertex_ai.py
index 87bf11a9026..452d9f0cbf5 100644
--- a/litellm/types/llms/vertex_ai.py
+++ b/litellm/types/llms/vertex_ai.py
@@ -39,6 +39,7 @@ class PartType(TypedDict, total=False):
     inline_data: BlobType
     file_data: FileDataType
     function_call: FunctionCall
+    functionCall: FunctionCall
     function_response: FunctionResponse
     thought: bool
     thoughtSignature: str
diff --git a/tests/test_litellm/llms/vertex_ai/gemini/test_vertex_ai_gemini_transformation.py b/tests/test_litellm/llms/vertex_ai/gemini/test_vertex_ai_gemini_transformation.py
index 2c53d9970c8..68de50d3b0c 100644
--- a/tests/test_litellm/llms/vertex_ai/gemini/test_vertex_ai_gemini_transformation.py
+++ b/tests/test_litellm/llms/vertex_ai/gemini/test_vertex_ai_gemini_transformation.py
@@ -569,6 +569,55 @@ def test_parallel_tool_calls_copy_thought_signature_from_thinking_block():
     assert all(p.get("thoughtSignature") == "sig-turn-123" for p in function_parts)
 
 
+def test_parallel_tool_calls_copy_thought_signature_from_text_thinking_block():
+    """Text-fallback thinking blocks still carry the turn signature."""
+    messages = [
+        {
+            "role": "assistant",
+            "content": None,
+            "thinking_blocks": [
+                {
+                    "type": "thinking",
+                    "thinking": "I need to call both tools.",
+                    "signature": "sig-text-thinking",
+                }
+            ],
+            "tool_calls": [
+                {
+                    "id": "call_1",
+                    "type": "function",
+                    "function": {
+                        "name": "get_current_temperature",
+                        "arguments": '{"location": "Paris"}',
+                    },
+                    "index": 0,
+                },
+                {
+                    "id": "call_2",
+                    "type": "function",
+                    "function": {
+                        "name": "get_current_temperature",
+                        "arguments": '{"location": "London"}',
+                    },
+                    "index": 1,
+                },
+            ],
+        }
+    ]
+
+    contents = _gemini_convert_messages_with_history(messages, model="gemini-2.5-flash")
+
+    function_parts = [
+        p
+        for p in contents[0]["parts"]
+        if p.get("functionCall") is not None or p.get("function_call") is not None
+    ]
+    assert len(function_parts) == 2
+    assert all(
+        p.get("thoughtSignature") == "sig-text-thinking" for p in function_parts
+    )
+
+
 def test_thought_signature_with_function_call_mode():
     """Test thought signature extraction in function_call mode (is_function_call=True)"""
     from litellm.llms.vertex_ai.gemini.vertex_and_google_ai_studio_gemini import (