diff --git a/litellm/litellm_core_utils/prompt_templates/factory.py b/litellm/litellm_core_utils/prompt_templates/factory.py index 0ed15c43ccf9..b676077ab0e8 100644 --- a/litellm/litellm_core_utils/prompt_templates/factory.py +++ b/litellm/litellm_core_utils/prompt_templates/factory.py @@ -1200,13 +1200,14 @@ def _encode_tool_call_id_with_signature(tool_call_id: str, thought_signature: st return tool_call_id -def _get_thought_signature_from_tool(tool: dict, model: str | None = None) -> str | None: +def _get_thought_signature_from_tool(tool: dict) -> str | None: """Extract thought signature from tool call's provider_specific_fields. If not provided try to extract thought signature from tool call id Checks both tool.provider_specific_fields and tool.function.provider_specific_fields. - If no signature is found and model is gemini-3, returns a dummy signature. + Returns None when the tool call carries no signature; callers decide whether a + placeholder signature is needed. """ # First check tool's provider_specific_fields provider_fields: Final = tool.get("provider_specific_fields") or {} @@ -1236,13 +1237,6 @@ def _get_thought_signature_from_tool(tool: dict, model: str | None = None) -> st if len(parts) == 2: _, signature = parts return signature - # If no signature found and model is gemini-3, return dummy signature - from litellm.llms.vertex_ai.gemini.vertex_and_google_ai_studio_gemini import ( - VertexGeminiConfig, - ) - - if model and VertexGeminiConfig._is_gemini_3_or_newer(model): - return _get_dummy_thought_signature() return None @@ -1251,10 +1245,14 @@ def _get_dummy_thought_signature() -> str: This is used when transferring conversation history from older models (like gemini-2.5-flash) to gemini-3, which requires thought_signature - for strict validation. + for strict validation. Google documents it as a last resort that "will + negatively impact model performance", so callers must only fall back to it + when no real signature is available. + + See: + https://ai.google.dev/gemini-api/docs/thought-signatures#faqs + https://docs.cloud.google.com/gemini-enterprise-agent-platform/models/thinking/thought-signatures """ - # Return a base64-encoded dummy signature string - # Below dummy signature is recommended by google - https://ai.google.dev/gemini-api/docs/thought-signatures#faqs dummy_data: Final = b"skip_thought_signature_validator" return base64.b64encode(dummy_data).decode("utf-8") @@ -1312,8 +1310,10 @@ def convert_to_gemini_tool_call_invoke( VertexGeminiConfig, ) + needs_dummy_signature: Final = model is not None and VertexGeminiConfig._is_gemini_3_or_newer(model) + if tool_calls is not None: - for idx, tool in enumerate(tool_calls): + for tool in tool_calls: if "function" in tool: gemini_function_call: VertexFunctionCall | None = _gemini_tool_call_invoke_helper( function_call_params=tool["function"], @@ -1321,7 +1321,13 @@ def convert_to_gemini_tool_call_invoke( ) if gemini_function_call is not None: part_dict: VertexPartType = {"function_call": gemini_function_call} - thought_signature = _get_thought_signature_from_tool(dict(tool), model=model) + thought_signature = _get_thought_signature_from_tool(dict(tool)) + # Gemini signs only the first functionCall part of a parallel batch, so scope the + # placeholder fallback to that part instead of fabricating one per sibling call: + # https://docs.cloud.google.com/gemini-enterprise-agent-platform/models/thinking/thought-signatures#parallel_function_calling_example + is_first_function_call = len(_parts_list) == 0 + if not thought_signature and is_first_function_call and needs_dummy_signature: + thought_signature = _get_dummy_thought_signature() if thought_signature: part_dict["thoughtSignature"] = thought_signature @@ -1344,7 +1350,7 @@ def convert_to_gemini_tool_call_invoke( thought_signature = provider_fields.get("thought_signature") # If no signature found and model is gemini-3, use dummy signature - if not thought_signature and model and VertexGeminiConfig._is_gemini_3_or_newer(model): + if not thought_signature and needs_dummy_signature: thought_signature = _get_dummy_thought_signature() if thought_signature: diff --git a/litellm/llms/vertex_ai/gemini/transformation.py b/litellm/llms/vertex_ai/gemini/transformation.py index f2d318a9ffda..11c026010ee7 100644 --- a/litellm/llms/vertex_ai/gemini/transformation.py +++ b/litellm/llms/vertex_ai/gemini/transformation.py @@ -645,10 +645,9 @@ def _collect_tool_call_thought_signatures( the text part as well would send two copies and double-bill the previous turn's reasoning tokens on gemini-3 and newer models. - Detection deliberately calls _get_thought_signature_from_tool without the - model argument: with a gemini-3 model that helper synthesizes a dummy - signature for unsigned tool calls, which must not suppress a real - text-part signature (e.g. replaying gemini-2.5 history to a newer model). + Only real signatures count here; a synthesized placeholder must not + suppress a genuine text-part signature (e.g. replaying gemini-2.5 history + to a newer model). """ signatures: tuple[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 8ee8186f6bba..8c1de12e7d91 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 @@ -1,3 +1,7 @@ +import base64 + +import pytest + from litellm.litellm_core_utils.prompt_templates.factory import ( convert_to_gemini_tool_call_result, ) @@ -784,6 +788,367 @@ def test_dummy_signature_with_function_call_mode(): assert gemini_parts[0]["thoughtSignature"] == expected_dummy +def _parallel_tool_calls(*signatures): + return [ + { + "id": f"call_{idx}", + "type": "function", + "function": { + "name": f"tool_{idx}", + "arguments": '{"location": "Paris"}', + **( + {"provider_specific_fields": {"thought_signature": signature}} + if signature is not None + else {} + ), + }, + "index": idx, + } + for idx, signature in enumerate(signatures) + ] + + +def _parallel_tool_calls_signed_via_id(*signatures): + """Parallel tool calls in the shape LiteLLM actually hands back to clients. + + The signature rides in the tool call id behind __thought__, which is what an + OpenAI-format client echoes back on the next turn. + """ + from litellm.litellm_core_utils.prompt_templates.factory import ( + _encode_tool_call_id_with_signature, + ) + + return [ + { + "id": _encode_tool_call_id_with_signature(f"call_{idx}", signature), + "type": "function", + "function": {"name": f"tool_{idx}", "arguments": '{"location": "Paris"}'}, + "index": idx, + } + for idx, signature in enumerate(signatures) + ] + + +REAL_THOUGHT_SIGNATURE = "Co4CAdHtim/rWgXbz2Ghp4tShzLeMASrPw6JJyYIC3cbVyZnKzU3uv8/wVzyS2sKRPL2m8QQHHXbNQhEEz500G7n" +PLACEHOLDER_SIGNATURE = base64.b64encode(b"skip_thought_signature_validator").decode( + "utf-8" +) + + +def test_dummy_signature_only_on_first_parallel_tool_call(): + """Google documents the placeholder as a last resort that degrades quality, so an unsigned + parallel turn replayed to gemini-3 gets a budget of exactly one.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls(None, None, None), + }, + model="gemini-3-pro-preview", + ) + + assert len(gemini_parts) == 3 + assert gemini_parts[0]["thoughtSignature"] == PLACEHOLDER_SIGNATURE + assert "thoughtSignature" not in gemini_parts[1] + assert "thoughtSignature" not in gemini_parts[2] + + +def test_real_signature_on_first_parallel_tool_call_leaves_siblings_empty(): + """Gemini signs only the first of N parallel function calls, so a faithful replay has + nothing to attach to the siblings.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls(REAL_THOUGHT_SIGNATURE, None, None), + }, + model="gemini-3-pro-preview", + ) + + assert len(gemini_parts) == 3 + assert gemini_parts[0]["thoughtSignature"] == REAL_THOUGHT_SIGNATURE + assert "thoughtSignature" not in gemini_parts[1] + assert "thoughtSignature" not in gemini_parts[2] + + +def test_real_signature_on_later_parallel_tool_call_is_preserved(): + """Clients may reorder or drop calls, so a signature that lands on a non-first call is + still the model's own and must survive the round trip.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls(None, REAL_THOUGHT_SIGNATURE), + }, + model="gemini-3-pro-preview", + ) + + assert len(gemini_parts) == 2 + assert gemini_parts[0]["thoughtSignature"] == PLACEHOLDER_SIGNATURE + assert gemini_parts[1]["thoughtSignature"] == REAL_THOUGHT_SIGNATURE + + +def test_no_signatures_on_parallel_tool_calls_for_gemini_2_5(): + """Non-gemini-3 models never get a placeholder signature, on any call.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls(None, None), + }, + model="gemini-2.5-flash", + ) + + assert len(gemini_parts) == 2 + assert all("thoughtSignature" not in part for part in gemini_parts) + + +def test_signature_embedded_in_tool_call_id_only_on_first_parallel_call(): + """The production shape: the signature arrives inside the first call's id, siblings have bare ids.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls_signed_via_id( + REAL_THOUGHT_SIGNATURE, None, None + ), + }, + model="gemini-3-pro-preview", + ) + + assert len(gemini_parts) == 3 + assert gemini_parts[0]["thoughtSignature"] == REAL_THOUGHT_SIGNATURE + assert "thoughtSignature" not in gemini_parts[1] + assert "thoughtSignature" not in gemini_parts[2] + + +def test_tool_level_provider_specific_fields_signature_leaves_siblings_empty(): + """A signature on the tool call itself, rather than on its function, behaves the same way.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + tool_calls = _parallel_tool_calls(None, None) + tool_calls[0]["provider_specific_fields"] = { + "thought_signature": REAL_THOUGHT_SIGNATURE + } + + gemini_parts = convert_to_gemini_tool_call_invoke( + {"role": "assistant", "content": None, "tool_calls": tool_calls}, + model="gemini-3-pro-preview", + ) + + assert len(gemini_parts) == 2 + assert gemini_parts[0]["thoughtSignature"] == REAL_THOUGHT_SIGNATURE + assert "thoughtSignature" not in gemini_parts[1] + + +def test_placeholder_lands_on_first_emitted_part_not_first_tool_call_entry(): + """A non-function entry (e.g. an OpenAI custom tool call) emits no part, so it must not + consume the one placeholder slot and leave the real first function call bare.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + tool_calls = [ + {"id": "call_custom", "type": "custom", "custom": {"name": "noop", "input": ""}} + ] + _parallel_tool_calls(None, None) + + gemini_parts = convert_to_gemini_tool_call_invoke( + {"role": "assistant", "content": None, "tool_calls": tool_calls}, + model="gemini-3-pro-preview", + ) + + assert len(gemini_parts) == 2 + assert gemini_parts[0]["thoughtSignature"] == PLACEHOLDER_SIGNATURE + assert "thoughtSignature" not in gemini_parts[1] + + +def test_no_placeholder_when_model_is_unknown(): + """Without a model there is nothing to prove the target needs a placeholder, so none is added.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls(None, None), + }, + ) + + assert len(gemini_parts) == 2 + assert all("thoughtSignature" not in part for part in gemini_parts) + + +def test_real_signature_forwarded_to_gemini_2_5_without_placeholder_siblings(): + """Older models still receive a real signature that a client replays, and still get no placeholder.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls(REAL_THOUGHT_SIGNATURE, None), + }, + model="gemini-2.5-flash", + ) + + assert len(gemini_parts) == 2 + assert gemini_parts[0]["thoughtSignature"] == REAL_THOUGHT_SIGNATURE + assert "thoughtSignature" not in gemini_parts[1] + + +def test_parallel_tool_call_history_replayed_through_full_message_conversion(): + """End to end through the message-history converter, the path a real /chat/completions replay takes.""" + from litellm.llms.vertex_ai.gemini.transformation import ( + _gemini_convert_messages_with_history, + ) + + messages = [ + {"role": "user", "content": "Weather in Paris, London and Tokyo?"}, + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls_signed_via_id( + REAL_THOUGHT_SIGNATURE, None, None + ), + }, + ] + + contents = _gemini_convert_messages_with_history( + messages=messages, model="gemini-3-pro-preview" + ) + + model_parts = contents[1]["parts"] + assert len(model_parts) == 3 + assert model_parts[0]["thoughtSignature"] == REAL_THOUGHT_SIGNATURE + assert "thoughtSignature" not in model_parts[1] + assert "thoughtSignature" not in model_parts[2] + + +@pytest.mark.parametrize( + "model", + ["gemini-3.5-flash", "vertex_ai/gemini-3.5-flash", "gemini/gemini-3.5-flash"], +) +def test_natively_signed_parallel_turn_never_carries_a_placeholder(model): + """A native gemini-3.5 parallel turn replays with zero skip_thought_signature_validator parts. + + Fabricating the placeholder alongside a real signature is what produced empty text responses + on gemini-3.5 parallel function calling, so the whole payload has to stay placeholder-free. + """ + import json + + from litellm.llms.vertex_ai.gemini.transformation import ( + _gemini_convert_messages_with_history, + ) + + messages = [ + {"role": "user", "content": "Weather in Paris, London and Tokyo?"}, + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls_signed_via_id( + REAL_THOUGHT_SIGNATURE, None, None + ), + }, + ] + + contents = _gemini_convert_messages_with_history(messages=messages, model=model) + + model_parts = contents[1]["parts"] + assert len(model_parts) == 3 + assert model_parts[0]["thoughtSignature"] == REAL_THOUGHT_SIGNATURE + assert "thoughtSignature" not in model_parts[1] + assert "thoughtSignature" not in model_parts[2] + assert PLACEHOLDER_SIGNATURE not in json.dumps(contents) + + +@pytest.mark.parametrize( + "model", + [ + "gemini-3-pro-preview", + "gemini-3-flash-preview", + "gemini-3.1-pro-preview", + "gemini-3.5-flash", + "gemini-3.6-flash", + "gemini-3.7-flash", + "vertex_ai/gemini-3.5-flash", + "vertex_ai/gemini-3.7-flash", + "gemini/gemini-3.5-flash", + "gemini/gemini-3.7-flash", + ], +) +def test_placeholder_scoped_to_first_call_across_gemini_3_variants(model): + """The gemini-3 gate is a substring match, so every family member and prefix form has to + land on the same one-placeholder budget rather than only the versions we happened to try.""" + from litellm.litellm_core_utils.prompt_templates.factory import ( + convert_to_gemini_tool_call_invoke, + ) + + gemini_parts = convert_to_gemini_tool_call_invoke( + { + "role": "assistant", + "content": None, + "tool_calls": _parallel_tool_calls(None, None, None), + }, + model=model, + ) + + assert len(gemini_parts) == 3 + assert gemini_parts[0]["thoughtSignature"] == PLACEHOLDER_SIGNATURE + assert "thoughtSignature" not in gemini_parts[1] + assert "thoughtSignature" not in gemini_parts[2] + + +def test_signed_text_part_survives_alongside_unsigned_parallel_tool_calls(): + """Text-part and function-call signatures are collected by separate code paths, so scoping the + placeholder must not disturb a real signature that arrived on the text part.""" + from litellm.llms.vertex_ai.gemini.transformation import ( + _gemini_convert_messages_with_history, + ) + + msg = { + "role": "assistant", + "content": "Checking all three cities.", + "provider_specific_fields": {"thought_signatures": ["real_25_signature"]}, + "tool_calls": _parallel_tool_calls(None, None, None), + } + + parts = _gemini_convert_messages_with_history( + messages=[msg], model="gemini-3-pro-preview" + )[0]["parts"] + + assert parts[0]["text"] == "Checking all three cities." + assert parts[0]["thoughtSignature"] == "real_25_signature" + assert parts[1]["thoughtSignature"] == PLACEHOLDER_SIGNATURE + assert "thoughtSignature" not in parts[2] + assert "thoughtSignature" not in parts[3] + + # Tests for media_resolution (detail parameter) handling - Issue #17084 class TestMediaResolution: """Tests for media_resolution handling in Gemini 2.x models"""