"""Test suite for create_agent with structured output response_format permutations."""

import json
from collections.abc import Callable, Sequence
from dataclasses import dataclass
from typing import Any
from unittest.mock import patch

import pytest
from langchain_core.language_models import LanguageModelInput
from langchain_core.language_models.chat_models import BaseChatModel
from langchain_core.language_models.fake_chat_models import GenericFakeChatModel
from langchain_core.messages import HumanMessage
from langchain_core.runnables import Runnable
from pydantic import BaseModel, Field
from typing_extensions import TypedDict

from langchain.agents import create_agent
from langchain.agents.middleware.types import (
    AgentMiddleware,
    ModelCallResult,
    ModelRequest,
    ModelResponse,
)
from langchain.agents.structured_output import (
    MultipleStructuredOutputsError,
    ProviderStrategy,
    StructuredOutputValidationError,
    ToolStrategy,
)
from langchain.messages import AIMessage
from langchain.tools import BaseTool, tool
from tests.unit_tests.agents.model import FakeToolCallingModel


# Test data models
class WeatherBaseModel(BaseModel):
    """Weather response."""

    temperature: float = Field(description="The temperature in fahrenheit")
    condition: str = Field(description="Weather condition")


@dataclass
class WeatherDataclass:
    """Weather response."""

    temperature: float
    condition: str


class WeatherTypedDict(TypedDict):
    """Weather response."""

    temperature: float
    condition: str


weather_json_schema = {
    "type": "object",
    "properties": {
        "temperature": {"type": "number", "description": "Temperature in fahrenheit"},
        "condition": {"type": "string", "description": "Weather condition"},
    },
    "title": "weather_schema",
    "required": ["temperature", "condition"],
}


class LocationResponse(BaseModel):
    city: str = Field(description="The city name")
    country: str = Field(description="The country name")


class LocationTypedDict(TypedDict):
    city: str
    country: str


location_json_schema = {
    "type": "object",
    "properties": {
        "city": {"type": "string", "description": "The city name"},
        "country": {"type": "string", "description": "The country name"},
    },
    "title": "location_schema",
    "required": ["city", "country"],
}


@tool
def get_weather() -> str:
    """Get the weather."""
    return "The weather is sunny and 75°F."


@tool
def get_location() -> str:
    """Get the current location."""
    return "You are in New York, USA."


# Standardized test data
WEATHER_DATA: dict[str, float | str] = {"temperature": 75.0, "condition": "sunny"}
LOCATION_DATA: dict[str, str] = {"city": "New York", "country": "USA"}

# Standardized expected responses
EXPECTED_WEATHER_PYDANTIC = WeatherBaseModel(temperature=75.0, condition="sunny")
EXPECTED_WEATHER_DATACLASS = WeatherDataclass(temperature=75.0, condition="sunny")
EXPECTED_WEATHER_DICT: WeatherTypedDict = {"temperature": 75.0, "condition": "sunny"}
EXPECTED_LOCATION = LocationResponse(city="New York", country="USA")
EXPECTED_LOCATION_DICT: LocationTypedDict = {"city": "New York", "country": "USA"}


class TestResponseFormatAsModel:
    def test_pydantic_model(self) -> None:
        """Test response_format as Pydantic model."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(model, [get_weather], response_format=WeatherBaseModel)
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC
        assert len(response["messages"]) == 5

    def test_dataclass(self) -> None:
        """Test response_format as dataclass."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "WeatherDataclass",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(model, [get_weather], response_format=WeatherDataclass)
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DATACLASS
        assert len(response["messages"]) == 5

    def test_typed_dict(self) -> None:
        """Test response_format as TypedDict."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "WeatherTypedDict",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(model, [get_weather], response_format=WeatherTypedDict)
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DICT
        assert len(response["messages"]) == 5

    def test_json_schema(self) -> None:
        """Test response_format as JSON schema."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "weather_schema",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(model, [get_weather], response_format=weather_json_schema)
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DICT
        assert len(response["messages"]) == 5

    def test_autostrategy_with_anonymous_json_schema(self) -> None:
        """Test response_format as anonymous JSON schema (AutoStrategy).

        Verifies that tool name mismatch is avoided when using AutoStrategy with
        schemas that generate random names by ensuring the ToolStrategy instance
        is reused during execution.
        """
        anonymous_schema = {
            "type": "object",
            "properties": {
                "result": {"type": "string"},
            },
            "required": ["result"],
        }

        with patch("langchain.agents.factory._supports_provider_strategy", return_value=False):
            model = FakeToolCallingModel(tool_calls=[])
            agent = create_agent(model, [], response_format=anonymous_schema)

            # We expect a recursion error or similar because we didn't mock the tool call
            # matching our anonymous schema, but it should NOT raise ValueError
            # during the binding phase.
            try:
                agent.invoke({"messages": [HumanMessage("hi")]}, config={"recursion_limit": 1})
            except ValueError as e:
                if "which wasn't declared" in str(e):
                    pytest.fail(f"Tool name mismatch occurred: {e}")
            except Exception:  # noqa: S110
                # Other exceptions mean we passed the binding phase
                pass


class TestResponseFormatAsToolStrategy:
    def test_pydantic_model(self) -> None:
        """Test response_format as ToolStrategy with Pydantic model."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(model, [get_weather], response_format=ToolStrategy(WeatherBaseModel))
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC
        assert len(response["messages"]) == 5

    def test_dataclass(self) -> None:
        """Test response_format as ToolStrategy with dataclass."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "WeatherDataclass",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(model, [get_weather], response_format=ToolStrategy(WeatherDataclass))
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DATACLASS
        assert len(response["messages"]) == 5

    def test_typed_dict(self) -> None:
        """Test response_format as ToolStrategy with TypedDict."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "WeatherTypedDict",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(model, [get_weather], response_format=ToolStrategy(WeatherTypedDict))
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DICT
        assert len(response["messages"]) == 5

    def test_json_schema(self) -> None:
        """Test response_format as ToolStrategy with JSON schema."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "weather_schema",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model, [get_weather], response_format=ToolStrategy(weather_json_schema)
        )
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DICT
        assert len(response["messages"]) == 5

    def test_union_of_json_schemas(self) -> None:
        """Test response_format as ToolStrategy with union of JSON schemas."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "weather_schema",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [get_weather, get_location],
            response_format=ToolStrategy({"oneOf": [weather_json_schema, location_json_schema]}),
        )
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DICT
        assert len(response["messages"]) == 5

        # Test with LocationResponse
        tool_calls_location = [
            [{"args": {}, "id": "1", "name": "get_location"}],
            [
                {
                    "name": "location_schema",
                    "id": "2",
                    "args": LOCATION_DATA,
                }
            ],
        ]

        model_location = FakeToolCallingModel(tool_calls=tool_calls_location)

        agent_location = create_agent(
            model_location,
            [get_weather, get_location],
            response_format=ToolStrategy({"oneOf": [weather_json_schema, location_json_schema]}),
        )
        response_location = agent_location.invoke({"messages": [HumanMessage("Where am I?")]})

        assert response_location["structured_response"] == EXPECTED_LOCATION_DICT
        assert len(response_location["messages"]) == 5

    def test_union_of_types(self) -> None:
        """Test response_format as ToolStrategy with Union of various types."""
        # Test with WeatherBaseModel
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "2",
                    "args": WEATHER_DATA,
                }
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [get_weather, get_location],
            response_format=ToolStrategy(WeatherBaseModel | LocationResponse),
        )
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC
        assert len(response["messages"]) == 5

        # Test with LocationResponse
        tool_calls_location = [
            [{"args": {}, "id": "1", "name": "get_location"}],
            [
                {
                    "name": "LocationResponse",
                    "id": "2",
                    "args": LOCATION_DATA,
                }
            ],
        ]

        model_location = FakeToolCallingModel(tool_calls=tool_calls_location)

        agent_location = create_agent(
            model_location,
            [get_weather, get_location],
            response_format=ToolStrategy(WeatherBaseModel | LocationResponse),
        )
        response_location = agent_location.invoke({"messages": [HumanMessage("Where am I?")]})

        assert response_location["structured_response"] == EXPECTED_LOCATION
        assert len(response_location["messages"]) == 5

    def test_multiple_structured_outputs_error_without_retry(self) -> None:
        """Test multiple structured outputs error without retry.

        Test that MultipleStructuredOutputsError is raised when model returns multiple
        structured tool calls without retry.
        """
        tool_calls = [
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "1",
                    "args": WEATHER_DATA,
                },
                {
                    "name": "LocationResponse",
                    "id": "2",
                    "args": LOCATION_DATA,
                },
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [],
            response_format=ToolStrategy(
                WeatherBaseModel | LocationResponse,
                handle_errors=False,
            ),
        )

        with pytest.raises(
            MultipleStructuredOutputsError,
            match=r".*WeatherBaseModel.*LocationResponse.*",
        ):
            agent.invoke({"messages": [HumanMessage("Give me weather and location")]})

    def test_multiple_structured_outputs_with_retry(self) -> None:
        """Test that retry handles multiple structured output tool calls."""
        tool_calls = [
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "1",
                    "args": WEATHER_DATA,
                },
                {
                    "name": "LocationResponse",
                    "id": "2",
                    "args": LOCATION_DATA,
                },
            ],
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "3",
                    "args": WEATHER_DATA,
                },
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [],
            response_format=ToolStrategy(
                WeatherBaseModel | LocationResponse,
                handle_errors=True,
            ),
        )

        response = agent.invoke({"messages": [HumanMessage("Give me weather")]})

        # HumanMessage, AIMessage, ToolMessage, ToolMessage, AI, ToolMessage
        assert len(response["messages"]) == 6
        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC

    def test_structured_output_parsing_error_without_retry(self) -> None:
        """Test structured output parsing error without retry.

        Test that StructuredOutputValidationError is raised when tool args fail to parse
        without retry.
        """
        tool_calls = [
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "1",
                    "args": {"invalid": "data"},
                },
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [],
            response_format=ToolStrategy(
                WeatherBaseModel,
                handle_errors=False,
            ),
        )

        with pytest.raises(
            StructuredOutputValidationError,
            match=r".*WeatherBaseModel.*",
        ):
            agent.invoke({"messages": [HumanMessage("What's the weather?")]})

    def test_structured_output_parsing_error_with_retry(self) -> None:
        """Test that retry handles parsing errors for structured output."""
        tool_calls = [
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "1",
                    "args": {"invalid": "data"},
                },
            ],
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "2",
                    "args": WEATHER_DATA,
                },
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [],
            response_format=ToolStrategy(
                WeatherBaseModel,
                handle_errors=(StructuredOutputValidationError,),
            ),
        )

        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        # HumanMessage, AIMessage, ToolMessage, AIMessage, ToolMessage
        assert len(response["messages"]) == 5
        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC

    def test_retry_with_custom_function(self) -> None:
        """Test retry with custom message generation."""
        tool_calls = [
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "1",
                    "args": WEATHER_DATA,
                },
                {
                    "name": "LocationResponse",
                    "id": "2",
                    "args": LOCATION_DATA,
                },
            ],
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "3",
                    "args": WEATHER_DATA,
                },
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        def custom_message(exception: Exception) -> str:
            if isinstance(exception, MultipleStructuredOutputsError):
                return "Custom error: Multiple outputs not allowed"
            return "Custom error"

        agent = create_agent(
            model,
            [],
            response_format=ToolStrategy(
                WeatherBaseModel | LocationResponse,
                handle_errors=custom_message,
            ),
        )

        response = agent.invoke({"messages": [HumanMessage("Give me weather")]})

        # HumanMessage, AIMessage, ToolMessage, ToolMessage, AI, ToolMessage
        assert len(response["messages"]) == 6
        assert response["messages"][2].content == "Custom error: Multiple outputs not allowed"
        assert response["messages"][3].content == "Custom error: Multiple outputs not allowed"
        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC

    def test_retry_with_custom_string_message(self) -> None:
        """Test retry with custom static string message."""
        tool_calls = [
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "1",
                    "args": {"invalid": "data"},
                },
            ],
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "2",
                    "args": WEATHER_DATA,
                },
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [],
            response_format=ToolStrategy(
                WeatherBaseModel,
                handle_errors="Please provide valid weather data with temperature and condition.",
            ),
        )

        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert len(response["messages"]) == 5
        assert (
            response["messages"][2].content
            == "Please provide valid weather data with temperature and condition."
        )
        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC

    def test_validation_error_with_invalid_response(self) -> None:
        """Test validation error with invalid response.

        Test that StructuredOutputValidationError is raised when tool strategy receives
        invalid response.
        """
        tool_calls = [
            [
                {
                    "name": "WeatherBaseModel",
                    "id": "1",
                    "args": {"invalid_field": "wrong_data", "another_bad_field": 123},
                },
            ],
        ]

        model = FakeToolCallingModel(tool_calls=tool_calls)

        agent = create_agent(
            model,
            [],
            response_format=ToolStrategy(
                WeatherBaseModel,
                handle_errors=False,  # Disable retry to ensure error is raised
            ),
        )

        with pytest.raises(
            StructuredOutputValidationError,
            match=r".*WeatherBaseModel.*",
        ):
            agent.invoke({"messages": [HumanMessage("What's the weather?")]})


class TestResponseFormatAsProviderStrategy:
    def test_pydantic_model(self) -> None:
        """Test response_format as ProviderStrategy with Pydantic model."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
        ]

        model = FakeToolCallingModel(
            tool_calls=tool_calls, structured_response=EXPECTED_WEATHER_PYDANTIC
        )

        agent = create_agent(
            model, [get_weather], response_format=ProviderStrategy(WeatherBaseModel)
        )
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC
        assert len(response["messages"]) == 4

    def test_validation_error_with_invalid_response(self) -> None:
        """Test validation error with invalid response.

        Test that StructuredOutputValidationError is raised when provider strategy
        receives invalid response.
        """
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
        ]

        # But we're using WeatherBaseModel which has different field requirements
        model = FakeToolCallingModel(
            tool_calls=tool_calls,
            structured_response={"invalid": "data"},  # Wrong structure
        )

        agent = create_agent(
            model, [get_weather], response_format=ProviderStrategy(WeatherBaseModel)
        )

        with pytest.raises(
            StructuredOutputValidationError,
            match=r".*WeatherBaseModel.*",
        ):
            agent.invoke({"messages": [HumanMessage("What's the weather?")]})

    def test_dataclass(self) -> None:
        """Test response_format as ProviderStrategy with dataclass."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
        ]

        model = FakeToolCallingModel(
            tool_calls=tool_calls, structured_response=EXPECTED_WEATHER_DATACLASS
        )

        agent = create_agent(
            model, [get_weather], response_format=ProviderStrategy(WeatherDataclass)
        )
        response = agent.invoke(
            {"messages": [HumanMessage("What's the weather?")]},
        )

        assert response["structured_response"] == EXPECTED_WEATHER_DATACLASS
        assert len(response["messages"]) == 4

    def test_typed_dict(self) -> None:
        """Test response_format as ProviderStrategy with TypedDict."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
        ]

        model = FakeToolCallingModel(
            tool_calls=tool_calls, structured_response=EXPECTED_WEATHER_DICT
        )

        agent = create_agent(
            model, [get_weather], response_format=ProviderStrategy(WeatherTypedDict)
        )
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DICT
        assert len(response["messages"]) == 4

    def test_json_schema(self) -> None:
        """Test response_format as ProviderStrategy with JSON schema."""
        tool_calls = [
            [{"args": {}, "id": "1", "name": "get_weather"}],
        ]

        model = FakeToolCallingModel(
            tool_calls=tool_calls, structured_response=EXPECTED_WEATHER_DICT
        )

        agent = create_agent(
            model, [get_weather], response_format=ProviderStrategy(weather_json_schema)
        )
        response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        assert response["structured_response"] == EXPECTED_WEATHER_DICT
        assert len(response["messages"]) == 4


class TestDynamicModelWithResponseFormat:
    """Test response_format with middleware that modifies the model."""

    def test_middleware_model_swap_provider_to_tool_strategy(self) -> None:
        """Test that strategy resolution is deferred until after middleware modifies the model.

        Verifies that when a raw schema is provided, `_supports_provider_strategy` is called
        on the middleware-modified model (not the original), ensuring the correct strategy is
        selected based on the final model's capabilities.
        """

        # Custom model that we'll use to test whether the tool strategy is applied
        # correctly at runtime.
        class CustomModel(GenericFakeChatModel):
            tool_bindings: list[Any] = Field(default_factory=list)

            def bind_tools(
                self,
                tools: Sequence[dict[str, Any] | type[BaseModel] | Callable[..., Any] | BaseTool],
                **kwargs: Any,
            ) -> Runnable[LanguageModelInput, AIMessage]:
                # Record every tool binding event.
                self.tool_bindings.append(tools)
                return self

        model = CustomModel(
            messages=iter(
                [
                    # Simulate model returning structured output directly
                    # (this is what provider strategy would do)
                    json.dumps(WEATHER_DATA),
                ]
            )
        )

        # Create middleware that swaps the model in the request
        class ModelSwappingMiddleware(AgentMiddleware):
            def wrap_model_call(
                self,
                request: ModelRequest,
                handler: Callable[[ModelRequest], ModelResponse],
            ) -> ModelCallResult:
                # Replace the model with our custom test model
                return handler(request.override(model=model))

        # Track which model is checked for provider strategy support
        calls = []

        def mock_supports_provider_strategy(
            model: str | BaseChatModel, tools: list[Any] | None = None
        ) -> bool:
            """Track which model is checked and return True for ProviderStrategy."""
            calls.append(model)
            return True

        # Use raw Pydantic model (not wrapped in ToolStrategy or ProviderStrategy)
        # This should auto-detect strategy based on model capabilities
        agent = create_agent(
            model=model,
            tools=[],
            # Raw schema - should auto-detect strategy
            response_format=WeatherBaseModel,
            middleware=[ModelSwappingMiddleware()],
        )

        with patch(
            "langchain.agents.factory._supports_provider_strategy",
            side_effect=mock_supports_provider_strategy,
        ):
            response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

        # Verify strategy resolution was deferred: check was called once during _get_bound_model
        assert len(calls) == 1

        # Verify successful parsing of JSON as structured output via ProviderStrategy
        assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC
        # Two messages: Human input message and AI response with JSON content
        assert len(response["messages"]) == 2
        ai_message = response["messages"][1]
        assert isinstance(ai_message, AIMessage)
        # ProviderStrategy doesn't use tool calls - it parses content directly
        assert ai_message.tool_calls == []
        assert ai_message.content == json.dumps(WEATHER_DATA)


def test_union_of_types() -> None:
    """Test response_format as ProviderStrategy with Union (if supported)."""
    tool_calls = [
        [{"args": {}, "id": "1", "name": "get_weather"}],
        [
            {
                "name": "WeatherBaseModel",
                "id": "2",
                "args": WEATHER_DATA,
            }
        ],
    ]

    model = FakeToolCallingModel(
        tool_calls=tool_calls, structured_response=EXPECTED_WEATHER_PYDANTIC
    )

    agent = create_agent(
        model,
        [get_weather, get_location],
        response_format=ToolStrategy(WeatherBaseModel | LocationResponse),
    )
    response = agent.invoke({"messages": [HumanMessage("What's the weather?")]})

    assert response["structured_response"] == EXPECTED_WEATHER_PYDANTIC
    assert len(response["messages"]) == 5
