[BUG] AgentResult.structured_output returns BaseModel | None

[LeviLong01]

Checks

• I have updated to the lastest minor and patch version of Strands
• I have checked the documentation and this is not expected behavior
• I have searched ./issues and there are no duplicates of my issue

Strands Version

1.14.0

Python Version

3.11.14

Operating System

macOS 15.7

Installation Method

pip

Steps to Reproduce

Error:

    def some_function(self) -> TestOutputModel:
        agent = Agent(structured_output_model=TestOutputModel)
        agent_response = agent("This is a test")

        return agent_response.structured_output # mypy fails due to error: Incompatible return value type (got "BaseModel | None", expected "TestOutputModel")  [return-value]

Expected Behavior

Workaround:

    def some_function(self) -> TestOutputModel:
        agent = Agent(structured_output_model=TestOutputModel)
        agent_response = agent("This is a test")

        return cast(TestOutputModel, agent_response.structured_output)

I expect that it would behave the same as Agent.structured_output with it's return type.

Actual Behavior

Error:

    def some_function(self) -> TestOutputModel:
        agent = Agent(structured_output_model=TestOutputModel)
        agent_response = agent("This is a test")

        return agent_response.structured_output # mypy fails due to error: Incompatible return value type (got "BaseModel | None", expected "TestOutputModel")  [return-value]

Additional Context

No response

Possible Solution

Handle generic types for structured_output on the AgentResult

Related Issues

No response