MiddlewareSet fix

[rodrigobr-msft]

This pull request makes significant improvements to the MiddlewareSet pipeline in the microsoft-agents-hosting-core library, focusing on correctness, flexibility, and test coverage. The changes refactor how middleware is registered and invoked, clarify method signatures and return values, and add comprehensive tests to ensure expected behavior. Additionally, the pull request improves type annotations and documentation throughout the middleware system.

Middleware pipeline improvements and refactoring

• Refactored MiddlewareSet to clarify and streamline middleware registration and invocation:

  • The use method now returns the MiddlewareSet instance for chaining and raises a TypeError if invalid middleware is registered.
  • Middleware short-circuiting and context passing are handled more explicitly.
  • The internal middleware execution logic was moved to a private method (_receive_activity_internal) and method signatures were updated for clarity and type safety.
  • The on_turn and receive_activity_with_status methods now properly run middleware and final logic, and do not return the result of the final logic (always returning None).

• Updated the Middleware protocol and all relevant implementations to accept an optional logic parameter and improved docstrings for clarity. [1] [2]

Type annotations and API consistency

• Updated type annotations for middleware and callback functions throughout the middleware and transcript logger code, ensuring that logic is consistently typed as an optional callable accepting a TurnContext. [1] [2]

Test coverage

• Added a new test suite, test_middleware_set.py, with comprehensive tests for MiddlewareSet covering registration, chaining, short-circuiting, context passing, nesting, and exception propagation.
• Improved transcript logger middleware tests to cover outgoing activity logging by callbacks.

Public API updates

• Exported MiddlewareSet from the package’s __init__.py and updated the __all__ list to include it, making it officially part of the public API. [1] [2]

Minor fixes

• Updated run_pipeline in channel_adapter.py to no longer return the result of the middleware pipeline, aligning with the new middleware pipeline behavior.

[Copilot]

Pull request overview

This PR refactors the MiddlewareSet execution pipeline in microsoft-agents-hosting-core to clarify middleware registration/execution behavior, align adapter pipeline behavior with the new semantics, and add targeted test coverage for middleware ordering, short-circuiting, and transcript logging.

Changes:

• Refactors MiddlewareSet to support fluent .use() chaining, stricter middleware validation, and clearer internal execution flow.
• Updates middleware callback typing/invocation to consistently pass TurnContext into the “next” logic function.
• Adds new unit tests for MiddlewareSet behavior and extends transcript logger middleware tests to cover outgoing activities sent by callback logic.

Reviewed changes

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

Show a summary per file

File	Description
tests/hosting_core/test_middleware_set.py	Adds comprehensive tests for middleware registration, ordering, context passing, short-circuiting, and nesting.
tests/hosting_core/storage/test_transcript_logger_middleware.py	Adds a regression test ensuring outgoing activities sent by callback are logged to the transcript.
libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/storage/transcript_logger.py	Updates middleware logic typing and invocation to pass context into the callback.
libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/middleware_set.py	Refactors middleware pipeline internals and public methods (use, on_turn, receive_activity_with_status).
libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/channel_adapter.py	Aligns adapter pipeline to no longer return the middleware pipeline result.
libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/init.py	Exports MiddlewareSet as part of the public hosting core API.

Comments suppressed due to low confidence (1)

libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/storage/transcript_logger.py:120

• The logic callback is now invoked as await logic(context), but the docstring still describes it generically as a no-arg end-of-chain callback. Updating the docstring to reflect the callable's signature (and that it may be None) will prevent confusion for middleware authors.

    async def on_turn(
        self, context: TurnContext, logic: Callable[[TurnContext], Awaitable] | None
    ):
        """Initialization for middleware.
        :param context: Context for the current turn of conversation with the user.
        :param logic: Function to call at the end of the middleware chain.
        """

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[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 3 comments.

[Copilot]

Pull request overview

Copilot reviewed 6 out of 6 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

Copilot reviewed 7 out of 7 changed files in this pull request and generated 3 comments.

Comments suppressed due to low confidence (1)

libraries/microsoft-agents-hosting-core/microsoft_agents/hosting/core/storage/transcript_logger.py:120

• TranscriptLoggerMiddleware.on_turn now invokes the continuation as logic(context), but the docstring still describes it generically as a function called at the end of the chain. Updating the docstring to reflect the required argument and the middleware-continuation semantics will prevent incorrect implementations/callers.

        """Initialization for middleware.
        :param context: Context for the current turn of conversation with the user.
        :param logic: Function to call at the end of the middleware chain.
        """