refactor: refactor FastAPI route setup and docs

[martimfasantos]

Description

Summary

This PR improves the current implementation of A2AFastAPIApplication class that enables serving A2A endpoints using a FastAPI application. (#104)

Implementation Details

Refactors the add_routes_to_app method in src/a2a/server/apps/jsonrpc/fastapi_app.py to simplify route definitions by:

• Directly associating handler methods with FastAPI route decorators
• Removing unnecessary nested async function definitions by directly passing handler methods (self._handle_requests, self._handle_get_agent_card, and self._handle_get_authenticated_extended_agent_card) to the FastAPI decorators (app.post and app.get)
• Enabling method descriptions to appear in Swagger documentation, improving developer experience

These changes make the code more readable, maintainable, and better integrated with FastAPI's documentation features.

Screenshots

Before

After

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Continues #104 🦕

[gemini-code-assist]

Summary of Changes

Hello @martimfasantos, I'm Gemini Code Assist¹! I'm currently reviewing this pull request and will post my feedback shortly. In the meantime, here's a summary to help you and other reviewers quickly get up to speed!

This pull request introduces a significant refactoring to the A2AFastAPIApplication class, specifically within its add_routes_to_app method. The primary goal is to simplify the way FastAPI routes are defined and to improve the auto-generated Swagger documentation, making the codebase more readable and maintainable.

Highlights

• Route Definition Simplification: The add_routes_to_app method in A2AFastAPIApplication has been refactored to directly associate handler methods (self._handle_requests, self._handle_get_agent_card, self._handle_get_authenticated_extended_agent_card) with FastAPI route decorators (app.post and app.get).
• Code Readability and Maintainability: Unnecessary nested async def function definitions that previously wrapped the actual handler methods have been removed, leading to cleaner and more concise route declarations.
• Improved Documentation: This refactoring enables method descriptions to appear correctly in the Swagger documentation, enhancing the developer experience and API discoverability.

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[gemini-code-assist]

Code Review

This pull request refactors the FastAPI route registration in A2AFastAPIApplication. The change simplifies the code by removing wrapper functions and directly associating the handler methods with the route decorators. This is a great improvement for code clarity and maintainability. As a key benefit, this change allows FastAPI to correctly generate endpoint descriptions from the handler docstrings for the OpenAPI documentation, which significantly improves the developer experience. The implementation is clean, correct, and achieves its goals effectively. I have no concerns with this change.