refactor(server): move REST routing into dedicated RestDispatcher

[guglielmo-san]

Description

This PR centralizes the execution logic for REST endpoints by extracting it from the routing layer (rest_routes.py) into a dedicated RestDispatcher class. It simplifies the pipeline by directly binding the server endpoints to the core RequestHandler.

Fixes #797 🦕

[gemini-code-assist]

Summary of Changes

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This pull request significantly refactors the server's REST API handling by extracting the core execution logic from the routing layer into a dedicated RestDispatcher class. This change centralizes the processing of REST requests, directly binding server endpoints to the RequestHandler and simplifying the overall API pipeline. The refactoring improves maintainability and clarity by separating concerns, making the system more modular and easier to understand.

Highlights

• Centralized REST Routing: Introduced a new RestDispatcher class to centralize the execution logic for REST endpoints, moving it out of the routing layer.
• Removed RESTHandler: The RESTHandler class, which previously contained the REST endpoint logic, has been removed.
• Simplified rest_routes.py: The rest_routes.py file was refactored to utilize the new RestDispatcher, simplifying the routing setup and improving modularity.
• Updated validate_version Decorator: Modified the validate_version decorator in helpers.py to remove the implicit self parameter from wrapped function signatures.
• Comprehensive Testing: Added a new test file with extensive unit tests for the RestDispatcher class, ensuring its correct functionality.

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[github-actions]

🧪 Code Coverage (vs 1.0-dev)

⬇️ Download Full Report

	Base	PR	Delta
src/a2a/server/routes/rest_routes.py	77.11%	73.53%	🔴 -3.58%
src/a2a/server/routes/rest_dispatcher.py (new)	—	92.43%	—
Total	91.47%	91.56%	🟢 +0.10%

Generated by coverage-comment.yml

[gemini-code-assist]

Code Review

This pull request refactors the REST API handling by introducing a new RestDispatcher class, replacing the previous RESTHandler. The rest_routes.py file has been updated to utilize this new dispatcher for defining routes, centralizing the dispatch logic. A new test file, test_rest_dispatcher.py, has been added to cover the functionality of the RestDispatcher. Minor adjustments were also made to the validate_version decorator in src/a2a/utils/helpers.py. There is a bug where JSONRPCHandler is exported in src/a2a/server/request_handlers/__init__.py but not imported, which will cause a NameError. Additionally, it is recommended to add tests for successful streaming responses in test_rest_dispatcher.py to ensure robustness.

[holtskinner]

Suggested change

	class RestDispatcher:
	class RESTDispatcher:

Not sure if there's a general standard on this, but we should probably keep these acronyms as capitals, like we did for A2A, and how the previous RESTHandler class was setup