refactor(server)!: migrate from Application wrappers to Starlette route-based endpoints for jsonrpc

[guglielmo-san]

Description

This PR refactors the jsonrpc server implementation to expose Starlette Route components directly (via AgentCardRoutes, JsonRpcRoutes) instead of requiring full FastAPI or Starlette application wrappers.

Ref #797 🦕

[gemini-code-assist]

Summary of Changes

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This pull request significantly refactors the server-side implementation for handling JSON-RPC and agent card endpoints. Instead of providing framework-specific application classes, the system now offers granular routing components (JsonRpcRoutes and AgentCardRoutes). This change enhances the modularity and flexibility of the server, allowing developers to integrate these functionalities more seamlessly into existing Starlette or FastAPI applications by composing routes, rather than relying on pre-built application wrappers.

Highlights

• Modularization of JSON-RPC and Agent Card Endpoints: The previous monolithic A2AFastAPIApplication and A2AStarletteApplication classes have been removed. Their functionalities are now split into dedicated JsonRpcRoutes and AgentCardRoutes classes, promoting better separation of concerns and reusability.
• Refactoring of JSONRPCApplication to JsonRpcDispatcher: The core logic for handling JSON-RPC requests, previously encapsulated in JSONRPCApplication, has been refactored into a new class named JsonRpcDispatcher. This dispatcher focuses solely on processing JSON-RPC messages, decoupling it from the web framework routing specifics.
• Simplified Application Setup: Sample and test files have been updated to reflect the new modular structure, demonstrating how to integrate JsonRpcRoutes and AgentCardRoutes directly with Starlette and FastAPI applications by extending their route lists.
• Removal of Redundant Application Classes: The fastapi_app.py and starlette_app.py modules within a2a.server.apps.jsonrpc have been removed, along with their corresponding imports and __all__ entries, as their functionality is now handled by the new routing system.

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[github-actions]

🧪 Code Coverage (vs 1.0-dev)

⬇️ Download Full Report

	Base	PR	Delta
src/a2a/server/routes/agent_card_routes.py (new)	—	65.00%	—
src/a2a/server/routes/jsonrpc_dispatcher.py (new)	—	85.78%	—
src/a2a/server/routes/jsonrpc_routes.py (new)	—	58.33%	—
Total	91.45%	91.35%	🔴 -0.10%

Generated by coverage-comment.yml

[gemini-code-assist]

Code Review

This pull request is a significant refactoring that removes the framework-specific A2AFastAPIApplication and A2AStarletteApplication in favor of a more modular approach using JsonRpcRoutes and AgentCardRoutes. This improves decoupling from web frameworks and increases flexibility. The changes are well-executed across the application and test suite. However, I've found a critical issue where a test file seems to have been missed in the refactoring, causing it to break. I've also noted some areas where test coverage might have been unintentionally reduced. Additionally, there are a few minor suggestions for improving code style and clarity.

[guglielmo-san]

/gemini review

[gemini-code-assist]

Code Review

The pull request successfully refactors the JSON-RPC server implementation to use Starlette route-based endpoints, replacing the previous application wrappers. This change streamlines the architecture by introducing dedicated JsonRpcRoutes and AgentCardRoutes classes, which are then integrated directly into the main FastAPI/Starlette application. The removal of old application wrapper files and corresponding imports across the codebase is consistent with the refactoring goal. However, there are a couple of areas that could be improved for better encapsulation and explicit handling of request constraints.

[ishymko]

Revoke