fix: fixing JSONRPC error mapping

[maeste]

Final Error Mapping (JSON-RPC 2.0 Compliant):

• -32700: Parse error (invalid JSON)
• -32600: Invalid Request (missing/invalid jsonrpc, invalid id type, oversized payload)
• -32601: Method not found (unknown method names)
• -32602: Invalid params (valid method, invalid parameters) -32603: Internal error (unexpected server exceptions)
• -32000 to -32099: Server-defined errors (A2A-specific, pass through unchanged)

Fixes #413 🦕

[gemini-code-assist]

Summary of Changes

Hello @maeste, 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 refactors the JSON-RPC request handling within the application to ensure strict compliance with the JSON-RPC 2.0 specification for error mapping. The changes introduce a more robust and granular validation process for incoming requests, allowing for precise error responses based on the nature of the request issue, such as invalid structure, unknown methods, or incorrect parameters. This significantly improves the reliability and predictability of the API's error reporting.

Highlights

• Strict JSON-RPC 2.0 Compliance: The pull request explicitly implements error mapping for various JSON-RPC 2.0 compliant error codes, including -32700 (Parse error), -32600 (Invalid Request), -32601 (Method not found), -32602 (Invalid params), and -32603 (Internal error). This ensures that the API responses are more precise and adhere to the standard.
• Improved Request Validation Flow: The request handling logic in jsonrpc_app.py has been significantly refactored to include a multi-stage validation process. This now includes checks for valid request_id types, early detection of oversized payloads, base JSON-RPC structure validation, and method-specific routing with parameter validation. This structured approach ensures robust error handling at each stage of request processing.
• Refined JSONRPCRequest Model: The JSONRPCRequest model in types.py has been refined. The jsonrpc field no longer has a default value, enforcing its presence. Additionally, the params field's type has been broadened from dict[str, Any] | None to Any, providing greater flexibility for different parameter structures as allowed by the JSON-RPC specification.

Using Gemini Code Assist

The full guide for Gemini Code Assist can be found on our documentation page, here are some quick tips.

Invoking Gemini

You can request assistance from Gemini at any point in your pull request via creating an issue comment (i.e. comment on the pull request page) using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands.

Feature	Command	Description
Code Review	/gemini review	Performs a code review for the current pull request in its current state.
Pull Request Summary	/gemini summary	Provides a summary of the current pull request in its current state.
Comment	@gemini-code-assist	Responds in comments when explicitly tagged, both in issue comments and review comments.
Help	/gemini help	Displays a list of available commands.

Customization

To customize Gemini Code Assist for GitHub experience, repository maintainers can create a configuration file and/or provide a custom code review style guide (such as PEP-8 for Python) by creating and adding files to a .gemini/ folder in the base of the repository. Detailed instructions can be found here.

Limitations & Feedback

Gemini Code Assist may make mistakes. Please leave feedback on any instances where its feedback is incorrect or counter productive. You can react with 👍 and 👎 on @gemini-code-assist comments. If you're interested in giving your feedback about your experience with Gemini Code Assist for Github and other Google products, sign up here.

You can also get AI-powered code generation, chat, as well as code reviews directly in the IDE at no cost with the Gemini Code Assist IDE Extension.

Footnotes

1. Review the Privacy Notices, Generative AI Prohibited Use Policy, Terms of Service, and learn how to configure Gemini Code Assist in GitHub here. Gemini can make mistakes, so double check it and use code with caution. ↩

[gemini-code-assist]

Code Review

This pull request significantly improves the JSON-RPC error handling by implementing a more granular, multi-step validation process that aligns with the JSON-RPC 2.0 specification. The changes correctly map different failure scenarios (e.g., invalid request structure, unknown method, invalid parameters) to their standard error codes. The modifications to the Pydantic types also enhance spec compliance.

My review includes suggestions to improve logging practices by replacing traceback.print_exc() with structured logging and adjusting a debug-style log message. I've also proposed a refactoring of the method routing logic to enhance maintainability.

[holtskinner]

@maeste Don't make direct changes to types.py these need to be adjusted in https://github.com/a2aproject/a2a

[maeste]

Tested similar conditions on TCK to avoid type.py changes. Other changes are valid and required