fix: fractional number as id -> invalid request

[brandonh-msft]

This pull request includes updates to improve JSON-RPC request validation, enhance test coverage, and adjust project dependencies. The most important changes include stricter validation of the id field in JSON-RPC requests, expanded unit tests, and dependency adjustments in the A2A.csproj file.

JSON-RPC Request Validation Updates:

• Updated the id field validation in JsonRpcRequestConverter.cs to ensure that numeric IDs must be non-fractional, throwing an exception for fractional numbers. The error message was updated accordingly. (src/A2A/JsonRpc/JsonRpcRequestConverter.cs, src/A2A/JsonRpc/JsonRpcRequestConverter.csL74-R80)

Unit Test Enhancements:

• Added test cases in A2AJsonRpcProcessorTests to validate fractional number IDs as invalid and ensure proper error handling. (tests/A2A.AspNetCore.UnitTests/A2AJsonRpcProcessorTests.cs, tests/A2A.AspNetCore.UnitTests/A2AJsonRpcProcessorTests.csL11-R12)
• Expanded test cases in JsonRpcRequestConverterTests to include fractional number IDs as invalid and updated assertions to match the new error message. (tests/A2A.UnitTests/JsonRpc/JsonRpcRequestConverterTests.cs, [1] [2]

Project Dependency Adjustments:

• Added System.Threading.Channels as a dependency for the netstandard2.0 target framework and removed it from global dependencies in A2A.csproj. (src/A2A/A2A.csproj, [1] [2]
• Removed the NoWarn directive for CA1510, as it is no longer relevant. (src/A2A/A2A.csproj, src/A2A/A2A.csprojL13-L14)

[Copilot]

Pull Request Overview

This PR enhances JSON-RPC request validation by adding stricter validation for the id field to reject fractional numbers, while also improving test coverage and optimizing project dependencies.

• Validates that numeric IDs in JSON-RPC requests must be non-fractional integers
• Adds comprehensive test cases for fractional number ID validation
• Optimizes dependency configuration by moving System.Threading.Channels to target-specific scope

Reviewed Changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

File	Description
src/A2A/JsonRpc/JsonRpcRequestConverter.cs	Added validation logic to reject fractional numbers as IDs and updated error message
tests/A2A.UnitTests/JsonRpc/JsonRpcRequestConverterTests.cs	Added test case for fractional number ID and updated assertion message
tests/A2A.AspNetCore.UnitTests/A2AJsonRpcProcessorTests.cs	Added test cases for valid integer and invalid fractional number IDs
src/A2A/A2A.csproj	Moved System.Threading.Channels dependency to netstandard2.0-specific scope and removed obsolete NoWarn directive

[gemini-code-assist]

Summary of Changes

Hello @brandonh-msft, 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 primarily focuses on enhancing the robustness of JSON-RPC request handling by enforcing stricter validation rules for the id field, specifically disallowing fractional numbers. It also includes corresponding updates to unit tests to ensure proper error handling and minor adjustments to project dependencies for better target framework specificity and code analysis.

Highlights

• JSON-RPC Validation Enhancement: The id field validation in JSON-RPC requests has been made stricter. It now explicitly rejects fractional numbers, ensuring that numeric IDs must be non-fractional integers. The corresponding error message has been updated to reflect this new requirement.
• Unit Test Coverage Expansion: New unit tests have been added across A2AJsonRpcProcessorTests and JsonRpcRequestConverterTests to validate the proper handling and rejection of fractional number IDs, ensuring the updated validation logic works as expected. Existing tests for valid numeric IDs were also enabled.
• Project Dependency Refinement: The A2A.csproj file was updated to adjust project dependencies. Specifically, System.Threading.Channels is now conditionally included only for the netstandard2.0 target framework, and an irrelevant NoWarn directive for CA1510 has been removed.

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[gemini-code-assist]

Code Review

This pull request correctly implements validation to reject fractional numbers as JSON-RPC request IDs, as per the spec's recommendation. The changes include updating the validation logic, adjusting the error message, and adding corresponding unit tests to ensure the new behavior is covered. The project dependencies have also been correctly adjusted for different target frameworks. My main feedback is a suggestion to refactor the validation logic for better readability.

[adamsitnik]

LGTM, thank you @brandonh-msft !