Merge main into 1.0-dev

[lkawka]

Description

Thank you for opening a Pull Request!
Before submitting your PR, there are a few things you can do to make sure it goes smoothly:

• Follow the CONTRIBUTING Guide.
• Make your Pull Request title in the https://www.conventionalcommits.org/ specification.
  • Important Prefixes for release-please:
    • fix: which represents bug fixes, and correlates to a SemVer patch.
    • feat: represents a new feature, and correlates to a SemVer minor.
    • feat!:, or fix!:, refactor!:, etc., which represent a breaking change (indicated by the !) and will result in a SemVer major.
• Ensure the tests and linter pass (Run bash scripts/format.sh from the repository root to format)
• Appropriate docs were updated (if necessary)

Fixes #<issue_number_goes_here> 🦕

[gemini-code-assist]

Summary of Changes

Hello @lkawka, 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 significantly enhances the security and flexibility of the A2A SDK by introducing agent card signing and verification, allowing clients to cryptographically validate the authenticity of agent metadata. It also refines client-side message sending with per-call configuration options and improves server-side request context management through customizable ID generation. Additionally, several minor bug fixes and documentation improvements contribute to overall stability and clarity.

Highlights

• Agent Card Signing & Verification: Implemented JSON Web Signature (JWS) based signing and verification for Agent Cards, enhancing security and trust in agent interactions. This includes a new signing.py module, PyJWT dependency, and integration across client transports and card resolution logic.
• Per-Call Message Configuration: Added the ability to override message sending behavior (e.g., history length, blocking, accepted output modes) on a per-call basis in BaseClient.send_message, providing greater flexibility for client interactions.
• Custom ID Generation: Introduced an IDGenerator interface and a UUIDGenerator implementation, allowing for customizable task and context ID generation within the SimpleRequestContextBuilder on the server side.
• Improved Error Handling: Enhanced streaming error handling in JSON-RPC and REST transports to more effectively catch and propagate httpx.HTTPStatusError exceptions, leading to more robust client-server communication.

Ignored Files

• Ignored by pattern: .github/workflows/** (5)
  • .github/workflows/linter.yaml
  • .github/workflows/python-publish.yml
  • .github/workflows/stale.yaml
  • .github/workflows/unit-tests.yml
  • .github/workflows/update-a2a-types.yml
• Ignored by pattern: CHANGELOG.md (1)
  • CHANGELOG.md

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 by creating a comment using either /gemini <command> or @gemini-code-assist <command>. Below is a summary of the supported commands on the current page.

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 pull request 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 introduces a major feature for agent card signing and verification using JWT, along with several other improvements. The changes include adding a new signing utility, updating dependencies, and modifying client transports and factories to support signature verification. Additionally, there are enhancements to configuration handling, error management in streaming, and several minor typo and grammar fixes. The new functionality is well-tested with new unit and integration tests.

My review includes a critical fix for a potential data loss bug in the new canonicalization helper function and several minor suggestions for typo fixes and code cleanup.

[gemini-code-assist]

The condition if v to filter dictionary values will incorrectly remove falsy values such as 0 or False. This could lead to unintended data loss during canonicalization. To fix this, you should explicitly check if the value is not None.

Suggested change

	return {k: v for k, v in cleaned_dict.items() if v}
	return {k: v for k, v in cleaned_dict.items() if v is not None}

[gemini-code-assist]

Similar to the dictionary filtering, the condition if v for list filtering will incorrectly remove falsy values like 0 or False. This should be changed to if v is not None to avoid data loss.

Suggested change

	return [v for v in cleaned_list if v]
	return [v for v in cleaned_list if v is not None]

[gemini-code-assist]

This change adds a comma for better readability, which is a good grammatical correction.

[gemini-code-assist]

The imports from a2a.types are duplicated. You can combine them into a single block for better readability.

from a2a.types import (
    AgentCard,
    AgentCapabilities,
    AgentSkill,
    AgentCardSignature,
)