fix(go/plugins/mcp): capture server errors

[hugoaguirre]

• Refactored serverRef.Error to be an error instead of a string
• NewGenkitMCPClient now returns an error if the connection or init fails.
• connect captures any transport error detected

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)
• Docs updated (updated docs or a docs bug required)

[gemini-code-assist]

Summary of Changes

Hello @hugoaguirre, 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 error handling mechanisms within the Go MCP client. By transitioning from string-based error messages to Go's native error type and propagating these errors more consistently throughout the client's lifecycle, the changes ensure that connection, initialization, and operational failures are properly captured and reported. This improves the reliability and debuggability of the MCP client by providing clearer indications of underlying issues.

Highlights

• Improved Error Handling: The ServerRef.Error field has been refactored from a string to a proper error type, allowing for more robust error propagation and handling throughout the MCP client.
• Enhanced Client Initialization: The NewGenkitMCPClient function now explicitly checks for and returns any initialization or connection errors captured in client.server.Error, ensuring that client creation failures are immediately apparent.
• Consistent Error Capture: The connect function now consistently captures transport-related errors and assigns them to c.server.Error, preventing silent failures during connection setup.
• Error Propagation in Client Methods: Various client methods, including GetPrompt, GetActivePrompts, GetActiveResources, readMCPResource, and GetActiveTools, now check the c.server.Error state and return an appropriate error if the client is in a failed state.
• Refactored initializeClient: The initializeClient function has been updated to return an error directly instead of a string, aligning with Go's idiomatic error handling practices.

🧠 New Feature in Public Preview: You can now enable Memory to help Gemini Code Assist learn from your team's feedback. This makes future code reviews more consistent and personalized to your project's style. Click here to enable Memory in your admin console.

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 significantly improves error handling within the MCP client by transitioning the ServerRef.Error field from a string to a proper error type. This change allows for more robust error wrapping and propagation across various client operations, including connection, initialization, and restart. The addition of checks for the client's error state in key methods ensures that operations are not attempted when the client is already in a failed state, contributing to a more stable and predictable system. Overall, these changes enhance the reliability and debuggability of the MCP client.