fix(genkit-tools/mcp): Fix MCP server failing to spin up runtime

[ssbushi]

• Add explicit runtime health check
• Add optional file logging to MCP CLI command
• Use non-interactive mode and specify project root for ProcessManager.
• Tests for changes.

Checklist (if applicable):

• PR title is following https://www.conventionalcommits.org/en/v1.0.0/
• Tested (manually, unit tested, etc.)

[gemini-code-assist]

Summary of Changes

Hello @ssbushi, 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 addresses a critical issue where the MCP server was failing to spin up its runtime reliably. The changes introduce a robust runtime health check, provide an optional file logging mechanism for better diagnostics, and refine the process management to ensure managed processes start correctly in a non-interactive environment with the appropriate project context. These improvements collectively aim to make the MCP server more stable and easier to debug.

Highlights

• Runtime Health Check: An explicit health check mechanism has been introduced to ensure the MCP server's runtime is properly spun up and registered, preventing failures during startup.
• Optional File Logging: A new --debug option has been added to the MCP CLI command, allowing users to enable detailed file logging for easier debugging and troubleshooting.
• Improved Process Management: The ProcessManager now operates in a non-interactive mode by default for managed processes and correctly specifies the project root, enhancing stability and predictability.
• Enhanced Test Coverage: New unit tests have been added for the start command and the waitForRuntime utility, ensuring the reliability of the new features and fixes.

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[gemini-code-assist]

Code Review

This pull request effectively resolves an issue where the MCP server could fail to properly start a runtime due to a race condition. The core of the fix is the new waitForRuntime function, which explicitly waits for the runtime process to initialize and register itself. This is a robust solution that significantly improves the reliability of the tool.

The supporting changes are also well-implemented. The modification to onRuntimeEvent to return an unsubscribe function is a crucial improvement for preventing resource leaks. The enhancements to ProcessManager for better handling of non-interactive processes and the addition of a --debug flag for file logging improve the tool's debuggability. Furthermore, the introduction of comprehensive unit tests for the new logic is commendable and ensures the changes are solid. Overall, this is a high-quality contribution that strengthens the stability and usability of the MCP server.

[ssbushi]

/gemini review

[gemini-code-assist]

Code Review

This pull request addresses an issue where the MCP server fails to reliably spin up a runtime. The core of the fix is the introduction of an explicit waitForRuntime health check, which ensures the server waits for the runtime process to properly register before proceeding. The changes also include adding a file-based debug logging option, correctly setting the process to non-interactive mode, and providing the project root as the working directory. The addition of comprehensive tests for the new logic is a great touch. My review includes a couple of suggestions to enhance the robustness of the process cleanup logic and to refactor the new waitForRuntime function for better readability and maintainability.

[ssbushi]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces several improvements to fix the MCP server's runtime startup failures. Key changes include adding an explicit health check (waitForRuntime) when starting a dev process, enabling non-interactive mode for the process manager, and allowing file-based debugging for the MCP command. The changes are well-structured and include new tests for the added functionality.

I've found a potential race condition in the new waitForRuntime function that could lead to incorrect timeouts. I've also noted a pattern in the new tests that could lead to flakiness. My detailed comments provide suggestions for addressing these points.