Claude Code mods: Minesweeper and testkit

Developer Reporails has introduced a custom Minesweeper game built as a mod for Claude Code, the AI-powered coding agent. Since version 2.1.287, Claude Code supports mods—plugins that run JavaScript or TypeScript hooks directly within the agent's interface. The project highlights the technical challenges of building interactive UI components within a terminal-based agent, including managing keyboard focus, handling hotkeys, and ensuring responsive layouts. The author details a robust testing strategy using a custom test kit that mocks engine calls, allowing for rapid validation of UI behavior without requiring active credentials. The implementation also addresses common pitfalls like race conditions between user input and UI redraws. This project serves as a practical case study for developers looking to extend Claude Code with custom functionality, demonstrating how to maintain high-quality, testable code while navigating the constraints of an evolving plugin architecture.