Claude Code plugins can now execute code inside the assistant

Claude Code plugins can now run code inside the assistant through special functions. That gives developers a middleware-like way to add behavior, and users can ask Claude to write these “mods” instead of building every tool from scratch.

The update pushes Claude Code beyond one-off prompts toward a more extensible runtime for developer-built tools. Addy Osmani’s mod turns context-window usage into a weather forecast, while Mem0 demonstrated preserving codebase context across sessions on October 1, 2026.