Claude Mods are TypeScript or JavaScript plugins that hook into Claude Code's events, letting you control when the agent interrupts you and what it shows you. The author compares this approach with ChatGPT's Intelligent UI and Cursor's PR Routing, arguing that Mods let the user design the interface rather than accept one a company built.

• Mods are middleware that intercept prompts, tool calls, and renders, so you can change how Claude Code behaves and displays information at runtime.
• The built-in You Should Know mod caught uncommitted work in 45 files that a demo edit would have discarded, showing how a side agent can flag what the main agent buries.
• The author's Next Steps Supervisor fired on 99 of 111 turns, so the noise and token cost (roughly 5–6k tokens per check) undercut its value, and mods are unsandboxed code running with your permissions.