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Claude Code now lets you change Claude Code. Mods are small JavaScript or TypeScript files, packaged as plugins, that run inside your session. They can draw new UI, rewrite prompts, and step into tool calls. You can ask Claude to write one for you.
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That sounds like hooks. It isn't quite. A settings hook runs a shell command for each event. A mod loads once and stays in your session, so it can keep state, replace built-in features, and draw panes and buttons. Even /diff now ships as a mod.
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Three samples from Anthropic: • Token Weather: a context window forecast above your prompt • Blast Radius: pauses rm -rf or a force push and shows what it would change • Replay Theater: /replay steps through last turn's edits, one diff at a time https://github.com/anthropics/claude-code-playground/tree/main/claude-code/mods
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One catch: mods aren't sandboxed. They run with your permissions, so only install ones you trust. Start with Token Weather. The tutorial has a prompt you paste into Claude Code, and it builds the mod for you. Announcement: https://claude.com/blog/claude-code-mods Tutorial: https://claude.dev/blog/getting-started-with-claude-code-mods/ Docs: https://code.claude.com/docs/en/plugins/mods/overview
