Anthropic opens Claude Code to mods that rewrite its own functions

Anthropic has handed developers a screwdriver and invited them to open up Claude Code. Its AI coding tool now supports mods, small functions that can rewrite how the tool behaves and change what its interface looks like. The update landed on October 1, 2026. What mods actually do Technically, mods are small, event-driven functions written in TypeScript or JavaScript. They hook into internal events inside Claude Code, which means they fire when specific things happen in the tool. Once triggered, a mod can alter the prompts Claude receives. It can adjust the tool calls the AI makes, change interface elements, or bolt on entirely new features. Mods slot into Claude Code’s existing plugin system rather than replacing it. They work in both the command-line version and the desktop app. Getting them running requires Claude Code v2.1.287 or later. In supported versions, mods are switched on by default, so there is no extra setup flag to flip. Installation and management run through the existing /plugin command and plugin marketplaces. Anthropic ate its own cooking Several built-in pieces of Claude Code have been converted into mods. That list includes the ‘/diff’ pane, the agents.md loader...