Anthropic introduced mods for Claude Code, TypeScript functions that change how it works and looks

On October 1, 2026, Anthropic introduced mods for Claude Code: small TypeScript functions shipped inside plugins that hook into events, rewrite prompts and tool calls, decide permission requests and change the interface.

Archive entry: this covers an event from October 1, 2026, and we published it on November 8, 2026. The details come from sources dated at the time and may have changed since.

On October 1, 2026, Anthropic introduced mods for Claude Code in a Claude blog post on customizing Claude Code with mods. A mod is a small TypeScript function that changes how Claude Code works and looks. Mods shipped inside plugins, so they were installed and shared like any plugin, and they worked in both the Claude Code CLI and the desktop app.

What mods could change

A mod hooked into a Claude Code event, such as a tool call, a permission request or drawing part of the screen. It could run before, after or instead of the event, or wrap it.
Mods could rewrite a prompt; block, rewrite or retry a tool call; approve or deny a permission request; redact secrets from tool output; and edit or replace parts of the interface.
When several mods hooked the same event, they ran in load order.
Claude Code could write, install and hot reload a mod during a session.
Some built-in features, for example /diff, shipped as mods.

What it meant for people who build with AI

Developers could reshape Claude Code's prompts, permissions and interface themselves instead of waiting for features. The same reach carried a cost: mods ran with the same access to the machine as Claude Code and were not sandboxed, so Anthropic advised installing mods only from trusted sources. Unsandboxed mods were also a supply-chain risk.

Release details

Claude Code v2.1.287, released the same day, added Claude Mods and a built-in “You should know” mod, in which a side agent flags things the user or Claude might miss. It was turned on with /plugin enable cc-plugin-you-should-know@builtin. The Claude Code v2.1.287 release notes on GitHub recorded the change.

Sources

Customize Claude Code with mods (Anthropic (Claude blog), October 1, 2026, official)
Release v2.1.287 · anthropics/claude-code · GitHub (Anthropic (GitHub), October 1, 2026, official)

Written with AI assistance, strictly from the sources listed above. Before it went live, automated checks verified its dates, sources and every language edition.