The Pulse
Anthropic Adds TypeScript Mods to Claude Code
Anthropic added TypeScript mods to Claude Code, letting developers change prompts, tool calls and the interface through plugins. Mods are available in the CLI and desktop app, but run with the same machine access as Claude Code and are not
AI.info Team · Written with AI ·
“Mods run with the same access to your machine as Claude Code itself. They aren’t sandboxed.”
Anthropic
Anthropic introduced TypeScript mods for Claude Code on October 1, giving developers a way to change the coding agent’s behavior and interface through small functions packaged as plugins. The feature is available in Claude Code’s command-line interface and desktop app. Anthropic’s warning is central to the release: mods are executable code, not isolated add-ons, and the company says users should install them only from sources they trust.
A mod can intervene in events such as a tool call, a permission request or the rendering of part of the interface. Depending on where it hooks in, it can run before or after an event, replace it, or wrap it with code on both sides. That gives extension authors control over actions that existing hooks do not cover, including rewriting events and drawing new interface elements.
Mods can change prompts, permissions and the interface
Anthropic lists several uses: rewriting a prompt before it reaches the model, blocking or retrying a tool call, approving or denying a permission request, and redacting secrets from tool output before Claude reads it. Mods can also edit or replace interface elements, including tool results and questions from Claude, or add buttons and inputs. A mod can target the terminal, the desktop app or both.
Extensions that hook the same event run in load order. Anthropic says the first mod loaded sees the event first and its result last, a sequence that lets developers combine mods from different authors. Claude Code can also write a mod on a user’s request, install it and hot reload it into the current session.
The built-in /diff is already a mod
The launch is more than a new plugin type: Anthropic says some existing Claude Code features now ship as mods. The built-in /diff view is one example; users can turn it off through /plugin or replace it with their own version. Anthropic says it plans to move more built-in features into mods, allowing users to remove functions they do not want and add alternatives.
That approach puts more of the product’s behavior within reach of extension authors, but it also makes the trust warning more consequential. A mod can affect permission decisions and tool calls, not just presentation. Because it runs with Claude Code’s access to the machine, a plugin’s origin and code matter even when its purpose appears limited to a display change.
Anthropic gives administrators controls—and a default mod
Mods are distributed inside plugins, so existing plugin controls apply. Team and Enterprise owners can allow or block plugin marketplaces in the admin console; on Claude API and third-party API plans, administrators can push managed settings to users’ machines. Anthropic says a built-in mod called sec-default loads first on Team and Enterprise plans and on machines with managed settings.
The security mod is intended to stop user-installed mods from taking actions such as overriding permission-deny rules. Administrators can instead load their own mods first, but Anthropic advises them to include sec-default if they want to retain its restrictions. The company also points to potential team uses such as showing CI/CD status beside a conversation, requiring confirmation before commands touch production configuration, and recording calls made by other mods.
Available through the CLI and Claude directory
Users can install plugins containing mods from the Claude directory or by running /plugin in the CLI. Developers can package a mod in a plugin and submit it to the directory. Anthropic’s release makes custom TypeScript code a direct extension point for Claude Code; it also makes the distinction between a trusted plugin and arbitrary code on a developer’s machine a practical part of adopting the feature.