Claude Mods: Flipping the Harness Inside Out

For the last few weeks I’ve used Claude Mods to mold Claude Code to my AI engineering workflow Claude Code is great out of the box, but every engineering workflow is different Claude Mods let you make Claude Code yours, in the way you want to pay attention

Details

The “paying attention” part is now the most important thing In a recent Latent Space post, The Evolution of the Agent Harness, I argued that as models absorb more of the harness into their weights, the part that’s left faces the human It becomes the Attention Interface: the layer that decides when the agent interrupts you, what it shows you, and which decisions it needs you to make

Context

Claude Mods are an early version of the Attention Interface, and one you can shape yourself Here’s my bet: ultimately, the harness becomes a platform that other companies build on, with models as the engine Just as the browser became a platform for web apps, the harness could become a platform for the interfaces between people and agents A mod is a Claude Code plugin that consists of TypeScript or JavaScript functions that run inside Claude Code

Impact

These functions customize the behavior and appearance of the interface in the CLI and Desktop Mods respond to events, like a prompt, tool call or interface render They can observe the event, modify how it’s rendered, and handle it in place of the default behavior Claude Mods are middleware for the agent harness They inject code that changes Claude Code’s execution and rendering flow, changing how the application behaves at runtime

What's Next

Claude Mods let the human and the agent build the human-facing part of the harness together You can now work with Claude to design how Claude works with you That is the essence of the “Attention Interface.” The harness reversal The agent harness started as an interface between the agent and the machine it runs on It lets you prompt the agent and the agent then sends commands, edits files and calls tools

Background

Now it’s gradually becoming a way for the agent to interface with the human Claude Mods let you reverse the direction of the harness Rather than the harness pointing from the agent to the machine, you point it from the agent to the human operator, and the harness becomes a way to interface with human attention Claude Mods make the human layer programmable, by the human who uses Claude

Analysis

Claude Code has a built-in skill that teaches it how to build mods, so you can ask for the mod you want in plain language and Claude will build it Mods in practice Some of Claude Code’s own features are already mods Anthropic has shipped six of them built-in You can see these by running /plugin and opening Installed, where they’re listed under Built-in: agents-md: loads AGENTS.md as project instructions

More

diff: takes over /diff and draws its pane plugin-authoring: gives Claude the skill it uses to write mods for you sec-default: guards what your organization manages from the mods a user installs telemetry: sends the analytics records that Claude Code and its built-in mods log you-should-know: a side agent that shows a note above the prompt when it finds something you might have missed