Whiteboard Defense — AI skill for Claude Code

Whiteboard Defense

**Know what your AI agent built, and where it just used its defaults.**

A skill and plugin for Claude Code, Codex, and OpenCode. After substantial work, it briefs you on how the thing works, which decisions were made, who made each one (you, the context, or the agent's habit), where it fails, and the questions you should be able to answer if someone pulled you aside at a whiteboard.

Site: https://avestura.github.io/whiteboard-defense/

Why

Mitchell Hashimoto's [whiteboard defense](https://x.com/mitchellh/status/2100249348345057389): you should be able to explain any customer-facing system you shipped and defend its decisions, even if you did not write the code. PoCs and demos are exempt. Anything customers touch is not.

Agents make dozens of decisions you never see. Many are not decisions at all, but defaults: the same logo idea, the same slide-deck mechanics, the same stack. Anthropic's own advice for Opus 5.5 is to name the styles you do *not* want, because a general "avoid generic" mostly swaps one default for another. This project extends that idea past design: it tells you where defaults were used, so you can steer next time.

Install

One command. It installs for every supported agent it finds on your PATH.

macOS / Linux / Git Bash:

curl -fsSL https://raw.githubusercontent.com/avestura/whiteboard-defense/main/install.sh | sh

Windows PowerShell:

irm https://raw.githubusercontent.com/avestura/whiteboard-defense/main/install.ps1 | iex

Pick agents explicitly: `... | sh -s -- claude codex opencode`. Remove with `--uninstall`.

Per agent, manually

**Claude Code**

claude plugin marketplace add avestura/whiteboard-defense
claude plugin install whiteboard-defense@whiteboard-defense

Run it with `/whiteboard-defense:whiteboard`.

**Codex**: copy the skill into your personal skills directory, then run `$whiteboard`.

git clone https://github.com/avestura/whiteboard-defense && cp -r whi