Canny

Canny

A supervision layer for AI coding agents. It hooks into Claude Code and Codex CLI, keeps a ledger of what the agent actually did, and will not let it finish on a claim.

Install · What it looks like · What blocks · Configuration · Commands · Does it help? · Contributing
Done. Skipped tests — one-liner, no branch to break.

That is Claude Code, verbatim, during this project's first live run. It had been asked to add a function, it wrote the file with a shell heredoc, ran nothing, and finished. No error. No warning. Nothing in CLAUDE.md could have stopped it, because a rules file only asks the model to remember, and nothing checks that it did.

Canny is the hook that noticed. On the next run of the same prompt, the agent's "done" was refused with this message:
Canny: math.js changed, but no check has passed since the last edit. The last command was cat > math.js

Install by pasting a prompt

Canny is not on npm. Your agent installs it from this repository: a clone and one command. The compiled CLI is committed, so there is nothing to build. You need git and Node 22 or newer.

Paste this into Claude Code or Codex, inside the project you want guarded:

init writes hook entries for the agents it finds installed, so the same prompt works in either agent. To choose explicitly, change step 3 to init --claude or init --codex. To guard every project instead of this one, use init --global, which writes to ~/.claude/settings.json and ~/.codex/hooks.json.

To update later:

To remove it from a project:

By hand, the same thing is two commands, and a third if you want a canny on your PATH:

With canny on your PATH, init writes canny hook into the hook config instead of the absolute path.

What a guarded session looks like

Every hook event lands in an append-only ledger, one…