Agent skill

One skill file that teaches a coding agent when and how to publish. It works in Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode and any other agent that reads Agent Skills. Once installed, the agent reaches for Colophon on its own whenever it has produced files that a person needs a link to.

Install#

The CLI installs the skill into every coding agent it finds on your machine:

npm install -g @strangenoob/colophon
colophon skill install

It looks for Claude Code, Codex, Cursor, Gemini CLI, GitHub Copilot, OpenCode and a few more, and says what it did for each. Name agents to be selective:

colophon skill install codex cursor

Claude Code gets the skill as a plugin — restart Claude Code once after installing. Every other agent is served by the cross-agent installer npx skills: one shared copy in ~/.agents/skills, which Codex, Cursor, Gemini CLI and OpenCode all read, or a link in the agent’s own directory for those that don’t. Every agent gets the release of the skill that your version of the CLI names, never whatever its repository holds that day.

By hand, without the CLI:

# Claude Code
claude plugin marketplace add StrangeNoob/colophon-skill
claude plugin install colophon@colophon

# any other agent
npx skills add StrangeNoob/colophon-skill -g -a codex

Or copy skills/colophon from the repository into ~/.agents/skills/colophon, the shared location Codex and others read, or into the agent’s own skills directory.

Agent by agent#

Codex in particular has no plugin to add and nothing to configure. After colophon skill install codex, ask Codex which skills it has and colophon is in the list. From then on it publishes on its own when it has produced files that need a link, and follows the same rule as every other agent: it asks you to run colophon login rather than asking for a key. Running the command again from a newer CLI picks up a newer version of the skill.

What it needs#

A way to be signed in: on your own machine, colophon login; on a headless one, an API key in COLOPHON_TOKEN. The whole picture is in Signing in.

colophon login

What it teaches#

• To publish with colophon publish and hand back the URL, choosing unlisted unless told otherwise.
• That re-publishing the same slug replaces what is live and keeps the URL — so it updates a site rather than publishing a second one per draft.
• Which access level fits a request, and that restricted and private mean the reader signs in first.
• To stop and tell you to run colophon login if nothing is signed in, rather than guess or work around it.
• What every error means — including that a quota error is yours to resolve, and it must not delete a site to make room on its own.

Try it#

In any project, ask for something that produces files and needs a link:

Make a one-page HTML summary of this repo and give me a link to it.

The agent writes the page, runs colophon publish, and replies with the URL. The site appears in your dashboard under Sites, with its version and traffic.

Updating and removing#

Each CLI release names one release of the skill, a tag and the commit it points to, so a change to the skill reaches your agents only in a CLI release. To update, update the CLI and run colophon skill install again: it moves every copy to the release that CLI names. To remove:

# Claude Code
claude plugin uninstall colophon@colophon

# everything else
npx skills remove colophon -g

The skill is public at github.com/StrangeNoob/colophon-skill — a single SKILL.md in the open Agent Skills format, which is why one file serves every agent.