Setup

One

Install the skill

The skill is for Claude. Two routes — take the one that matches where you write.

/plugin marketplace add fchinaglia/colophon
/plugin install colophon@colophon

Typed in Claude Code itself, not in a terminal: the first line says where to look, the second installs.

claude plugin marketplace update colophon
claude plugin update colophon

Two commands, in that order, and the order is the whole of it: the first refreshes the local copy of the repository, the second compares what it now declares against what you have. Without the first, the second reads the manifest it already had and answers that you are up to date.

1  download colophon.zip

2  Customize → Skills → Add → colophon.zip

The zip has the skill folder at its root, as required. The download is also the button at the foot of this page.

Two

Get your signing key

The first time you say you are about to write — in the chat, to the assistant you were going to write with anyway — it sets you up before anything else, in a short conversation. It asks three things: your name, a contact email, and, if you want one, an ORCID or a domain. All three end up on the verification page a reader opens.

Then it makes your signing key: a private key and a public key, made once together and kept for as long as you use the method. They go to different places:

the private key — stays on your machine

Saved at ~/.ssh/colophon. It never leaves that file: nothing uploads it, nothing publishes it, nothing fetches it. Back it up somewhere you will still have in ten years — it is what says a record is yours, and there is no recovering it.

the public key — travels inside every case

Copied into each case folder when you seal it, so whoever holds your work already holds what checks it.

It is a key, not a certificate — and the difference matters here more than usual. Nobody issued it and nobody vouches for it. It proves that this register was signed by your key, and that nobody without that key has touched the record since; it says the same hand sealed these, never this hand belongs to that person.

The thing that names a person is a qualified electronic signature. It comes from a trust service and not from this setup, it is optional, and it happens at the end of a piece — see the last step of the writing cycle.