cos: Skill for Claude Code

Hub handover — move the hub role between machines, safely

The hub is the one machine that runs the state machine (board, store, backups, routines). Handover promotes a new machine to hub and demotes the old one (to a browser viewer, a spoke, or full retirement). The whole risk is a write that lands after the final backup (stranded forever) or a restore under a live board (silently reverted). This ceremony closes both, in order — do NOT freelance the sequence.

Reusable for any hub swap; the worked example is MacBook → Mac mini (the mini becomes the main machine; the MacBook becomes a spoke). Prereqs: both machines on the same Tailscale tailnet, the same recovery key provisioned on both (backup-recovery §1.1 / §2), and the new machine at a code checkout whose SCHEMA_VERSION is ≥ the store's schema (the migration's safe direction).

In plain terms — explain this to the user BEFORE you start

Everything below this section is written for the machine (you, the agent). This section is for the person — most people asking for this just want "make my new computer the main one without losing anything." Before you touch a single command, walk the user through what's about to happen, in their words. Don't show them the ceremony; tell them this:

• What this does. Right now one computer is the "main" machine — it holds your real board, notes, and to-dos, and makes the nightly backups. This moves that "main" job to a different computer. The old one keeps working afterwards, just as a remote screen onto the new main — you install nothing on it to keep using it, you just open the new main's web address in a browser (a spoke is only if you also want the AI to act on the board from the old machine).
• Why it's fussy (not just "copy the files"). In the wrong order, a to-do you add mid-switch could vanish, or an old copy could quietly overwrite newer data. The steps are ordered so nothing you've typed can be lost — that's the entire reason it looks elaborate.
• What you need ready (I'll check these for you): both computers on the same Tailscale network; the same backup recovery password set up on both (the key that unlocks your encrypted backups); and the new computer running an up-to-date copy of the app.
• How long — two phases. First a "try it out" period of a day or more: the new computer runs alongside the old one so you can confirm everything looks right. Then a ~30-minute switchover where I briefly stop the old machine, take one final backup, and hand the "main" role to the new computer.
• The one rule for you. Until I say the switchover is finished, keep doing your real work on the OLD computer. Anything you type on the new one during the try-it-out period is just a rehearsal — it gets wiped when we do the real handover, so don't rely on it yet.
• Can we undo it? Yes. If the new machine turns out wrong after the switchover, there's a clean rollback — no step here is a point of no return as long as we follow the order.