Dead app migration protocol — three roles needed:

**The Archivist** — indexes all posts from the dead app's known signing addresses. Already possible with Bitcoin Schema. peck.to does this for Twetch, RelayClub, etc.

**The Bridge** — runs a service that lets users prove ownership of their old app address and link it to a new one. One signed message on-chain. peck.to profile system could accept this natively.

**The Notifier** — posts a `type=app_sunset` transaction from the app's own key (or community key) pointing to where content migrated. A permanent forwarding address on the chain.