cairn — Immich sync

cairn reconciles your iPhone photo library against your own Immich server. When you delete a photo on your phone, cairn moves the matching photo on Immich to Trash.

That's the whole job. cairn doesn't upload photos, show albums, edit metadata, or run AI — the Immich app already does those things. cairn closes the one loop the Immich app doesn't: photos that live on the server after you've deleted them from your phone.

HOW IT WORKS
— Content identity is SHA1 (the same identifier Immich uses server-side).
— cairn subscribes to iOS's deletion log, so it sees soft-deletes as you make them.
— A configurable quarantine window holds confirmed deletions before anything moves, so an accidental mass-offload has time to be caught.
— Every run shows you the candidate list first. Nothing happens on the server until you confirm.

SAFETY MODEL
— Trash, not delete. cairn moves assets into your Immich Trash — Immich retains them for 30 days, and restore is one tap.
— Percent cap + floor. If a single run would move more than a threshold of your matched photos to Trash, it aborts without touching the server.
— Breadcrumbs. Every run is tagged on Immich (cairn/v1/run/[id]) so you can find it server-side.
— Forensic journal. Local append-only log records every step — planned, tagged, trashed, restored, failed.
— Exclusions. Protect specific photos from ever being flagged.
— Indexing scope. Restrict cairn to a specific set of Photos albums. Photos outside the scope are silently ignored — never hashed, never proposed for trash. Useful if you want to manage just one album and leave synced family albums alone.

PRIVACY
— No analytics, no telemetry, no crash reporting, no ads.
— No cairn backend. Your iPhone talks directly to your Immich server using your API key.
— Credentials stay in the iOS Keychain. Nothing leaves your device besides requests you configured.

REQUIREMENTS
— An Immich server you run or control.
— An Immich API key. cairn requests these scopes: asset.read, asset.view, asset.download, asset.delete, tag.create, tag.asset, tag.read. The Setup screen lists them when you paste your key.

cairn is not affiliated with the Immich project. It talks to Immich over its public API; compatibility only.

Source is MIT-licensed at github.com/glarue/cairn.