Attach a thumbnail to any event

Tempo can show an image inline on an event. UniFi Protect uses this to put a camera snapshot on a motion alert, but it is not Protect-only: any source can do it. Put a base64 data URI in metadata.thumbnail:

{
  "title": "Document scanned",
  "providerIdentifier": "com.noodlesoft.hazel.scan",
  "metadata": {
    "thumbnail": "data:image/jpeg;base64,/9j/4AAQSkZJRg..."
  }
}

A Hazel rule that grabs a frame, a script that snapshots a screen, a webhook from any tool that can attach an image: all of it shows up as a preview on the event.

Pick images that read at a glance

In v1.1 the thumbnail is not clickable (there is no zoom yet). Tempo shows it scaled to the width of the actions panel, so it is a preview, not a viewer. That makes it perfect for things you recognize instantly:

• a face or a scene (who is at the door)
• a chart or a status screen
• a poster or an album cover

It is the wrong tool for anything that needs detail to be legible, like a scan of a text document: shrunk to preview size you cannot read it. Attach the recognizable image, and keep the source app as the place you open the full thing (each event’s Open in action takes you there).

Keep an eye on size

Thumbnails travel inside the event (roughly 10 to 60 KB each), so a busy source with thumbnails on can grow the database. Tempo keeps each image for the window set in Settings > Database > Image retention, then strips just the image while the event itself survives. Pick the longest window you actually look back at.