RWR: onlooker alert

RWR watches through the front camera for people looking at your screen from behind (shoulder surfers). When it sees one, it:

• pops up a card over whatever app you are using with a snapshot of the onlooker (boxed in red, with "laser eyes" showing where they look),
• posts a notification,
• saves a photo or a short video clip (for example 10 s before to 10 s after) to your gallery, and optionally to your own Immich server.

It runs in the background and can be switched on and off from the Quick Settings panel.

Detection

• Head tracking: a face turned toward the screen counts as looking. Lightest on battery.
• Eye tracking: follows the irises and combines them with head pose, so it alerts only when the eyes point at the screen.
• Your own face is recognised and ignored, and faces too far away to read the screen don't count.
• A debug view shows live what the detector sees and why each face counts or not.

Private by design

• Detection runs on the phone, offline, with bundled open-source models (YuNet and MediaPipe Face Landmarker). No analytics, no ads, no accounts.
• Nothing leaves the phone unless you pair it with your own RWR server (Docker, open source, in the same repository). Then frames go only to your server, over TLS: detection runs there at full frame rate without draining your battery, and snapshots can be uploaded to Immich.
• The camera is always off while the screen is off. Android shows its camera indicator while RWR is watching.

Requires Android 10 or newer and a front camera. The pop-up needs the "Display over other apps" permission.

First F-Droid release (1.5.0).
- Face detection now uses the open-source YuNet detector (same as the RWR server) instead of Google ML Kit: about half the CPU, and good at small faces.
- MediaPipe's usage-statistics client can no longer send anything: its Google telemetry transport is replaced by a do-nothing stand-in.
- Fewer false alerts: far-away faces never count, every candidate face is verified, an onlooker must stay half a second.