Savanna Grass
Screen time becomes grass debt
Every hour on screens owes 10 minutes outside. Distracting time counts 1.5×. Capped at an hour a day. A plain formula you can check by hand.
A companion to SavannaTime
Your screen time, turned into reasons to go outside.
Savanna Grass reads your day from SavannaTime and turns it into grass debt. Then Twiga the giraffe, an AI guide that lives on your phone, plans a small outdoor quest to pay it back. Your screen time never leaves the device for the AI.
Free · 58 MB · Android 7.0+ (64-bit) · signed APK from GitHub Releases
How it works
Twiga plans a quest
Not "go for a walk". Something specific and sensory, built from the shape of your day, the time, whether it's dark, and where you are.
Go outside, pay it back
A calm timer, phone in pocket. When you're back, the break is logged to SavannaTime, the debt goes down and your week fills in.
See it in 80 seconds
Twiga lives on your phone
SavannaTime has one rule it won't bend: no activity data ever reaches an external AI vendor. Which apps you use, how long, at 2 a.m. That's intimate. So Twiga is an open-weight model that runs on the device, offline.
- Your day never leaves the phone for the AI. Only totals and top app names reach the prompt.
- Works with no signal, which is exactly where you're going.
- No API key in the app, no vendor, no bill per walk.
- Open source, so you can read every line.
| Cloud AI | Twiga | |
|---|---|---|
| Your app usage leaves the phone | yes | no |
| Works offline | no | yes |
| API key or per-request cost | yes | no |
| Inspect or swap the model | no | yes |
Install on Android
- Download savanna-grass.apk on your phone.
- Open it. If Android asks, allow your browser to install unknown apps (Settings → Apps → your browser → Install unknown apps). It's needed for any app installed outside Play.
- Install, then open Savanna Grass.
- Sign in with your SavannaTime account.
- Tap "Bring Twiga home" on Wi-Fi. It's a one-time ~555 MB download, and after that Twiga works offline.
Requirements
- Android 7.0 (API 24) or newer, 64-bit (arm64). Nearly every phone from the last eight years.
- ~1 GB free space for the app and Twiga
- A recent phone. Twiga uses the GPU when it can and falls back to the CPU.
- A SavannaTime account. Its desktop tracker measures the screen time this app sends you outside to pay back.
Verify the download
Release APKs are signed with this certificate (SHA-256):
E4:D7:5A:20:19:CC:32:2D:BC:9E:78:62:A2:BF:C5:29:2F:72:00:68:1C:D6:E3:29:42:71:F2:ED:01:D0:43:4B
Check it with apksigner verify --print-certs savanna-grass.apk. Each release also lists the APK's SHA-256 checksum.
iPhone: not yet. The app is built with Flutter, so an iOS build is on the roadmap.
Questions
Do I need SavannaTime?
Yes. Savanna Grass reads your screen time from your SavannaTime account and logs your breaks back to it as time entries, so they show up on your SavannaTime dashboard.
What does Twiga see?
Today's totals, how much was distracting, your top three app names, the time of day, and whether you chose Home, Work or Out. No window titles, no URLs. It all stays on your phone.
What is Twiga, technically?
Twiga is Gemma 3 1B, an open-weight model from Google, running locally through LiteRT/MediaPipe. The app downloads an unmodified copy, mirrored on this project's GitHub Releases.
What if Twiga isn't downloaded yet?
You get classic hand-written quests. The debt, the timer and the logging all work without the model.
Does it work offline?
Quests and the timer do. Finished breaks are saved on your phone and sync to SavannaTime when you're back online, exactly once.