Zone
A phone network that works when every network is gone — and can tell the difference
between a phone that went quiet and a phone that was destroyed.
Native Android app (Kotlin + Jetpack Compose) that forms an offline Bluetooth
store-carry-forward mesh between phones during a disaster. Built for Avinya 2026,
problem statements PS2 (Ground-Zero Communication Blackout) and PS5
(Post-Disaster Information Fog).
- No servers, no internet, no analytics, no downloaded map tiles. Runs identically
in airplane mode.
- One APK, three modes chosen on first launch: Citizen / Responder / Map (EOC).
- A trapped person's phone broadcasts a 31-byte packet over BLE. Any phone in
range copies it and rebroadcasts it with a hop count; duplicates drop by content
hash. The signal physically walks out of the zone in a rescuer's pocket.
Live:
site ·
download the APK ·
install card (QR)
The USP — the Dead Man's Packet
Every packet declares next_expected_tx — how many seconds until the sender
intends to transmit again. So when a phone goes silent, the network can classify
that silence:
| Silence | Meaning |
|---|
| Expected | Battery was critical; the phone warned us. Deprioritise. |
| Unexpected | Promised to speak in 60 s, vanished at 12 s with 70 % battery. The phone was destroyed. Escalate. |
| Cell loss | ≥ 3 phones in one ~100 m cell, ≥ 80 % gone within 120 s. The area collapsed — rendered as a hatched, timestamped hole on the map. |
We infer destruction from the shape of the hole in the data.
It also produces a triage signal no other system has: rank victims by who is about
to stop transmitting — reach the phone at 4 % before it goes dark, not after.
Get the app
Prebuilt APK (signed release build, com.thezone, ~7 MB, minSdk 26):
adb install -r pwa/zone.apk
On the phone: install, allow "install from this source" the first time, open,
pick a mode (Citizen / Responder / Map). Grant Bluetooth + Location when asked
(Android requires Location for BLE scanning). Settings → Apps → Zone → Battery
→ Unrestricted, or the OS throttles the radio in the background.
Package id: com.thezone · label: Zone.
There is no GitHub Release for this project — the signed APK is only
distributed through the Vercel link above and the committed pwa/zone.apk,
so there is exactly one artifact to keep current, not two.
Build from source
Requires JDK 17 and the Android SDK (API 34). If you have Android Studio, its
bundled JBR works:
export JAVA_HOME="/Applications/Android Studio.app/Contents/jbr/Contents/Home"
./gradlew :app:testDebugUnitTest # 56 unit tests — packet codec, silence, triage
./gradlew :app:assembleDebug # -> app/build/outputs/apk/debug/app-debug.apk
./gradlew :app:installDebug # build + install on every attached device
Helper scripts:
| Script | What it does |
|---|
scripts/deploy.sh [--launch] | build, install on every adb device, grant perms, doze-whitelist, print BT/airplane/location state |
scripts/release.sh | build the APK and stage it at pwa/zone.apk for the site |
scripts/make-explainer-pdf.sh | render docs/EXPLAINER.html → docs/Zone-Explainer.pdf |
The three-phone demo
Full field checklist in docs/PHONE_TEST.md; recorded
results in docs/H8_VALIDATION.md.
| Role | Phone in our validation | Why |
|---|
| P1 — Trapped | Samsung Galaxy S23 | only phone with a barometer (vertical triage) |
| P2 — Carrier | Realme 7 | has Coded PHY; the phone that covers distance |
| P3 — Responder | Motorola Edge 50 Pro | best screen, mirrored to the projector |
The moment: P1 broadcasts from another room with its Bluetooth off after pickup;
P2 is walked from P1 to P3; P3 now shows P1's signal at hop 2. The message
crossed the room in someone's pocket.
If BLE won't cooperate on stage: any phone → long-press → Debug → H2 → Simulated
→ Start. Every non-walk part of the demo still runs — the logic is transport-agnostic.
Project layout
app/src/main/kotlin/com/thezone/
transport/ ReportTransport interface + BleTransport / SimulatedTransport / FileTransport
BleForegroundService keeps the active transport alive across screen lock
packet/ Packet, PacketCodec (31 bytes, pure Kotlin, unit tested), DeviceIdentity
core/ ReportStore (content-addressed, union merge) · SilenceEvaluator (Dead Man's Packet)
TriageScorer · CorroborationScorer · Barometry · GridCells
sensors/ PressureReader -> Altitude (relative, EMA-smoothed, trend)
ui/ CitizenScreen · ResponderScreen + DigHereScreen · MapScreen · theme/
probe/ MainActivity — mode router, permission gate, H0/H2 debug host
config/ IncidentConfig (position origin, shared responder key) · LangStore
persistence/ StatePersistence — crash-safe JSON snapshot of the store + collapses
diagnostics/ CrashLog — on-device crash file, no analytics
app/src/test/ JVM unit tests (no Android deps in core/, packet/, or identity/)
pwa/ landing page + staged zone.apk + install card (Vercel: outputDirectory = pwa, see vercel.json)
docs/ specs, build plan, field checklist, explainer
scripts/ deploy / release / pdf helpers
.github/ CI — unit tests + assembleDebug on push
core/ and packet/ have zero Android imports and run on the plain JVM.
Docs
Status
Hackathon build (v0.1) — validated on three real phones in airplane mode
(2026-08-30): direct link, 2-hop store-carry-forward, expected vs unexpected
silence told apart, barometric floor detection, drowning escalation, Dig Here,
and cell loss in a 500-node simulator replaying the real Rasuwagadhi toll curve
(22 → 95 → 469 → 626 over 72 h).
v0.3 adds crash-safe persistence, a real GPS position with a configurable
incident origin, inferred TRAPPED from sustained immobility, a real app
identity + icon, Sybil-resistant scoring, an on-device crash log, a "Keep Zone
alive" battery-setup screen, a pre-shared responder key (verifiable RESPONDER
packets, no crypto library), a RESOLVE packet type (mesh-wide "reached"),
hot/cold Dig Here, an optional headcount, continuous live-EOC auto-export,
a sneakernet mesh-state file, the Citizen screen in
Hindi/Nepali, and CI. Single-phone re-check on the Realme 7 (2026-09-04): GPS,
battery ladder, responder key, no crashes. The mesh half re-runs on three phones.
Outstanding: a 30-minute soak run and a range survey.
Known limits (stated on purpose): iOS cannot participate (no Web Bluetooth on
Safari; native background advertising is locked down — needs an Apple entitlement
or a hardware beacon). 2.4 GHz penetrates rubble poorly — the answer is a pinned
phone advertising for days at low duty cycle until a rescuer walks within ~10 m.
The RESPONDER tier verifies against a pre-shared key; full per-device
signatures would need a crypto library and more than 31 bytes.
License
MIT.
