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Opening the About sheet runs a release check, and an exhausted quota fed itself: only successes were cached, and a 403 reporting zero remaining was classed retryable, so every sheet open spent three more requests rediscovering the same limit. Unauthenticated GitHub allows 60 requests an hour per IP, and over Tor that IP is an exit node shared with every other user on it, so the ceiling arrives far sooner than per-user maths suggests. Three changes: - Conditional requests. The client now stores the release ETag and replays it as If-None-Match. GitHub does not charge a 304 against the rate limit, so revalidating an expired cache is free where an unconditional refetch costs one of the 60. This is why neither polling nor long polling is the right answer here. - A rate-limit gate. X-RateLimit-Reset and Retry-After were read only to interpolate into an error string; they now set a deadline before which no request is sent at all. While blocked, a stale cached release is served in preference to an error the user cannot act on. Clamped to an hour so a bad header cannot lock the feature out, and a reset time in the past falls back to a fixed backoff rather than unblocking a skewed clock immediately. - Rate limits are no longer retried in-loop. The gate decides when it is worth asking again. A plain 403 is a permissions failure and is no longer retried either. The gate's decision logic is pure and unit tested. The wiring around it is not: that needs a MockWebServer, which is not currently a dependency. Known gap: the cache and ETag are in memory only, so a process restart still costs one request. Persisting them needs a Context threaded into what is currently a context-free object; left as a follow-up. Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
bitchat for Android
A decentralized peer-to-peer messaging app with dual transport architecture: local Bluetooth mesh networks for offline communication and internet-based Nostr protocol for global reach. No accounts, no phone numbers, no central servers.
This is the Android implementation of bitchat, fully protocol-compatible with the iOS version for cross-platform mesh communication.
See it in action
| Offline mesh conversation | Geohash globe picker |
|---|---|
 |
 |
License
This project is released into the public domain. See the LICENSE file for details.
Features
- Dual Transport Architecture: Bluetooth LE mesh for offline messaging, Nostr relays for internet-based messaging
- Location-Based Channels: Geographic chat rooms using geohash coordinates over Nostr relays
- Intelligent Message Routing: Automatically chooses the best transport, with queuing and retry when a peer is unreachable
- End-to-End Encryption: Noise Protocol (XX pattern, X25519 + ChaCha20-Poly1305) for private messages over the mesh
- Decentralized Mesh Network: Automatic peer discovery and multi-hop relay over Bluetooth LE (max 7 hops)
- Wi-Fi Aware Transport: Higher-bandwidth local mesh on supported devices
- Channel Chats: Topic-based group messaging with optional password protection (Argon2id + AES-256-GCM)
- IRC-Style Commands: Familiar
/join,/msg,/whostyle interface - Tor Support: Built-in Tor (Arti) for private internet connectivity
- Emergency Wipe: Triple-tap to instantly clear all data
- Cross-Platform: Binary protocol compatible with bitchat on iOS and macOS
Technical Architecture
Bluetooth Mesh Network (Offline)
- Direct peer-to-peer within Bluetooth range, multi-hop relay through nearby devices
- Noise Protocol sessions with forward secrecy; peer identities derived from static keys
- Compact binary packet format with fragmentation, TTL routing, and deduplication
- Adaptive duty cycling and connection limits for battery efficiency
- Foreground service keeps the mesh alive within Android background execution limits
Nostr Protocol (Internet)
- Global reach via public relays, geohash-based location channels
- Private messages fall back to Nostr for mutual favorites when the mesh is unavailable
- Ephemeral keys per geohash area
Android Stack
- Kotlin, Jetpack Compose (Material 3), MVVM
- Coroutines and Flow for all networking and state
- Core components:
MeshForegroundService(persistent connectivity),BluetoothMeshService/WifiAwareMeshService(transports),UnifiedMeshService(transport selection),NoiseSessionManager(encryption sessions),MessageRouter(mesh/Nostr routing with outbox retry)
Building
Requires Android Studio and the Android SDK (API 26+).
git clone https://github.com/permissionlesstech/bitchat-android.git
cd bitchat-android
./gradlew assembleDebug
Install on a connected device:
adb install -r app/build/outputs/apk/debug/app-debug.apk
The app requests Bluetooth, location (required for BLE scanning), and notification permissions at runtime.
Release APKs and the Android App Bundle can be rebuilt byte-for-byte in the pinned Linux container. Maintainers should follow the Android release guide. See Reproducible builds for the build trust model and public GitHub/Google Play verification procedures.
Testing
# Unit tests
./gradlew test
# Lint
./gradlew lint
# Instrumented tests (requires a device or emulator)
./gradlew connectedAndroidTest
Note that BLE mesh behavior is difficult to emulate; protocol and session logic is covered by unit tests, while radio-level behavior needs real devices.