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* Reconnect hygiene: paced acks, persistent gift-wrap dedup, self-fragment sync fix
Remaining findings from the July 7 locked-phone test sessions, all rooted
in reconnect/relaunch behavior:
- All Nostr acks (READ and DELIVERED, direct and geohash) now flow through
the paced queue that previously only throttled direct READ receipts.
Reconnect redelivery produced 8 DELIVERED acks in under a second, which
damus rejects ("noting too much").
- Processed gift-wrap event IDs persist across launches
(NostrProcessedEventStore, wired through MessageDeduplicationService,
debounced writes, wiped on the existing clear/panic paths). NIP-59
randomizes gift-wrap timestamps, so the 24h-lookback DM subscriptions
redeliver the same events every launch; without a cross-launch record
each relaunch reprocessed old PMs and acks — the re-ack bursts and the
"delivered ack for unknown mid" warnings (now debug: a stale ack is
expected occasionally and not actionable).
- Own fragments handed back by sync replay (the deliberate RSR ttl=0
restore path) now re-enter the gossip sync store before the self-drop.
The fragment store is not archived, so after a relaunch our sync filter
did not cover our own fragments and peers re-offered them every 30s
round indefinitely; recording them stops the redelivery after one round
while keeping assembly skipped.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
* Address Codex review on #1398: shared ack pacer, transient clears keep disk record
- Geohash acks are sent through short-lived NostrTransport instances
(makeGeohashNostrTransport creates one per ack), so the per-instance ack
queue never paced a burst. Acks now flow through a pacer shared across
instances: Dependencies.live wires the process-wide sharedAckPacer, and
the default Dependencies init builds an isolated pacer from the same
injected scheduleAfter so tests keep stepping the throttle manually.
- clearNostrCaches() runs on every geohash channel switch, so it no longer
wipes the persisted gift-wrap record (that stays on the clearAll/panic
path). Persistence is now append-merge instead of snapshot-overwrite —
serialized on the store's IO queue — so a transient in-memory clear
between debounced flushes can't shrink the on-disk record either.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
---------
Co-authored-by: jack <jackjackbits@users.noreply.github.com>
Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
bitchat
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. It's the side-groupchat.
License
This project is released into the public domain. See the LICENSE file for details.
Features
- Dual Transport Architecture: Bluetooth mesh for offline + Nostr protocol for internet-based messaging
- Location-Based Channels: Geographic chat rooms using geohash coordinates over global Nostr relays
- Intelligent Message Routing: Automatically chooses best transport (Bluetooth → Nostr fallback)
- Decentralized Mesh Network: Automatic peer discovery and multi-hop message relay over Bluetooth LE
- Privacy First: No accounts, no phone numbers, no persistent identifiers
- Private Message End-to-End Encryption: Noise Protocol for mesh, NIP-17 for Nostr
- IRC-Style Commands: Familiar
/slap,/msg,/whostyle interface - Universal App: Native support for iOS and macOS
- Emergency Wipe: Triple-tap to instantly clear all data
- Performance Optimizations: LZ4 message compression, adaptive battery modes, and optimized networking
Technical Architecture
BitChat uses a hybrid messaging architecture with two complementary transport layers:
Bluetooth Mesh Network (Offline)
- Local Communication: Direct peer-to-peer within Bluetooth range
- Multi-hop Relay: Messages route through nearby devices (max 7 hops)
- No Internet Required: Works completely offline in disaster scenarios
- Noise Protocol Encryption: End-to-end encryption with forward secrecy
- Binary Protocol: Compact packet format optimized for Bluetooth LE constraints
- Automatic Discovery: Peer discovery and connection management
- Adaptive Power: Battery-optimized duty cycling
Nostr Protocol (Internet)
- Global Reach: Connect with users worldwide via internet relays
- Location Channels: Geographic chat rooms using geohash coordinates
- 290+ Relay Network: Distributed across the globe for reliability
- NIP-17 Encryption: Gift-wrapped private messages for internet privacy
- Ephemeral Keys: Fresh cryptographic identity per geohash area
Channel Types
mesh #bluetooth
- Transport: Bluetooth Low Energy mesh network
- Scope: Local devices within multi-hop range
- Internet: Not required
- Use Case: Offline communication, protests, disasters, remote areas
Location Channels (block #dr5rsj7, neighborhood #dr5rs, country #dr)
- Transport: Nostr protocol over internet
- Scope: Geographic areas defined by geohash precision
block(7 chars): City block levelneighborhood(6 chars): District/neighborhoodcity(5 chars): City levelprovince(4 chars): State/provinceregion(2 chars): Country/large region
- Internet: Required (connects to Nostr relays)
- Use Case: Location-based community chat, local events, regional discussions
Direct Message Routing
Private messages use intelligent transport selection:
-
Bluetooth First (preferred when available)
- Direct connection with established Noise session
- Fastest and most private option
-
Nostr Fallback (when Bluetooth unavailable)
- Uses recipient's Nostr public key
- NIP-17 gift-wrapping for privacy
- Routes through global relay network
-
Smart Queuing (when neither available)
- Messages queued until transport becomes available
- Automatic delivery when connection established
For detailed protocol documentation, see the Technical Whitepaper.
Setup
Option 1: Using Xcode
cd bitchat
open bitchat.xcodeproj
To run on a device there're a few steps to prepare the code:
- Clone the local configs:
cp Configs/Local.xcconfig.example Configs/Local.xcconfig - Add your Developer Team ID into the newly created
Configs/Local.xcconfig- Bundle ID would be set to
chat.bitchat.<team_id>(unless you set to something else)
- Bundle ID would be set to
- Entitlements need to be updated manually (TODO: Automate):
- Search and replace
group.chat.bitchatwithgroup.<your_bundle_id>(e.g.group.chat.bitchat.ABC123)
- Search and replace
Option 2: Using just
brew install just
Want to try this on macos: just run will set it up and run from source.
Run just clean afterwards to restore things to original state for mobile app building and development.
Localization
- Base app resources live under
bitchat/Localization/Base.lproj/. Add new copy toLocalizable.stringsand plural rules toLocalizable.stringsdict. - Share extension strings are separate in
bitchatShareExtension/Localization/Base.lproj/Localizable.strings. - Prefer keys that describe intent (
app_info.features.offline.title) and reuse existing ones where possible. - Run
xcodebuild -project bitchat.xcodeproj -scheme "bitchat (macOS)" -configuration Debug CODE_SIGNING_ALLOWED=NO buildto compile-check any localization updates.