Merge branch 'main' into source-routing-packet-format

bitchat/Services/GeohashParticipantTracker.swift

@@ -83,6 +83,9 @@ public final class GeohashParticipantTracker: ObservableObject {
         var map = participants[geohash] ?? [:]
         map[key] = Date()
         participants[geohash] = map
+        
+        // Always notify observers that state has changed so counts in UI update
+        objectWillChange.send()
 
         // Only refresh visible list if this geohash is currently active
         if activeGeohash == geohash {

bitchat/Services/GeohashPresenceService.swift

@@ -0,0 +1,171 @@
+//
+// GeohashPresenceService.swift
+// bitchat
+//
+// Manages the broadcasting of ephemeral presence heartbeats (Kind 20001)
+// to geohash location channels.
+//
+// This is free and unencumbered software released into the public domain.
+//
+
+import Foundation
+import Combine
+import BitLogger
+import Tor
+
+/// Service that coordinates the broadcasting of presence heartbeats.
+///
+/// Behavior:
+/// - Monitors location changes via LocationStateManager
+/// - Broadcasts Kind 20001 events to low-precision geohash channels
+/// - Uses randomized timing (40-80s loop) and decorrelated bursts
+/// - Respects privacy by NOT broadcasting to Neighborhood/Block/Building levels
+@MainActor
+final class GeohashPresenceService: ObservableObject {
+    static let shared = GeohashPresenceService()
+
+    private var subscriptions = Set<AnyCancellable>()
+    private var heartbeatTimer: Timer?
+    private let idBridge = NostrIdentityBridge()
+    
+    // MARK: - Constants
+
+    // Loop interval range in seconds
+    private let loopMinInterval: TimeInterval = 40.0
+    private let loopMaxInterval: TimeInterval = 80.0
+    
+    // Per-broadcast decorrelation delay range in seconds
+    private let burstMinDelay: TimeInterval = 2.0
+    private let burstMaxDelay: TimeInterval = 5.0
+
+    // Privacy: Only broadcast to these levels
+    private let allowedPrecisions: Set<Int> = [
+        GeohashChannelLevel.region.precision,    // 2
+        GeohashChannelLevel.province.precision,  // 4
+        GeohashChannelLevel.city.precision       // 5
+    ]
+
+    private init() {
+        setupObservers()
+    }
+    
+    /// Start the service (safe to call multiple times)
+    func start() {
+        SecureLogger.info("Presence: service starting...", category: .session)
+        scheduleNextHeartbeat()
+    }
+
+    private func setupObservers() {
+        // Monitor location channel changes
+        LocationStateManager.shared.$availableChannels
+            .dropFirst()
+            .sink { [weak self] _ in
+                self?.handleLocationChange()
+            }
+            .store(in: &subscriptions)
+
+        // Monitor Tor readiness to kick off heartbeat if it was stalled
+        NotificationCenter.default.publisher(for: .TorDidBecomeReady)
+            .sink { [weak self] _ in
+                self?.handleConnectivityChange()
+            }
+            .store(in: &subscriptions)
+    }
+
+    private func handleLocationChange() {
+        // When location changes, we trigger an immediate (but slightly delayed) heartbeat
+        // to announce presence in the new zone, then reset the loop.
+        SecureLogger.debug("Presence: location changed, scheduling update", category: .session)
+        heartbeatTimer?.invalidate()
+        
+        // Small delay to allow location state to settle
+        heartbeatTimer = Timer.scheduledTimer(withTimeInterval: 5.0, repeats: false) { [weak self] _ in
+            Task { @MainActor [weak self] in
+                self?.performHeartbeat()
+            }
+        }
+    }
+    
+    private func handleConnectivityChange() {
+        SecureLogger.debug("Presence: connectivity restored, triggering heartbeat", category: .session)
+        // If we were waiting for network, do it now
+        if heartbeatTimer == nil || !heartbeatTimer!.isValid {
+            scheduleNextHeartbeat()
+        }
+    }
+
+    private func scheduleNextHeartbeat() {
+        heartbeatTimer?.invalidate()
+        let interval = TimeInterval.random(in: loopMinInterval...loopMaxInterval)
+        heartbeatTimer = Timer.scheduledTimer(withTimeInterval: interval, repeats: false) { [weak self] _ in
+            Task { @MainActor [weak self] in
+                self?.performHeartbeat()
+            }
+        }
+    }
+
+    private func performHeartbeat() {
+        // Always schedule next loop first ensures continuity even if this one fails/skips
+        defer { scheduleNextHeartbeat() }
+
+        // 1. Check preconditions
+        guard TorManager.shared.isReady else {
+            SecureLogger.debug("Presence: skipping heartbeat (Tor not ready)", category: .session)
+            return
+        }
+        
+        // App must be active (or at least we shouldn't broadcast if in background, usually)
+        if !TorManager.shared.isForeground() {
+            return
+        }
+
+        // 2. Get channels
+        let channels = LocationStateManager.shared.availableChannels
+        guard !channels.isEmpty else { return }
+
+        // 3. Filter and broadcast
+        // We use Task + sleep for decorrelation to allow the main runloop to proceed
+        for channel in channels {
+            // Check privacy restriction
+            if !self.allowedPrecisions.contains(channel.geohash.count) {
+                continue
+            }
+            
+            // Launch independent task for each channel's delay
+            Task { @MainActor in
+                // Random delay for decorrelation
+                let delay = TimeInterval.random(in: self.burstMinDelay...self.burstMaxDelay)
+                let nanoseconds = UInt64(delay * 1_000_000_000)
+                try? await Task.sleep(nanoseconds: nanoseconds)
+                
+                self.broadcastPresence(for: channel.geohash)
+            }
+        }
+    }
+
+    private func broadcastPresence(for geohash: String) {
+        do {
+            guard let identity = try? idBridge.deriveIdentity(forGeohash: geohash) else {
+                return
+            }
+            
+            let event = try NostrProtocol.createGeohashPresenceEvent(
+                geohash: geohash,
+                senderIdentity: identity
+            )
+            
+            // Send via RelayManager
+            let targetRelays = GeoRelayDirectory.shared.closestRelays(
+                toGeohash: geohash,
+                count: TransportConfig.nostrGeoRelayCount
+            )
+            
+            if !targetRelays.isEmpty {
+                NostrRelayManager.shared.sendEvent(event, to: targetRelays)
+                SecureLogger.debug("Presence: sent heartbeat for \(geohash) (pub=\(identity.publicKeyHex.prefix(6))...)", category: .session)
+            }
+        } catch {
+            SecureLogger.error("Presence: failed to create event for \(geohash): \(error)", category: .session)
+        }
+    }
+}