Split ChatNostrCoordinator into owned components along domain boundaries

The 1,109-line coordinator becomes a 187-line facade wiring three
components, each with its own narrow context protocol:
GeohashSubscriptionManager (384 lines - subscription IDs + relay
lifecycle, the only NostrRelayManager toucher), NostrInboundPipeline
(490 lines - the hot event path, dedup-before-verify ordering preserved
verbatim), and GeoPresenceTracker (192 lines - teleport detection,
sampling LRU, notification cooldowns, now directly tested).

Perf baselines confirm the hot path is unchanged: fresh events
2,131 -> 2,138/sec, duplicates ~1.41M/sec.

Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>

bitchat/ViewModels/GeoPresenceTracker.swift

@@ -0,0 +1,192 @@
+import BitFoundation
+import BitLogger
+import Foundation
+import SwiftUI
+
+/// The narrow surface `GeoPresenceTracker` needs from its owner.
+///
+/// Split out of `ChatNostrContext`: member names are shared with the sibling
+/// component contexts so `ChatViewModel` provides a single witness for each.
+@MainActor
+protocol GeoPresenceContext: AnyObject {
+    var activeChannel: ChannelID { get }
+    /// Per-geohash notification cooldown: geohash -> last notify time.
+    var lastGeoNotificationAt: [String: Date] { get set }
+    var geoNicknames: [String: String] { get }
+    var teleportedGeoCount: Int { get }
+
+    func deriveNostrIdentity(forGeohash geohash: String) throws -> NostrIdentity
+    func isNostrBlocked(pubkeyHexLowercased: String) -> Bool
+    func parseMentions(from content: String) -> [String]
+
+    func recordGeoParticipant(pubkeyHex: String, geohash: String)
+    func geoParticipantCount(for geohash: String) -> Int
+    func markGeoTeleported(_ pubkeyHexLowercased: String)
+
+    func appendGeohashMessageIfAbsent(_ message: BitchatMessage, toGeohash geohash: String) -> Bool
+    func synchronizePublicConversationStore(forGeohash geohash: String)
+}
+
+extension ChatViewModel: GeoPresenceContext {
+    // `activeChannel`, `lastGeoNotificationAt`, `geoNicknames`, the Nostr
+    // identity/blocking members, and `synchronizePublicConversationStore`
+    // already have witnesses on `ChatViewModel`. The members below flatten
+    // nested service accesses into intent-named calls.
+
+    func appendGeohashMessageIfAbsent(_ message: BitchatMessage, toGeohash geohash: String) -> Bool {
+        timelineStore.appendIfAbsent(message, toGeohash: geohash)
+    }
+
+    var teleportedGeoCount: Int {
+        locationPresenceStore.teleportedGeo.count
+    }
+
+    func recordGeoParticipant(pubkeyHex: String, geohash: String) {
+        participantTracker.recordParticipant(pubkeyHex: pubkeyHex, geohash: geohash)
+    }
+
+    func geoParticipantCount(for geohash: String) -> Int {
+        participantTracker.participantCount(for: geohash)
+    }
+
+    func markGeoTeleported(_ pubkeyHexLowercased: String) {
+        locationPresenceStore.markTeleported(pubkeyHexLowercased)
+    }
+}
+
+/// Geohash presence bookkeeping that is independent of relay subscriptions:
+/// teleport-tag detection and marking, the sampling-event LRU dedup, and the
+/// per-geohash notification cooldown for sampled activity.
+final class GeoPresenceTracker {
+    private weak var context: (any GeoPresenceContext)?
+    private var recentGeoSamplingEventIDs = Set<String>()
+    private var recentGeoSamplingEventIDOrder: [String] = []
+
+    init(context: any GeoPresenceContext) {
+        self.context = context
+    }
+
+    /// True when the event carries a `["t", "teleport"]` tag.
+    static func hasTeleportTag(_ event: NostrEvent) -> Bool {
+        event.tags.contains { tag in
+            tag.count >= 2 && tag[0].lowercased() == "t" && tag[1].lowercased() == "teleport"
+        }
+    }
+
+    /// Marks a peer teleported on a follow-up main-actor hop (keeps the
+    /// inbound hot path free of presence-store writes).
+    @MainActor
+    func scheduleMarkPeerTeleported(_ key: String, logged: Bool) {
+        Task { @MainActor [weak context] in
+            guard let context else { return }
+            context.markGeoTeleported(key)
+            if logged {
+                SecureLogger.info(
+                    "GeoTeleport: mark peer teleported key=\(key.prefix(8))… total=\(context.teleportedGeoCount)",
+                    category: .session
+                )
+            }
+        }
+    }
+
+    @MainActor
+    func subscribeNostrEvent(_ event: NostrEvent, gh: String) {
+        guard let context else { return }
+        guard (event.kind == NostrProtocol.EventKind.ephemeralEvent.rawValue
+            || event.kind == NostrProtocol.EventKind.geohashPresence.rawValue)
+        else {
+            return
+        }
+        guard event.isValidSignature() else { return }
+        guard shouldProcessGeoSamplingEvent(event.id) else { return }
+
+        let existingCount = context.geoParticipantCount(for: gh)
+        context.recordGeoParticipant(pubkeyHex: event.pubkey, geohash: gh)
+
+        guard let content = event.content.trimmedOrNilIfEmpty else { return }
+        if context.isNostrBlocked(pubkeyHexLowercased: event.pubkey.lowercased()) { return }
+        if let my = try? context.deriveNostrIdentity(forGeohash: gh),
+           my.publicKeyHex.lowercased() == event.pubkey.lowercased() {
+            return
+        }
+        guard existingCount == 0 else { return }
+
+        let eventTime = Date(timeIntervalSince1970: TimeInterval(event.created_at))
+        if Date().timeIntervalSince(eventTime) > 30 { return }
+
+        #if os(iOS)
+        guard UIApplication.shared.applicationState == .active else { return }
+        if case .location(let channel) = context.activeChannel, channel.geohash == gh { return }
+        #elseif os(macOS)
+        guard NSApplication.shared.isActive else { return }
+        if case .location(let channel) = context.activeChannel, channel.geohash == gh { return }
+        #endif
+
+        cooldownPerGeohash(gh, content: content, event: event)
+    }
+
+    @MainActor
+    func cooldownPerGeohash(_ gh: String, content: String, event: NostrEvent) {
+        guard let context else { return }
+        let now = Date()
+        let last = context.lastGeoNotificationAt[gh] ?? .distantPast
+        if now.timeIntervalSince(last) < TransportConfig.uiGeoNotifyCooldownSeconds { return }
+
+        let preview: String = {
+            let maxLen = TransportConfig.uiGeoNotifySnippetMaxLen
+            if content.count <= maxLen { return content }
+            let idx = content.index(content.startIndex, offsetBy: maxLen)
+            return String(content[..<idx]) + "…"
+        }()
+
+        Task { @MainActor [weak context] in
+            guard let context else { return }
+            context.lastGeoNotificationAt[gh] = now
+            let senderSuffix = String(event.pubkey.suffix(4))
+            let nick = context.geoNicknames[event.pubkey.lowercased()]
+            let senderName = (nick?.isEmpty == false ? nick! : "anon") + "#" + senderSuffix
+
+            let rawTs = Date(timeIntervalSince1970: TimeInterval(event.created_at))
+            let ts = min(rawTs, Date())
+            let mentions = context.parseMentions(from: content)
+            let message = BitchatMessage(
+                id: event.id,
+                sender: senderName,
+                content: content,
+                timestamp: ts,
+                isRelay: false,
+                senderPeerID: PeerID(nostr: event.pubkey),
+                mentions: mentions.isEmpty ? nil : mentions
+            )
+            if context.appendGeohashMessageIfAbsent(message, toGeohash: gh) {
+                context.synchronizePublicConversationStore(forGeohash: gh)
+                NotificationService.shared.sendGeohashActivityNotification(geohash: gh, bodyPreview: preview)
+            }
+        }
+    }
+
+    /// First-seen check for sampled geohash events with LRU eviction so the
+    /// dedup set stays bounded across long sampling sessions.
+    func shouldProcessGeoSamplingEvent(_ eventID: String) -> Bool {
+        guard !eventID.isEmpty else { return true }
+        guard recentGeoSamplingEventIDs.insert(eventID).inserted else {
+            return false
+        }
+        recentGeoSamplingEventIDOrder.append(eventID)
+
+        let cap = TransportConfig.geoSamplingEventLRUCap
+        if recentGeoSamplingEventIDOrder.count > cap {
+            let removeCount = recentGeoSamplingEventIDOrder.count - cap
+            for staleID in recentGeoSamplingEventIDOrder.prefix(removeCount) {
+                recentGeoSamplingEventIDs.remove(staleID)
+            }
+            recentGeoSamplingEventIDOrder.removeFirst(removeCount)
+        }
+        return true
+    }
+
+    func clearGeoSamplingEventDedup() {
+        recentGeoSamplingEventIDs.removeAll()
+        recentGeoSamplingEventIDOrder.removeAll()
+    }
+}