Geohash Bookmarks + Rising‑Edge Notifications + Friendly Names (#538)

* Add geohash bookmarks: persistence, sampling integration, and UI\n\n- Add GeohashBookmarksStore with UserDefaults persistence and toggle API\n- Sample union of regional + bookmarked geohashes for activity notifications\n- LocationChannelsSheet: bookmark icons on nearby rows and a Bookmarked section\n- Header toolbar: toggle bookmark for current geohash\n- Tests: GeohashBookmarksStoreTests for normalization and persistence\n\nRationale: Bookmarked geohashes are always sampled for new activity notifications and quickly selectable from the sheet.

* Notifications: remove background 'new chats!' nudge; geohash activity only on zero→alive; mesh 'nearby' only on zero→alive\n\n- Geohash sampling: notify only when previous participant count in last 5m was zero, with 30s freshness gate\n- Suppress old sampled events after (re)subscribe\n- Remove channel inactivity nudge\n- Mesh: reset rising-edge gate immediately when peer list goes empty (strict zero→alive)

* Geohash notifications: ensure triggering message appears\n\n- On zero→alive sampling, pre-populate geoTimelines[gh] with the triggering message\n- Dedup on per-geohash timeline and UI messages by message ID to avoid duplicates after subscribe\n- Keeps participant update, block/self checks, and cooldown intact

---------

Co-authored-by: jack <jackjackbits@users.noreply.github.com>

bitchat/Services/GeohashBookmarksStore.swift

@@ -0,0 +1,227 @@
+import Foundation
+import Combine
+#if os(iOS) || os(macOS)
+import CoreLocation
+#endif
+
+/// Stores a user-maintained list of bookmarked geohash channels.
+/// - Persistence: UserDefaults (JSON string array)
+/// - Semantics: geohashes are normalized to lowercase base32 and de-duplicated
+final class GeohashBookmarksStore: ObservableObject {
+    static let shared = GeohashBookmarksStore()
+
+    @Published private(set) var bookmarks: [String] = []
+    @Published private(set) var bookmarkNames: [String: String] = [:] // geohash -> friendly name
+
+    private let storeKey = "locationChannel.bookmarks"
+    private let namesStoreKey = "locationChannel.bookmarkNames"
+    private var membership: Set<String> = []
+    #if os(iOS) || os(macOS)
+    private let geocoder = CLGeocoder()
+    private var resolving: Set<String> = []
+    #endif
+
+    private init() {
+        load()
+    }
+
+    // MARK: - Public API
+    func isBookmarked(_ geohash: String) -> Bool {
+        return membership.contains(Self.normalize(geohash))
+    }
+
+    func toggle(_ geohash: String) {
+        let gh = Self.normalize(geohash)
+        if membership.contains(gh) {
+            remove(gh)
+        } else {
+            add(gh)
+        }
+    }
+
+    func add(_ geohash: String) {
+        let gh = Self.normalize(geohash)
+        guard !gh.isEmpty else { return }
+        guard !membership.contains(gh) else { return }
+        bookmarks.insert(gh, at: 0)
+        membership.insert(gh)
+        persist()
+        // Resolve and persist a friendly name once when added
+        resolveNameIfNeeded(for: gh)
+    }
+
+    func remove(_ geohash: String) {
+        let gh = Self.normalize(geohash)
+        guard membership.contains(gh) else { return }
+        if let idx = bookmarks.firstIndex(of: gh) { bookmarks.remove(at: idx) }
+        membership.remove(gh)
+        // Clean up stored name to avoid stale cache growth
+        if bookmarkNames.removeValue(forKey: gh) != nil {
+            persistNames()
+        }
+        persist()
+    }
+
+    // MARK: - Persistence
+    private func load() {
+        guard let data = UserDefaults.standard.data(forKey: storeKey) else { return }
+        if let arr = try? JSONDecoder().decode([String].self, from: data) {
+            // Sanitize, normalize, dedupe while preserving order (first occurrence wins)
+            var seen = Set<String>()
+            var list: [String] = []
+            for raw in arr {
+                let gh = Self.normalize(raw)
+                guard !gh.isEmpty else { continue }
+                if !seen.contains(gh) {
+                    seen.insert(gh)
+                    list.append(gh)
+                }
+            }
+            bookmarks = list
+            membership = seen
+        }
+        // Load any saved names
+        if let namesData = UserDefaults.standard.data(forKey: namesStoreKey),
+           let dict = try? JSONDecoder().decode([String: String].self, from: namesData) {
+            bookmarkNames = dict
+        }
+    }
+
+    private func persist() {
+        if let data = try? JSONEncoder().encode(bookmarks) {
+            UserDefaults.standard.set(data, forKey: storeKey)
+        }
+    }
+
+    private func persistNames() {
+        if let data = try? JSONEncoder().encode(bookmarkNames) {
+            UserDefaults.standard.set(data, forKey: namesStoreKey)
+        }
+    }
+
+    // MARK: - Helpers
+    private static func normalize(_ s: String) -> String {
+        let allowed = Set("0123456789bcdefghjkmnpqrstuvwxyz")
+        return s
+            .trimmingCharacters(in: .whitespacesAndNewlines)
+            .lowercased()
+            .replacingOccurrences(of: "#", with: "")
+            .filter { allowed.contains($0) }
+    }
+
+    // MARK: - Name Resolution
+    /// Attempt to resolve and persist a friendly place name for a bookmarked geohash.
+    func resolveNameIfNeeded(for geohash: String) {
+        let gh = Self.normalize(geohash)
+        guard !gh.isEmpty else { return }
+        if bookmarkNames[gh] != nil { return }
+        #if os(iOS) || os(macOS)
+        if resolving.contains(gh) { return }
+        resolving.insert(gh)
+        // For very coarse geohashes, sample multiple points to capture multiple admin areas
+        if gh.count <= 2 {
+            let b = Geohash.decodeBounds(gh)
+            let pts: [CLLocation] = [
+                CLLocation(latitude: (b.latMin + b.latMax) / 2, longitude: (b.lonMin + b.lonMax) / 2), // center
+                CLLocation(latitude: b.latMin, longitude: b.lonMin),
+                CLLocation(latitude: b.latMin, longitude: b.lonMax),
+                CLLocation(latitude: b.latMax, longitude: b.lonMin),
+                CLLocation(latitude: b.latMax, longitude: b.lonMax)
+            ]
+            resolveCompositeAdminName(geohash: gh, points: pts)
+        } else {
+            let center = Geohash.decodeCenter(gh)
+            let loc = CLLocation(latitude: center.lat, longitude: center.lon)
+            geocoder.reverseGeocodeLocation(loc) { [weak self] placemarks, _ in
+                guard let self = self else { return }
+                defer { self.resolving.remove(gh) }
+                if let pm = placemarks?.first {
+                    let name = Self.nameForGeohashLength(gh.count, from: pm)
+                    if let name = name, !name.isEmpty {
+                        DispatchQueue.main.async {
+                            self.bookmarkNames[gh] = name
+                            self.persistNames()
+                        }
+                    }
+                }
+            }
+        }
+        #endif
+    }
+
+    #if os(iOS) || os(macOS)
+    private func resolveCompositeAdminName(geohash gh: String, points: [CLLocation]) {
+        var uniqueAdmins = OrderedSet<String>()
+        var idx = 0
+        func step() {
+            if idx >= points.count {
+                // Compose up to 2 names joined by ' and '
+                let finalName: String? = {
+                    let names = uniqueAdmins.array
+                    if names.count >= 2 { return names[0] + " and " + names[1] }
+                    return names.first
+                }()
+                if let finalName = finalName, !finalName.isEmpty {
+                    DispatchQueue.main.async {
+                        self.bookmarkNames[gh] = finalName
+                        self.persistNames()
+                    }
+                }
+                self.resolving.remove(gh)
+                return
+            }
+            let loc = points[idx]
+            idx += 1
+            geocoder.reverseGeocodeLocation(loc) { [weak self] placemarks, _ in
+                guard self != nil else { return }
+                if let pm = placemarks?.first {
+                    if let admin = pm.administrativeArea, !admin.isEmpty {
+                        uniqueAdmins.insert(admin)
+                    } else if let country = pm.country, !country.isEmpty {
+                        uniqueAdmins.insert(country)
+                    }
+                }
+                // Proceed to next point
+                step()
+            }
+        }
+        step()
+    }
+
+    // Minimal ordered-set for stable joining
+    private struct OrderedSet<Element: Hashable> {
+        private var set: Set<Element> = []
+        private(set) var array: [Element] = []
+        mutating func insert(_ element: Element) {
+            if set.insert(element).inserted { array.append(element) }
+        }
+    }
+
+    private static func nameForGeohashLength(_ len: Int, from pm: CLPlacemark) -> String? {
+        switch len {
+        case 0...2:
+            // Prefer administrative area if available at this coarse level
+            return pm.administrativeArea ?? pm.country
+        case 3...4:
+            return pm.administrativeArea ?? pm.subAdministrativeArea ?? pm.country
+        case 5:
+            return pm.locality ?? pm.subAdministrativeArea ?? pm.administrativeArea
+        case 6...7:
+            return pm.subLocality ?? pm.locality ?? pm.administrativeArea
+        default:
+            return pm.subLocality ?? pm.locality ?? pm.administrativeArea ?? pm.country
+        }
+    }
+    #endif
+
+    #if DEBUG
+    /// Testing-only reset helper
+    func _resetForTesting() {
+        bookmarks.removeAll()
+        membership.removeAll()
+        bookmarkNames.removeAll()
+        persist()
+        persistNames()
+    }
+    #endif
+}