chore: centralize more constants in TransportConfig (BLE thresholds, Nostr read-ack, UI caps) and adopt in BLEService/ChatViewModel/NostrTransport

bitchat/Services/BLEService.swift

@@ -1921,10 +1921,10 @@ final class BLEService: NSObject {
         }
         lastIsolatedAt = nil
         // Base threshold when connected
-        var threshold = -90
+        var threshold = TransportConfig.bleDynamicRSSIThresholdDefault
         // If we're at budget or queue is large, prefer closer peers
         let linkCount = peripherals.values.filter { $0.isConnected || $0.isConnecting }.count
-        if linkCount >= maxCentralLinks || connectionCandidates.count > 20 {
+        if linkCount >= maxCentralLinks || connectionCandidates.count > TransportConfig.bleConnectionCandidatesMax {
             threshold = -85
         }
         // If we have many recent timeouts, raise further
@@ -2666,7 +2666,7 @@ extension BLEService: CBPeripheralManagerDelegate {
                 }
             } else {
                 // If buffer grows suspiciously large, reset to avoid memory leak
-                if combined.count > 1_000_000 { // 1MB cap for safety
+                if combined.count > TransportConfig.blePendingWriteBufferCapBytes { // cap for safety
                     pendingWriteBuffers.removeValue(forKey: centralUUID)
                     SecureLogger.log("⚠️ Dropping oversized pending write buffer (\(combined.count) bytes) for central \(centralUUID)", category: SecureLogger.session, level: .warning)
                 }

bitchat/Services/NostrTransport.swift

@@ -20,7 +20,7 @@ final class NostrTransport: Transport {
     }
     private var readQueue: [QueuedRead] = []
     private var isSendingReadAcks = false
-    private let readAckInterval: TimeInterval = 0.35 // ~3 per second
+    private let readAckInterval: TimeInterval = TransportConfig.nostrReadAckInterval
 
     var myPeerID: String { senderPeerID }
     var myNickname: String { "" }

bitchat/Services/TransportConfig.swift

@@ -25,4 +25,16 @@ enum TransportConfig {
     static let bleDutyOnDuration: TimeInterval = 5.0
     static let bleDutyOffDuration: TimeInterval = 10.0
     static let bleAnnounceMinInterval: TimeInterval = 1.0
+
+    // BLE discovery/quality thresholds
+    static let bleDynamicRSSIThresholdDefault: Int = -90
+    static let bleConnectionCandidatesMax: Int = 20
+    static let blePendingWriteBufferCapBytes: Int = 1_000_000
+
+    // Nostr
+    static let nostrReadAckInterval: TimeInterval = 0.35 // ~3 per second
+
+    // UI thresholds
+    static let uiLateInsertThreshold: TimeInterval = 15.0
+    static let uiProcessedNostrEventsCap: Int = 2000
 }

bitchat/ViewModels/ChatViewModel.swift

@@ -349,7 +349,7 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
     // PeerManager replaced by UnifiedPeerService
     private var processedNostrEvents = Set<String>()  // Simple deduplication
     private var processedNostrEventOrder: [String] = []
-    private let maxProcessedNostrEvents = 2000
+    private let maxProcessedNostrEvents = TransportConfig.uiProcessedNostrEventsCap
     private let userDefaults = UserDefaults.standard
     private let nicknameKey = "bitchat.nickname"
     // Location channel state (macOS supports manual geohash selection)
@@ -432,7 +432,7 @@ class ChatViewModel: ObservableObject, BitchatDelegate {
     private var dynamicPublicFlushInterval: TimeInterval = TransportConfig.basePublicFlushInterval
     private var recentBatchSizes: [Int] = []
     @Published private(set) var isBatchingPublic: Bool = false
-    private let lateInsertThreshold: TimeInterval = 15.0
+    private let lateInsertThreshold: TimeInterval = TransportConfig.uiLateInsertThreshold
     
     // Track sent read receipts to avoid duplicates (persisted across launches)
     // Note: Persistence happens automatically in didSet, no lifecycle observers needed