Sample BLE notification backpressure logs

The enqueue/drain/still-full logs fire per fragment during media
transfers (~150 lines for one 35KB image in field captures). They now
sample first + every 25th with a running event count, the sent/pending
lines merge into one, and the redundant peripheral-ready line is gone -
same treatment the relay event logs received. The drop-after-exhaustion
error stays unsampled.

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

bitchat/Services/BLE/BLEService.swift

@@ -91,6 +91,10 @@ final class BLEService: NSObject {
     private var pendingNoiseSessionQueues = BLENoiseSessionQueues()
     // Queue for notifications that failed due to full queue
     private var pendingNotifications = BLEOutboundNotificationBuffer<CBCentral>()
+    // Backpressure logging fires per fragment during media transfers
+    // (hundreds of lines per image); sampled via this counter, which is
+    // only touched inside collectionsQueue barriers (no sync needed).
+    var notificationBackpressureLogCount = 0
 
     // Accumulate long write chunks per central until a full frame decodes
     private var pendingWriteBuffers = BLEInboundWriteBuffer()
@@ -924,7 +928,7 @@ final class BLEService: NSObject {
             )
 
             if case let .enqueued(count) = result {
-                SecureLogger.debug("📋 Queued \(context) packet for retry (pending=\(count))", category: .session)
+                self.logBackpressureSampled("📋 Queued \(context) packet for retry (pending=\(count))")
                 return
             }
 
@@ -2045,11 +2049,17 @@ extension BLEService: CBPeripheralManagerDelegate {
     }
     
     func peripheralManagerIsReady(toUpdateSubscribers peripheral: CBPeripheralManager) {
-        SecureLogger.debug("📤 Peripheral manager ready to send more notifications", category: .session)
-
         drainPendingNotifications(logPrefix: "✅ Sent")
     }
 
+    private func logBackpressureSampled(_ message: @autoclosure () -> String) {
+        notificationBackpressureLogCount += 1
+        if notificationBackpressureLogCount == 1 ||
+            notificationBackpressureLogCount.isMultiple(of: TransportConfig.bleBackpressureLogInterval) {
+            SecureLogger.debug("\(message()) [backpressure event #\(notificationBackpressureLogCount)]", category: .session)
+        }
+    }
+
     private func drainPendingNotifications(logPrefix: String) {
         collectionsQueue.async(flags: .barrier) { [weak self] in
             guard let self = self,
@@ -2060,11 +2070,7 @@ extension BLEService: CBPeripheralManagerDelegate {
             let sentCount = self.sendPendingNotifications(pending, characteristic: characteristic)
 
             if sentCount > 0 {
-                SecureLogger.debug("\(logPrefix) \(sentCount) pending notifications from retry queue", category: .session)
+                self.logBackpressureSampled("\(logPrefix) \(sentCount) pending notifications from retry queue (\(self.pendingNotifications.count) still pending)")
-            }
-
-            if !self.pendingNotifications.isEmpty {
-                SecureLogger.debug("📋 Still have \(self.pendingNotifications.count) pending notifications", category: .session)
             }
         }
     }
@@ -2082,7 +2088,7 @@ extension BLEService: CBPeripheralManagerDelegate {
             guard success else {
                 let remaining = Array(pending.dropFirst(index))
                 pendingNotifications.prepend(remaining)
-                SecureLogger.debug("⚠️ Notification queue still full after \(sentCount) sent, re-queuing \(remaining.count) items", category: .session)
+                logBackpressureSampled("⚠️ Notification queue still full after \(sentCount) sent, re-queuing \(remaining.count) items")
                 break
             }
 

bitchat/Services/TransportConfig.swift

@@ -41,6 +41,9 @@ enum TransportConfig {
     static let blePendingNotificationsCapCount: Int = 128
     static let bleNotificationRetryDelayMs: Int = 25
     static let bleNotificationRetryMaxAttempts: Int = 80
+    // Sample interval for notification backpressure logs (fire per fragment
+    // during media transfers).
+    static let bleBackpressureLogInterval: Int = 25
 
     // Nostr
     static let nostrReadAckInterval: TimeInterval = 0.35 // ~3 per second