Фикс: дубликат CallKit вызова, disconnect recovery, WebRTC packet buffering и E2EE rebind loop

Rosetta/Core/Network/Protocol/ProtocolManager.swift

@@ -95,6 +95,10 @@ final class ProtocolManager: @unchecked Sendable {
     private var webRTCHandlers: [UUID: (PacketWebRTC) -> Void] = [:]
     private var iceServersHandlers: [UUID: (PacketIceServers) -> Void] = [:]
 
+    /// Background task to keep WebSocket alive during brief background periods (active call).
+    /// iOS gives ~30s; enough for the call to survive app switching / notification interactions.
+    private var callBackgroundTask: UIBackgroundTaskIdentifier = .invalid
+
     // Saved credentials for auto-reconnect
     private var savedPublicKey: String?
     private var savedPrivateHash: String?
@@ -185,6 +189,16 @@ final class ProtocolManager: @unchecked Sendable {
     func forceReconnectOnForeground() {
         guard savedPublicKey != nil, savedPrivateHash != nil else { return }
 
+        // During an active call the WebSocket may still be alive (background task
+        // keeps the process running for ~30s). Tearing it down would break signaling
+        // and trigger server re-delivery of .call — causing endCallBecauseBusy.
+        // If the connection is authenticated, trust it and skip reconnect.
+        if CallManager.shared.uiState.phase != .idle,
+           connectionState == .authenticated {
+            Self.logger.info("⚡ Foreground reconnect skipped — active call, WS authenticated")
+            return
+        }
+
         // Android parity: skip if handshake or device verification is in progress.
         // These are active flows that should not be interrupted.
         switch connectionState {
@@ -209,6 +223,25 @@ final class ProtocolManager: @unchecked Sendable {
         client.forceReconnect()
     }
 
+    // MARK: - Call Background Task
+
+    /// Keeps the process alive during active calls so WebSocket survives brief background.
+    func beginCallBackgroundTask() {
+        guard callBackgroundTask == .invalid else { return }
+        callBackgroundTask = UIApplication.shared.beginBackgroundTask(withName: "RosettaCall") { [weak self] in
+            self?.endCallBackgroundTask()
+        }
+        Self.logger.info("📞 Background task started for call")
+    }
+
+    func endCallBackgroundTask() {
+        guard callBackgroundTask != .invalid else { return }
+        let task = callBackgroundTask
+        callBackgroundTask = .invalid
+        UIApplication.shared.endBackgroundTask(task)
+        Self.logger.info("📞 Background task ended for call")
+    }
+
     /// Android parity: `reconnectNowIfNeeded()` — if already in an active state,
     /// skip reconnect. Otherwise reset backoff and connect immediately.
     func reconnectIfNeeded() {