fix: harden node bridge keepalive

apps/macos/Sources/Clawdbot/NodeMode/MacNodeBridgeSession.swift

@@ -1,6 +1,7 @@
 import ClawdbotKit
 import Foundation
 import Network
+import OSLog
 
 actor MacNodeBridgeSession {
     private struct TimeoutError: LocalizedError {
@@ -15,8 +16,10 @@ actor MacNodeBridgeSession {
         case failed(message: String)
     }
 
+    private let logger = Logger(subsystem: "com.clawdbot", category: "node.bridge-session")
     private let encoder = JSONEncoder()
     private let decoder = JSONDecoder()
+    private let clock = ContinuousClock()
 
     private var connection: NWConnection?
     private var queue: DispatchQueue?
@@ -24,8 +27,7 @@ actor MacNodeBridgeSession {
     private var pendingRPC: [String: CheckedContinuation<BridgeRPCResponse, Error>] = [:]
     private var serverEventSubscribers: [UUID: AsyncStream<BridgeEventFrame>.Continuation] = [:]
     private var pingTask: Task<Void, Never>?
-    private var lastPongAt: Date?
-    private var lastPingId: String?
+    private var lastPongAt: ContinuousClock.Instant?
 
     private(set) var state: State = .idle
 
@@ -41,6 +43,12 @@ actor MacNodeBridgeSession {
 
         let params = NWParameters.tcp
         params.includePeerToPeer = true
+        let tcpOptions = NWProtocolTCP.Options()
+        tcpOptions.enableKeepalive = true
+        tcpOptions.keepaliveIdle = 30
+        tcpOptions.keepaliveInterval = 15
+        tcpOptions.keepaliveCount = 3
+        params.defaultProtocolStack.transportProtocol = tcpOptions
         let connection = NWConnection(to: endpoint, using: params)
         let queue = DispatchQueue(label: "com.clawdbot.macos.bridge-session")
         self.connection = connection
@@ -50,6 +58,10 @@ actor MacNodeBridgeSession {
         connection.start(queue: queue)
 
         try await Self.waitForReady(stateStream, timeoutSeconds: 6)
+        connection.stateUpdateHandler = { [weak self] state in
+            guard let self else { return }
+            Task { await self.handleConnectionState(state) }
+        }
 
         try await AsyncTimeout.withTimeout(
             seconds: 6,
@@ -193,7 +205,6 @@ actor MacNodeBridgeSession {
         self.pingTask?.cancel()
         self.pingTask = nil
         self.lastPongAt = nil
-        self.lastPingId = nil
 
         self.connection?.cancel()
         self.connection = nil
@@ -300,7 +311,7 @@ actor MacNodeBridgeSession {
 
     private func startPingLoop() {
         self.pingTask?.cancel()
-        self.lastPongAt = Date()
+        self.lastPongAt = self.clock.now
         self.pingTask = Task { [weak self] in
             guard let self else { return }
             await self.runPingLoop()
@@ -308,30 +319,29 @@ actor MacNodeBridgeSession {
     }
 
     private func runPingLoop() async {
-        let intervalSeconds = 15.0
-        let timeoutSeconds = 45.0
+        let interval: Duration = .seconds(15)
+        let timeout: Duration = .seconds(45)
 
         while !Task.isCancelled {
-            do {
-                try await Task.sleep(nanoseconds: UInt64(intervalSeconds * 1_000_000_000))
-            } catch {
-                return
-            }
+            try? await Task.sleep(for: interval)
 
             guard self.connection != nil else { return }
 
-            if let last = self.lastPongAt,
-               Date().timeIntervalSince(last) > timeoutSeconds
-            {
-                await self.disconnect()
-                return
+            if let last = self.lastPongAt {
+                let now = self.clock.now
+                if now > last.advanced(by: timeout) {
+                    let age = last.duration(to: now)
+                    self.logger.warning("Node bridge heartbeat timed out; disconnecting (age: \(String(describing: age), privacy: .public)).")
+                    await self.disconnect()
+                    return
+                }
             }
 
             let id = UUID().uuidString
-            self.lastPingId = id
             do {
                 try await self.send(BridgePing(type: "ping", id: id))
             } catch {
+                self.logger.warning("Node bridge ping send failed; disconnecting (error: \(String(describing: error), privacy: .public)).")
                 await self.disconnect()
                 return
             }
@@ -340,7 +350,20 @@ actor MacNodeBridgeSession {
 
     private func notePong(_ pong: BridgePong) {
         _ = pong
-        self.lastPongAt = Date()
+        self.lastPongAt = self.clock.now
+    }
+
+    private func handleConnectionState(_ state: NWConnection.State) async {
+        switch state {
+        case let .failed(error):
+            self.logger.warning("Node bridge connection failed; disconnecting (error: \(String(describing: error), privacy: .public)).")
+            await self.disconnect()
+        case .cancelled:
+            self.logger.warning("Node bridge connection cancelled; disconnecting.")
+            await self.disconnect()
+        default:
+            break
+        }
     }
 
     private static func makeStateStream(