Remote: Server-seitiger Heartbeat mit Timeout für tote WebSocket-Verbindungen

- Server sendet alle 30s Ping an Client, Client antwortet mit Pong
- LastActivityAt wird bei jeder empfangenen Nachricht aktualisiert
- Nach 90s Inaktivität wird Verbindung als tot erkannt und aufgeräumt
- HeartbeatLoop läuft parallel zum ReceiveLoop
- remote.ps1: ping-Handler hinzugefügt

Endpoints/RemoteEndpoint.cs

@@ -50,9 +50,20 @@ public static class RemoteEndpoint
         using var ws = await ctx.WebSockets.AcceptWebSocketAsync();
         var conn = mgr.Register(ws);
 
+        using var heartbeatCts = CancellationTokenSource.CreateLinkedTokenSource(ct);
+
         try
         {
-            await ReceiveLoop(ws, conn, mgr, ct);
+            var receiveTask = ReceiveLoop(ws, conn, mgr, heartbeatCts.Token);
+            var heartbeatTask = HeartbeatLoop(ws, conn, heartbeatCts);
+
+            // Warten bis einer von beiden endet (Receive-Fehler oder Heartbeat-Timeout)
+            await Task.WhenAny(receiveTask, heartbeatTask);
+            heartbeatCts.Cancel();
+
+            // Beide Tasks sauber abwarten
+            try { await receiveTask; } catch { }
+            try { await heartbeatTask; } catch { }
         }
         catch (WebSocketException)
         {
@@ -104,6 +115,8 @@ public static class RemoteEndpoint
             try { msg = JsonSerializer.Deserialize<JsonElement>(json); }
             catch { continue; }
 
+            conn.LastActivityAt = DateTime.UtcNow;
+
             var type = msg.TryGetProperty("type", out var tp) ? tp.GetString() : "";
 
             switch (type)
@@ -129,10 +142,54 @@ public static class RemoteEndpoint
                     var pong = Encoding.UTF8.GetBytes("{\"type\":\"pong\"}");
                     await ws.SendAsync(pong, WebSocketMessageType.Text, true, ct);
                     break;
+
+                case "pong":
+                    // Antwort auf Server-Ping → LastActivityAt ist schon gesetzt
+                    break;
             }
         }
     }
 
+    private static async Task HeartbeatLoop(WebSocket ws, RemoteConnection conn, CancellationTokenSource heartbeatCts)
+    {
+        const int pingIntervalSeconds = 30;
+        const int deadTimeoutSeconds = 90;
+        var pingBytes = Encoding.UTF8.GetBytes("{\"type\":\"ping\"}");
+
+        try
+        {
+            while (!heartbeatCts.IsCancellationRequested && ws.State == WebSocketState.Open)
+            {
+                await Task.Delay(TimeSpan.FromSeconds(pingIntervalSeconds), heartbeatCts.Token);
+
+                // Prüfe ob der Client noch lebt
+                var silenceSec = (DateTime.UtcNow - conn.LastActivityAt).TotalSeconds;
+                if (silenceSec > deadTimeoutSeconds)
+                {
+                    Console.WriteLine($"[Remote] Heartbeat timeout ({silenceSec:F0}s): {conn.Id} ({conn.Hostname})");
+                    heartbeatCts.Cancel();
+                    return;
+                }
+
+                // Ping senden
+                try
+                {
+                    await ws.SendAsync(pingBytes, WebSocketMessageType.Text, true, heartbeatCts.Token);
+                }
+                catch
+                {
+                    // Send fehlgeschlagen → Verbindung tot
+                    heartbeatCts.Cancel();
+                    return;
+                }
+            }
+        }
+        catch (OperationCanceledException)
+        {
+            // Normal – ReceiveLoop hat beendet
+        }
+    }
+
     private static IResult GetConnections(RemoteConnectionManager mgr)
     {
         var connections = mgr.GetAll().Select(c => new

Services/RemoteConnectionManager.cs

@@ -17,6 +17,7 @@ public class RemoteConnection
     public string Username { get; set; }
     public string OsVersion { get; set; }
     public DateTime ConnectedAt { get; set; }
+    public DateTime LastActivityAt { get; set; }
     public string AssignedSessionId { get; set; }
     public WebSocket Socket { get; set; }
 
@@ -42,6 +43,7 @@ public class RemoteConnectionManager
         {
             Id = Guid.NewGuid().ToString("N")[..12],
             ConnectedAt = DateTime.UtcNow,
+            LastActivityAt = DateTime.UtcNow,
             Socket = socket
         };
         _connections[conn.Id] = conn;

wwwroot/remote.ps1

@@ -153,6 +153,10 @@ try {
                 Write-Host "  [Exit: $exitCode]" -ForegroundColor $(if ($exitCode -eq 0) { "Green" } else { "Red" })
                 Write-Host ""
             }
+            "ping" {
+                # Server-Heartbeat → mit pong antworten
+                Send-WsMessage $ws '{"type":"pong"}' $ct
+            }
             "pong" {
                 # Heartbeat-Antwort - ignorieren
             }