Refactor PlayerPresenceController and NotifyHub: enhance online presence tracking and improve connection handling logic

DorkNet.Server/Controllers/Match/PlayerPresenceController.cs

@@ -35,7 +35,9 @@ namespace DorkNet.Server.Controllers.Match;
 /// null. Players who haven't /goto'd anywhere still report offline.
 /// </summary>
 [ApiController]
-public class PlayerPresenceController(PlayerPresenceService presence) : ControllerBase
+public class PlayerPresenceController(
+    PlayerPresenceService presence,
+    OnlinePresenceService onlinePresence) : ControllerBase
 {
     [HttpGet("/player")]
     public ActionResult<List<PlayerPresenceDto>> GetPresences()
@@ -81,17 +83,19 @@ public class PlayerPresenceController(PlayerPresenceService presence) : Controll
         // privacy concern actually applies.
         var callerId = this.CurrentPlayerId();
         var callerRoom = callerId is long cid ? presence.GetRoom(cid) : null;
+        var onlineIds = onlinePresence.OnlinePlayerIds().ToHashSet();
         var result = ids.Select(id =>
         {
             var room = presence.GetRoom(id);
-            // IsOnline is derived from current room presence: a player
-            // who has heartbeated recently has a non-null RoomInstance
-            // in PlayerPresenceService; one who hasn't shows up as
-            // null. Without this, IsOnline defaulted to `true` and the
-            // watch's friends list showed every queried account as
-            // Online regardless of actual session state — verified live
-            // (six accounts shown Online despite none being connected).
-            var isOnline = room is not null;
+            // Other players need both a room presence and an active
+            // notify connection. Presence keys intentionally live for
+            // minutes to survive long room loads, so using them alone
+            // leaves friends stuck online after a graceful disconnect.
+            // For self, keep using room presence: boot-time bulk probes
+            // can race the SignalR connection, and returning self as
+            // offline there can desync the heartbeat cache.
+            var isSelf = callerId == id;
+            var isOnline = room is not null && (isSelf || onlineIds.Contains(id));
             return new PlayerPresenceDto
             {
                 PlayerId         = (int)id,
@@ -109,9 +113,9 @@ public class PlayerPresenceController(PlayerPresenceService presence) : Controll
                 // joins; returning a redacted same-room instance there
                 // leaves the 2020 client with an incomplete roomInstance
                 // and can null-ref while reconciling player presence.
-                RoomInstance     = ShouldExposeFullRoom(callerId, callerRoom, id, room)
+                RoomInstance     = isOnline && ShouldExposeFullRoom(callerId, callerRoom, id, room)
                     ? room
-                    : RoomInstanceDto.Redact(room),
+                    : RoomInstanceDto.Redact(isOnline ? room : null),
                 IsOnline         = isOnline,
             };
         }).ToList();

DorkNet.Server/Hubs/NotifyHub.cs

@@ -1,5 +1,6 @@
 using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.SignalR;
+using DorkNet.Server.Data;
 using DorkNet.Server.Services;
 using System.Security.Claims;
 using System.Text.Json;
@@ -40,6 +41,8 @@ namespace DorkNet.Server.Hubs;
 public class NotifyHub(
     OnlinePresenceService presence,
     NotificationService notifications,
+    DorkNetDbContext db,
+    ServerSettingsService serverSettings,
     ILogger<NotifyHub> logger) : Hub
 {
     /// <summary>SignalR group name for a given player id. Use this
@@ -111,11 +114,17 @@ public class NotifyHub(
         var pid = TryGetPlayerId();
         if (pid is long id)
         {
-            await presence.RemoveConnectionAsync(id, Context.ConnectionId);
+            var wentOffline = await presence.RemoveConnectionAsync(id, Context.ConnectionId);
             await Groups.RemoveFromGroupAsync(Context.ConnectionId, GroupForPlayer(id));
+            if (wentOffline)
+            {
+                var friendIds = await RelationshipQueries.EffectiveFriendIdsAsync(db, serverSettings, id);
+                if (friendIds.Count > 0)
+                    await notifications.PlayerWentOffline(friendIds, id);
+            }
             logger.LogInformation(
-                "[hub] disconnected player={PlayerId} conn={ConnectionId} error={Error}",
-                id, Context.ConnectionId, exception?.Message);
+                "[hub] disconnected player={PlayerId} conn={ConnectionId} wentOffline={WentOffline} error={Error}",
+                id, Context.ConnectionId, wentOffline, exception?.Message);
         }
         else
         {

DorkNet.Server/Services/OnlinePresenceService.cs

@@ -68,7 +68,10 @@ public class OnlinePresenceService
         lock (set) set.Add(connectionId);
     }
 
-    public async Task RemoveConnectionAsync(long playerId, string connectionId)
+    /// <summary>Remove one SignalR connection. Returns true when that was
+    /// the player's final active connection and they should now be treated
+    /// as offline by friends-list presence.</summary>
+    public async Task<bool> RemoveConnectionAsync(long playerId, string connectionId)
     {
         if (_redis is { } mux)
         {
@@ -84,16 +87,25 @@ public class OnlinePresenceService
                     // from the online set so admin queries see "offline".
                     await db.SetRemoveAsync(OnlineSetKey, playerId);
                     await db.KeyDeleteAsync(connsKey);
+                    return true;
                 }
             }
-            return;
+            return false;
         }
 
         if (_localConns.TryGetValue(playerId, out var set))
         {
-            lock (set) set.Remove(connectionId);
-            if (set.Count == 0) _localConns.TryRemove(playerId, out _);
+            lock (set)
+            {
+                set.Remove(connectionId);
+                if (set.Count != 0) return false;
             }
+
+            _localConns.TryRemove(playerId, out _);
+            return true;
+        }
+
+        return false;
     }
 
     /// <summary>Snapshot of SignalR connection ids that currently belong