feat(server): member last seen and a live per-account space activity stream

server/src/WebDrop.Api/ApiJson.cs

@@ -159,6 +159,9 @@ public sealed class MemberBody
     /// <summary>该账号在本频道登记过的设备(终端)数;设备只是账号的属性,不是独立成员。</summary>
     [JsonPropertyName("devices")] public required int Devices { get; init; }
     [JsonPropertyName("online_devices")] public required int OnlineDevices { get; init; }
+
+    /// <summary>该账号任一设备最近一次活跃的 Unix 时间戳(登录时是秒,活跃续期后是毫秒,客户端按量级区分);没有登录过设备时为 0。</summary>
+    [JsonPropertyName("last_seen")] public required long LastSeen { get; init; }
 }
 
 public sealed class AccountProfileRequest

server/src/WebDrop.Api/ChannelHub.cs

@@ -12,6 +12,10 @@ public sealed class ChannelHub : IChannelEvents
     private readonly object _gate = new();
     private readonly Dictionary<Id16, Signal> _signals = [];
 
+    // 账号级的「有频道前进了」信号:不管有没有人订阅这个频道都会记录,供空间列表上的未读提示用
+    private readonly Dictionary<Id16, long> _advanced = [];
+    private TaskCompletionSource _anyAdvanced = new(TaskCreationOptions.RunContinuationsAsynchronously);
+
     // 在线状态:频道 -> 账号 -> 账号设备 -> 活动订阅数。只记账号。
     private readonly Dictionary<Id16, Dictionary<string, Dictionary<string, int>>> _presence = [];
 
@@ -66,7 +70,24 @@ public sealed class ChannelHub : IChannelEvents
         public void Dispose() => Interlocked.Exchange(ref _release, null)?.Invoke();
     }
 
-    public void Advanced(Id16 channelId, long seq) => Publish(channelId, s => s.Seq = Math.Max(s.Seq, seq));
+    public void Advanced(Id16 channelId, long seq)
+    {
+        TaskCompletionSource old;
+        lock (_gate)
+        {
+            _advanced[channelId] = Math.Max(_advanced.GetValueOrDefault(channelId), seq);
+            old = _anyAdvanced;
+            _anyAdvanced = new(TaskCreationOptions.RunContinuationsAsynchronously);
+        }
+        old.TrySetResult();
+        Publish(channelId, s => s.Seq = Math.Max(s.Seq, seq));
+    }
+
+    /// <summary>先取这个任务、再读 <see cref="AdvancedSeq"/>,最后等待任务:不会漏掉中间的前进。</summary>
+    public Task AnyAdvanced { get { lock (_gate) return _anyAdvanced.Task; } }
+
+    /// <summary>本进程启动以来该频道见到的最大序号;没有见到过为 0。</summary>
+    public long AdvancedSeq(Id16 channelId) { lock (_gate) return _advanced.GetValueOrDefault(channelId); }
     public void SettingsChanged(Id16 channelId) => Publish(channelId, s => s.SettingsVersion++);
     public void MembersChanged(Id16 channelId) => Publish(channelId, s => s.MembersVersion++);
     public void ChannelDeleted(Id16 channelId) => Publish(channelId, s => s.Deleted = true);

server/src/WebDrop.Api/Endpoints.ChannelAccess.cs

@@ -12,6 +12,44 @@ public static partial class Endpoints
             if (!TryAccount(ctx, accounts, out var username)) throw new WebDropException(ErrorCode.AccountRequired);
             return Json(svc.AccountSpaces(username).ToList(), ApiJson.Default.ListChannelInfo);
         });
+        // 空间列表的实时提示:账号所在空间有新内容就推一条 {id,last_seq}。只含序号,不含内容
+        api.MapGet("/accounts/spaces/events", async (HttpContext ctx, ChannelService svc, ChannelHub hub) =>
+        {
+            if (!TryAccount(ctx, accounts, out var username)) throw new WebDropException(ErrorCode.AccountRequired);
+            var ct = ctx.RequestAborted;
+            ctx.Response.ContentType = "text/event-stream";
+            ctx.Response.Headers["X-Accel-Buffering"] = "no";
+            await ctx.Response.StartAsync(ct);
+            var sent = new Dictionary<Id16, long>();
+            try
+            {
+                while (!ct.IsCancellationRequested)
+                {
+                    // 每次唤醒都重新核对登录:退出登录、被移除设备后,这条流立刻结束
+                    if (!TryAccount(ctx, accounts, out var current) || current != username)
+                    {
+                        await ctx.Response.WriteAsync("event: error\ndata: {\"error\":\"account_required\"}\n\n", ct);
+                        break;
+                    }
+                    var changed = hub.AnyAdvanced;
+                    foreach (var id in svc.AccountSpaceIds(username))
+                    {
+                        var seq = hub.AdvancedSeq(id);
+                        // 第一次只记下当前值:连接建立前的进展客户端已经从列表里拿到了
+                        if (!sent.TryGetValue(id, out var known)) { sent[id] = seq; continue; }
+                        if (seq <= known) continue;
+                        sent[id] = seq;
+                        await ctx.Response.WriteAsync($"event: space\ndata: {{\"id\":\"{id.ToBase64Url()}\",\"last_seq\":{seq}}}\n\n", ct);
+                    }
+                    await ctx.Response.Body.FlushAsync(ct);
+                    var idle = Task.Delay(TimeSpan.FromSeconds(20), ct);
+                    // 久无变化就发心跳,客户端据此判断连接还活着
+                    if (await Task.WhenAny(changed, idle) == idle) { await ctx.Response.WriteAsync("event: ping\ndata: 1\n\n", ct); await ctx.Response.Body.FlushAsync(ct); }
+                }
+            }
+            catch (OperationCanceledException) { }
+            return Results.Empty;
+        });
         api.MapGet("/accounts/channels", (HttpContext ctx, ChannelService svc) =>
         {
             if (!TryAccount(ctx, accounts, out var username)) throw new WebDropException(ErrorCode.AccountRequired);
@@ -54,8 +92,10 @@ public static partial class Endpoints
             {
                 var (online, onlineDevices) = hub.Presence(channelId, member.Username);
                 // 设备是账号的属性:总数取账号的登录设备,在线数取该账号在本频道有订阅的设备
+                var devices = accounts.Devices(member.Username, null);
                 return new MemberBody { Username = member.Username, Role = member.Role, JoinedAt = member.JoinedAt,
-                    Online = online, Devices = Math.Max(accounts.Devices(member.Username, null).Count, onlineDevices), OnlineDevices = onlineDevices };
+                    Online = online, Devices = Math.Max(devices.Count, onlineDevices), OnlineDevices = onlineDevices,
+                    LastSeen = devices.Count == 0 ? 0 : devices.Max(device => device.LastSeen) };
             }).ToList();
             return Json(members, ApiJson.Default.ListMemberBody);
         });