Change lightfinder permissions for groups

Reviewed-on: #34

LightlessSyncServer/LightlessSyncServer/Hubs/LightlessHub.Chat.cs

@@ -0,0 +1,630 @@
+using System;
+using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
+using System.Text.Json;
+using LightlessSync.API.Data.Enum;
+using LightlessSync.API.Dto.Chat;
+using LightlessSync.API.Dto.User;
+using LightlessSyncServer.Models;
+using LightlessSyncServer.Services;
+using LightlessSyncServer.Utils;
+using LightlessSyncShared.Models;
+using Microsoft.AspNetCore.Authorization;
+using Microsoft.AspNetCore.SignalR;
+using Microsoft.EntityFrameworkCore;
+
+namespace LightlessSyncServer.Hubs;
+
+public partial class LightlessHub
+{
+    private const int MaxChatMessageLength = 400;
+    private const int ChatRateLimitMessages = 7;
+    private static readonly TimeSpan ChatRateLimitWindow = TimeSpan.FromMinutes(1);
+    private static readonly ConcurrentDictionary<string, ChatRateLimitState> ChatRateLimiters = new(StringComparer.Ordinal);
+
+    private sealed class ChatRateLimitState
+    {
+        public readonly Queue<DateTime> Events = new();
+        public readonly object SyncRoot = new();
+    }
+    private static readonly JsonSerializerOptions ChatReportSnapshotSerializerOptions = new(JsonSerializerDefaults.General)
+    {
+        WriteIndented = false
+    };
+
+    [Authorize(Policy = "Identified")]
+    public Task<IReadOnlyList<ZoneChatChannelInfoDto>> GetZoneChatChannels()
+    {
+        return Task.FromResult(_chatChannelService.GetZoneChannelInfos());
+    }
+
+    [Authorize(Policy = "Identified")]
+    public async Task<IReadOnlyList<GroupChatChannelInfoDto>> GetGroupChatChannels()
+    {
+        var userUid = UserUID;
+
+        var groupInfos = await DbContext.Groups
+            .AsNoTracking()
+            .Where(g => g.OwnerUID == userUid
+                        || DbContext.GroupPairs.Any(p => p.GroupGID == g.GID && p.GroupUserUID == userUid))
+            .ToListAsync()
+            .ConfigureAwait(false);
+
+        return groupInfos
+            .Select(g =>
+            {
+                var displayName = string.IsNullOrWhiteSpace(g.Alias) ? g.GID : g.Alias!;
+                var descriptor = new ChatChannelDescriptor
+                {
+                    Type = ChatChannelType.Group,
+                    WorldId = 0,
+                    ZoneId = 0,
+                    CustomKey = g.GID
+                };
+
+                return new GroupChatChannelInfoDto(
+                    descriptor,
+                    displayName,
+                    g.GID,
+                    g.OwnerUID == userUid);
+            })
+            .OrderBy(info => info.DisplayName, StringComparer.OrdinalIgnoreCase)
+            .ToList();
+    }
+
+    [Authorize(Policy = "Identified")]
+    public async Task UpdateChatPresence(ChatPresenceUpdateDto presence)
+    {
+        var channel = presence.Channel.WithNormalizedCustomKey();
+
+        var userRecord = await DbContext.Users
+            .AsNoTracking()
+            .SingleAsync(u => u.UID == UserUID, cancellationToken: RequestAbortedToken)
+            .ConfigureAwait(false);
+
+        if (userRecord.ChatBanned)
+        {
+            _chatChannelService.RemovePresence(UserUID);
+            await NotifyChatBanAsync(UserUID).ConfigureAwait(false);
+            return;
+        }
+
+        if (!presence.IsActive)
+        {
+            _chatChannelService.RemovePresence(UserUID, channel);
+            return;
+        }
+
+        switch (channel.Type)
+        {
+            case ChatChannelType.Zone:
+                if (!_chatChannelService.TryResolveZone(channel.CustomKey, out var definition))
+                {
+                    throw new HubException("Unsupported chat channel.");
+                }
+
+                if (channel.WorldId == 0 || !WorldRegistry.IsKnownWorld(channel.WorldId))
+                {
+                    throw new HubException("Unsupported chat channel.");
+                }
+
+                if (presence.TerritoryId == 0 || !definition.TerritoryIds.Contains(presence.TerritoryId))
+                {
+                    throw new HubException("Zone chat is only available in supported territories.");
+                }
+
+                string? hashedCid = null;
+                var isLightfinder = false;
+                if (IsValidHashedCid(UserCharaIdent))
+                {
+                    var (entry, expiry) = await TryGetBroadcastEntryAsync(UserCharaIdent).ConfigureAwait(false);
+                    isLightfinder = HasActiveBroadcast(entry, expiry);
+                    if (isLightfinder)
+                    {
+                        hashedCid = UserCharaIdent;
+                    }
+                }
+
+                _chatChannelService.UpdateZonePresence(
+                    UserUID,
+                    definition,
+                    channel.WorldId,
+                    presence.TerritoryId,
+                    hashedCid,
+                    isLightfinder,
+                    isActive: true);
+                break;
+
+            case ChatChannelType.Group:
+                var groupKey = channel.CustomKey ?? string.Empty;
+                if (string.IsNullOrEmpty(groupKey))
+                {
+                    throw new HubException("Unsupported chat channel.");
+                }
+
+                var userData = userRecord.ToUserData();
+
+                var group = await DbContext.Groups
+                    .AsNoTracking()
+                    .SingleOrDefaultAsync(g => g.GID == groupKey, cancellationToken: RequestAbortedToken)
+                    .ConfigureAwait(false);
+
+                if (group is null)
+                {
+                    throw new HubException("Unsupported chat channel.");
+                }
+
+                var isMember = string.Equals(group.OwnerUID, UserUID, StringComparison.Ordinal)
+                    || await DbContext.GroupPairs
+                        .AsNoTracking()
+                        .AnyAsync(gp => gp.GroupGID == groupKey && gp.GroupUserUID == UserUID, cancellationToken: RequestAbortedToken)
+                        .ConfigureAwait(false);
+
+                if (!isMember)
+                {
+                    throw new HubException("Join the syncshell before using chat.");
+                }
+
+                var displayName = string.IsNullOrWhiteSpace(group.Alias) ? group.GID : group.Alias;
+
+                _chatChannelService.UpdateGroupPresence(
+                    UserUID,
+                    group.GID,
+                    displayName,
+                    userData,
+                    IsValidHashedCid(UserCharaIdent) ? UserCharaIdent : null,
+                    isActive: true);
+                break;
+
+            default:
+                throw new HubException("Unsupported chat channel.");
+        }
+    }
+
+    [Authorize(Policy = "Identified")]
+    public async Task SendChatMessage(ChatSendRequestDto request)
+    {
+        if (string.IsNullOrWhiteSpace(request.Message))
+        {
+            throw new HubException("Message cannot be empty.");
+        }
+
+        var channel = request.Channel.WithNormalizedCustomKey();
+
+        if (await HandleIfChatBannedAsync(UserUID).ConfigureAwait(false))
+        {
+            throw new HubException("Chat access has been revoked.");
+        }
+
+        if (!_chatChannelService.TryGetPresence(UserUID, channel, out var presence))
+        {
+            throw new HubException("Join a chat channel before sending messages.");
+        }
+
+        if (!UseChatRateLimit(UserUID))
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Warning, "You can send at most " + ChatRateLimitMessages + " chat messages per minute. Please wait before sending more.").ConfigureAwait(false);
+            return;
+        }
+
+        var sanitizedMessage = request.Message.Trim().ReplaceLineEndings(" ");
+        if (sanitizedMessage.Length > MaxChatMessageLength)
+        {
+            sanitizedMessage = sanitizedMessage[..MaxChatMessageLength];
+        }
+
+        var recipients = _chatChannelService.GetMembers(presence.Channel);
+        var recipientsList = recipients.ToList();
+        if (recipientsList.Count == 0)
+        {
+            return;
+        }
+
+        var bannedRecipients = recipientsList.Count == 0
+            ? new List<string>()
+            : await DbContext.Users.AsNoTracking()
+                .Where(u => recipientsList.Contains(u.UID) && u.ChatBanned)
+                .Select(u => u.UID)
+                .ToListAsync(RequestAbortedToken)
+                .ConfigureAwait(false);
+
+        HashSet<string>? bannedSet = null;
+        if (bannedRecipients.Count > 0)
+        {
+            bannedSet = new HashSet<string>(bannedRecipients, StringComparer.Ordinal);
+            foreach (var bannedUid in bannedSet)
+            {
+                _chatChannelService.RemovePresence(bannedUid);
+                await NotifyChatBanAsync(bannedUid).ConfigureAwait(false);
+            }
+        }
+
+        var deliveryTargets = new Dictionary<string, (string Uid, bool IncludeSensitive)>(StringComparer.Ordinal);
+        foreach (var uid in recipientsList)
+        {
+            if (bannedSet != null && bannedSet.Contains(uid))
+            {
+                continue;
+            }
+
+            if (_userConnections.TryGetValue(uid, out var connectionId))
+            {
+                var includeSensitive = await AllowsLightfinderDetailsAsync(presence.Channel, uid).ConfigureAwait(false);
+                if (deliveryTargets.TryGetValue(connectionId, out var existing))
+                {
+                    deliveryTargets[connectionId] = (existing.Uid, existing.IncludeSensitive || includeSensitive);
+                }
+                else
+                {
+                    deliveryTargets[connectionId] = (uid, includeSensitive);
+                }
+            }
+            else
+            {
+                _chatChannelService.RemovePresence(uid);
+            }
+        }
+
+        if (deliveryTargets.Count == 0)
+        {
+            return;
+        }
+
+        var timestamp = DateTime.UtcNow;
+        var messageId = _chatChannelService.RecordMessage(presence.Channel, presence.Participant, sanitizedMessage, timestamp);
+        var sendTasks = new List<Task>(deliveryTargets.Count);
+
+        foreach (var (connectionId, target) in deliveryTargets)
+        {
+            var sender = BuildSenderDescriptor(presence.Channel, presence.Participant, target.IncludeSensitive);
+            var payload = new ChatMessageDto(
+                presence.Channel,
+                sender,
+                sanitizedMessage,
+                timestamp,
+                messageId);
+
+            sendTasks.Add(Clients.Client(connectionId).Client_ChatReceive(payload));
+        }
+
+        await Task.WhenAll(sendTasks).ConfigureAwait(false);
+    }
+
+    [Authorize(Policy = "Identified")]
+    public async Task<ChatParticipantResolveResultDto?> ResolveChatParticipant(ChatParticipantResolveRequestDto request)
+    {
+        var channel = request.Channel.WithNormalizedCustomKey();
+
+        if (!_chatChannelService.TryGetPresence(UserUID, channel, out _))
+        {
+            throw new HubException("Join the chat channel before resolving participants.");
+        }
+
+        if (!_chatChannelService.TryResolveParticipant(channel, request.Token, out var participant))
+        {
+            return null;
+        }
+
+        var viewerAllowsDetails = await ViewerAllowsLightfinderDetailsAsync(channel).ConfigureAwait(false);
+        var includeSensitiveInfo = channel.Type == ChatChannelType.Group || viewerAllowsDetails;
+
+        var sender = BuildSenderDescriptor(channel, participant, includeSensitiveInfo);
+
+        if (!includeSensitiveInfo)
+        {
+            return new ChatParticipantResolveResultDto(channel, sender, null);
+        }
+
+        UserProfileDto? profile = null;
+        if (channel.Type == ChatChannelType.Group)
+        {
+            profile = await LoadChatParticipantProfileAsync(participant.UserUid).ConfigureAwait(false);
+        }
+        else if (participant.IsLightfinder && !string.IsNullOrEmpty(participant.HashedCid))
+        {
+            profile = await LoadChatParticipantProfileAsync(participant.UserUid).ConfigureAwait(false);
+        }
+
+        return new ChatParticipantResolveResultDto(channel, sender, profile);
+    }
+
+    [Authorize(Policy = "Identified")]
+    public async Task ReportChatMessage(ChatReportSubmitDto request)
+    {
+        var channel = request.Channel.WithNormalizedCustomKey();
+
+        if (!_chatChannelService.TryGetPresence(UserUID, channel, out _))
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Error, "Join the chat channel before reporting messages.").ConfigureAwait(false);
+            return;
+        }
+
+        if (!_chatChannelService.TryGetMessage(request.MessageId, out var messageEntry))
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Error, "Unable to locate the reported message. It may have already expired.").ConfigureAwait(false);
+            return;
+        }
+
+        var requestedChannelKey = ChannelKey.FromDescriptor(channel);
+        var messageChannelKey = ChannelKey.FromDescriptor(messageEntry.Channel.WithNormalizedCustomKey());
+        if (!requestedChannelKey.Equals(messageChannelKey))
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Error, "The reported message no longer matches this channel.").ConfigureAwait(false);
+            return;
+        }
+
+        if (string.Equals(messageEntry.SenderUserUid, UserUID, StringComparison.Ordinal))
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Warning, "You cannot report your own message.").ConfigureAwait(false);
+            return;
+        }
+
+        var reason = request.Reason?.Trim();
+        if (string.IsNullOrWhiteSpace(reason))
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Warning, "Please provide a short explanation for the report.").ConfigureAwait(false);
+            return;
+        }
+
+        const int MaxReasonLength = 500;
+        if (reason.Length > MaxReasonLength)
+        {
+            reason = reason[..MaxReasonLength];
+        }
+
+        var additionalContext = string.IsNullOrWhiteSpace(request.AdditionalContext)
+            ? null
+            : request.AdditionalContext.Trim();
+
+        const int MaxContextLength = 1000;
+        if (!string.IsNullOrEmpty(additionalContext) && additionalContext.Length > MaxContextLength)
+        {
+            additionalContext = additionalContext[..MaxContextLength];
+        }
+
+        var alreadyReported = await DbContext.ReportedChatMessages
+            .AsNoTracking()
+            .AnyAsync(r => r.MessageId == request.MessageId && r.ReporterUserUid == UserUID && !r.Resolved, cancellationToken: RequestAbortedToken)
+            .ConfigureAwait(false);
+
+        if (alreadyReported)
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Warning, "You already reported this message and it is pending review.").ConfigureAwait(false);
+            return;
+        }
+
+        var oneHourAgo = DateTime.UtcNow - TimeSpan.FromHours(1);
+        var reportRateLimited = await DbContext.ReportedChatMessages
+            .AsNoTracking()
+            .AnyAsync(r => r.ReporterUserUid == UserUID && r.ReportTimeUtc >= oneHourAgo, cancellationToken: RequestAbortedToken)
+            .ConfigureAwait(false);
+
+        if (reportRateLimited)
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Warning, "You can file at most one chat report per hour.").ConfigureAwait(false);
+            return;
+        }
+
+        if (!string.IsNullOrEmpty(messageEntry.SenderUserUid))
+        {
+            var targetAlreadyPending = await DbContext.ReportedChatMessages
+                .AsNoTracking()
+                .AnyAsync(r => r.ReportedUserUid == messageEntry.SenderUserUid && !r.Resolved, cancellationToken: RequestAbortedToken)
+                .ConfigureAwait(false);
+
+            if (targetAlreadyPending)
+            {
+                await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Information, "This user already has a report pending review.").ConfigureAwait(false);
+                return;
+            }
+        }
+
+        var snapshotEntries = _chatChannelService.GetRecentMessages(messageEntry.Channel, 25);
+        var snapshotItems = snapshotEntries
+            .Select(e => new ChatReportSnapshotItem(
+                e.MessageId,
+                e.SentAtUtc,
+                e.SenderUserUid,
+                e.SenderUser?.AliasOrUID,
+                e.SenderIsLightfinder,
+                e.SenderHashedCid,
+                e.Message))
+            .ToArray();
+
+        var snapshotJson = JsonSerializer.Serialize(snapshotItems, ChatReportSnapshotSerializerOptions);
+
+        var report = new ReportedChatMessage
+        {
+            ReportTimeUtc = DateTime.UtcNow,
+            ReporterUserUid = UserUID,
+            ReportedUserUid = messageEntry.SenderUserUid,
+            ChannelType = messageEntry.Channel.Type,
+            WorldId = messageEntry.Channel.WorldId,
+            ZoneId = messageEntry.Channel.ZoneId,
+            ChannelKey = messageEntry.Channel.CustomKey ?? string.Empty,
+            MessageId = messageEntry.MessageId,
+            MessageSentAtUtc = messageEntry.SentAtUtc,
+            MessageContent = messageEntry.Message,
+            SenderToken = messageEntry.SenderToken,
+            SenderHashedCid = messageEntry.SenderHashedCid,
+            SenderDisplayName = messageEntry.SenderUser?.AliasOrUID,
+            SenderWasLightfinder = messageEntry.SenderIsLightfinder,
+            SnapshotJson = snapshotJson,
+            Reason = reason,
+            AdditionalContext = additionalContext
+        };
+
+        DbContext.ReportedChatMessages.Add(report);
+        await DbContext.SaveChangesAsync(RequestAbortedToken).ConfigureAwait(false);
+
+        await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Information, "Thank you. Your report has been queued for moderator review.").ConfigureAwait(false);
+    }
+
+    private ChatSenderDescriptor BuildSenderDescriptor(ChatChannelDescriptor descriptor, ChatParticipantInfo participant, bool includeSensitiveInfo = false)
+    {
+        var kind = descriptor.Type == ChatChannelType.Group
+            ? ChatSenderKind.IdentifiedUser
+            : ChatSenderKind.Anonymous;
+
+        string? displayName;
+        if (kind == ChatSenderKind.IdentifiedUser)
+        {
+            displayName = participant.User?.Alias ?? participant.User?.UID ?? participant.UserUid;
+        }
+        else if (includeSensitiveInfo && participant.IsLightfinder && !string.IsNullOrEmpty(participant.HashedCid))
+        {
+            displayName = participant.HashedCid;
+        }
+        else
+        {
+            var source = participant.UserUid ?? string.Empty;
+            var suffix = source.Length >= 4 ? source[^4..] : source;
+            displayName = string.IsNullOrEmpty(suffix) ? "Anonymous" : $"Anon-{suffix}";
+        }
+
+        var hashedCid = includeSensitiveInfo && participant.IsLightfinder
+            ? participant.HashedCid
+            : null;
+
+        var canResolveProfile = kind == ChatSenderKind.IdentifiedUser || participant.IsLightfinder;
+
+        return new ChatSenderDescriptor(
+            kind,
+            participant.Token,
+            displayName,
+            hashedCid,
+            descriptor.Type == ChatChannelType.Group ? participant.User : null,
+            canResolveProfile);
+    }
+
+    private async Task<UserProfileDto?> LoadChatParticipantProfileAsync(string userUid)
+    {
+        if (string.IsNullOrEmpty(userUid))
+            return null;
+
+        var targetUser = await DbContext.Users
+            .AsNoTracking()
+            .SingleOrDefaultAsync(u => u.UID == userUid, cancellationToken: RequestAbortedToken)
+            .ConfigureAwait(false);
+
+        if (targetUser is null)
+            return null;
+
+        var userData = targetUser.ToUserData();
+
+        var profileData = await DbContext.UserProfileData
+            .AsNoTracking()
+            .SingleOrDefaultAsync(p => p.UserUID == userUid, cancellationToken: RequestAbortedToken)
+            .ConfigureAwait(false);
+
+        if (profileData is null)
+        {
+            return new UserProfileDto(userData, Disabled: false, IsNSFW: null, ProfilePictureBase64: null, BannerPictureBase64: null, Description: null, Tags: Array.Empty<int>());
+        }
+
+        if (profileData.FlaggedForReport)
+        {
+            return new UserProfileDto(userData, Disabled: true, IsNSFW: null, ProfilePictureBase64: null, BannerPictureBase64: null, Description: "This profile is flagged for report and pending evaluation", Tags: Array.Empty<int>());
+        }
+
+        if (profileData.ProfileDisabled)
+        {
+            return new UserProfileDto(userData, Disabled: true, IsNSFW: null, ProfilePictureBase64: null, BannerPictureBase64: null, Description: "This profile was permanently disabled", Tags: Array.Empty<int>());
+        }
+
+        return profileData.ToDTO();
+    }
+
+    private async Task<bool> ViewerAllowsLightfinderDetailsAsync(ChatChannelDescriptor descriptor)
+    {
+        if (descriptor.Type == ChatChannelType.Group)
+        {
+            return true;
+        }
+
+        var viewerCid = UserCharaIdent;
+        if (!IsValidHashedCid(viewerCid))
+        {
+            return false;
+        }
+
+        var (entry, expiry) = await TryGetBroadcastEntryAsync(viewerCid).ConfigureAwait(false);
+        return HasActiveBroadcast(entry, expiry);
+    }
+
+    private async Task<bool> AllowsLightfinderDetailsAsync(ChatChannelDescriptor descriptor, string userUid)
+    {
+        if (descriptor.Type == ChatChannelType.Group)
+        {
+            return true;
+        }
+
+        if (_chatChannelService.TryGetPresence(userUid, descriptor, out var presence))
+        {
+            if (!presence.Participant.IsLightfinder || !IsValidHashedCid(presence.Participant.HashedCid))
+            {
+                return false;
+            }
+
+            var (entry, expiry) = await TryGetBroadcastEntryAsync(presence.Participant.HashedCid!).ConfigureAwait(false);
+            if (!IsActiveBroadcastForUser(entry, expiry, userUid))
+            {
+                _chatChannelService.RefreshLightfinderState(userUid, null, isLightfinder: false);
+                return false;
+            }
+
+            return true;
+        }
+
+        return false;
+    }
+
+    private async Task<bool> HandleIfChatBannedAsync(string userUid)
+    {
+        var isBanned = await DbContext.Users
+            .AsNoTracking()
+            .AnyAsync(u => u.UID == userUid && u.ChatBanned, RequestAbortedToken)
+            .ConfigureAwait(false);
+
+        if (!isBanned)
+            return false;
+
+        _chatChannelService.RemovePresence(userUid);
+        await NotifyChatBanAsync(userUid).ConfigureAwait(false);
+        return true;
+    }
+
+    private async Task NotifyChatBanAsync(string userUid)
+    {
+        if (string.Equals(userUid, UserUID, StringComparison.Ordinal))
+        {
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Error, "Your chat access has been revoked.").ConfigureAwait(false);
+        }
+        else if (_userConnections.TryGetValue(userUid, out var connectionId))
+        {
+            await Clients.Client(connectionId).Client_ReceiveServerMessage(MessageSeverity.Error, "Your chat access has been revoked.").ConfigureAwait(false);
+        }
+    }
+
+    private static bool UseChatRateLimit(string userUid)
+    {
+        var state = ChatRateLimiters.GetOrAdd(userUid, _ => new ChatRateLimitState());
+        lock (state.SyncRoot)
+        {
+            var now = DateTime.UtcNow;
+            while (state.Events.Count > 0 && now - state.Events.Peek() >= ChatRateLimitWindow)
+            {
+                state.Events.Dequeue();
+            }
+
+            if (state.Events.Count >= ChatRateLimitMessages)
+            {
+                return false;
+            }
+
+            state.Events.Enqueue(now);
+            return true;
+        }
+    }
+}

LightlessSyncServer/LightlessSyncServer/Hubs/LightlessHub.ClientStubs.cs

@@ -1,6 +1,7 @@
 using LightlessSync.API.Data;
 using LightlessSync.API.Data.Enum;
 using LightlessSync.API.Dto;
+using LightlessSync.API.Dto.Chat;
 using LightlessSync.API.Dto.CharaData;
 using LightlessSync.API.Dto.Group;
 using LightlessSync.API.Dto.User;
@@ -38,5 +39,6 @@ namespace LightlessSyncServer.Hubs
         public Task Client_GposeLobbyPushCharacterData(CharaDataDownloadDto charaDownloadDto) => throw new PlatformNotSupportedException("Calling clientside method on server not supported");
         public Task Client_GposeLobbyPushPoseData(UserData userData, PoseData poseData) => throw new PlatformNotSupportedException("Calling clientside method on server not supported");
         public Task Client_GposeLobbyPushWorldData(UserData userData, WorldData worldData) => throw new PlatformNotSupportedException("Calling clientside method on server not supported");
+        public Task Client_ChatReceive(ChatMessageDto message) => throw new PlatformNotSupportedException("Calling clientside method on server not supported");
     }
 }

LightlessSyncServer/LightlessSyncServer/Hubs/LightlessHub.Groups.cs

@@ -995,11 +995,11 @@ public partial class LightlessHub
             return false;
         }
 
-        var (isOwner, _) = await TryValidateOwner(dto.GID).ConfigureAwait(false);
+        var (isOwner, _) = await TryValidateGroupModeratorOrOwner(dto.GID).ConfigureAwait(false);
         if (!isOwner)
         {
             _logger.LogCallWarning(LightlessHubLogger.Args("Unauthorized syncshell broadcast change", "User", UserUID, "GID", dto.GID));
-            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Error, "You must be the owner of the syncshell to broadcast it.");
+            await Clients.Caller.Client_ReceiveServerMessage(MessageSeverity.Error, "You must be the owner or moderator of the syncshell to broadcast it.");
             return false;
         }
 

LightlessSyncServer/LightlessSyncServer/Hubs/LightlessHub.User.cs

@@ -13,7 +13,6 @@ using Microsoft.AspNetCore.Authorization;
 using Microsoft.AspNetCore.SignalR;
 using Microsoft.EntityFrameworkCore;
 using SixLabors.ImageSharp;
-using SixLabors.ImageSharp.PixelFormats;
 using StackExchange.Redis;
 using System.Text;
 using System.Text.Json;
@@ -464,6 +463,7 @@ public partial class LightlessHub
             await db.StringSetAsync(broadcastKey, json, _broadcastConfiguration.BroadcastEntryTtl).ConfigureAwait(false);
             await db.StringSetAsync(ownershipKey, hashedCid, _broadcastConfiguration.BroadcastEntryTtl).ConfigureAwait(false);
             _logger.LogCallInfo(LightlessHubLogger.Args("broadcast enabled", hashedCid, "GID", gid));
+            _chatChannelService.RefreshLightfinderState(UserUID, hashedCid, isLightfinder: true);
         }
         else
         {
@@ -504,6 +504,7 @@ public partial class LightlessHub
             }
 
             _logger.LogCallInfo(LightlessHubLogger.Args("broadcast disabled", hashedCid, "GID", entry.GID));
+            _chatChannelService.RefreshLightfinderState(UserUID, null, isLightfinder: false);
         }
     }
 
@@ -1244,4 +1245,4 @@ public partial class LightlessHub
 
     private ClientPair OppositeEntry(string otherUID) =>
                                     DbContext.ClientPairs.AsNoTracking().SingleOrDefault(w => w.User.UID == otherUID && w.OtherUser.UID == UserUID);
-}
+}

LightlessSyncServer/LightlessSyncServer/Hubs/LightlessHub.cs

@@ -1,6 +1,7 @@
 using LightlessSync.API.Data;
 using LightlessSync.API.Data.Enum;
 using LightlessSync.API.Dto;
+using LightlessSync.API.Dto.Chat;
 using LightlessSync.API.SignalR;
 using LightlessSyncServer.Services;
 using LightlessSyncServer.Configuration;
@@ -16,6 +17,8 @@ using Microsoft.AspNetCore.SignalR;
 using Microsoft.EntityFrameworkCore;
 using StackExchange.Redis.Extensions.Core.Abstractions;
 using System.Collections.Concurrent;
+using System.Collections.Generic;
+using System.Linq;
 
 namespace LightlessSyncServer.Hubs;
 
@@ -43,6 +46,7 @@ public partial class LightlessHub : Hub<ILightlessHub>, ILightlessHub
     private LightlessDbContext DbContext => _dbContextLazy.Value;
     private readonly int _maxCharaDataByUser;
     private readonly int _maxCharaDataByUserVanity;
+    private readonly ChatChannelService _chatChannelService;
 
     private CancellationToken RequestAbortedToken => _contextAccessor.HttpContext?.RequestAborted ?? Context?.ConnectionAborted ?? CancellationToken.None;
 
@@ -50,7 +54,8 @@ public partial class LightlessHub : Hub<ILightlessHub>, ILightlessHub
         IDbContextFactory<LightlessDbContext> lightlessDbContextFactory, ILogger<LightlessHub> logger, SystemInfoService systemInfoService,
         IConfigurationService<ServerConfiguration> configuration, IHttpContextAccessor contextAccessor,
         IRedisDatabase redisDb, OnlineSyncedPairCacheService onlineSyncedPairCacheService, LightlessCensus lightlessCensus,
-        GPoseLobbyDistributionService gPoseLobbyDistributionService, IBroadcastConfiguration broadcastConfiguration, PairService pairService)
+        GPoseLobbyDistributionService gPoseLobbyDistributionService, IBroadcastConfiguration broadcastConfiguration, PairService pairService,
+        ChatChannelService chatChannelService)
     {
         _lightlessMetrics = lightlessMetrics;
         _systemInfoService = systemInfoService;
@@ -71,6 +76,7 @@ public partial class LightlessHub : Hub<ILightlessHub>, ILightlessHub
         _dbContextLazy = new Lazy<LightlessDbContext>(() => lightlessDbContextFactory.CreateDbContext());
         _broadcastConfiguration = broadcastConfiguration;
         _pairService = pairService;
+        _chatChannelService = chatChannelService;
     }
 
     protected override void Dispose(bool disposing)
@@ -221,6 +227,7 @@ public partial class LightlessHub : Hub<ILightlessHub>, ILightlessHub
             catch { }
             finally
             {
+                _chatChannelService.RemovePresence(UserUID);
                 _userConnections.Remove(UserUID, out _);
             }
         }

LightlessSyncServer/LightlessSyncServer/LightlessSyncServer.csproj

@@ -21,6 +21,7 @@
 
   <ItemGroup>
     <PackageReference Include="AspNetCoreRateLimit" Version="5.0.0" />
+    <PackageReference Include="Blake3" Version="2.0.0" />
     <PackageReference Include="IDisposableAnalyzers" Version="4.0.8">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>

LightlessSyncServer/LightlessSyncServer/Models/BroadcastRedisEntry.cs

@@ -9,4 +9,4 @@ public class BroadcastRedisEntry()
     public bool OwnedBy(string userUid) => !string.IsNullOrEmpty(userUid) && string.Equals(OwnerUID, userUid, StringComparison.Ordinal);
 
     public bool HasOwner() => !string.IsNullOrEmpty(OwnerUID);
-}
+}

LightlessSyncServer/LightlessSyncServer/Models/ChatModels.cs

@@ -0,0 +1,59 @@
+using System;
+using System.Collections.Generic;
+using LightlessSync.API.Data;
+using LightlessSync.API.Dto.Chat;
+
+namespace LightlessSyncServer.Models;
+
+internal readonly record struct ChatReportSnapshotItem(
+    string MessageId,
+    DateTime SentAtUtc,
+    string SenderUserUid,
+    string? SenderAlias,
+    bool SenderIsLightfinder,
+    string? SenderHashedCid,
+    string Message);
+
+public readonly record struct ChatPresenceEntry(
+    ChatChannelDescriptor Channel,
+    ChannelKey ChannelKey,
+    string DisplayName,
+    ChatParticipantInfo Participant,
+    DateTime UpdatedAt);
+
+public readonly record struct ChatParticipantInfo(
+    string Token,
+    string UserUid,
+    UserData? User,
+    string? HashedCid,
+    bool IsLightfinder);
+
+public readonly record struct ChatMessageLogEntry(
+    string MessageId,
+    ChatChannelDescriptor Channel,
+    DateTime SentAtUtc,
+    string SenderToken,
+    string SenderUserUid,
+    UserData? SenderUser,
+    bool SenderIsLightfinder,
+    string? SenderHashedCid,
+    string Message);
+
+public readonly record struct ZoneChannelDefinition(
+    string Key,
+    string DisplayName,
+    ChatChannelDescriptor Descriptor,
+    IReadOnlyList<string> TerritoryNames,
+    IReadOnlySet<ushort> TerritoryIds);
+
+public readonly record struct ChannelKey(ChatChannelType Type, ushort WorldId, string CustomKey)
+{
+    public static ChannelKey FromDescriptor(ChatChannelDescriptor descriptor) =>
+        new(
+            descriptor.Type,
+            descriptor.Type == ChatChannelType.Zone ? descriptor.WorldId : (ushort)0,
+            NormalizeKey(descriptor.CustomKey));
+
+    private static string NormalizeKey(string? value) =>
+        string.IsNullOrWhiteSpace(value) ? string.Empty : value.Trim().ToUpperInvariant();
+}

LightlessSyncServer/LightlessSyncServer/Models/ChatZoneDefinitions.cs

@@ -0,0 +1,67 @@
+using System.Collections.Generic;
+using LightlessSync.API.Dto.Chat;
+
+namespace LightlessSyncServer.Models;
+
+internal static class ChatZoneDefinitions
+{
+    public static IReadOnlyList<ZoneChannelDefinition> Defaults { get; } =
+        new[]
+        {
+            new ZoneChannelDefinition(
+                Key: "limsa",
+                DisplayName: "Limsa Lominsa",
+                Descriptor: new ChatChannelDescriptor
+                {
+                    Type = ChatChannelType.Zone,
+                    WorldId = 0,
+                    ZoneId = 0,
+                    CustomKey = "limsa"
+                },
+                TerritoryNames: new[]
+                {
+                    "Limsa Lominsa Lower Decks",
+                    "Limsa Lominsa Upper Decks"
+                },
+                TerritoryIds: TerritoryRegistry.GetIds(
+                    "Limsa Lominsa Lower Decks",
+                    "Limsa Lominsa Upper Decks")),
+            new ZoneChannelDefinition(
+                Key: "gridania",
+                DisplayName: "Gridania",
+                Descriptor: new ChatChannelDescriptor
+                {
+                    Type = ChatChannelType.Zone,
+                    WorldId = 0,
+                    ZoneId = 0,
+                    CustomKey = "gridania"
+                },
+                TerritoryNames: new[]
+                {
+                    "New Gridania",
+                    "Old Gridania"
+                },
+                TerritoryIds: TerritoryRegistry.GetIds(
+                    "New Gridania",
+                    "Old Gridania")),
+            new ZoneChannelDefinition(
+                Key: "uldah",
+                DisplayName: "Ul'dah",
+                Descriptor: new ChatChannelDescriptor
+                {
+                    Type = ChatChannelType.Zone,
+                    WorldId = 0,
+                    ZoneId = 0,
+                    CustomKey = "uldah"
+                },
+                TerritoryNames: new[]
+                {
+                    "Ul'dah - Steps of Nald",
+                    "Ul'dah - Steps of Thal"
+                },
+                TerritoryIds: TerritoryRegistry.GetIds(
+                    "Ul'dah - Steps of Nald",
+                    "Ul'dah - Steps of Thal"))
+        };
+
+}

LightlessSyncServer/LightlessSyncServer/Models/TerritoryDefinition.cs

@@ -0,0 +1,5 @@
+namespace LightlessSyncServer.Models;
+
+internal readonly record struct TerritoryDefinition(
+    ushort TerritoryId,
+    string Name);

LightlessSyncServer/LightlessSyncServer/Models/WorldDefinition.cs

@@ -0,0 +1,7 @@
+namespace LightlessSyncServer.Models;
+
+internal readonly record struct WorldDefinition(
+    ushort WorldId,
+    string Name,
+    string Region,
+    string DataCenter);

LightlessSyncServer/LightlessSyncServer/Models/WorldRegistry.generated.cs

@@ -0,0 +1,117 @@
+// <auto-generated />
+using System;
+using System.Collections.Generic;
+using System.Collections.ObjectModel;
+using System.Linq;
+
+namespace LightlessSyncServer.Models;
+
+internal static class WorldRegistry
+{
+    private static readonly WorldDefinition[] WorldArray = new[]
+    {
+        new WorldDefinition(80, "Cerberus", "Europe", "Chaos"),
+        new WorldDefinition(83, "Louisoix", "Europe", "Chaos"),
+        new WorldDefinition(71, "Moogle", "Europe", "Chaos"),
+        new WorldDefinition(39, "Omega", "Europe", "Chaos"),
+        new WorldDefinition(401, "Phantom", "Europe", "Chaos"),
+        new WorldDefinition(97, "Ragnarok", "Europe", "Chaos"),
+        new WorldDefinition(400, "Sagittarius", "Europe", "Chaos"),
+        new WorldDefinition(85, "Spriggan", "Europe", "Chaos"),
+        new WorldDefinition(402, "Alpha", "Europe", "Light"),
+        new WorldDefinition(36, "Lich", "Europe", "Light"),
+        new WorldDefinition(66, "Odin", "Europe", "Light"),
+        new WorldDefinition(56, "Phoenix", "Europe", "Light"),
+        new WorldDefinition(403, "Raiden", "Europe", "Light"),
+        new WorldDefinition(67, "Shiva", "Europe", "Light"),
+        new WorldDefinition(33, "Twintania", "Europe", "Light"),
+        new WorldDefinition(42, "Zodiark", "Europe", "Light"),
+        new WorldDefinition(90, "Aegis", "Japan", "Elemental"),
+        new WorldDefinition(68, "Atomos", "Japan", "Elemental"),
+        new WorldDefinition(45, "Carbuncle", "Japan", "Elemental"),
+        new WorldDefinition(58, "Garuda", "Japan", "Elemental"),
+        new WorldDefinition(94, "Gungnir", "Japan", "Elemental"),
+        new WorldDefinition(49, "Kujata", "Japan", "Elemental"),
+        new WorldDefinition(72, "Tonberry", "Japan", "Elemental"),
+        new WorldDefinition(50, "Typhon", "Japan", "Elemental"),
+        new WorldDefinition(43, "Alexander", "Japan", "Gaia"),
+        new WorldDefinition(69, "Bahamut", "Japan", "Gaia"),
+        new WorldDefinition(92, "Durandal", "Japan", "Gaia"),
+        new WorldDefinition(46, "Fenrir", "Japan", "Gaia"),
+        new WorldDefinition(59, "Ifrit", "Japan", "Gaia"),
+        new WorldDefinition(98, "Ridill", "Japan", "Gaia"),
+        new WorldDefinition(76, "Tiamat", "Japan", "Gaia"),
+        new WorldDefinition(51, "Ultima", "Japan", "Gaia"),
+        new WorldDefinition(44, "Anima", "Japan", "Mana"),
+        new WorldDefinition(23, "Asura", "Japan", "Mana"),
+        new WorldDefinition(70, "Chocobo", "Japan", "Mana"),
+        new WorldDefinition(47, "Hades", "Japan", "Mana"),
+        new WorldDefinition(48, "Ixion", "Japan", "Mana"),
+        new WorldDefinition(96, "Masamune", "Japan", "Mana"),
+        new WorldDefinition(28, "Pandaemonium", "Japan", "Mana"),
+        new WorldDefinition(61, "Titan", "Japan", "Mana"),
+        new WorldDefinition(24, "Belias", "Japan", "Meteor"),
+        new WorldDefinition(82, "Mandragora", "Japan", "Meteor"),
+        new WorldDefinition(60, "Ramuh", "Japan", "Meteor"),
+        new WorldDefinition(29, "Shinryu", "Japan", "Meteor"),
+        new WorldDefinition(30, "Unicorn", "Japan", "Meteor"),
+        new WorldDefinition(52, "Valefor", "Japan", "Meteor"),
+        new WorldDefinition(31, "Yojimbo", "Japan", "Meteor"),
+        new WorldDefinition(32, "Zeromus", "Japan", "Meteor"),
+        new WorldDefinition(73, "Adamantoise", "North America", "Aether"),
+        new WorldDefinition(79, "Cactuar", "North America", "Aether"),
+        new WorldDefinition(54, "Faerie", "North America", "Aether"),
+        new WorldDefinition(63, "Gilgamesh", "North America", "Aether"),
+        new WorldDefinition(40, "Jenova", "North America", "Aether"),
+        new WorldDefinition(65, "Midgardsormr", "North America", "Aether"),
+        new WorldDefinition(99, "Sargatanas", "North America", "Aether"),
+        new WorldDefinition(57, "Siren", "North America", "Aether"),
+        new WorldDefinition(91, "Balmung", "North America", "Crystal"),
+        new WorldDefinition(34, "Brynhildr", "North America", "Crystal"),
+        new WorldDefinition(74, "Coeurl", "North America", "Crystal"),
+        new WorldDefinition(62, "Diabolos", "North America", "Crystal"),
+        new WorldDefinition(81, "Goblin", "North America", "Crystal"),
+        new WorldDefinition(75, "Malboro", "North America", "Crystal"),
+        new WorldDefinition(37, "Mateus", "North America", "Crystal"),
+        new WorldDefinition(41, "Zalera", "North America", "Crystal"),
+        new WorldDefinition(408, "Cuchulainn", "North America", "Dynamis"),
+        new WorldDefinition(411, "Golem", "North America", "Dynamis"),
+        new WorldDefinition(406, "Halicarnassus", "North America", "Dynamis"),
+        new WorldDefinition(409, "Kraken", "North America", "Dynamis"),
+        new WorldDefinition(407, "Maduin", "North America", "Dynamis"),
+        new WorldDefinition(404, "Marilith", "North America", "Dynamis"),
+        new WorldDefinition(410, "Rafflesia", "North America", "Dynamis"),
+        new WorldDefinition(405, "Seraph", "North America", "Dynamis"),
+        new WorldDefinition(78, "Behemoth", "North America", "Primal"),
+        new WorldDefinition(93, "Excalibur", "North America", "Primal"),
+        new WorldDefinition(53, "Exodus", "North America", "Primal"),
+        new WorldDefinition(35, "Famfrit", "North America", "Primal"),
+        new WorldDefinition(95, "Hyperion", "North America", "Primal"),
+        new WorldDefinition(55, "Lamia", "North America", "Primal"),
+        new WorldDefinition(64, "Leviathan", "North America", "Primal"),
+        new WorldDefinition(77, "Ultros", "North America", "Primal"),
+        new WorldDefinition(22, "Bismarck", "Oceania", "Materia"),
+        new WorldDefinition(21, "Ravana", "Oceania", "Materia"),
+        new WorldDefinition(86, "Sephirot", "Oceania", "Materia"),
+        new WorldDefinition(87, "Sophia", "Oceania", "Materia"),
+        new WorldDefinition(88, "Zurvan", "Oceania", "Materia"),
+    };
+
+    public static IReadOnlyList<WorldDefinition> All { get; } = Array.AsReadOnly(WorldArray);
+    public static IReadOnlyDictionary<ushort, WorldDefinition> ById { get; } = new ReadOnlyDictionary<ushort, WorldDefinition>(WorldArray.ToDictionary(w => w.WorldId));
+    public static IReadOnlyDictionary<string, IReadOnlyList<WorldDefinition>> ByDataCenter { get; } = new ReadOnlyDictionary<string, IReadOnlyList<WorldDefinition>>(WorldArray
+        .GroupBy(w => w.DataCenter, StringComparer.OrdinalIgnoreCase)
+        .ToDictionary(
+            g => g.Key,
+            g => (IReadOnlyList<WorldDefinition>)g.OrderBy(w => w.Name, StringComparer.Ordinal).ToArray(),
+            StringComparer.OrdinalIgnoreCase));
+    public static IReadOnlyDictionary<string, IReadOnlyList<WorldDefinition>> ByRegion { get; } = new ReadOnlyDictionary<string, IReadOnlyList<WorldDefinition>>(WorldArray
+        .GroupBy(w => w.Region, StringComparer.OrdinalIgnoreCase)
+        .ToDictionary(
+            g => g.Key,
+            g => (IReadOnlyList<WorldDefinition>)g.OrderBy(w => w.Name, StringComparer.Ordinal).ToArray(),
+            StringComparer.OrdinalIgnoreCase));
+
+    public static bool TryGet(ushort worldId, out WorldDefinition definition) => ById.TryGetValue(worldId, out definition);
+    public static bool IsKnownWorld(ushort worldId) => ById.ContainsKey(worldId);
+}

LightlessSyncServer/LightlessSyncServer/Services/ChatChannelService.cs

@@ -0,0 +1,461 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Security.Cryptography;
+using LightlessSync.API.Data;
+using LightlessSync.API.Dto.Chat;
+using LightlessSyncServer.Models;
+using Microsoft.Extensions.Logging;
+
+namespace LightlessSyncServer.Services;
+
+public sealed class ChatChannelService
+{
+    private readonly ILogger<ChatChannelService> _logger;
+    private readonly Dictionary<string, ZoneChannelDefinition> _zoneDefinitions;
+    private readonly Dictionary<ChannelKey, HashSet<string>> _membersByChannel = new();
+    private readonly Dictionary<string, Dictionary<ChannelKey, ChatPresenceEntry>> _presenceByUser = new(StringComparer.Ordinal);
+    private readonly Dictionary<ChannelKey, Dictionary<string, ChatParticipantInfo>> _participantsByChannel = new();
+    private readonly Dictionary<ChannelKey, LinkedList<ChatMessageLogEntry>> _messagesByChannel = new();
+    private readonly Dictionary<string, (ChannelKey Channel, LinkedListNode<ChatMessageLogEntry> Node)> _messageIndex = new(StringComparer.Ordinal);
+    private readonly object _syncRoot = new();
+    private const int MaxMessagesPerChannel = 200;
+
+    public ChatChannelService(ILogger<ChatChannelService> logger)
+    {
+        _logger = logger;
+        _zoneDefinitions = ChatZoneDefinitions.Defaults
+            .ToDictionary(definition => definition.Key, StringComparer.OrdinalIgnoreCase);
+    }
+
+    public IReadOnlyList<ZoneChatChannelInfoDto> GetZoneChannelInfos() =>
+        _zoneDefinitions.Values
+            .Select(definition => new ZoneChatChannelInfoDto(
+                definition.Descriptor,
+                definition.DisplayName,
+                definition.TerritoryNames))
+            .ToArray();
+
+    public bool TryResolveZone(string? key, out ZoneChannelDefinition definition)
+    {
+        definition = default;
+        if (string.IsNullOrWhiteSpace(key))
+            return false;
+
+        return _zoneDefinitions.TryGetValue(key, out definition);
+    }
+
+    public ChatPresenceEntry? UpdateZonePresence(
+        string userUid,
+        ZoneChannelDefinition definition,
+        ushort worldId,
+        ushort territoryId,
+        string? hashedCid,
+        bool isLightfinder,
+        bool isActive)
+    {
+        if (worldId == 0 || !WorldRegistry.IsKnownWorld(worldId))
+        {
+            _logger.LogWarning("Rejected zone chat presence for {User} in {Zone}: unknown world {WorldId}", userUid, definition.Key, worldId);
+            return null;
+        }
+
+        if (!definition.TerritoryIds.Contains(territoryId))
+        {
+            _logger.LogWarning("Rejected zone chat presence for {User} in {Zone}: invalid territory {TerritoryId}", userUid, definition.Key, territoryId);
+            return null;
+        }
+
+        var descriptor = definition.Descriptor with { WorldId = worldId, ZoneId = territoryId };
+        var participant = new ChatParticipantInfo(
+            Token: string.Empty,
+            UserUid: userUid,
+            User: null,
+            HashedCid: isLightfinder ? hashedCid : null,
+            IsLightfinder: isLightfinder);
+
+        return UpdatePresence(
+            userUid,
+            descriptor,
+            definition.DisplayName,
+            participant,
+            isActive,
+            replaceExistingOfSameType: true);
+    }
+
+    public ChatPresenceEntry? UpdateGroupPresence(
+        string userUid,
+        string groupId,
+        string displayName,
+        UserData user,
+        string? hashedCid,
+        bool isActive)
+    {
+        var descriptor = new ChatChannelDescriptor
+        {
+            Type = ChatChannelType.Group,
+            WorldId = 0,
+            ZoneId = 0,
+            CustomKey = groupId
+        };
+
+        var participant = new ChatParticipantInfo(
+            Token: string.Empty,
+            UserUid: userUid,
+            User: user,
+            HashedCid: hashedCid,
+            IsLightfinder: !string.IsNullOrEmpty(hashedCid));
+
+        return UpdatePresence(
+            userUid,
+            descriptor,
+            displayName,
+            participant,
+            isActive,
+            replaceExistingOfSameType: false);
+    }
+
+    public bool TryGetPresence(string userUid, ChatChannelDescriptor channel, out ChatPresenceEntry presence)
+    {
+        var key = ChannelKey.FromDescriptor(channel);
+
+        lock (_syncRoot)
+        {
+            if (_presenceByUser.TryGetValue(userUid, out var entries) && entries.TryGetValue(key, out presence))
+            {
+                return true;
+            }
+        }
+
+        presence = default;
+        return false;
+    }
+
+    public IReadOnlyCollection<string> GetMembers(ChatChannelDescriptor channel)
+    {
+        var key = ChannelKey.FromDescriptor(channel);
+
+        lock (_syncRoot)
+        {
+            if (_membersByChannel.TryGetValue(key, out var members))
+            {
+                return members.ToArray();
+            }
+        }
+
+        return Array.Empty<string>();
+    }
+
+    public string RecordMessage(ChatChannelDescriptor channel, ChatParticipantInfo participant, string message, DateTime sentAtUtc)
+    {
+        var key = ChannelKey.FromDescriptor(channel);
+        var messageId = Guid.NewGuid().ToString("N");
+        var entry = new ChatMessageLogEntry(
+            messageId,
+            channel,
+            sentAtUtc,
+            participant.Token,
+            participant.UserUid,
+            participant.User,
+            participant.IsLightfinder,
+            participant.HashedCid,
+            message);
+
+        lock (_syncRoot)
+        {
+            if (!_messagesByChannel.TryGetValue(key, out var list))
+            {
+                list = new LinkedList<ChatMessageLogEntry>();
+                _messagesByChannel[key] = list;
+            }
+
+            var node = list.AddLast(entry);
+            _messageIndex[messageId] = (key, node);
+
+            while (list.Count > MaxMessagesPerChannel)
+            {
+                var removedNode = list.First;
+                if (removedNode is null)
+                {
+                    break;
+                }
+
+                list.RemoveFirst();
+                _messageIndex.Remove(removedNode.Value.MessageId);
+            }
+        }
+
+        return messageId;
+    }
+
+    public bool TryGetMessage(string messageId, out ChatMessageLogEntry entry)
+    {
+        lock (_syncRoot)
+        {
+            if (_messageIndex.TryGetValue(messageId, out var located))
+            {
+                entry = located.Node.Value;
+                return true;
+            }
+        }
+
+        entry = default;
+        return false;
+    }
+
+    public IReadOnlyList<ChatMessageLogEntry> GetRecentMessages(ChatChannelDescriptor descriptor, int maxCount)
+    {
+        lock (_syncRoot)
+        {
+            var key = ChannelKey.FromDescriptor(descriptor);
+            if (!_messagesByChannel.TryGetValue(key, out var list) || list.Count == 0)
+            {
+                return Array.Empty<ChatMessageLogEntry>();
+            }
+
+            var take = Math.Min(maxCount, list.Count);
+            var result = new ChatMessageLogEntry[take];
+            var node = list.Last;
+            for (var i = take - 1; i >= 0 && node is not null; i--)
+            {
+                result[i] = node.Value;
+                node = node.Previous;
+            }
+
+            return result;
+        }
+    }
+
+    public bool RemovePresence(string userUid, ChatChannelDescriptor? channel = null)
+    {
+        ArgumentException.ThrowIfNullOrEmpty(userUid);
+
+        lock (_syncRoot)
+        {
+            if (!_presenceByUser.TryGetValue(userUid, out var entries))
+            {
+                return false;
+            }
+
+            if (channel is null)
+            {
+                foreach (var existing in entries.Keys.ToList())
+                {
+                    RemovePresenceInternal(userUid, entries, existing);
+                }
+
+                _presenceByUser.Remove(userUid);
+                return true;
+            }
+
+            var key = ChannelKey.FromDescriptor(channel.Value);
+            var removed = RemovePresenceInternal(userUid, entries, key);
+
+            if (entries.Count == 0)
+            {
+                _presenceByUser.Remove(userUid);
+            }
+
+            return removed;
+        }
+    }
+
+    public bool TryResolveParticipant(ChatChannelDescriptor channel, string token, out ChatParticipantInfo participant)
+    {
+        var key = ChannelKey.FromDescriptor(channel);
+
+        lock (_syncRoot)
+        {
+            if (_participantsByChannel.TryGetValue(key, out var participants) &&
+                participants.TryGetValue(token, out participant))
+            {
+                return true;
+            }
+        }
+
+        participant = default;
+        return false;
+    }
+
+    public void RefreshLightfinderState(string userUid, string? hashedCid, bool isLightfinder)
+    {
+        ArgumentException.ThrowIfNullOrEmpty(userUid);
+
+        lock (_syncRoot)
+        {
+            if (!_presenceByUser.TryGetValue(userUid, out var entries) || entries.Count == 0)
+            {
+                return;
+            }
+
+            foreach (var (key, existing) in entries.ToArray())
+            {
+                var updatedParticipant = existing.Participant with
+                {
+                    HashedCid = isLightfinder ? hashedCid : null,
+                    IsLightfinder = isLightfinder
+                };
+
+                var updatedEntry = existing with
+                {
+                    Participant = updatedParticipant,
+                    UpdatedAt = DateTime.UtcNow
+                };
+
+                entries[key] = updatedEntry;
+
+                if (_participantsByChannel.TryGetValue(key, out var participants))
+                {
+                    participants[updatedParticipant.Token] = updatedParticipant;
+                }
+            }
+        }
+    }
+
+    private ChatPresenceEntry? UpdatePresence(
+        string userUid,
+        ChatChannelDescriptor descriptor,
+        string displayName,
+        ChatParticipantInfo participant,
+        bool isActive,
+        bool replaceExistingOfSameType)
+    {
+        ArgumentException.ThrowIfNullOrEmpty(userUid);
+
+        var normalizedDescriptor = descriptor.WithNormalizedCustomKey();
+        var key = ChannelKey.FromDescriptor(normalizedDescriptor);
+
+        lock (_syncRoot)
+        {
+            if (!_presenceByUser.TryGetValue(userUid, out var entries))
+            {
+                if (!isActive)
+                    return null;
+
+                entries = new Dictionary<ChannelKey, ChatPresenceEntry>();
+                _presenceByUser[userUid] = entries;
+            }
+
+            string? reusableToken = null;
+
+            if (entries.TryGetValue(key, out var existing))
+            {
+                reusableToken = existing.Participant.Token;
+                RemovePresenceInternal(userUid, entries, key);
+            }
+
+            if (replaceExistingOfSameType)
+            {
+                foreach (var candidate in entries.Keys.Where(k => k.Type == key.Type).ToList())
+                {
+                    if (entries.TryGetValue(candidate, out var entry))
+                    {
+                        reusableToken ??= entry.Participant.Token;
+                    }
+
+                    RemovePresenceInternal(userUid, entries, candidate);
+                }
+
+                if (!isActive)
+                {
+                    if (entries.Count == 0)
+                    {
+                        _presenceByUser.Remove(userUid);
+                    }
+
+                    _logger.LogDebug("Chat presence cleared for {User} ({Type})", userUid, normalizedDescriptor.Type);
+                    return null;
+                }
+            }
+            else if (!isActive)
+            {
+                var removed = RemovePresenceInternal(userUid, entries, key);
+                if (removed)
+                {
+                    _logger.LogDebug("Chat presence removed for {User} from {Channel}", userUid, Describe(key));
+                }
+
+                if (entries.Count == 0)
+                {
+                    _presenceByUser.Remove(userUid);
+                }
+
+                return null;
+            }
+
+            var token = !string.IsNullOrEmpty(participant.Token)
+                ? participant.Token
+                : reusableToken ?? GenerateToken();
+
+            var finalParticipant = participant with { Token = token };
+            var entryToStore = new ChatPresenceEntry(
+                normalizedDescriptor,
+                key,
+                displayName,
+                finalParticipant,
+                DateTime.UtcNow);
+
+            entries[key] = entryToStore;
+
+            if (!_membersByChannel.TryGetValue(key, out var members))
+            {
+                members = new HashSet<string>(StringComparer.Ordinal);
+                _membersByChannel[key] = members;
+            }
+
+            members.Add(userUid);
+
+            if (!_participantsByChannel.TryGetValue(key, out var participantsByToken))
+            {
+                participantsByToken = new Dictionary<string, ChatParticipantInfo>(StringComparer.Ordinal);
+                _participantsByChannel[key] = participantsByToken;
+            }
+
+            participantsByToken[token] = finalParticipant;
+
+            _logger.LogDebug("Chat presence updated for {User} in {Channel}", userUid, Describe(key));
+            return entryToStore;
+        }
+    }
+
+    private bool RemovePresenceInternal(string userUid, Dictionary<ChannelKey, ChatPresenceEntry> entries, ChannelKey key)
+    {
+        if (!entries.TryGetValue(key, out var existing))
+        {
+            return false;
+        }
+
+        entries.Remove(key);
+
+        if (_membersByChannel.TryGetValue(key, out var members))
+        {
+            members.Remove(userUid);
+            if (members.Count == 0)
+            {
+                _membersByChannel.Remove(key);
+                // Preserve message history even when a channel becomes empty so moderation can still resolve reports.
+            }
+        }
+
+        if (_participantsByChannel.TryGetValue(key, out var participants))
+        {
+            participants.Remove(existing.Participant.Token);
+            if (participants.Count == 0)
+            {
+                _participantsByChannel.Remove(key);
+            }
+        }
+
+        return true;
+    }
+
+    private static string GenerateToken()
+    {
+        Span<byte> buffer = stackalloc byte[8];
+        RandomNumberGenerator.Fill(buffer);
+        return Convert.ToHexString(buffer);
+    }
+
+    private static string Describe(ChannelKey key)
+        => $"{key.Type}:{key.WorldId}:{key.CustomKey}";
+}

LightlessSyncServer/LightlessSyncServer/Startup.cs

@@ -93,6 +93,7 @@ public class Startup
         services.AddSingleton<ServerTokenGenerator>();
         services.AddSingleton<SystemInfoService>();
         services.AddSingleton<OnlineSyncedPairCacheService>();
+        services.AddSingleton<ChatChannelService>();
         services.AddHostedService(provider => provider.GetService<SystemInfoService>());
         // configure services based on main server status
         ConfigureServicesBasedOnShardType(services, lightlessConfig, isMainServer);

LightlessSyncServer/LightlessSyncServices/Discord/DiscordBot.cs

@@ -1,3 +1,9 @@
+using System.Collections.Generic;
+using System;
+using System.Globalization;
+using System.Text;
+using System.Text.Json;
+using System.Linq;
 using Discord;
 using Discord.Interactions;
 using Discord.Rest;
@@ -5,6 +11,7 @@ using Discord.WebSocket;
 using LightlessSyncShared.Data;
 using LightlessSyncShared.Models;
 using LightlessSyncShared.Services;
+using LightlessSync.API.Dto.Chat;
 using LightlessSyncShared.Utils.Configuration;
 using Microsoft.EntityFrameworkCore;
 using StackExchange.Redis;
@@ -13,6 +20,12 @@ namespace LightlessSyncServices.Discord;
 
 internal class DiscordBot : IHostedService
 {
+    private static readonly JsonSerializerOptions ChatReportSerializerOptions = new(JsonSerializerDefaults.General)
+    {
+        PropertyNameCaseInsensitive = true
+    };
+    private const string ChatReportButtonPrefix = "lightless-chat-report-button";
+
     private readonly DiscordBotServices _botServices;
     private readonly IConfigurationService<ServicesConfiguration> _configurationService;
     private readonly IConnectionMultiplexer _connectionMultiplexer;
@@ -21,7 +34,7 @@ internal class DiscordBot : IHostedService
     private readonly IDbContextFactory<LightlessDbContext> _dbContextFactory;
     private readonly IServiceProvider _services;
     private InteractionService _interactionModule;
-    private readonly CancellationTokenSource? _processReportQueueCts;
+    private CancellationTokenSource? _chatReportProcessingCts;
     private CancellationTokenSource? _clientConnectedCts;
 
     public DiscordBot(DiscordBotServices botServices, IServiceProvider services, IConfigurationService<ServicesConfiguration> configuration,
@@ -66,6 +79,7 @@ internal class DiscordBot : IHostedService
                 var ctx = new SocketInteractionContext(_discordClient, x);
                 await _interactionModule.ExecuteCommandAsync(ctx, _services).ConfigureAwait(false);
             };
+            _discordClient.ButtonExecuted += OnChatReportButton;
             _discordClient.UserJoined += OnUserJoined;
 
             await _botServices.Start().ConfigureAwait(false);
@@ -94,9 +108,11 @@ internal class DiscordBot : IHostedService
         if (!string.IsNullOrEmpty(_configurationService.GetValueOrDefault(nameof(ServicesConfiguration.DiscordBotToken), string.Empty)))
         {
             await _botServices.Stop().ConfigureAwait(false);
-            _processReportQueueCts?.Cancel();
+            _chatReportProcessingCts?.Cancel();
+            _chatReportProcessingCts?.Dispose();
             _clientConnectedCts?.Cancel();
 
+            _discordClient.ButtonExecuted -= OnChatReportButton;
             await _discordClient.LogoutAsync().ConfigureAwait(false);
             await _discordClient.StopAsync().ConfigureAwait(false);
             _interactionModule?.Dispose();
@@ -112,6 +128,13 @@ internal class DiscordBot : IHostedService
         _clientConnectedCts = new();
         _ = UpdateStatusAsync(_clientConnectedCts.Token);
 
+        _chatReportProcessingCts?.Cancel();
+        _chatReportProcessingCts?.Dispose();
+        _chatReportProcessingCts = new();
+        _ = PollChatReportsAsync(_chatReportProcessingCts.Token);
+
+        await PublishChatReportsAsync(CancellationToken.None).ConfigureAwait(false);
+
         await CreateOrUpdateModal(guild).ConfigureAwait(false);
         _botServices.UpdateGuild(guild);
         await _botServices.LogToChannel("Bot startup complete.").ConfigureAwait(false);
@@ -120,6 +143,358 @@ internal class DiscordBot : IHostedService
         _ = RemoveUnregisteredUsers(_clientConnectedCts.Token);
     }
 
+    private async Task PollChatReportsAsync(CancellationToken token)
+    {
+        while (!token.IsCancellationRequested)
+        {
+            try
+            {
+                await PublishChatReportsAsync(token).ConfigureAwait(false);
+            }
+            catch (OperationCanceledException)
+            {
+                break;
+            }
+            catch (Exception ex)
+            {
+                _logger.LogWarning(ex, "Failed while polling chat reports");
+            }
+
+            try
+            {
+                await Task.Delay(TimeSpan.FromMinutes(10), token).ConfigureAwait(false);
+            }
+            catch (OperationCanceledException)
+            {
+                break;
+            }
+        }
+    }
+
+    private async Task PublishChatReportsAsync(CancellationToken token)
+    {
+        var reportChannelId = _configurationService.GetValueOrDefault(nameof(ServicesConfiguration.DiscordChannelForChatReports), (ulong?)null);
+        if (reportChannelId is null)
+        {
+            return;
+        }
+
+        var channel = await _discordClient.Rest.GetChannelAsync(reportChannelId.Value).ConfigureAwait(false) as RestTextChannel;
+        if (channel is null)
+        {
+            _logger.LogWarning("Configured chat report channel {ChannelId} could not be resolved.", reportChannelId);
+            return;
+        }
+
+        using var dbContext = await _dbContextFactory.CreateDbContextAsync(token).ConfigureAwait(false);
+        var pendingReports = await dbContext.ReportedChatMessages
+            .Where(r => !r.Resolved && r.DiscordMessageId == null)
+            .OrderBy(r => r.ReportTimeUtc)
+            .Take(10)
+            .ToListAsync(token)
+            .ConfigureAwait(false);
+
+        if (pendingReports.Count == 0)
+        {
+            return;
+        }
+
+        foreach (var report in pendingReports)
+        {
+            var embed = await BuildChatReportEmbedAsync(dbContext, report, token).ConfigureAwait(false);
+
+            var components = new ComponentBuilder()
+                .WithButton("Actioned", $"{ChatReportButtonPrefix}-resolve-{report.ReportId}", ButtonStyle.Danger)
+                .WithButton("Dismiss", $"{ChatReportButtonPrefix}-dismiss-{report.ReportId}", ButtonStyle.Secondary)
+                .WithButton("Ban From Chat", $"{ChatReportButtonPrefix}-banchat-{report.ReportId}", ButtonStyle.Danger);
+
+            var postedMessage = await channel.SendMessageAsync(embed: embed.Build(), components: components.Build()).ConfigureAwait(false);
+
+            report.DiscordMessageId = postedMessage.Id;
+            report.DiscordMessagePostedAtUtc = DateTime.UtcNow;
+        }
+
+        await dbContext.SaveChangesAsync(token).ConfigureAwait(false);
+    }
+
+    private async Task<EmbedBuilder> BuildChatReportEmbedAsync(LightlessDbContext dbContext, ReportedChatMessage report, CancellationToken token)
+    {
+        var reporter = await FormatUserForEmbedAsync(dbContext, report.ReporterUserUid, token).ConfigureAwait(false);
+        var reportedUser = await FormatUserForEmbedAsync(dbContext, report.ReportedUserUid, token).ConfigureAwait(false);
+        var channelDescription = await DescribeChannelAsync(dbContext, report, token).ConfigureAwait(false);
+
+        var embed = new EmbedBuilder()
+            .WithTitle("Chat Report")
+            .WithColor(Color.DarkTeal)
+            .WithTimestamp(report.ReportTimeUtc)
+            .AddField("Report ID", report.ReportId, inline: true)
+            .AddField("Reporter", reporter, inline: true)
+            .AddField("Reported User", string.IsNullOrEmpty(reportedUser) ? "-" : reportedUser, inline: true)
+            .AddField("Channel", channelDescription, inline: false)
+            .AddField("Reason", string.IsNullOrWhiteSpace(report.Reason) ? "-" : report.Reason);
+
+        if (!string.IsNullOrWhiteSpace(report.AdditionalContext))
+        {
+            embed.AddField("Additional Context", report.AdditionalContext);
+        }
+
+        embed.AddField("Message", $"```{Truncate(report.MessageContent, 1000)}```");
+
+        var snapshotPreview = BuildSnapshotPreview(report.SnapshotJson);
+        if (!string.IsNullOrEmpty(snapshotPreview))
+        {
+            embed.AddField("Recent Activity", snapshotPreview);
+        }
+
+        embed.WithFooter($"Message ID: {report.MessageId}");
+
+        return embed;
+    }
+
+    private async Task<string> DescribeChannelAsync(LightlessDbContext dbContext, ReportedChatMessage report, CancellationToken token)
+    {
+        if (report.ChannelType == ChatChannelType.Group)
+        {
+            if (!string.IsNullOrEmpty(report.ChannelKey))
+            {
+                var group = await dbContext.Groups.AsNoTracking()
+                    .SingleOrDefaultAsync(g => g.GID == report.ChannelKey, token)
+                    .ConfigureAwait(false);
+                if (group != null)
+                {
+                    var name = string.IsNullOrWhiteSpace(group.Alias) ? group.GID : group.Alias;
+                    return $"Group: {name} ({group.GID})";
+                }
+            }
+
+            return $"Group: {report.ChannelKey ?? "unknown"}";
+        }
+
+        return $"Zone: {report.ChannelKey ?? "unknown"} (World {report.WorldId}, Zone {report.ZoneId})";
+    }
+
+    private async Task<string> FormatUserForEmbedAsync(LightlessDbContext dbContext, string? userUid, CancellationToken token)
+    {
+        if (string.IsNullOrEmpty(userUid))
+        {
+            return "-";
+        }
+
+        var user = await dbContext.Users.AsNoTracking()
+            .SingleOrDefaultAsync(u => u.UID == userUid, token)
+            .ConfigureAwait(false);
+
+        var display = user?.Alias ?? user?.UID ?? userUid;
+
+        var lodestone = await dbContext.LodeStoneAuth
+            .Include(l => l.User)
+            .AsNoTracking()
+            .SingleOrDefaultAsync(l => l.User != null && l.User.UID == userUid, token)
+            .ConfigureAwait(false);
+
+        if (lodestone != null)
+        {
+            display = $"{display} (<@{lodestone.DiscordId}>)";
+        }
+
+        return display;
+    }
+
+    private string BuildSnapshotPreview(string snapshotJson)
+    {
+        if (string.IsNullOrWhiteSpace(snapshotJson))
+        {
+            return string.Empty;
+        }
+
+        try
+        {
+            var snapshot = JsonSerializer.Deserialize<List<ChatReportSnapshotItem>>(snapshotJson, ChatReportSerializerOptions);
+            if (snapshot is null || snapshot.Count == 0)
+            {
+                return string.Empty;
+            }
+
+            var builder = new StringBuilder();
+            foreach (var item in snapshot.TakeLast(5))
+            {
+                var sender = item.SenderAlias ?? item.SenderUserUid;
+                builder.AppendLine($"{item.SentAtUtc:HH\\:mm} {sender}: {Truncate(item.Message, 120)}");
+            }
+
+            return $"```{builder.ToString().TrimEnd()}```";
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "Failed to parse chat report snapshot");
+            return string.Empty;
+        }
+    }
+
+    private static string Truncate(string value, int maxLength)
+    {
+        if (string.IsNullOrEmpty(value) || value.Length <= maxLength)
+        {
+            return value;
+        }
+
+        return value[..maxLength] + "...";
+    }
+
+    private async Task OnChatReportButton(SocketMessageComponent arg)
+    {
+        if (!arg.Data.CustomId.StartsWith(ChatReportButtonPrefix, StringComparison.Ordinal))
+        {
+            return;
+        }
+
+        if (arg.GuildId is null)
+        {
+            await arg.RespondAsync("This action is only available inside the server.", ephemeral: true).ConfigureAwait(false);
+            return;
+        }
+
+        var guild = _discordClient.GetGuild(arg.GuildId.Value);
+        if (guild is null)
+        {
+            await arg.RespondAsync("Unable to resolve the guild for this interaction.", ephemeral: true).ConfigureAwait(false);
+            return;
+        }
+
+        var guildUser = guild.GetUser(arg.User.Id);
+        if (guildUser is null || !(guildUser.GuildPermissions.ManageMessages || guildUser.GuildPermissions.BanMembers || guildUser.GuildPermissions.Administrator))
+        {
+            await arg.RespondAsync("You do not have permission to resolve chat reports.", ephemeral: true).ConfigureAwait(false);
+            return;
+        }
+
+        var parts = arg.Data.CustomId.Split('-', StringSplitOptions.RemoveEmptyEntries);
+        if (parts.Length < 5 || !int.TryParse(parts[^1], NumberStyles.Integer, CultureInfo.InvariantCulture, out var reportId))
+        {
+            await arg.RespondAsync("Invalid report action.", ephemeral: true).ConfigureAwait(false);
+            return;
+        }
+
+        var action = parts[^2];
+
+        await using var dbContext = await _dbContextFactory.CreateDbContextAsync().ConfigureAwait(false);
+        var report = await dbContext.ReportedChatMessages.SingleOrDefaultAsync(r => r.ReportId == reportId).ConfigureAwait(false);
+        if (report is null)
+        {
+            await arg.RespondAsync("This report could not be found.", ephemeral: true).ConfigureAwait(false);
+            return;
+        }
+
+        if (report.Resolved)
+        {
+            await arg.RespondAsync("This report has already been processed.", ephemeral: true).ConfigureAwait(false);
+            return;
+        }
+
+        string resolutionLabel;
+        switch (action)
+        {
+            case "resolve":
+                resolutionLabel = "Actioned";
+                break;
+            case "dismiss":
+                resolutionLabel = "Dismissed";
+                break;
+            case "banchat":
+                resolutionLabel = "Chat access revoked";
+                if (!string.IsNullOrEmpty(report.ReportedUserUid))
+                {
+                    var targetUser = await dbContext.Users.SingleOrDefaultAsync(u => u.UID == report.ReportedUserUid).ConfigureAwait(false);
+                    if (targetUser is not null && !targetUser.ChatBanned)
+                    {
+                        targetUser.ChatBanned = true;
+                        dbContext.Update(targetUser);
+                    }
+                }
+                break;
+            default:
+                await arg.RespondAsync("Unknown action.", ephemeral: true).ConfigureAwait(false);
+                return;
+        }
+
+        try
+        {
+            await UpdateChatReportMessageAsync(report, action, guildUser).ConfigureAwait(false);
+        }
+        catch (Exception ex)
+        {
+            _logger.LogWarning(ex, "Failed to update Discord message for resolved report {ReportId}", report.ReportId);
+        }
+
+        dbContext.ReportedChatMessages.Remove(report);
+        await dbContext.SaveChangesAsync().ConfigureAwait(false);
+
+        string responseText = action switch
+        {
+            "resolve" => "actioned",
+            "dismiss" => "dismissed",
+            "banchat" => "chat access revoked",
+            _ => "processed"
+        };
+
+        await arg.RespondAsync($"Report {report.ReportId} {responseText}.", ephemeral: true).ConfigureAwait(false);
+    }
+
+    private async Task UpdateChatReportMessageAsync(ReportedChatMessage report, string action, SocketGuildUser moderator)
+    {
+        if (report.DiscordMessageId is null)
+        {
+            return;
+        }
+
+        var reportChannelId = _configurationService.GetValueOrDefault(nameof(ServicesConfiguration.DiscordChannelForChatReports), (ulong?)null);
+        if (reportChannelId is null)
+        {
+            return;
+        }
+
+        var channel = await _discordClient.Rest.GetChannelAsync(reportChannelId.Value).ConfigureAwait(false) as RestTextChannel;
+        if (channel is null)
+        {
+            return;
+        }
+
+        var message = await channel.GetMessageAsync(report.DiscordMessageId.Value).ConfigureAwait(false) as IUserMessage;
+        if (message is null)
+        {
+            return;
+        }
+
+        var existingEmbed = message.Embeds.FirstOrDefault();
+        var embedBuilder = existingEmbed is Embed richEmbed
+            ? richEmbed.ToEmbedBuilder()
+            : new EmbedBuilder().WithTitle("Chat Report");
+
+        embedBuilder.Fields.RemoveAll(f => string.Equals(f.Name, "Resolution", StringComparison.OrdinalIgnoreCase));
+        var resolutionText = action switch
+        {
+            "resolve" => "Actioned",
+            "dismiss" => "Dismissed",
+            "banchat" => "Chat access revoked",
+            _ => "Processed"
+        };
+        var resolutionColor = action switch
+        {
+            "resolve" => Color.DarkRed,
+            "dismiss" => Color.Green,
+            "banchat" => Color.DarkRed,
+            _ => Color.LightGrey
+        };
+        embedBuilder.AddField("Resolution", $"{resolutionText} by {moderator.Mention} at <t:{DateTimeOffset.UtcNow.ToUnixTimeSeconds()}:F>");
+        embedBuilder.WithColor(resolutionColor);
+
+        await message.ModifyAsync(props =>
+        {
+            props.Embed = embedBuilder.Build();
+            props.Components = new ComponentBuilder().Build();
+        }).ConfigureAwait(false);
+    }
+
     private async Task UpdateVanityRoles(RestGuild guild, CancellationToken token)
     {
         while (!token.IsCancellationRequested)
@@ -488,6 +863,15 @@ internal class DiscordBot : IHostedService
         }
     }
 
+    private sealed record ChatReportSnapshotItem(
+        string MessageId,
+        DateTime SentAtUtc,
+        string SenderUserUid,
+        string? SenderAlias,
+        bool SenderIsLightfinder,
+        string? SenderHashedCid,
+        string Message);
+
     private async Task UpdateStatusAsync(CancellationToken token)
     {
         while (!token.IsCancellationRequested)
@@ -500,4 +884,4 @@ internal class DiscordBot : IHostedService
             await Task.Delay(TimeSpan.FromSeconds(10)).ConfigureAwait(false);
         }
     }
-}
+}

LightlessSyncServer/LightlessSyncServices/Discord/MareWizardModule.cs

@@ -329,13 +329,12 @@ public partial class LightlessWizardModule : InteractionModuleBase
 
     private int? ParseCharacterIdFromLodestoneUrl(string lodestoneUrl)
     {
-        var regex = new Regex(@"https:\/\/(na|eu|de|fr|jp)\.finalfantasyxiv\.com\/lodestone\/character\/\d+");
+        var regex = new Regex(@"^https:\/\/(na|eu|de|fr|jp)\.finalfantasyxiv\.com\/lodestone\/character\/(\d+)/?$");
         var matches = regex.Match(lodestoneUrl);
         var isLodestoneUrl = matches.Success;
         if (!isLodestoneUrl || matches.Groups.Count < 1) return null;
+        var stringId = matches.Groups[2].ToString();
 
-        lodestoneUrl = matches.Groups[0].ToString();
-        var stringId = lodestoneUrl.Split('/', StringSplitOptions.RemoveEmptyEntries).Last();
         if (!int.TryParse(stringId, out int lodestoneId))
         {
             return null;

LightlessSyncServer/LightlessSyncShared/Data/MareDbContext.cs

@@ -45,6 +45,7 @@ public class LightlessDbContext : DbContext
     public DbSet<UserProfileData> UserProfileData { get; set; }
     public DbSet<User> Users { get; set; }
     public DbSet<UserPermissionSet> Permissions { get; set; }
+    public DbSet<ReportedChatMessage> ReportedChatMessages { get; set; }
     public DbSet<GroupPairPreferredPermission> GroupPairPreferredPermissions { get; set; }
     public DbSet<UserDefaultPreferredPermission> UserDefaultPreferredPermissions { get; set; }
     public DbSet<CharaData> CharaData { get; set; }
@@ -90,6 +91,12 @@ public class LightlessDbContext : DbContext
         mb.Entity<GroupProfile>().ToTable("group_profiles");
         mb.Entity<GroupProfile>().HasKey(u => u.GroupGID);
         mb.Entity<GroupProfile>().HasIndex(c => c.GroupGID);
+        mb.Entity<Group>()
+            .HasOne(g => g.Profile)
+            .WithOne(p => p.Group)
+            .HasForeignKey<GroupProfile>(p => p.GroupGID)
+            .IsRequired(false)
+            .OnDelete(DeleteBehavior.Cascade);
         mb.Entity<GroupTempInvite>().ToTable("group_temp_invites");
         mb.Entity<GroupTempInvite>().HasKey(u => new { u.GroupGID, u.Invite });
         mb.Entity<GroupTempInvite>().HasIndex(c => c.GroupGID);
@@ -153,5 +160,11 @@ public class LightlessDbContext : DbContext
         mb.Entity<CharaDataAllowance>().HasIndex(c => c.ParentId);
         mb.Entity<CharaDataAllowance>().HasOne(u => u.AllowedGroup).WithMany().HasForeignKey(u => u.AllowedGroupGID).OnDelete(DeleteBehavior.Cascade);
         mb.Entity<CharaDataAllowance>().HasOne(u => u.AllowedUser).WithMany().HasForeignKey(u => u.AllowedUserUID).OnDelete(DeleteBehavior.Cascade);
+
+        mb.Entity<ReportedChatMessage>().ToTable("reported_chat_messages");
+        mb.Entity<ReportedChatMessage>().HasIndex(r => r.ReporterUserUid);
+        mb.Entity<ReportedChatMessage>().HasIndex(r => r.ReportedUserUid);
+        mb.Entity<ReportedChatMessage>().HasIndex(r => r.MessageId).IsUnique();
+        mb.Entity<ReportedChatMessage>().HasIndex(r => r.DiscordMessageId);
     }
 }

LightlessSyncServer/LightlessSyncShared/Migrations/20251028215549_ChatReports.cs

@@ -0,0 +1,90 @@
+using System;
+using Microsoft.EntityFrameworkCore.Migrations;
+using Npgsql.EntityFrameworkCore.PostgreSQL.Metadata;
+
+#nullable disable
+
+namespace LightlessSyncServer.Migrations
+{
+    /// <inheritdoc />
+    public partial class ChatReports : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.CreateTable(
+                name: "reported_chat_messages",
+                columns: table => new
+                {
+                    report_id = table.Column<int>(type: "integer", nullable: false)
+                        .Annotation("Npgsql:ValueGenerationStrategy", NpgsqlValueGenerationStrategy.IdentityByDefaultColumn),
+                    report_time_utc = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
+                    reporter_user_uid = table.Column<string>(type: "text", nullable: false),
+                    reported_user_uid = table.Column<string>(type: "text", nullable: true),
+                    channel_type = table.Column<byte>(type: "smallint", nullable: false),
+                    world_id = table.Column<int>(type: "integer", nullable: false),
+                    zone_id = table.Column<int>(type: "integer", nullable: false),
+                    channel_key = table.Column<string>(type: "text", nullable: false),
+                    message_id = table.Column<string>(type: "text", nullable: false),
+                    message_sent_at_utc = table.Column<DateTime>(type: "timestamp with time zone", nullable: false),
+                    message_content = table.Column<string>(type: "text", nullable: false),
+                    sender_token = table.Column<string>(type: "text", nullable: false),
+                    sender_hashed_cid = table.Column<string>(type: "text", nullable: true),
+                    sender_display_name = table.Column<string>(type: "text", nullable: true),
+                    sender_was_lightfinder = table.Column<bool>(type: "boolean", nullable: false),
+                    snapshot_json = table.Column<string>(type: "text", nullable: true),
+                    reason = table.Column<string>(type: "text", nullable: true),
+                    additional_context = table.Column<string>(type: "text", nullable: true),
+                    discord_message_id = table.Column<decimal>(type: "numeric(20,0)", nullable: true),
+                    discord_message_posted_at_utc = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
+                    resolved = table.Column<bool>(type: "boolean", nullable: false),
+                    resolved_at_utc = table.Column<DateTime>(type: "timestamp with time zone", nullable: true),
+                    resolution_notes = table.Column<string>(type: "text", nullable: true),
+                    resolved_by_user_uid = table.Column<string>(type: "text", nullable: true)
+                },
+                constraints: table =>
+                {
+                    table.PrimaryKey("pk_reported_chat_messages", x => x.report_id);
+                });
+
+            migrationBuilder.AddColumn<bool>(
+                name: "chat_banned",
+                table: "users",
+                type: "boolean",
+                nullable: false,
+                defaultValue: false);
+
+            migrationBuilder.CreateIndex(
+                name: "ix_reported_chat_messages_discord_message_id",
+                table: "reported_chat_messages",
+                column: "discord_message_id");
+
+            migrationBuilder.CreateIndex(
+                name: "ix_reported_chat_messages_message_id",
+                table: "reported_chat_messages",
+                column: "message_id",
+                unique: true);
+
+            migrationBuilder.CreateIndex(
+                name: "ix_reported_chat_messages_reported_user_uid",
+                table: "reported_chat_messages",
+                column: "reported_user_uid");
+
+            migrationBuilder.CreateIndex(
+                name: "ix_reported_chat_messages_reporter_user_uid",
+                table: "reported_chat_messages",
+                column: "reporter_user_uid");
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropTable(
+                name: "reported_chat_messages");
+
+            migrationBuilder.DropColumn(
+                name: "chat_banned",
+                table: "users");
+        }
+    }
+}

LightlessSyncServer/LightlessSyncShared/Migrations/20251117153226_FixForeignKeyGroupProfiles.cs

@@ -0,0 +1,41 @@
+using Microsoft.EntityFrameworkCore.Migrations;
+
+#nullable disable
+
+namespace LightlessSyncServer.Migrations
+{
+    /// <inheritdoc />
+    public partial class FixForeignKeyGroupProfiles : Migration
+    {
+        /// <inheritdoc />
+        protected override void Up(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "fk_group_profiles_groups_group_gid",
+                table: "group_profiles");
+
+            migrationBuilder.AddForeignKey(
+                name: "fk_group_profiles_groups_group_gid",
+                table: "group_profiles",
+                column: "group_gid",
+                principalTable: "groups",
+                principalColumn: "gid",
+                onDelete: ReferentialAction.Cascade);
+        }
+
+        /// <inheritdoc />
+        protected override void Down(MigrationBuilder migrationBuilder)
+        {
+            migrationBuilder.DropForeignKey(
+                name: "fk_group_profiles_groups_group_gid",
+                table: "group_profiles");
+
+            migrationBuilder.AddForeignKey(
+                name: "fk_group_profiles_groups_group_gid",
+                table: "group_profiles",
+                column: "group_gid",
+                principalTable: "groups",
+                principalColumn: "gid");
+        }
+    }
+}

LightlessSyncServer/LightlessSyncShared/Migrations/LightlessDbContextModelSnapshot.cs

@@ -683,6 +683,131 @@ namespace LightlessSyncServer.Migrations
                     b.ToTable("lodestone_auth", (string)null);
                 });
 
+            modelBuilder.Entity("LightlessSyncShared.Models.ReportedChatMessage", b =>
+                {
+                    b.Property<int>("ReportId")
+                        .ValueGeneratedOnAdd()
+                        .HasColumnType("integer")
+                        .HasColumnName("report_id");
+
+                    NpgsqlPropertyBuilderExtensions.UseIdentityByDefaultColumn(b.Property<int>("ReportId"));
+
+                    b.Property<string>("AdditionalContext")
+                        .HasColumnType("text")
+                        .HasColumnName("additional_context");
+
+                    b.Property<string>("ChannelKey")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("channel_key");
+
+                    b.Property<byte>("ChannelType")
+                        .HasColumnType("smallint")
+                        .HasColumnName("channel_type");
+
+                    b.Property<decimal?>("DiscordMessageId")
+                        .HasColumnType("numeric(20,0)")
+                        .HasColumnName("discord_message_id");
+
+                    b.Property<DateTime?>("DiscordMessagePostedAtUtc")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("discord_message_posted_at_utc");
+
+                    b.Property<string>("MessageContent")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("message_content");
+
+                    b.Property<string>("MessageId")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("message_id");
+
+                    b.Property<DateTime>("MessageSentAtUtc")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("message_sent_at_utc");
+
+                    b.Property<string>("Reason")
+                        .HasColumnType("text")
+                        .HasColumnName("reason");
+
+                    b.Property<DateTime>("ReportTimeUtc")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("report_time_utc");
+
+                    b.Property<string>("ReportedUserUid")
+                        .HasColumnType("text")
+                        .HasColumnName("reported_user_uid");
+
+                    b.Property<string>("ReporterUserUid")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("reporter_user_uid");
+
+                    b.Property<string>("ResolutionNotes")
+                        .HasColumnType("text")
+                        .HasColumnName("resolution_notes");
+
+                    b.Property<bool>("Resolved")
+                        .HasColumnType("boolean")
+                        .HasColumnName("resolved");
+
+                    b.Property<DateTime?>("ResolvedAtUtc")
+                        .HasColumnType("timestamp with time zone")
+                        .HasColumnName("resolved_at_utc");
+
+                    b.Property<string>("ResolvedByUserUid")
+                        .HasColumnType("text")
+                        .HasColumnName("resolved_by_user_uid");
+
+                    b.Property<string>("SenderDisplayName")
+                        .HasColumnType("text")
+                        .HasColumnName("sender_display_name");
+
+                    b.Property<string>("SenderHashedCid")
+                        .HasColumnType("text")
+                        .HasColumnName("sender_hashed_cid");
+
+                    b.Property<string>("SenderToken")
+                        .IsRequired()
+                        .HasColumnType("text")
+                        .HasColumnName("sender_token");
+
+                    b.Property<bool>("SenderWasLightfinder")
+                        .HasColumnType("boolean")
+                        .HasColumnName("sender_was_lightfinder");
+
+                    b.Property<string>("SnapshotJson")
+                        .HasColumnType("text")
+                        .HasColumnName("snapshot_json");
+
+                    b.Property<int>("WorldId")
+                        .HasColumnType("integer")
+                        .HasColumnName("world_id");
+
+                    b.Property<int>("ZoneId")
+                        .HasColumnType("integer")
+                        .HasColumnName("zone_id");
+
+                    b.HasKey("ReportId")
+                        .HasName("pk_reported_chat_messages");
+
+                    b.HasIndex("DiscordMessageId")
+                        .HasDatabaseName("ix_reported_chat_messages_discord_message_id");
+
+                    b.HasIndex("MessageId")
+                        .IsUnique()
+                        .HasDatabaseName("ix_reported_chat_messages_message_id");
+
+                    b.HasIndex("ReportedUserUid")
+                        .HasDatabaseName("ix_reported_chat_messages_reported_user_uid");
+
+                    b.HasIndex("ReporterUserUid")
+                        .HasDatabaseName("ix_reported_chat_messages_reporter_user_uid");
+
+                    b.ToTable("reported_chat_messages", (string)null);
+                });
+
             modelBuilder.Entity("LightlessSyncShared.Models.User", b =>
                 {
                     b.Property<string>("UID")
@@ -695,6 +820,10 @@ namespace LightlessSyncServer.Migrations
                         .HasColumnType("character varying(15)")
                         .HasColumnName("alias");
 
+                    b.Property<bool>("ChatBanned")
+                        .HasColumnType("boolean")
+                        .HasColumnName("chat_banned");
+
                     b.Property<bool>("HasVanity")
                         .HasColumnType("boolean")
                         .HasColumnName("has_vanity");
@@ -1091,6 +1220,7 @@ namespace LightlessSyncServer.Migrations
                     b.HasOne("LightlessSyncShared.Models.Group", "Group")
                         .WithOne("Profile")
                         .HasForeignKey("LightlessSyncShared.Models.GroupProfile", "GroupGID")
+                        .OnDelete(DeleteBehavior.Cascade)
                         .HasConstraintName("fk_group_profiles_groups_group_gid");
 
                     b.Navigation("Group");

LightlessSyncServer/LightlessSyncShared/Models/ReportedChatMessage.cs

@@ -0,0 +1,69 @@
+using System;
+using System.ComponentModel.DataAnnotations;
+using System.ComponentModel.DataAnnotations.Schema;
+using LightlessSync.API.Dto.Chat;
+
+namespace LightlessSyncShared.Models;
+
+/// <summary>
+///     Stores metadata about chat reports submitted by users.
+/// </summary>
+public class ReportedChatMessage
+{
+    [Key]
+    [DatabaseGenerated(DatabaseGeneratedOption.Identity)]
+    public int ReportId { get; set; }
+
+    [Required]
+    public DateTime ReportTimeUtc { get; set; }
+
+    [Required]
+    public string ReporterUserUid { get; set; } = string.Empty;
+
+    public string? ReportedUserUid { get; set; }
+
+    [Required]
+    public ChatChannelType ChannelType { get; set; }
+
+    public ushort WorldId { get; set; }
+
+    public ushort ZoneId { get; set; }
+
+    [Required]
+    public string ChannelKey { get; set; } = string.Empty;
+
+    [Required]
+    public string MessageId { get; set; } = string.Empty;
+
+    public DateTime MessageSentAtUtc { get; set; }
+
+    [Required]
+    public string MessageContent { get; set; } = string.Empty;
+
+    [Required]
+    public string SenderToken { get; set; } = string.Empty;
+
+    public string? SenderHashedCid { get; set; }
+
+    public string? SenderDisplayName { get; set; }
+
+    public bool SenderWasLightfinder { get; set; }
+
+    public string SnapshotJson { get; set; } = string.Empty;
+
+    public string? Reason { get; set; }
+
+    public string? AdditionalContext { get; set; }
+
+    public ulong? DiscordMessageId { get; set; }
+
+    public DateTime? DiscordMessagePostedAtUtc { get; set; }
+
+    public bool Resolved { get; set; }
+
+    public DateTime? ResolvedAtUtc { get; set; }
+
+    public string? ResolutionNotes { get; set; }
+
+    public string? ResolvedByUserUid { get; set; }
+}

LightlessSyncServer/LightlessSyncShared/Models/User.cs

@@ -22,6 +22,8 @@ public class User
     [MaxLength(9)]
     public string? TextGlowColorHex { get; set; } = string.Empty;
 
+    public bool ChatBanned { get; set; } = false;
+
     public DateTime LastLoggedIn { get; set; }
     [MaxLength(15)]
     public string Alias { get; set; }

LightlessSyncServer/LightlessSyncShared/Utils/Configuration/ServicesConfiguration.cs

@@ -7,6 +7,7 @@ public class ServicesConfiguration : LightlessConfigurationBase
     public string DiscordBotToken { get; set; } = string.Empty;
     public ulong? DiscordChannelForMessages { get; set; } = null;
     public ulong? DiscordChannelForCommands { get; set; } = null;
+    public ulong? DiscordChannelForChatReports { get; set; } = null;
     public ulong? DiscordRoleAprilFools2024 { get; set; } = null;
     public ulong? DiscordChannelForBotLog { get; set; } = null!;
     public ulong? DiscordRoleRegistered { get; set; } = null!;
@@ -22,6 +23,7 @@ public class ServicesConfiguration : LightlessConfigurationBase
         sb.AppendLine($"{nameof(MainServerAddress)} => {MainServerAddress}");
         sb.AppendLine($"{nameof(DiscordChannelForMessages)} => {DiscordChannelForMessages}");
         sb.AppendLine($"{nameof(DiscordChannelForCommands)} => {DiscordChannelForCommands}");
+        sb.AppendLine($"{nameof(DiscordChannelForChatReports)} => {DiscordChannelForChatReports}");
         sb.AppendLine($"{nameof(DiscordRoleAprilFools2024)} => {DiscordRoleAprilFools2024}");
         sb.AppendLine($"{nameof(DiscordRoleRegistered)} => {DiscordRoleRegistered}");
         sb.AppendLine($"{nameof(KickNonRegisteredUsers)} => {KickNonRegisteredUsers}");

LightlessSyncServer/LightlessSyncStaticFilesServer/Controllers/ServerFilesController.cs

@@ -1,4 +1,5 @@
-using K4os.Compression.LZ4.Legacy;
+using Blake3;
+using K4os.Compression.LZ4.Legacy;
 using LightlessSync.API.Dto.Files;
 using LightlessSync.API.Routes;
 using LightlessSync.API.SignalR;
@@ -208,11 +209,14 @@ public class ServerFilesController : ControllerBase
     [RequestSizeLimit(200 * 1024 * 1024)]
     public async Task<IActionResult> UploadFile(string hash, CancellationToken requestAborted)
     {
-        using var dbContext = await _lightlessDbContext.CreateDbContextAsync();
+        await using var dbContext = await _lightlessDbContext.CreateDbContextAsync();
 
         _logger.LogInformation("{user}|{file}: Uploading", LightlessUser, hash);
+        if (hash.Length == 40)
+        {
+            hash = hash.ToUpperInvariant();
+        }
 
-        hash = hash.ToUpperInvariant();
         var existingFile = await dbContext.Files.SingleOrDefaultAsync(f => f.Hash == hash);
         if (existingFile != null) return Ok();
 
@@ -263,10 +267,14 @@ public class ServerFilesController : ControllerBase
     [RequestSizeLimit(200 * 1024 * 1024)]
     public async Task<IActionResult> UploadFileMunged(string hash, CancellationToken requestAborted)
     {
-        using var dbContext = await _lightlessDbContext.CreateDbContextAsync();
+        await using var dbContext = await _lightlessDbContext.CreateDbContextAsync();
 
         _logger.LogInformation("{user}|{file}: Uploading munged", LightlessUser, hash);
-        hash = hash.ToUpperInvariant();
+        if (hash.Length == 40)
+        {
+            hash = hash.ToUpperInvariant();
+        }
+
         var existingFile = await dbContext.Files.SingleOrDefaultAsync(f => f.Hash == hash);
         if (existingFile != null) return Ok();
 
@@ -319,20 +327,26 @@ public class ServerFilesController : ControllerBase
     private async Task StoreData(string hash, LightlessDbContext dbContext, MemoryStream compressedFileStream)
     {
         var decompressedData = LZ4Wrapper.Unwrap(compressedFileStream.ToArray());
-        // reset streams
         compressedFileStream.Seek(0, SeekOrigin.Begin);
 
-        // compute hash to verify
-        var hashString = BitConverter.ToString(SHA1.HashData(decompressedData))
-            .Replace("-", "", StringComparison.Ordinal).ToUpperInvariant();
-        if (!string.Equals(hashString, hash, StringComparison.Ordinal))
-            throw new InvalidOperationException($"{LightlessUser}|{hash}: Hash does not match file, computed: {hashString}, expected: {hash}");
+        bool valid;
 
-        // save file
-        var path = FilePathUtil.GetFilePath(_basePath, hash);
-        using var fileStream = new FileStream(path, FileMode.Create);
-        await compressedFileStream.CopyToAsync(fileStream).ConfigureAwait(false);
-        _logger.LogDebug("{user}|{file}: Uploaded file saved to {path}", LightlessUser, hash, path);
+        if (hash.Length == 40)
+        {
+            var sha1Hex = Convert.ToHexString(SHA1.HashData(decompressedData));
+            valid = string.Equals(sha1Hex, hash, StringComparison.OrdinalIgnoreCase);
+        }
+        else
+        {
+            var blakeHash = Hasher.Hash(decompressedData);
+            var blakeHex = Convert.ToHexString(blakeHash.AsSpan());
+            valid = string.Equals(blakeHex, hash, StringComparison.OrdinalIgnoreCase);
+        }
+
+        if (!valid)
+            throw new InvalidOperationException(
+                $"{LightlessUser}|{hash}: Hash does not match file, computed mismatch."
+            );
 
         // update on db
         await dbContext.Files.AddAsync(new FileCache()

LightlessSyncServer/LightlessSyncStaticFilesServer/LightlessSyncStaticFilesServer.csproj

@@ -18,6 +18,7 @@
   </ItemGroup>
 
   <ItemGroup>
+    <PackageReference Include="Blake3" Version="2.0.0" />
     <PackageReference Include="IDisposableAnalyzers" Version="4.0.8">
       <PrivateAssets>all</PrivateAssets>
       <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>