Merge pull request #91: feat: Discord OAuth и платформонезависимый Web Dashboard (issue #34)

- Discord OAuth 2.0 login flow (identify + guilds scopes)
- Platform-agnostic auth via (platform, external_user_id)
- Cookie Authentication with ClaimsPrincipal
- Razor Pages updated to *ForCurrentUserAsync APIs
- CSRF protection for Discord OAuth
- V019 migration for audit log platform identity
- Version bumped to 2.8.0

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

.env.example

@@ -14,6 +14,13 @@ TELEGRAM_MINI_APP_URL=
 # Можно получить в Discord Developer Portal (https://discord.com/developers/applications)
 DISCORD_BOT_TOKEN=YOUR_DISCORD_BOT_TOKEN_HERE
 
+# Discord OAuth (для Web Dashboard)
+# Client ID и Secret из OAuth2 раздела Discord Developer Portal
+# Redirect URI должен указывать на /auth/discord/callback вашего домена
+DISCORD_CLIENT_ID=YOUR_DISCORD_CLIENT_ID_HERE
+DISCORD_CLIENT_SECRET=YOUR_DISCORD_CLIENT_SECRET_HERE
+DISCORD_REDIRECT_URI=https://your-domain.example/auth/discord/callback
+
 # Пароль для базы данных PostgreSQL
 POSTGRES_PASSWORD=StrongPasswordForDatabase
 

.gitea/workflows/deploy.yml

@@ -6,7 +6,7 @@ on:
       - main 
 
 env:
-  VERSION: 2.7.2
+  VERSION: 2.8.0
 
 jobs:
   # ЧАСТЬ 1: Собираем образы и кладем в Gitea (чтобы делиться с ребятами)
@@ -113,6 +113,9 @@ jobs:
           echo "DISCORD_BOT_TOKEN=${{ secrets.DISCORD_BOT_TOKEN }}" >> .env
           echo "TELEGRAM_BOT_USERNAME=${{ secrets.TELEGRAM_BOT_USERNAME }}" >> .env
           echo "TELEGRAM_MINI_APP_URL=${{ secrets.TELEGRAM_MINI_APP_URL }}" >> .env
+          echo "DISCORD_CLIENT_ID=${{ secrets.DISCORD_CLIENT_ID }}" >> .env
+          echo "DISCORD_CLIENT_SECRET=${{ secrets.DISCORD_CLIENT_SECRET }}" >> .env
+          echo "DISCORD_REDIRECT_URI=${{ secrets.DISCORD_REDIRECT_URI }}" >> .env
 
       - name: Deploy Containers
         run: |

Directory.Build.props

@@ -1,6 +1,6 @@
 <Project>
   <PropertyGroup>
-    <Version>2.7.2</Version>
+    <Version>2.8.0</Version>
     <TargetFramework>net10.0</TargetFramework>
     <LangVersion>preview</LangVersion>
     <Nullable>enable</Nullable>

README.md

@@ -4,7 +4,7 @@
 
 Проект разработан с упором на производительность, архитектуру Vertical Slice, Native AOT (для бота) и удобство развертывания с использованием .NET Aspire.
 
-**Текущая версия:** `v2.7.2`.
+**Текущая версия:** `v2.8.0`.
 
 ---
 

compose.yaml

@@ -49,7 +49,7 @@ services:
         crond -f
 
   bot:
-    image: git.codeanddice.ru/toutsu/gmrelay-bot:2.7.2
+    image: git.codeanddice.ru/toutsu/gmrelay-bot:2.8.0
     restart: always
     depends_on:
       db:
@@ -67,7 +67,7 @@ services:
       retries: 3
 
   discord:
-    image: git.codeanddice.ru/toutsu/gmrelay-discord-bot:2.7.2
+    image: git.codeanddice.ru/toutsu/gmrelay-discord-bot:2.8.0
     restart: always
     depends_on:
       db:
@@ -84,7 +84,7 @@ services:
       retries: 3
 
   web:
-    image: git.codeanddice.ru/toutsu/gmrelay-web:2.7.2
+    image: git.codeanddice.ru/toutsu/gmrelay-web:2.8.0
     restart: always
     depends_on:
       db:
@@ -94,6 +94,9 @@ services:
       - "Telegram__BotToken=${TELEGRAM_BOT_TOKEN:?Set TELEGRAM_BOT_TOKEN in .env}"
       - "Telegram__BotUsername=${TELEGRAM_BOT_USERNAME:?Set TELEGRAM_BOT_USERNAME in .env}"
       - "Telegram__MiniAppUrl=${TELEGRAM_MINI_APP_URL:-}"
+      - "Discord__ClientId=${DISCORD_CLIENT_ID:-}"
+      - "Discord__ClientSecret=${DISCORD_CLIENT_SECRET:-}"
+      - "Discord__RedirectUri=${DISCORD_REDIRECT_URI:-}"
     ports:
       - "${GMRELAY_WEB_PORT:-8080}:8080"
     volumes:

src/GmRelay.Bot/Migrations/V019__audit_log_platform_identity.sql

@@ -0,0 +1,18 @@
+-- =============================================================
+-- V019: Rename session_audit_log.actor_telegram_id to actor_external_user_id
+-- =============================================================
+-- Scope: Support platform-agnostic audit log identity.
+-- =============================================================
+
+ALTER TABLE session_audit_log
+    ADD COLUMN actor_external_user_id VARCHAR(255);
+
+UPDATE session_audit_log
+   SET actor_external_user_id = actor_telegram_id::TEXT
+ WHERE actor_external_user_id IS NULL;
+
+ALTER TABLE session_audit_log
+    ALTER COLUMN actor_external_user_id SET NOT NULL;
+
+ALTER TABLE session_audit_log
+    DROP COLUMN actor_telegram_id;

src/GmRelay.Web/Components/Layout/NavMenu.razor

@@ -39,9 +39,19 @@
             <div class="nav-footer">
                 <div class="nav-user">
                     <div class="nav-user-avatar">
-                        @(context.User.Identity?.Name?.Substring(0, 1).ToUpper() ?? "?")
+                        @if (!string.IsNullOrWhiteSpace(context.User.GetAvatarUrl()))
+                        {
+                            <img src="@context.User.GetAvatarUrl()" alt="" />
+                        }
+                        else
+                        {
+                            @(context.User.Identity?.Name?.Substring(0, 1).ToUpper() ?? "?")
+                        }
+                    </div>
+                    <div class="nav-user-info">
+                        <span class="nav-user-name">@context.User.Identity?.Name</span>
+                        <span class="nav-user-platform">@GetPlatformLabel(context.User)</span>
                     </div>
-                    <span class="nav-user-name">@context.User.Identity?.Name</span>
                 </div>
 
                 <form action="/auth/logout" method="post">
@@ -56,7 +66,7 @@
                     </button>
                 </form>
 
-                <div class="nav-version">v2.7.2</div>
+                <div class="nav-version">v2.8.0</div>
             </div>
         </Authorized>
         <NotAuthorized>
@@ -79,4 +89,7 @@
 
     private void ToggleMenu() => isOpen = !isOpen;
     private void CloseMenu() => isOpen = false;
+
+    private static string GetPlatformLabel(System.Security.Claims.ClaimsPrincipal user) =>
+        user.TryGetDiscordId(out _) ? "Discord" : "Telegram";
 }

src/GmRelay.Web/Components/Pages/CampaignTemplates.razor

@@ -185,7 +185,7 @@
     private Guid selectedGroupId;
     private Guid? deletingTemplateId;
     private bool isCreatingTemplate;
-    private long telegramId;
+    private string? externalUserId;
     private string? errorMessage;
     private string? successMessage;
     private CampaignTemplateEditModel templateModel = new();
@@ -195,13 +195,13 @@
     protected override async Task OnInitializedAsync()
     {
         var authState = await AuthStateProvider.GetAuthenticationStateAsync();
-        if (!authState.User.TryGetTelegramId(out telegramId))
+        if (!authState.User.TryGetPlatformIdentity(out var platform, out externalUserId))
         {
             Navigation.NavigateTo("/access-denied");
             return;
         }
 
-        groups = await SessionService.GetGroupsForGmAsync(telegramId);
+        groups = await SessionService.GetGroupsForCurrentUserAsync();
         selectedGroupId = groups.FirstOrDefault()?.Id ?? Guid.Empty;
 
         if (selectedGroupId != Guid.Empty)
@@ -228,7 +228,7 @@
         campaignTemplates = null;
         campaignTemplateModels = [];
 
-        var templates = await SessionService.GetCampaignTemplatesForGmAsync(selectedGroupId, telegramId);
+        var templates = await SessionService.GetCampaignTemplatesForCurrentUserAsync(selectedGroupId);
         if (templates is null)
         {
             Navigation.NavigateTo("/access-denied");
@@ -260,9 +260,8 @@
 
         try
         {
-            await SessionService.CreateCampaignTemplateForGmAsync(
+            await SessionService.CreateCampaignTemplateForCurrentUserAsync(
                 selectedGroupId,
-                telegramId,
                 new CreateCampaignTemplateRequest(
                     templateModel.Name,
                     templateModel.Title,
@@ -298,7 +297,7 @@
 
         try
         {
-            await SessionService.DeleteCampaignTemplateForGmAsync(template.Id, telegramId);
+            await SessionService.DeleteCampaignTemplateForCurrentUserAsync(template.Id);
             successMessage = "Шаблон кампании удалён.";
             await LoadTemplates();
         }

src/GmRelay.Web/Components/Pages/EditSession.razor

@@ -87,13 +87,13 @@
     protected override async Task OnInitializedAsync()
     {
         var authState = await AuthStateProvider.GetAuthenticationStateAsync();
-        if (!authState.User.TryGetTelegramId(out var telegramId))
+        if (!authState.User.TryGetPlatformIdentity(out var platform, out var externalUserId))
         {
             Navigation.NavigateTo("/access-denied");
             return;
         }
 
-        session = await SessionService.GetSessionForGmAsync(SessionId, telegramId);
+        session = await SessionService.GetSessionForCurrentUserAsync(SessionId);
         if (session is null)
         {
             Navigation.NavigateTo("/access-denied");
@@ -114,7 +114,7 @@
         try
         {
             var authState = await AuthStateProvider.GetAuthenticationStateAsync();
-            if (!authState.User.TryGetTelegramId(out var telegramId))
+            if (!authState.User.TryGetPlatformIdentity(out var platform, out var externalUserId))
             {
                 Navigation.NavigateTo("/access-denied");
                 return;
@@ -122,7 +122,7 @@
 
             var utcTime = new DateTimeOffset(model.ScheduledAtLocal, TimeSpan.FromHours(3)).ToUniversalTime().UtcDateTime;
 
-            await SessionService.UpdateSessionForGmAsync(SessionId, telegramId, model.Title, utcTime, model.JoinLink, model.MaxPlayers);
+            await SessionService.UpdateSessionForCurrentUserAsync(SessionId, model.Title, utcTime, model.JoinLink, model.MaxPlayers);
             Navigation.NavigateTo($"/group/{session!.GroupId}");
         }
         catch (SessionAccessDeniedException)

src/GmRelay.Web/Components/Pages/GroupDetails.razor

@@ -40,8 +40,8 @@
                     </span>
                     @if (groupManagement.CurrentUserIsOwner && manager.Role == GroupManagerRoleExtensions.CoGmValue)
                     {
-                        <button type="button" class="btn-gm btn-gm-outline" style="font-size: 0.75rem; padding: 0.25rem 0.5rem;" disabled="@(removingCoGmId == manager.TelegramId)" @onclick="() => RemoveCoGm(manager.TelegramId)">
+                        <button type="button" class="btn-gm btn-gm-outline" style="font-size: 0.75rem; padding: 0.25rem 0.5rem;" disabled="@(removingCoGmId == manager.ExternalUserId)" @onclick="() => RemoveCoGm(manager.ExternalUserId ?? manager.TelegramId.ToString())">
-                            @(removingCoGmId == manager.TelegramId ? "⏳ Удаляем..." : "Убрать")
+                            @(removingCoGmId == manager.ExternalUserId ? "⏳ Удаляем..." : "Убрать")
                         </button>
                     }
                 }
@@ -403,9 +403,9 @@
     private Guid? promotingSessionId;
     private Guid? processingBatchId;
     private Guid? processingTemplateId;
-    private long? removingCoGmId;
+    private string? removingCoGmId;
     private bool isAddingCoGm;
-    private long telegramId;
+    private string? externalUserId;
     private string? errorMessage;
     private string? successMessage;
     private CoGmEditModel coGmModel = new();
@@ -417,7 +417,7 @@
     protected override async Task OnInitializedAsync()
     {
         var authState = await AuthStateProvider.GetAuthenticationStateAsync();
-        if (!authState.User.TryGetTelegramId(out telegramId))
+        if (!authState.User.TryGetPlatformIdentity(out var platform, out externalUserId))
         {
             Navigation.NavigateTo("/access-denied");
             return;
@@ -428,21 +428,21 @@
 
     private async Task LoadSessions()
     {
-        groupManagement = await SessionService.GetGroupManagementForGmAsync(GroupId, telegramId);
+        groupManagement = await SessionService.GetGroupManagementForCurrentUserAsync(GroupId);
         if (groupManagement is null)
         {
             Navigation.NavigateTo("/access-denied");
             return;
         }
 
-        sessions = await SessionService.GetUpcomingSessionsForGmAsync(GroupId, telegramId);
+        sessions = await SessionService.GetUpcomingSessionsForCurrentUserAsync(GroupId);
         if (sessions is null)
         {
             Navigation.NavigateTo("/access-denied");
             return;
         }
 
-        campaignTemplates = await SessionService.GetCampaignTemplatesForGmAsync(GroupId, telegramId);
+        campaignTemplates = await SessionService.GetCampaignTemplatesForCurrentUserAsync(GroupId);
         if (campaignTemplates is null)
         {
             Navigation.NavigateTo("/access-denied");
@@ -470,8 +470,8 @@
         {
             await SessionService.AddCoGmForOwnerAsync(
                 GroupId,
-                telegramId,
+                "Telegram",
-                coGmModel.TelegramId.Value,
+                coGmModel.TelegramId.Value.ToString(),
                 coGmModel.DisplayName,
                 coGmModel.TelegramUsername);
 
@@ -493,15 +493,15 @@
         }
     }
 
-    private async Task RemoveCoGm(long coGmTelegramId)
+    private async Task RemoveCoGm(string coGmExternalUserId)
     {
         errorMessage = null;
         successMessage = null;
-        removingCoGmId = coGmTelegramId;
+        removingCoGmId = coGmExternalUserId;
 
         try
         {
-            await SessionService.RemoveCoGmForOwnerAsync(GroupId, telegramId, coGmTelegramId);
+            await SessionService.RemoveCoGmForOwnerAsync(GroupId, "Telegram", coGmExternalUserId);
             successMessage = "Co-GM удалён.";
             await LoadSessions();
         }
@@ -527,7 +527,7 @@
 
         try
         {
-            await SessionService.PromoteWaitlistedPlayerForGmAsync(sessionId, telegramId);
+            await SessionService.PromoteWaitlistedPlayerForCurrentUserAsync(sessionId);
             await LoadSessions();
         }
         catch (SessionAccessDeniedException)
@@ -559,7 +559,7 @@
             loadingParticipantsSessionId = sessionId;
             try
             {
-                var participants = await SessionService.GetSessionParticipantsForGmAsync(sessionId, telegramId);
+                var participants = await SessionService.GetSessionParticipantsForCurrentUserAsync(sessionId);
                 participantsCache[sessionId] = participants ?? [];
             }
             catch (Exception ex)
@@ -582,7 +582,7 @@
 
         try
         {
-            await SessionService.RemovePlayerFromSessionForGmAsync(sessionId, telegramId, participantId);
+            await SessionService.RemovePlayerFromSessionForCurrentUserAsync(sessionId, participantId);
             participantsCache.Remove(sessionId);
             successMessage = "Игрок исключён.";
             await LoadSessions();
@@ -658,10 +658,9 @@
 
         try
         {
-            await SessionService.UpdateBatchDetailsForGmAsync(batch.BatchId, telegramId, batch.Title, batch.JoinLink);
+            await SessionService.UpdateBatchDetailsForCurrentUserAsync(batch.BatchId, batch.Title, batch.JoinLink);
-            await SessionService.UpdateBatchNotificationModeForGmAsync(
+            await SessionService.UpdateBatchNotificationModeForCurrentUserAsync(
                 batch.BatchId,
-                telegramId,
                 SessionNotificationModeExtensions.FromDatabaseValue(batch.NotificationMode));
             successMessage = "Настройки batch обновлены.";
             await LoadSessions();
@@ -696,7 +695,7 @@
         try
         {
             var utcTime = new DateTimeOffset(batch.FirstScheduledAtLocal, TimeSpan.FromHours(3)).ToUniversalTime().UtcDateTime;
-            await SessionService.RescheduleBatchForGmAsync(batch.BatchId, telegramId, utcTime, batch.IntervalDays);
+            await SessionService.RescheduleBatchForCurrentUserAsync(batch.BatchId, utcTime, batch.IntervalDays);
             successMessage = "Расписание пачки обновлено.";
             await LoadSessions();
         }
@@ -726,7 +725,7 @@
                 ? BatchCloneInterval.NextMonth
                 : BatchCloneInterval.NextWeek;
 
-            var clonedBatch = await SessionService.CloneBatchForGmAsync(batch.BatchId, telegramId, interval);
+            var clonedBatch = await SessionService.CloneBatchForCurrentUserAsync(batch.BatchId, interval);
             successMessage = $"Пачка склонирована: {clonedBatch.SessionCount} игр.";
             await LoadSessions();
         }
@@ -759,7 +758,7 @@
                 return;
             }
 
-            var createdBatch = await SessionService.CreateBatchFromCampaignTemplateForGmAsync(template.Id, telegramId, utcTime);
+            var createdBatch = await SessionService.CreateBatchFromCampaignTemplateForCurrentUserAsync(template.Id, utcTime);
             successMessage = $"Batch создан из шаблона: {createdBatch.SessionCount} игр.";
             await LoadSessions();
         }
@@ -836,7 +835,7 @@
     private bool IsTemplateBusy(CampaignTemplateUsageModel template) => processingTemplateId == template.Id;
 
     private string CurrentUserRole =>
-        groupManagement?.Managers.FirstOrDefault(manager => manager.TelegramId == telegramId)?.Role
+        groupManagement?.Managers.FirstOrDefault(manager => manager.ExternalUserId == externalUserId)?.Role
         ?? GroupManagerRoleExtensions.CoGmValue;
 
     private static string FormatRole(string role) =>

src/GmRelay.Web/Components/Pages/GroupStats.razor

@@ -5,7 +5,7 @@
 @using Microsoft.AspNetCore.Components.Authorization
 @using System.Security.Claims
 @attribute [Authorize]
-@inject ISessionStore SessionStore
+@inject AuthorizedSessionService SessionService
 @inject AuthenticationStateProvider AuthStateProvider
 @inject NavigationManager Navigation
 
@@ -85,9 +85,9 @@
                                 <td>
                                     <div class="player-info">
                                         <span class="player-name">@s.DisplayName</span>
-                                        @if (!string.IsNullOrEmpty(s.TelegramUsername))
+                                        @if (!string.IsNullOrEmpty(s.ExternalUsername))
                                         {
-                                            <span class="player-username">@@@s.TelegramUsername</span>
+                                            <span class="player-username">@@@s.ExternalUsername</span>
                                         }
                                     </div>
                                 </td>
@@ -171,21 +171,20 @@
             Navigation.NavigateTo("/login");
             return;
         }
-        var telegramIdClaim = user.FindFirst("telegram_id")?.Value
+        if (!user.TryGetPlatformIdentity(out var platform, out var externalUserId))
-            ?? user.FindFirst(ClaimTypes.NameIdentifier)?.Value;
-        if (!long.TryParse(telegramIdClaim, out var telegramId))
         {
             Navigation.NavigateTo("/login");
             return;
         }
         try
         {
-            if (!await SessionStore.IsGroupManagerAsync(GroupId, telegramId))
+            var groupManagement = await SessionService.GetGroupManagementForCurrentUserAsync(GroupId);
+            if (groupManagement is null)
             {
                 Navigation.NavigateTo("/access-denied");
                 return;
             }
-            stats = await SessionStore.GetGroupAttendanceStatsAsync(GroupId) ?? new();
+            stats = await SessionService.GetGroupAttendanceStatsForCurrentUserAsync(GroupId) ?? new();
             UpdateSortedStats();
         }
         catch (Exception ex)

src/GmRelay.Web/Components/Pages/Home.razor

@@ -43,7 +43,7 @@
                 <div class="glass-card group-card">
                     <div class="group-card-icon">🎮</div>
                     <h3 class="group-card-title">@group.Name</h3>
-                    <p class="group-card-id">ID: @group.TelegramChatId</p>
+                    <p class="group-card-id">ID: @(group.Platform == "Discord" ? group.ExternalGroupId : group.TelegramChatId.ToString())</p>
                     <span class="status-badge @(group.ManagerRole == GroupManagerRoleExtensions.OwnerValue ? "status-success" : "status-info")" style="align-self: flex-start; margin-bottom: 1rem;">
                         @FormatRole(group.ManagerRole)
                     </span>
@@ -93,13 +93,13 @@
         var user = authState.User;
         userName = user.Identity?.Name ?? "Мастер Игры";
 
-        if (!user.TryGetTelegramId(out var telegramId))
+        if (!user.TryGetPlatformIdentity(out _, out _))
         {
             Navigation.NavigateTo("/access-denied");
             return;
         }
 
-        groups = await SessionService.GetGroupsForGmAsync(telegramId);
+        groups = await SessionService.GetGroupsForCurrentUserAsync();
     }
 
     private static string FormatRole(string role) =>

src/GmRelay.Web/Components/Pages/Login.razor

@@ -10,7 +10,7 @@
     <div class="login-card">
         <img src="logo.png" alt="GM-Relay" class="login-logo" />
         <h1 class="login-title">GM-Relay</h1>
-        <p class="login-subtitle">Войдите через Telegram для управления игровыми сессиями</p>
+        <p class="login-subtitle">Войдите для управления игровыми сессиями</p>
 
         @if (Navigation.Uri.Contains("error=auth_failed"))
         {
@@ -20,6 +20,17 @@
         }
 
         <div id="telegram-login-container"></div>
+
+        <div class="login-divider">
+            <span>или</span>
+        </div>
+
+        <a href="/auth/discord" class="login-btn login-btn-discord">
+            <svg class="login-btn-icon" viewBox="0 0 24 24" fill="currentColor">
+                <path d="M20.317 4.37a19.791 19.791 0 0 0-4.885-1.515.074.074 0 0 0-.079.037c-.21.375-.444.864-.608 1.25a18.27 18.27 0 0 0-5.487 0 12.64 12.64 0 0 0-.617-1.25.077.077 0 0 0-.079-.037A19.736 19.736 0 0 0 3.677 4.37a.07.07 0 0 0-.032.027C.533 9.046-.32 13.58.099 18.057a.082.082 0 0 0 .031.057 19.9 19.9 0 0 0 5.993 3.03.078.078 0 0 0 .084-.028 14.09 14.09 0 0 0 1.226-1.994.076.076 0 0 0-.041-.106 13.107 13.107 0 0 1-1.872-.892.077.077 0 0 1-.008-.128 10.2 10.2 0 0 0 .372-.292.074.074 0 0 1 .077-.01c3.928 1.793 8.18 1.793 12.062 0a.074.074 0 0 1 .078.01c.12.098.246.198.373.292a.077.077 0 0 1-.006.127 12.299 12.299 0 0 1-1.873.892.077.077 0 0 0-.041.107c.36.698.772 1.362 1.225 1.993a.076.076 0 0 0 .084.028 19.839 19.839 0 0 0 6.002-3.03.077.077 0 0 0 .032-.054c.5-5.177-.838-9.674-3.549-13.66a.061.061 0 0 0-.031-.03zM8.02 15.33c-1.183 0-2.157-1.085-2.157-2.419 0-1.333.956-2.419 2.157-2.419 1.21 0 2.176 1.086 2.157 2.42 0 1.333-.956 2.418-2.157 2.418zm7.975 0c-1.183 0-2.157-1.085-2.157-2.419 0-1.333.955-2.419 2.157-2.419 1.21 0 2.176 1.086 2.157 2.42 0 1.333-.946 2.418-2.157 2.418z"/>
+            </svg>
+            Войти через Discord
+        </a>
     </div>
 </div>
 

src/GmRelay.Web/Components/Pages/SessionHistory.razor

@@ -56,7 +56,7 @@
                         {
                             <tr>
                                 <td>@entry.ChangedAt.ToString("dd.MM.yyyy HH:mm") UTC</td>
-                                <td>@entry.ActorName (@entry.ActorTelegramId)</td>
+                                <td>@entry.ActorName (@entry.ActorExternalUserId)</td>
                                 <td>
                                     <span class="status-badge @(GetBadgeClass(entry.ChangeType))">
                                         @GetChangeTypeLabel(entry.ChangeType)
@@ -82,13 +82,13 @@
     protected override async Task OnInitializedAsync()
     {
         var authState = await AuthStateProvider.GetAuthenticationStateAsync();
-        if (!authState.User.TryGetTelegramId(out var telegramId))
+        if (!authState.User.TryGetPlatformIdentity(out var platform, out var externalUserId))
         {
             Navigation.NavigateTo("/access-denied");
             return;
         }
 
-        var session = await SessionService.GetSessionForGmAsync(SessionId, telegramId);
+        var session = await SessionService.GetSessionForCurrentUserAsync(SessionId);
         if (session is null)
         {
             Navigation.NavigateTo("/access-denied");
@@ -97,7 +97,7 @@
 
         sessionTitle = session.Title;
         groupId = session.GroupId;
-        entries = await SessionService.GetSessionHistoryForGmAsync(SessionId, telegramId);
+        entries = await SessionService.GetSessionHistoryForCurrentUserAsync(SessionId);
     }
 
     private string GetChangeTypeLabel(string changeType) => changeType switch

src/GmRelay.Web/DiscordOAuthOptions.cs

@@ -0,0 +1,19 @@
+namespace GmRelay.Web;
+
+public sealed class DiscordOAuthOptions
+{
+    public string ClientId { get; set; } = string.Empty;
+    public string ClientSecret { get; set; } = string.Empty;
+    public string RedirectUri { get; set; } = string.Empty;
+    public string[] Scopes { get; set; } = ["identify", "guilds"];
+
+    public void Validate()
+    {
+        if (string.IsNullOrWhiteSpace(ClientId))
+            throw new InvalidOperationException("Discord:ClientId is required.");
+        if (string.IsNullOrWhiteSpace(ClientSecret))
+            throw new InvalidOperationException("Discord:ClientSecret is required.");
+        if (string.IsNullOrWhiteSpace(RedirectUri))
+            throw new InvalidOperationException("Discord:RedirectUri is required.");
+    }
+}

src/GmRelay.Web/Program.cs

@@ -1,3 +1,4 @@
+using GmRelay.Web;
 using GmRelay.Web.Components;
 using GmRelay.Web.Health;
 using GmRelay.Web.Services;
@@ -7,6 +8,7 @@ using Microsoft.AspNetCore.DataProtection;
 using Microsoft.AspNetCore.Diagnostics.HealthChecks;
 using Microsoft.Extensions.Diagnostics.HealthChecks;
 using System.Security.Claims;
+using System.Security.Cryptography;
 using System.Text.Json;
 using Telegram.Bot;
 using Npgsql;
@@ -16,6 +18,12 @@ var builder = WebApplication.CreateBuilder(args);
 // Add Aspire service defaults
 builder.AddServiceDefaults();
 
+// Add HttpClient
+builder.Services.AddHttpClient();
+
+// Add HttpContextAccessor for platform-agnostic identity resolution
+builder.Services.AddHttpContextAccessor();
+
 // Add health checks
 builder.Services.AddHealthChecks()
     .AddCheck<NpgsqlHealthCheck>("npgsql");
@@ -29,6 +37,8 @@ builder.AddNpgsqlDataSource("gmrelaydb");
 
 // Add Services
 builder.Services.AddSingleton<TelegramAuthService>();
+builder.Services.Configure<DiscordOAuthOptions>(builder.Configuration.GetSection("Discord"));
+builder.Services.AddSingleton<DiscordAuthService>();
 builder.Services.AddSingleton<ISessionStore, SessionService>();
 builder.Services.AddScoped<AuthorizedSessionService>();
 builder.Services.AddScoped<CalendarSubscriptionService>();
@@ -174,6 +184,56 @@ app.MapPost("/auth/logout", async (HttpContext context) =>
     return Results.Redirect("/");
 });
 
+// Discord OAuth endpoints
+app.MapGet("/auth/discord", (HttpContext context, DiscordAuthService discordAuth) =>
+{
+    var state = Guid.NewGuid().ToString("N");
+    context.Response.Cookies.Append("__DiscordOAuthState", state, new CookieOptions
+    {
+        HttpOnly = true,
+        Secure = true,
+        SameSite = SameSiteMode.Strict,
+        MaxAge = TimeSpan.FromMinutes(5)
+    });
+    var url = discordAuth.BuildAuthorizeUrl(state);
+    return Results.Redirect(url);
+});
+
+app.MapGet("/auth/discord/callback", async (
+    HttpContext context,
+    DiscordAuthService discordAuth,
+    ISessionStore sessionStore) =>
+{
+    var code = context.Request.Query["code"].ToString();
+    var state = context.Request.Query["state"].ToString();
+    var storedState = context.Request.Cookies["__DiscordOAuthState"];
+
+    context.Response.Cookies.Delete("__DiscordOAuthState");
+
+    if (string.IsNullOrWhiteSpace(code) ||
+        string.IsNullOrWhiteSpace(state) ||
+        !CryptographicOperations.FixedTimeEquals(
+            System.Text.Encoding.UTF8.GetBytes(state),
+            System.Text.Encoding.UTF8.GetBytes(storedState ?? string.Empty)))
+    {
+        return Results.Redirect("/login?error=auth_failed");
+    }
+
+    var user = await discordAuth.ExchangeCodeAsync(code);
+    if (user is null)
+        return Results.Redirect("/login?error=auth_failed");
+
+    await sessionStore.UpsertDiscordUserAsync(user.Id, user.DisplayName, user.AvatarUrl);
+
+    var authProperties = new AuthenticationProperties { IsPersistent = true };
+    await context.SignInAsync(
+        CookieAuthenticationDefaults.AuthenticationScheme,
+        CreateDiscordPrincipal(user.Id, user.DisplayName, user.AvatarUrl),
+        authProperties);
+
+    return Results.Redirect("/");
+});
+
 // Public calendar subscription endpoint (no auth required)
 app.MapGet("/calendar/{token}.ics", async (
     string token,
@@ -200,11 +260,29 @@ static ClaimsPrincipal CreateTelegramPrincipal(long telegramId, string name)
     {
         new(ClaimTypes.NameIdentifier, telegramId.ToString(System.Globalization.CultureInfo.InvariantCulture)),
         new(ClaimTypes.Name, name),
-        new("TelegramId", telegramId.ToString(System.Globalization.CultureInfo.InvariantCulture))
+        new("TelegramId", telegramId.ToString(System.Globalization.CultureInfo.InvariantCulture)),
+        new("Platform", "Telegram")
     };
 
     var claimsIdentity = new ClaimsIdentity(claims, CookieAuthenticationDefaults.AuthenticationScheme);
     return new ClaimsPrincipal(claimsIdentity);
 }
 
+static ClaimsPrincipal CreateDiscordPrincipal(string discordId, string name, string? avatarUrl)
+{
+    var claims = new List<Claim>
+    {
+        new(ClaimTypes.NameIdentifier, discordId),
+        new(ClaimTypes.Name, name),
+        new("DiscordId", discordId),
+        new("Platform", "Discord")
+    };
+
+    if (!string.IsNullOrWhiteSpace(avatarUrl))
+        claims.Add(new Claim("AvatarUrl", avatarUrl));
+
+    var claimsIdentity = new ClaimsIdentity(claims, CookieAuthenticationDefaults.AuthenticationScheme);
+    return new ClaimsPrincipal(claimsIdentity);
+}
+
 public sealed record TelegramWebAppAuthRequest(string InitData);

src/GmRelay.Web/Services/AuthorizedSessionService.cs

@@ -1,182 +1,237 @@
+using System.Security.Claims;
 using GmRelay.Shared.Domain;
 
 namespace GmRelay.Web.Services;
 
-public sealed class AuthorizedSessionService(ISessionStore sessionStore)
+public sealed class AuthorizedSessionService(ISessionStore sessionStore, IHttpContextAccessor httpContextAccessor)
 {
-    public Task<List<WebGameGroup>> GetGroupsForGmAsync(long gmId) =>
+    private (string Platform, string ExternalUserId, string Name)? GetCurrentIdentity()
-        sessionStore.GetGroupsForGmAsync(gmId);
-
-    public async Task<WebGroupManagement?> GetGroupManagementForGmAsync(Guid groupId, long gmId)
     {
-        if (!await GroupBelongsToGmAsync(groupId, gmId))
+        var user = httpContextAccessor.HttpContext?.User;
-        {
+        if (user is null || !user.TryGetPlatformIdentity(out var platform, out var externalUserId))
+            return null;
+
+        var name = user.FindFirst(ClaimTypes.Name)?.Value ?? externalUserId;
+        return (platform, externalUserId, name);
+    }
+
+    public Task<List<WebGameGroup>> GetGroupsForCurrentUserAsync()
+    {
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            return Task.FromResult(new List<WebGameGroup>());
+
+        return sessionStore.GetGroupsForUserAsync(identity.Value.Platform, identity.Value.ExternalUserId);
+    }
+
+    public async Task<WebGroupManagement?> GetGroupManagementForCurrentUserAsync(Guid groupId)
+    {
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            return null;
+
+        if (!await sessionStore.IsGroupManagerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId))
             return null;
-        }
 
         var group = await sessionStore.GetGroupAsync(groupId);
         if (group is null)
-        {
             return null;
-        }
 
         var managers = await sessionStore.GetGroupManagersAsync(groupId);
-        var isOwner = await sessionStore.IsGroupOwnerAsync(groupId, gmId);
+        var isOwner = await sessionStore.IsGroupOwnerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId);
         return new WebGroupManagement(group, managers, isOwner);
     }
 
-    public async Task<List<WebSession>?> GetUpcomingSessionsForGmAsync(Guid groupId, long gmId)
+    public async Task<List<WebSession>?> GetUpcomingSessionsForCurrentUserAsync(Guid groupId)
     {
-        if (!await GroupBelongsToGmAsync(groupId, gmId))
+        var identity = GetCurrentIdentity();
-        {
+        if (identity is null)
+            return null;
+
+        if (!await sessionStore.IsGroupManagerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId))
             return null;
-        }
 
         return await sessionStore.GetUpcomingSessionsAsync(groupId);
     }
 
-    public async Task<WebSession?> GetSessionForGmAsync(Guid sessionId, long gmId)
+    public async Task<WebSession?> GetSessionForCurrentUserAsync(Guid sessionId)
     {
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            return null;
+
         var session = await sessionStore.GetSessionAsync(sessionId);
         if (session is null)
-        {
             return null;
-        }
 
-        return await GroupBelongsToGmAsync(session.GroupId, gmId) ? session : null;
+        return await sessionStore.IsGroupManagerAsync(session.GroupId, identity.Value.Platform, identity.Value.ExternalUserId) ? session : null;
     }
 
-    public async Task<WebSessionBatch?> GetBatchForGmAsync(Guid batchId, long gmId)
+    public async Task<WebSessionBatch?> GetBatchForCurrentUserAsync(Guid batchId)
     {
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            return null;
+
         var batch = await sessionStore.GetBatchAsync(batchId);
         if (batch is null)
-        {
             return null;
-        }
 
-        return await GroupBelongsToGmAsync(batch.GroupId, gmId) ? batch : null;
+        return await sessionStore.IsGroupManagerAsync(batch.GroupId, identity.Value.Platform, identity.Value.ExternalUserId) ? batch : null;
     }
 
-    public async Task UpdateSessionForGmAsync(Guid sessionId, long gmId, string title, DateTime scheduledAt, string joinLink, int? maxPlayers)
+    public async Task UpdateSessionForCurrentUserAsync(Guid sessionId, string title, DateTime scheduledAt, string joinLink, int? maxPlayers)
     {
-        var session = await GetSessionForGmAsync(sessionId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var session = await GetSessionForCurrentUserAsync(sessionId);
         if (session is null)
         {
-            throw new SessionAccessDeniedException(sessionId, gmId);
+            throw new SessionAccessDeniedException(sessionId, identity.Value.ExternalUserId);
         }
 
         await sessionStore.UpdateSessionAsync(sessionId, session.GroupId, title, scheduledAt, joinLink, maxPlayers);
 
         if (session.Title != title)
-            await sessionStore.LogSessionChangeAsync(sessionId, gmId, "ГМ", "Title", session.Title, title);
+            await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "Title", session.Title, title);
         if (session.ScheduledAt != scheduledAt)
-            await sessionStore.LogSessionChangeAsync(sessionId, gmId, "ГМ", "Time", session.ScheduledAt.ToString("O"), scheduledAt.ToString("O"));
+            await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "Time", session.ScheduledAt.ToString("O"), scheduledAt.ToString("O"));
         if (session.JoinLink != joinLink)
-            await sessionStore.LogSessionChangeAsync(sessionId, gmId, "ГМ", "Link", session.JoinLink, joinLink);
+            await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "Link", session.JoinLink, joinLink);
         if (session.MaxPlayers != maxPlayers)
-            await sessionStore.LogSessionChangeAsync(sessionId, gmId, "ГМ", "MaxPlayers", session.MaxPlayers?.ToString(), maxPlayers?.ToString());
+            await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "MaxPlayers", session.MaxPlayers?.ToString(), maxPlayers?.ToString());
     }
 
-    public async Task PromoteWaitlistedPlayerForGmAsync(Guid sessionId, long gmId)
+    public async Task PromoteWaitlistedPlayerForCurrentUserAsync(Guid sessionId)
     {
-        var session = await GetSessionForGmAsync(sessionId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var session = await GetSessionForCurrentUserAsync(sessionId);
         if (session is null)
         {
-            throw new SessionAccessDeniedException(sessionId, gmId);
+            throw new SessionAccessDeniedException(sessionId, identity.Value.ExternalUserId);
         }
 
         await sessionStore.PromoteWaitlistedPlayerAsync(sessionId, session.GroupId);
-        await sessionStore.LogSessionChangeAsync(sessionId, gmId, "ГМ", "WaitlistPromote", null, null);
+        await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "WaitlistPromote", null, null);
     }
 
-    public async Task UpdateBatchDetailsForGmAsync(Guid batchId, long gmId, string title, string joinLink)
+    public async Task UpdateBatchDetailsForCurrentUserAsync(Guid batchId, string title, string joinLink)
     {
-        var batch = await GetBatchForGmAsync(batchId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var batch = await GetBatchForCurrentUserAsync(batchId);
         if (batch is null)
         {
-            throw new SessionAccessDeniedException(batchId, gmId);
+            throw new SessionAccessDeniedException(batchId, identity.Value.ExternalUserId);
         }
 
         await sessionStore.UpdateBatchDetailsAsync(batchId, batch.GroupId, title.Trim(), joinLink.Trim());
     }
 
-    public async Task UpdateBatchNotificationModeForGmAsync(Guid batchId, long gmId, SessionNotificationMode notificationMode)
+    public async Task UpdateBatchNotificationModeForCurrentUserAsync(Guid batchId, SessionNotificationMode notificationMode)
     {
-        var batch = await GetBatchForGmAsync(batchId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var batch = await GetBatchForCurrentUserAsync(batchId);
         if (batch is null)
         {
-            throw new SessionAccessDeniedException(batchId, gmId);
+            throw new SessionAccessDeniedException(batchId, identity.Value.ExternalUserId);
         }
 
         await sessionStore.UpdateBatchNotificationModeAsync(batchId, batch.GroupId, notificationMode);
     }
 
-    public async Task RescheduleBatchForGmAsync(Guid batchId, long gmId, DateTime firstScheduledAt, int intervalDays)
+    public async Task RescheduleBatchForCurrentUserAsync(Guid batchId, DateTime firstScheduledAt, int intervalDays)
     {
         if (intervalDays <= 0)
         {
             throw new ArgumentOutOfRangeException(nameof(intervalDays), intervalDays, "Interval must be greater than zero.");
         }
 
-        var batch = await GetBatchForGmAsync(batchId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var batch = await GetBatchForCurrentUserAsync(batchId);
         if (batch is null)
         {
-            throw new SessionAccessDeniedException(batchId, gmId);
+            throw new SessionAccessDeniedException(batchId, identity.Value.ExternalUserId);
         }
 
         await sessionStore.RescheduleBatchAsync(batchId, batch.GroupId, firstScheduledAt, intervalDays);
-        await sessionStore.LogSessionChangeAsync(batchId, gmId, "ГМ", "BatchRescheduled", batch.FirstScheduledAt.ToString("O"), firstScheduledAt.ToString("O"));
+        await sessionStore.LogSessionChangeAsync(batchId, identity.Value.ExternalUserId, identity.Value.Name, "BatchRescheduled", batch.FirstScheduledAt.ToString("O"), firstScheduledAt.ToString("O"));
     }
 
-    public async Task<WebSessionBatch> CloneBatchForGmAsync(Guid batchId, long gmId, BatchCloneInterval interval)
+    public async Task<WebSessionBatch> CloneBatchForCurrentUserAsync(Guid batchId, BatchCloneInterval interval)
     {
-        var batch = await GetBatchForGmAsync(batchId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var batch = await GetBatchForCurrentUserAsync(batchId);
         if (batch is null)
         {
-            throw new SessionAccessDeniedException(batchId, gmId);
+            throw new SessionAccessDeniedException(batchId, identity.Value.ExternalUserId);
         }
 
         return await sessionStore.CloneBatchAsync(batchId, batch.GroupId, interval);
     }
 
-    public async Task<List<WebCampaignTemplate>?> GetCampaignTemplatesForGmAsync(Guid groupId, long gmId)
+    public async Task<List<WebCampaignTemplate>?> GetCampaignTemplatesForCurrentUserAsync(Guid groupId)
     {
-        if (!await GroupBelongsToGmAsync(groupId, gmId))
+        var identity = GetCurrentIdentity();
-        {
+        if (identity is null)
+            return null;
+
+        if (!await sessionStore.IsGroupManagerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId))
             return null;
-        }
 
         return await sessionStore.GetCampaignTemplatesAsync(groupId);
     }
 
-    public async Task<WebCampaignTemplate> CreateCampaignTemplateForGmAsync(
+    public async Task<WebCampaignTemplate> CreateCampaignTemplateForCurrentUserAsync(
         Guid groupId,
-        long gmId,
         CreateCampaignTemplateRequest request)
     {
-        if (!await GroupBelongsToGmAsync(groupId, gmId))
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        if (!await sessionStore.IsGroupManagerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId))
         {
-            throw new SessionAccessDeniedException(groupId, gmId);
+            throw new SessionAccessDeniedException(groupId, identity.Value.ExternalUserId);
         }
 
         var normalizedRequest = NormalizeCampaignTemplateRequest(request);
         return await sessionStore.CreateCampaignTemplateAsync(groupId, normalizedRequest);
     }
 
-    public async Task DeleteCampaignTemplateForGmAsync(Guid templateId, long gmId)
+    public async Task DeleteCampaignTemplateForCurrentUserAsync(Guid templateId)
     {
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
         var template = await sessionStore.GetCampaignTemplateAsync(templateId);
-        if (template is null || !await GroupBelongsToGmAsync(template.GroupId, gmId))
+        if (template is null || !await sessionStore.IsGroupManagerAsync(template.GroupId, identity.Value.Platform, identity.Value.ExternalUserId))
         {
-            throw new SessionAccessDeniedException(templateId, gmId);
+            throw new SessionAccessDeniedException(templateId, identity.Value.ExternalUserId);
         }
 
         await sessionStore.DeleteCampaignTemplateAsync(templateId, template.GroupId);
     }
 
-    public async Task<WebSessionBatch> CreateBatchFromCampaignTemplateForGmAsync(
+    public async Task<WebSessionBatch> CreateBatchFromCampaignTemplateForCurrentUserAsync(
         Guid templateId,
-        long gmId,
         DateTime firstScheduledAt)
     {
         if (firstScheduledAt <= DateTime.UtcNow)
@@ -184,89 +239,112 @@ public sealed class AuthorizedSessionService(ISessionStore sessionStore)
             throw new ArgumentOutOfRangeException(nameof(firstScheduledAt), firstScheduledAt, "First scheduled time must be in the future.");
         }
 
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
         var template = await sessionStore.GetCampaignTemplateAsync(templateId);
-        if (template is null || !await GroupBelongsToGmAsync(template.GroupId, gmId))
+        if (template is null || !await sessionStore.IsGroupManagerAsync(template.GroupId, identity.Value.Platform, identity.Value.ExternalUserId))
         {
-            throw new SessionAccessDeniedException(templateId, gmId);
+            throw new SessionAccessDeniedException(templateId, identity.Value.ExternalUserId);
         }
 
         return await sessionStore.CreateBatchFromTemplateAsync(templateId, template.GroupId, firstScheduledAt);
     }
 
-    public async Task AddCoGmForOwnerAsync(Guid groupId, long ownerTelegramId, long coGmTelegramId, string displayName, string? telegramUsername)
+    public async Task AddCoGmForOwnerAsync(Guid groupId, string coGmPlatform, string coGmExternalUserId, string displayName, string? externalUsername)
     {
-        if (coGmTelegramId <= 0)
+        if (string.IsNullOrWhiteSpace(coGmExternalUserId))
         {
-            throw new ArgumentOutOfRangeException(nameof(coGmTelegramId), coGmTelegramId, "Telegram id must be greater than zero.");
+            throw new ArgumentException("External user id must not be empty.", nameof(coGmExternalUserId));
         }
 
-        if (ownerTelegramId == coGmTelegramId)
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        if (identity.Value.ExternalUserId == coGmExternalUserId && identity.Value.Platform == coGmPlatform)
         {
             throw new InvalidOperationException("Owner is already a group manager.");
         }
 
-        if (!await sessionStore.IsGroupOwnerAsync(groupId, ownerTelegramId))
+        if (!await sessionStore.IsGroupOwnerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId))
         {
-            throw new SessionAccessDeniedException(groupId, ownerTelegramId);
+            throw new SessionAccessDeniedException(groupId, identity.Value.ExternalUserId);
         }
 
         var normalizedName = string.IsNullOrWhiteSpace(displayName)
-            ? $"Telegram {coGmTelegramId.ToString(System.Globalization.CultureInfo.InvariantCulture)}"
+            ? $"{coGmPlatform} {coGmExternalUserId}"
             : displayName.Trim();
-        var normalizedUsername = string.IsNullOrWhiteSpace(telegramUsername)
+        var normalizedUsername = string.IsNullOrWhiteSpace(externalUsername)
             ? null
-            : telegramUsername.Trim().TrimStart('@');
+            : externalUsername.Trim().TrimStart('@');
 
-        await sessionStore.AddGroupCoGmAsync(groupId, ownerTelegramId, coGmTelegramId, normalizedName, normalizedUsername);
+        await sessionStore.AddGroupCoGmAsync(
+            groupId,
+            identity.Value.Platform, identity.Value.ExternalUserId,
+            coGmPlatform, coGmExternalUserId,
+            normalizedName, normalizedUsername);
     }
 
-    public async Task RemoveCoGmForOwnerAsync(Guid groupId, long ownerTelegramId, long coGmTelegramId)
+    public async Task RemoveCoGmForOwnerAsync(Guid groupId, string coGmPlatform, string coGmExternalUserId)
     {
-        if (!await sessionStore.IsGroupOwnerAsync(groupId, ownerTelegramId))
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        if (!await sessionStore.IsGroupOwnerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId))
         {
-            throw new SessionAccessDeniedException(groupId, ownerTelegramId);
+            throw new SessionAccessDeniedException(groupId, identity.Value.ExternalUserId);
         }
 
-        await sessionStore.RemoveGroupCoGmAsync(groupId, coGmTelegramId);
+        await sessionStore.RemoveGroupCoGmAsync(groupId, coGmPlatform, coGmExternalUserId);
     }
 
-    public async Task<List<WebParticipant>?> GetSessionParticipantsForGmAsync(Guid sessionId, long gmId)
+    public async Task<List<WebParticipant>?> GetSessionParticipantsForCurrentUserAsync(Guid sessionId)
     {
-        var session = await GetSessionForGmAsync(sessionId, gmId);
+        var session = await GetSessionForCurrentUserAsync(sessionId);
         if (session is null)
-        {
             return null;
-        }
 
         return await sessionStore.GetSessionParticipantsAsync(sessionId);
     }
 
-    public async Task<List<SessionAuditLogEntry>?> GetSessionHistoryForGmAsync(Guid sessionId, long gmId)
+    public async Task<List<SessionAuditLogEntry>?> GetSessionHistoryForCurrentUserAsync(Guid sessionId)
     {
-        var session = await GetSessionForGmAsync(sessionId, gmId);
+        var session = await GetSessionForCurrentUserAsync(sessionId);
         if (session is null)
-        {
             return null;
-        }
 
         return await sessionStore.GetSessionHistoryAsync(sessionId);
     }
 
-    public async Task RemovePlayerFromSessionForGmAsync(Guid sessionId, long gmId, Guid participantId)
+    public async Task RemovePlayerFromSessionForCurrentUserAsync(Guid sessionId, Guid participantId)
     {
-        var session = await GetSessionForGmAsync(sessionId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            throw new InvalidOperationException("User is not authenticated.");
+
+        var session = await GetSessionForCurrentUserAsync(sessionId);
         if (session is null)
         {
-            throw new SessionAccessDeniedException(sessionId, gmId);
+            throw new SessionAccessDeniedException(sessionId, identity.Value.ExternalUserId);
         }
 
         await sessionStore.RemovePlayerFromSessionAsync(sessionId, session.GroupId, participantId);
-        await sessionStore.LogSessionChangeAsync(sessionId, gmId, "ГМ", "PlayerRemoved", participantId.ToString(), null);
+        await sessionStore.LogSessionChangeAsync(sessionId, identity.Value.ExternalUserId, identity.Value.Name, "PlayerRemoved", participantId.ToString(), null);
     }
 
-    private async Task<bool> GroupBelongsToGmAsync(Guid groupId, long gmId)
+    public async Task<List<PlayerAttendanceStats>?> GetGroupAttendanceStatsForCurrentUserAsync(Guid groupId)
     {
-        return await sessionStore.IsGroupManagerAsync(groupId, gmId);
+        var identity = GetCurrentIdentity();
+        if (identity is null)
+            return null;
+
+        if (!await sessionStore.IsGroupManagerAsync(groupId, identity.Value.Platform, identity.Value.ExternalUserId))
+            return null;
+
+        return await sessionStore.GetGroupAttendanceStatsAsync(groupId);
     }
 
     private static CreateCampaignTemplateRequest NormalizeCampaignTemplateRequest(CreateCampaignTemplateRequest request)

src/GmRelay.Web/Services/ClaimsPrincipalExtensions.cs

@@ -6,4 +6,37 @@ public static class ClaimsPrincipalExtensions
 {
     public static bool TryGetTelegramId(this ClaimsPrincipal user, out long telegramId) =>
         long.TryParse(user.FindFirst("TelegramId")?.Value, out telegramId);
+
+    public static bool TryGetDiscordId(this ClaimsPrincipal user, out string? discordId)
+    {
+        discordId = user.FindFirst("DiscordId")?.Value;
+        return !string.IsNullOrWhiteSpace(discordId);
+    }
+
+    public static bool TryGetPlatformIdentity(this ClaimsPrincipal user, out string platform, out string externalUserId)
+    {
+        platform = string.Empty;
+        externalUserId = string.Empty;
+
+        var platformClaim = user.FindFirst("Platform")?.Value;
+        if (!string.IsNullOrWhiteSpace(platformClaim))
+        {
+            platform = platformClaim;
+            externalUserId = user.FindFirst(ClaimTypes.NameIdentifier)?.Value ?? string.Empty;
+            return !string.IsNullOrWhiteSpace(externalUserId);
+        }
+
+        // Fallback for legacy Telegram users before Platform claim was added
+        if (TryGetTelegramId(user, out var telegramId))
+        {
+            platform = "Telegram";
+            externalUserId = telegramId.ToString(System.Globalization.CultureInfo.InvariantCulture);
+            return true;
+        }
+
+        return false;
+    }
+
+    public static string? GetAvatarUrl(this ClaimsPrincipal user) =>
+        user.FindFirst("AvatarUrl")?.Value;
 }

src/GmRelay.Web/Services/DiscordAuthService.cs

@@ -0,0 +1,82 @@
+using System.Net.Http.Headers;
+using System.Security.Claims;
+using System.Text.Json;
+using System.Text.Json.Serialization;
+
+namespace GmRelay.Web.Services;
+
+public sealed class DiscordAuthService(IHttpClientFactory httpClientFactory, IConfiguration configuration)
+{
+    private readonly DiscordOAuthOptions _options = configuration.GetSection("Discord").Get<DiscordOAuthOptions>() ?? new DiscordOAuthOptions();
+
+    public string BuildAuthorizeUrl(string state)
+    {
+        _options.Validate();
+        var scopes = string.Join(" ", _options.Scopes);
+        return $"https://discord.com/oauth2/authorize?client_id={_options.ClientId}&redirect_uri={Uri.EscapeDataString(_options.RedirectUri)}&response_type=code&scope={Uri.EscapeDataString(scopes)}&state={Uri.EscapeDataString(state)}";
+    }
+
+    public async Task<DiscordUser?> ExchangeCodeAsync(string code)
+    {
+        _options.Validate();
+        var client = httpClientFactory.CreateClient();
+
+        var tokenResponse = await ExchangeCodeForTokenAsync(client, code);
+        if (tokenResponse is null)
+            return null;
+
+        return await FetchUserProfileAsync(client, tokenResponse.AccessToken);
+    }
+
+    private async Task<DiscordTokenResponse?> ExchangeCodeForTokenAsync(HttpClient client, string code)
+    {
+        var content = new FormUrlEncodedContent(new Dictionary<string, string>
+        {
+            ["grant_type"] = "authorization_code",
+            ["code"] = code,
+            ["redirect_uri"] = _options.RedirectUri,
+            ["client_id"] = _options.ClientId,
+            ["client_secret"] = _options.ClientSecret
+        });
+
+        var response = await client.PostAsync("https://discord.com/api/oauth2/token", content);
+        if (!response.IsSuccessStatusCode)
+            return null;
+
+        var json = await response.Content.ReadAsStringAsync();
+        return JsonSerializer.Deserialize<DiscordTokenResponse>(json);
+    }
+
+    private static async Task<DiscordUser?> FetchUserProfileAsync(HttpClient client, string accessToken)
+    {
+        client.DefaultRequestHeaders.Authorization = new AuthenticationHeaderValue("Bearer", accessToken);
+        var response = await client.GetAsync("https://discord.com/api/users/@me");
+        if (!response.IsSuccessStatusCode)
+            return null;
+
+        var json = await response.Content.ReadAsStringAsync();
+        return JsonSerializer.Deserialize<DiscordUser>(json);
+    }
+}
+
+public sealed record DiscordTokenResponse(
+    [property: JsonPropertyName("access_token")] string AccessToken,
+    [property: JsonPropertyName("token_type")] string TokenType,
+    [property: JsonPropertyName("expires_in")] int ExpiresIn,
+    [property: JsonPropertyName("scope")] string Scope);
+
+public sealed record DiscordUser(
+    [property: JsonPropertyName("id")] string Id,
+    [property: JsonPropertyName("username")] string Username,
+    [property: JsonPropertyName("discriminator")] string Discriminator,
+    [property: JsonPropertyName("avatar")] string? Avatar,
+    [property: JsonPropertyName("email")] string? Email)
+{
+    public string DisplayName =>
+        Discriminator == "0" ? Username : $"{Username}#{Discriminator}";
+
+    public string? AvatarUrl =>
+        !string.IsNullOrWhiteSpace(Avatar)
+            ? $"https://cdn.discordapp.com/avatars/{Id}/{Avatar}.png"
+            : null;
+}

src/GmRelay.Web/Services/ISessionStore.cs

@@ -5,33 +5,31 @@ namespace GmRelay.Web.Services;
 public sealed record PlayerAttendanceStats(
     Guid PlayerId,
     string DisplayName,
-    string? TelegramUsername,
+    string? ExternalUsername,
     long TotalSessions,
     long ConfirmedCount,
     long DeclinedCount,
     long NoResponseCount,
     long WaitlistedCount,
     long CancellationAffectedCount,
-    decimal AttendanceRate
+    decimal AttendanceRate);
-);
 
 public sealed record SessionAuditLogEntry(
     Guid Id,
     Guid SessionId,
-    long ActorTelegramId,
+    string ActorExternalUserId,
     string ActorName,
     string ChangeType,
     string? OldValue,
     string? NewValue,
-    DateTime ChangedAt
+    DateTime ChangedAt);
-);
 
 public interface ISessionStore
 {
-    Task<List<WebGameGroup>> GetGroupsForGmAsync(long gmId);
+    Task<List<WebGameGroup>> GetGroupsForUserAsync(string platform, string externalUserId);
     Task<WebGameGroup?> GetGroupAsync(Guid groupId);
-    Task<bool> IsGroupManagerAsync(Guid groupId, long telegramId);
+    Task<bool> IsGroupManagerAsync(Guid groupId, string platform, string externalUserId);
-    Task<bool> IsGroupOwnerAsync(Guid groupId, long telegramId);
+    Task<bool> IsGroupOwnerAsync(Guid groupId, string platform, string externalUserId);
     Task<List<WebGroupManager>> GetGroupManagersAsync(Guid groupId);
     Task<List<WebSession>> GetUpcomingSessionsAsync(Guid groupId);
     Task<WebSession?> GetSessionAsync(Guid sessionId);
@@ -47,11 +45,12 @@ public interface ISessionStore
     Task<WebCampaignTemplate> CreateCampaignTemplateAsync(Guid groupId, CreateCampaignTemplateRequest request);
     Task DeleteCampaignTemplateAsync(Guid templateId, Guid groupId);
     Task<WebSessionBatch> CreateBatchFromTemplateAsync(Guid templateId, Guid groupId, DateTime firstScheduledAt);
-    Task AddGroupCoGmAsync(Guid groupId, long ownerTelegramId, long coGmTelegramId, string displayName, string? telegramUsername);
+    Task AddGroupCoGmAsync(Guid groupId, string ownerPlatform, string ownerExternalUserId, string coGmPlatform, string coGmExternalUserId, string displayName, string? externalUsername);
-    Task RemoveGroupCoGmAsync(Guid groupId, long coGmTelegramId);
+    Task RemoveGroupCoGmAsync(Guid groupId, string coGmPlatform, string coGmExternalUserId);
     Task<List<WebParticipant>> GetSessionParticipantsAsync(Guid sessionId);
     Task RemovePlayerFromSessionAsync(Guid sessionId, Guid groupId, Guid participantId);
     Task<List<PlayerAttendanceStats>> GetGroupAttendanceStatsAsync(Guid groupId);
-    Task LogSessionChangeAsync(Guid sessionId, long actorTelegramId, string actorName, string changeType, string? oldValue, string? newValue);
+    Task LogSessionChangeAsync(Guid sessionId, string actorExternalUserId, string actorName, string changeType, string? oldValue, string? newValue);
     Task<List<SessionAuditLogEntry>> GetSessionHistoryAsync(Guid sessionId);
+    Task UpsertDiscordUserAsync(string discordId, string displayName, string? avatarUrl);
 }

src/GmRelay.Web/Services/SessionAccessDeniedException.cs

@@ -1,4 +1,4 @@
 namespace GmRelay.Web.Services;
 
-public sealed class SessionAccessDeniedException(Guid sessionId, long gmId)
+public sealed class SessionAccessDeniedException(Guid sessionId, string externalUserId)
-    : InvalidOperationException($"Session '{sessionId}' is not accessible for GM '{gmId}'.");
+    : InvalidOperationException($"Session '{sessionId}' is not accessible for user '{externalUserId}'.");

src/GmRelay.Web/Services/SessionService.cs

@@ -10,16 +10,32 @@ namespace GmRelay.Web.Services;
 public sealed record WebGameGroup(
     Guid Id,
     long TelegramChatId,
+    string? ExternalGroupId,
     string Name,
-    long GmTelegramId,
+    string? Platform,
-    string ManagerRole = GroupManagerRoleExtensions.OwnerValue);
+    string ManagerRole = GroupManagerRoleExtensions.OwnerValue)
+{
+    public long GmTelegramId { get; init; }
+
+    public WebGameGroup(Guid id, long telegramChatId, string name, long gmTelegramId)
+        : this(id, telegramChatId, null, name, null)
+    {
+        GmTelegramId = gmTelegramId;
+    }
+}
 
 public sealed record WebGroupManager(
     long TelegramId,
+    string? ExternalUserId,
     string DisplayName,
     string? TelegramUsername,
+    string? ExternalUsername,
     string Role,
-    DateTime AddedAt);
+    DateTime AddedAt)
+{
+    public WebGroupManager(long telegramId, string displayName, string? telegramUsername, string role, DateTime addedAt)
+        : this(telegramId, null, displayName, telegramUsername, null, role, addedAt) { }
+}
 
 public sealed record WebGroupManagement(
     WebGameGroup Group,
@@ -44,8 +60,10 @@ public sealed record WebSession(
 public sealed record WebParticipant(
     Guid Id,
     long TelegramId,
+    string? ExternalUserId,
     string DisplayName,
     string? TelegramUsername,
+    string? ExternalUsername,
     string RsvpStatus,
     string RegistrationStatus,
     bool IsGm,
@@ -83,23 +101,25 @@ public sealed class SessionService(
     ITelegramBotClient bot,
     ILogger<SessionService> logger) : ISessionStore
 {
-    public async Task<List<WebGameGroup>> GetGroupsForGmAsync(long gmId)
+    public async Task<List<WebGameGroup>> GetGroupsForUserAsync(string platform, string externalUserId)
     {
         await using var conn = await dataSource.OpenConnectionAsync();
         return (await conn.QueryAsync<WebGameGroup>(
             """
             SELECT g.id,
                    g.telegram_chat_id AS TelegramChatId,
+                   g.external_group_id AS ExternalGroupId,
                    g.name,
-                   g.gm_telegram_id AS GmTelegramId,
+                   g.platform AS Platform,
                    gm.role AS ManagerRole
             FROM group_managers gm
             JOIN players p ON p.id = gm.player_id
             JOIN game_groups g ON g.id = gm.group_id
-            WHERE p.telegram_id = @GmId
+            WHERE p.platform = @Platform
+              AND p.external_user_id = @ExternalUserId
             ORDER BY g.name
             """,
-            new { GmId = gmId })).ToList();
+            new { Platform = platform, ExternalUserId = externalUserId })).ToList();
     }
 
     public async Task<WebGameGroup?> GetGroupAsync(Guid groupId)
@@ -109,8 +129,9 @@ public sealed class SessionService(
             """
             SELECT g.id,
                    g.telegram_chat_id AS TelegramChatId,
+                   g.external_group_id AS ExternalGroupId,
                    g.name,
-                   g.gm_telegram_id AS GmTelegramId,
+                   g.platform AS Platform,
                    @OwnerRole AS ManagerRole
             FROM game_groups g
             WHERE g.id = @GroupId
@@ -118,7 +139,7 @@ public sealed class SessionService(
             new { GroupId = groupId, OwnerRole = GroupManagerRoleExtensions.OwnerValue });
     }
 
-    public async Task<bool> IsGroupManagerAsync(Guid groupId, long telegramId)
+    public async Task<bool> IsGroupManagerAsync(Guid groupId, string platform, string externalUserId)
     {
         await using var conn = await dataSource.OpenConnectionAsync();
         return await conn.ExecuteScalarAsync<bool>(
@@ -128,13 +149,14 @@ public sealed class SessionService(
                 FROM group_managers gm
                 JOIN players p ON p.id = gm.player_id
                 WHERE gm.group_id = @GroupId
-                  AND p.telegram_id = @TelegramId
+                  AND p.platform = @Platform
+                  AND p.external_user_id = @ExternalUserId
             )
             """,
-            new { GroupId = groupId, TelegramId = telegramId });
+            new { GroupId = groupId, Platform = platform, ExternalUserId = externalUserId });
     }
 
-    public async Task<bool> IsGroupOwnerAsync(Guid groupId, long telegramId)
+    public async Task<bool> IsGroupOwnerAsync(Guid groupId, string platform, string externalUserId)
     {
         await using var conn = await dataSource.OpenConnectionAsync();
         return await conn.ExecuteScalarAsync<bool>(
@@ -144,11 +166,12 @@ public sealed class SessionService(
                 FROM group_managers gm
                 JOIN players p ON p.id = gm.player_id
                 WHERE gm.group_id = @GroupId
-                  AND p.telegram_id = @TelegramId
+                  AND p.platform = @Platform
+                  AND p.external_user_id = @ExternalUserId
                   AND gm.role = @OwnerRole
             )
             """,
-            new { GroupId = groupId, TelegramId = telegramId, OwnerRole = GroupManagerRoleExtensions.OwnerValue });
+            new { GroupId = groupId, Platform = platform, ExternalUserId = externalUserId, OwnerRole = GroupManagerRoleExtensions.OwnerValue });
     }
 
     public async Task<List<WebGroupManager>> GetGroupManagersAsync(Guid groupId)
@@ -156,9 +179,11 @@ public sealed class SessionService(
         await using var conn = await dataSource.OpenConnectionAsync();
         return (await conn.QueryAsync<WebGroupManager>(
             """
-            SELECT p.telegram_id AS TelegramId,
+            SELECT COALESCE(p.telegram_id, 0) AS TelegramId,
+                   COALESCE(p.external_user_id, p.telegram_id::TEXT) AS ExternalUserId,
                    p.display_name AS DisplayName,
                    p.telegram_username AS TelegramUsername,
+                   COALESCE(p.external_username, p.telegram_username) AS ExternalUsername,
                    gm.role AS Role,
                    gm.created_at AS AddedAt
             FROM group_managers gm
@@ -179,7 +204,7 @@ public sealed class SessionService(
             SELECT
                 p.id AS PlayerId,
                 p.display_name AS DisplayName,
-                p.telegram_username AS TelegramUsername,
+                COALESCE(p.external_username, p.telegram_username) AS ExternalUsername,
                 COUNT(DISTINCT s.id) AS TotalSessions,
                 COUNT(DISTINCT CASE WHEN sp.rsvp_status = 'Confirmed' THEN s.id END) AS ConfirmedCount,
                 COUNT(DISTINCT CASE WHEN sp.rsvp_status = 'Declined' THEN s.id END) AS DeclinedCount,
@@ -198,21 +223,21 @@ public sealed class SessionService(
             WHERE s.group_id = @GroupId
               AND s.scheduled_at <= now()
               AND sp.is_gm = false
-            GROUP BY p.id, p.display_name, p.telegram_username
+            GROUP BY p.id, p.display_name, p.external_username, p.telegram_username
             ORDER BY AttendanceRate DESC, ConfirmedCount DESC
             """,
             new { GroupId = groupId })).ToList();
     }
 
-    public async Task LogSessionChangeAsync(Guid sessionId, long actorTelegramId, string actorName, string changeType, string? oldValue, string? newValue)
+    public async Task LogSessionChangeAsync(Guid sessionId, string actorExternalUserId, string actorName, string changeType, string? oldValue, string? newValue)
     {
         await using var conn = await dataSource.OpenConnectionAsync();
         await conn.ExecuteAsync(
             """
-            INSERT INTO session_audit_log (session_id, actor_telegram_id, actor_name, change_type, old_value, new_value)
+            INSERT INTO session_audit_log (session_id, actor_external_user_id, actor_name, change_type, old_value, new_value)
-            VALUES (@SessionId, @ActorTelegramId, @ActorName, @ChangeType, @OldValue, @NewValue)
+            VALUES (@SessionId, @ActorExternalUserId, @ActorName, @ChangeType, @OldValue, @NewValue)
             """,
-            new { SessionId = sessionId, ActorTelegramId = actorTelegramId, ActorName = actorName, ChangeType = changeType, OldValue = oldValue, NewValue = newValue });
+            new { SessionId = sessionId, ActorExternalUserId = actorExternalUserId, ActorName = actorName, ChangeType = changeType, OldValue = oldValue, NewValue = newValue });
     }
 
     public async Task<List<SessionAuditLogEntry>> GetSessionHistoryAsync(Guid sessionId)
@@ -220,7 +245,7 @@ public sealed class SessionService(
         await using var conn = await dataSource.OpenConnectionAsync();
         var entries = await conn.QueryAsync<SessionAuditLogEntry>(
             """
-            SELECT id, session_id AS SessionId, actor_telegram_id AS ActorTelegramId, actor_name AS ActorName,
+            SELECT id, session_id AS SessionId, actor_external_user_id AS ActorExternalUserId, actor_name AS ActorName,
                    change_type AS ChangeType, old_value AS OldValue, new_value AS NewValue, changed_at AS ChangedAt
             FROM session_audit_log
             WHERE session_id = @SessionId
@@ -230,32 +255,47 @@ public sealed class SessionService(
         return entries.ToList();
     }
 
+    public async Task UpsertDiscordUserAsync(string discordId, string displayName, string? avatarUrl)
+    {
+        await using var conn = await dataSource.OpenConnectionAsync();
+        await conn.ExecuteAsync(
+            """
+            INSERT INTO players (display_name, platform, external_user_id, external_username)
+            VALUES (@DisplayName, 'Discord', @DiscordId, @DisplayName)
+            ON CONFLICT (platform, external_user_id)
+            WHERE platform IS NOT NULL AND external_user_id IS NOT NULL
+            DO UPDATE
+            SET display_name = EXCLUDED.display_name,
+                external_username = EXCLUDED.external_username
+            """,
+            new { DisplayName = displayName, DiscordId = discordId });
+    }
+
     public async Task AddGroupCoGmAsync(
         Guid groupId,
-        long ownerTelegramId,
+        string ownerPlatform, string ownerExternalUserId,
-        long coGmTelegramId,
+        string coGmPlatform, string coGmExternalUserId,
-        string displayName,
+        string displayName, string? externalUsername)
-        string? telegramUsername)
     {
         await using var conn = await dataSource.OpenConnectionAsync();
         await using var transaction = await conn.BeginTransactionAsync();
 
         await conn.ExecuteAsync(
             """
-            INSERT INTO players (telegram_id, display_name, telegram_username, platform, external_user_id, external_username)
+            INSERT INTO players (display_name, telegram_username, platform, external_user_id, external_username)
-            VALUES (@TelegramId, @DisplayName, @TelegramUsername, 'Telegram', @TelegramId::TEXT, @TelegramUsername)
+            VALUES (@DisplayName, @ExternalUsername, @Platform, @ExternalUserId, @ExternalUsername)
-            ON CONFLICT (telegram_id) DO UPDATE
+            ON CONFLICT (platform, external_user_id)
+            WHERE platform IS NOT NULL AND external_user_id IS NOT NULL
+            DO UPDATE
             SET display_name = EXCLUDED.display_name,
-                telegram_username = EXCLUDED.telegram_username,
+                external_username = EXCLUDED.external_username
-                platform = COALESCE(players.platform, 'Telegram'),
-                external_user_id = COALESCE(players.external_user_id, EXCLUDED.telegram_id::TEXT),
-                external_username = COALESCE(players.external_username, EXCLUDED.telegram_username)
             """,
             new
             {
-                TelegramId = coGmTelegramId,
                 DisplayName = displayName,
-                TelegramUsername = telegramUsername
+                ExternalUsername = externalUsername,
+                Platform = coGmPlatform,
+                ExternalUserId = coGmExternalUserId
             },
             transaction);
 
@@ -267,8 +307,8 @@ public sealed class SessionService(
                    @CoGmRole,
                    owner_player.id
             FROM players co_gm
-            LEFT JOIN players owner_player ON owner_player.telegram_id = @OwnerTelegramId
+            LEFT JOIN players owner_player ON owner_player.platform = @OwnerPlatform AND owner_player.external_user_id = @OwnerExternalUserId
-            WHERE co_gm.telegram_id = @CoGmTelegramId
+            WHERE co_gm.platform = @CoGmPlatform AND co_gm.external_user_id = @CoGmExternalUserId
             ON CONFLICT (group_id, player_id) DO UPDATE
             SET role = CASE
                     WHEN group_managers.role = @OwnerRole THEN group_managers.role
@@ -279,8 +319,10 @@ public sealed class SessionService(
             new
             {
                 GroupId = groupId,
-                OwnerTelegramId = ownerTelegramId,
+                OwnerPlatform = ownerPlatform,
-                CoGmTelegramId = coGmTelegramId,
+                OwnerExternalUserId = ownerExternalUserId,
+                CoGmPlatform = coGmPlatform,
+                CoGmExternalUserId = coGmExternalUserId,
                 OwnerRole = GroupManagerRoleExtensions.OwnerValue,
                 CoGmRole = GroupManagerRoleExtensions.CoGmValue
             },
@@ -289,7 +331,7 @@ public sealed class SessionService(
         await transaction.CommitAsync();
     }
 
-    public async Task RemoveGroupCoGmAsync(Guid groupId, long coGmTelegramId)
+    public async Task RemoveGroupCoGmAsync(Guid groupId, string coGmPlatform, string coGmExternalUserId)
     {
         await using var conn = await dataSource.OpenConnectionAsync();
         await conn.ExecuteAsync(
@@ -298,13 +340,15 @@ public sealed class SessionService(
             USING players p
             WHERE gm.player_id = p.id
               AND gm.group_id = @GroupId
-              AND p.telegram_id = @CoGmTelegramId
+              AND p.platform = @Platform
+              AND p.external_user_id = @ExternalUserId
               AND gm.role = @CoGmRole
             """,
             new
             {
                 GroupId = groupId,
-                CoGmTelegramId = coGmTelegramId,
+                Platform = coGmPlatform,
+                ExternalUserId = coGmExternalUserId,
                 CoGmRole = GroupManagerRoleExtensions.CoGmValue
             });
     }
@@ -426,7 +470,7 @@ public sealed class SessionService(
 
         if (oldSession is null)
         {
-            throw new SessionAccessDeniedException(sessionId, 0);
+            throw new SessionAccessDeniedException(sessionId, "0");
         }
 
         var updatedRows = await conn.ExecuteAsync(
@@ -454,7 +498,7 @@ public sealed class SessionService(
 
         if (updatedRows == 0)
         {
-            throw new SessionAccessDeniedException(sessionId, 0);
+            throw new SessionAccessDeniedException(sessionId, "0");
         }
 
         await conn.ExecuteAsync(
@@ -513,7 +557,7 @@ public sealed class SessionService(
 
         if (session is null)
         {
-            throw new SessionAccessDeniedException(sessionId, 0);
+            throw new SessionAccessDeniedException(sessionId, "0");
         }
 
         var activeParticipants = await conn.ExecuteScalarAsync<int>(
@@ -597,9 +641,11 @@ public sealed class SessionService(
         return (await conn.QueryAsync<WebParticipant>(
             """
             SELECT sp.id AS Id,
-                   p.telegram_id AS TelegramId,
+                   COALESCE(p.telegram_id, 0) AS TelegramId,
+                   COALESCE(p.external_user_id, p.telegram_id::TEXT) AS ExternalUserId,
                    p.display_name AS DisplayName,
                    p.telegram_username AS TelegramUsername,
+                   COALESCE(p.external_username, p.telegram_username) AS ExternalUsername,
                    sp.rsvp_status AS RsvpStatus,
                    sp.registration_status AS RegistrationStatus,
                    sp.is_gm AS IsGm,
@@ -637,7 +683,7 @@ public sealed class SessionService(
 
         if (session is null)
         {
-            throw new SessionAccessDeniedException(sessionId, 0);
+            throw new SessionAccessDeniedException(sessionId, "0");
         }
 
         var participant = await conn.QuerySingleOrDefaultAsync<WebParticipant>(
@@ -744,7 +790,7 @@ public sealed class SessionService(
         var batch = await GetBatchInfoAsync(conn, batchId, groupId, transaction);
         if (batch is null)
         {
-            throw new SessionAccessDeniedException(batchId, 0);
+            throw new SessionAccessDeniedException(batchId, "0");
         }
 
         var updatedRows = await conn.ExecuteAsync(
@@ -767,7 +813,7 @@ public sealed class SessionService(
 
         if (updatedRows == 0)
         {
-            throw new SessionAccessDeniedException(batchId, 0);
+            throw new SessionAccessDeniedException(batchId, "0");
         }
 
         await transaction.CommitAsync();
@@ -786,7 +832,7 @@ public sealed class SessionService(
         var batch = await GetBatchInfoAsync(conn, batchId, groupId, transaction);
         if (batch is null)
         {
-            throw new SessionAccessDeniedException(batchId, 0);
+            throw new SessionAccessDeniedException(batchId, "0");
         }
 
         var updatedRows = await conn.ExecuteAsync(
@@ -807,7 +853,7 @@ public sealed class SessionService(
 
         if (updatedRows == 0)
         {
-            throw new SessionAccessDeniedException(batchId, 0);
+            throw new SessionAccessDeniedException(batchId, "0");
         }
 
         await transaction.CommitAsync();
@@ -844,7 +890,7 @@ public sealed class SessionService(
 
         if (batchSessions.Count == 0)
         {
-            throw new SessionAccessDeniedException(batchId, 0);
+            throw new SessionAccessDeniedException(batchId, "0");
         }
 
         var newSchedule = BatchSchedulePlanner.BuildFixedIntervalSchedule(
@@ -928,7 +974,7 @@ public sealed class SessionService(
 
         if (sourceSessions.Count == 0)
         {
-            throw new SessionAccessDeniedException(batchId, 0);
+            throw new SessionAccessDeniedException(batchId, "0");
         }
 
         var newBatchId = Guid.NewGuid();
@@ -1130,7 +1176,7 @@ public sealed class SessionService(
 
         if (template is null)
         {
-            throw new SessionAccessDeniedException(templateId, 0);
+            throw new SessionAccessDeniedException(templateId, "0");
         }
 
         var group = await conn.QuerySingleOrDefaultAsync<WebTemplateGroupDto>(
@@ -1140,7 +1186,7 @@ public sealed class SessionService(
 
         if (group is null)
         {
-            throw new SessionAccessDeniedException(groupId, 0);
+            throw new SessionAccessDeniedException(groupId, "0");
         }
 
         var schedule = BatchSchedulePlanner.BuildRecurringSchedule(

src/GmRelay.Web/wwwroot/app.css

@@ -1619,3 +1619,78 @@ body.telegram-mini-app .session-card-mobile {
         display: flex;
     }
 }
+
+/* === Discord Login Button === */
+.login-btn-discord {
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    gap: 0.75rem;
+    width: 100%;
+    padding: 0.75rem 1.25rem;
+    border-radius: var(--radius-md);
+    font-weight: 500;
+    font-size: 0.9375rem;
+    text-decoration: none;
+    transition: all 0.2s ease;
+    background-color: #5865F2;
+    color: white;
+    border: none;
+    cursor: pointer;
+}
+
+.login-btn-discord:hover {
+    background-color: #4752C4;
+    transform: translateY(-1px);
+}
+
+.login-btn-discord:active {
+    transform: translateY(0);
+}
+
+.login-btn-discord .login-btn-icon {
+    width: 20px;
+    height: 20px;
+    flex-shrink: 0;
+}
+
+.login-divider {
+    display: flex;
+    align-items: center;
+    margin: 1.25rem 0;
+    color: var(--text-muted);
+    font-size: 0.875rem;
+}
+
+.login-divider::before,
+.login-divider::after {
+    content: "";
+    flex: 1;
+    height: 1px;
+    background: var(--border-color);
+}
+
+.login-divider span {
+    padding: 0 1rem;
+}
+
+/* === Platform Indicator in Nav === */
+.nav-user-info {
+    display: flex;
+    flex-direction: column;
+    gap: 0.125rem;
+}
+
+.nav-user-platform {
+    font-size: 0.6875rem;
+    color: var(--text-muted);
+    text-transform: uppercase;
+    letter-spacing: 0.025em;
+}
+
+.nav-user-avatar img {
+    width: 100%;
+    height: 100%;
+    object-fit: cover;
+    border-radius: 50%;
+}

tests/GmRelay.Bot.Tests/Discord/DiscordProjectStructureTests.cs

@@ -61,7 +61,7 @@ public sealed class DiscordProjectStructureTests
         var prChecks = File.ReadAllText(Path.Combine(repoRoot, ".gitea", "workflows", "pr-checks.yml"));
         var deploy = File.ReadAllText(Path.Combine(repoRoot, ".gitea", "workflows", "deploy.yml"));
 
-        Assert.Contains("gmrelay-discord-bot:2.7.2", compose);
+        Assert.Contains("gmrelay-discord-bot:2.8.0", compose);
         Assert.Contains("Discord__Token=${DISCORD_BOT_TOKEN:?Set DISCORD_BOT_TOKEN in .env}", compose);
         Assert.Contains("src/GmRelay.DiscordBot/Dockerfile", deploy);
         Assert.Contains("DISCORD_BOT_TOKEN", deploy);
@@ -75,13 +75,13 @@ public sealed class DiscordProjectStructureTests
     {
         var repoRoot = GetRepoRoot();
 
-        Assert.Contains("<Version>2.7.2</Version>", File.ReadAllText(Path.Combine(repoRoot, "Directory.Build.props")));
+        Assert.Contains("<Version>2.8.0</Version>", File.ReadAllText(Path.Combine(repoRoot, "Directory.Build.props")));
-        Assert.Contains("VERSION: 2.7.2", File.ReadAllText(Path.Combine(repoRoot, ".gitea", "workflows", "deploy.yml")));
+        Assert.Contains("VERSION: 2.8.0", File.ReadAllText(Path.Combine(repoRoot, ".gitea", "workflows", "deploy.yml")));
-        Assert.Contains("gmrelay-bot:2.7.2", File.ReadAllText(Path.Combine(repoRoot, "compose.yaml")));
+        Assert.Contains("gmrelay-bot:2.8.0", File.ReadAllText(Path.Combine(repoRoot, "compose.yaml")));
-        Assert.Contains("gmrelay-web:2.7.2", File.ReadAllText(Path.Combine(repoRoot, "compose.yaml")));
+        Assert.Contains("gmrelay-web:2.8.0", File.ReadAllText(Path.Combine(repoRoot, "compose.yaml")));
-        Assert.Contains("gmrelay-discord-bot:2.7.2", File.ReadAllText(Path.Combine(repoRoot, "compose.yaml")));
+        Assert.Contains("gmrelay-discord-bot:2.8.0", File.ReadAllText(Path.Combine(repoRoot, "compose.yaml")));
         Assert.Contains(
-            "v2.7.2",
+            "v2.8.0",
             File.ReadAllText(Path.Combine(repoRoot, "src", "GmRelay.Web", "Components", "Layout", "NavMenu.razor")));
     }
 

tests/GmRelay.Bot.Tests/Web/AuthorizedSessionServiceTests.cs

@@ -1,10 +1,29 @@
 using GmRelay.Web.Services;
+using System.Security.Claims;
+using Microsoft.AspNetCore.Http;
 using GmRelay.Shared.Domain;
 
 namespace GmRelay.Bot.Tests.Web;
 
 public sealed class AuthorizedSessionServiceTests
 {
+    private static IHttpContextAccessor CreateAccessor(string externalUserId, string? name = null)
+    {
+        var claims = new List<Claim>
+        {
+            new Claim(ClaimTypes.NameIdentifier, externalUserId),
+            new Claim("TelegramId", externalUserId),
+            new Claim("Platform", "Telegram")
+        };
+        if (name is not null)
+            claims.Add(new Claim(ClaimTypes.Name, name));
+
+        var identity = new ClaimsIdentity(claims, "Test");
+        var principal = new ClaimsPrincipal(identity);
+        var httpContext = new DefaultHttpContext { User = principal };
+        return new HttpContextAccessor { HttpContext = httpContext };
+    }
+
     [Fact]
     public async Task GetUpcomingSessionsForGmAsync_ReturnsSessions_WhenGroupBelongsToGm()
     {
@@ -19,9 +38,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var sessions = await service.GetUpcomingSessionsForGmAsync(groupId, gmId);
+        var sessions = await service.GetUpcomingSessionsForCurrentUserAsync(groupId);
 
         Assert.NotNull(sessions);
         Assert.Single(sessions);
@@ -47,9 +67,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, coGmId, GroupManagerRole.CoGm)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(coGmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var sessions = await service.GetUpcomingSessionsForGmAsync(groupId, coGmId);
+        var sessions = await service.GetUpcomingSessionsForCurrentUserAsync(groupId);
 
         Assert.NotNull(sessions);
         Assert.Single(sessions);
@@ -65,9 +86,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, 42, "Alpha", 2002L)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var sessions = await service.GetUpcomingSessionsForGmAsync(groupId, 1001L);
+        var sessions = await service.GetUpcomingSessionsForCurrentUserAsync(groupId);
 
         Assert.Null(sessions);
     }
@@ -87,9 +109,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var session = await service.GetSessionForGmAsync(sessionId, gmId);
+        var session = await service.GetSessionForCurrentUserAsync(sessionId);
 
         Assert.NotNull(session);
         Assert.Equal(sessionId, session.Id);
@@ -109,9 +132,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var session = await service.GetSessionForGmAsync(sessionId, 1001L);
+        var session = await service.GetSessionForCurrentUserAsync(sessionId);
 
         Assert.Null(session);
     }
@@ -130,9 +154,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var action = () => service.UpdateSessionForGmAsync(sessionId, 1001L, "Updated", DateTime.UtcNow.AddDays(1), "https://example.test/b", 5);
+        var action = () => service.UpdateSessionForCurrentUserAsync(sessionId, "Updated", DateTime.UtcNow.AddDays(1), "https://example.test/b", 5);
 
         await Assert.ThrowsAsync<SessionAccessDeniedException>(action);
         Assert.False(store.UpdateCalled);
@@ -154,9 +179,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.UpdateSessionForGmAsync(sessionId, gmId, "Updated", scheduledAt, "https://example.test/b", 5);
+        await service.UpdateSessionForCurrentUserAsync(sessionId, "Updated", scheduledAt, "https://example.test/b", 5);
 
         Assert.True(store.UpdateCalled);
         Assert.Equal(groupId, store.LastUpdatedGroupId);
@@ -183,9 +209,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", originalTime, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.UpdateSessionForGmAsync(sessionId, gmId, "Updated Title", originalTime, "https://example.test/a", 4);
+        await service.UpdateSessionForCurrentUserAsync(sessionId, "Updated Title", originalTime, "https://example.test/a", 4);
 
         Assert.Single(store.LogEntries);
         Assert.Equal("Title", store.LogEntries[0].ChangeType);
@@ -209,10 +236,11 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", originalTime, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
         var newTime = originalTime.AddDays(1);
-        await service.UpdateSessionForGmAsync(sessionId, gmId, "Updated Title", newTime, "https://example.test/b", 5);
+        await service.UpdateSessionForCurrentUserAsync(sessionId, "Updated Title", newTime, "https://example.test/b", 5);
 
         Assert.Equal(4, store.LogEntries.Count);
         Assert.Contains(store.LogEntries, e => e.ChangeType == "Title");
@@ -237,9 +265,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", originalTime, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.UpdateSessionForGmAsync(sessionId, gmId, "Session A", originalTime, "https://example.test/a", 4);
+        await service.UpdateSessionForCurrentUserAsync(sessionId, "Session A", originalTime, "https://example.test/a", 4);
 
         Assert.Empty(store.LogEntries);
     }
@@ -259,9 +288,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var history = await service.GetSessionHistoryForGmAsync(sessionId, gmId);
+        var history = await service.GetSessionHistoryForCurrentUserAsync(sessionId);
 
         Assert.NotNull(history);
         Assert.Empty(history);
@@ -281,9 +311,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var history = await service.GetSessionHistoryForGmAsync(sessionId, 1001L);
+        var history = await service.GetSessionHistoryForCurrentUserAsync(sessionId);
 
         Assert.Null(history);
     }
@@ -303,9 +334,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(sessionId, groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", Guid.NewGuid(), 10, 42, 4, 3, 1)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.PromoteWaitlistedPlayerForGmAsync(sessionId, gmId);
+        await service.PromoteWaitlistedPlayerForCurrentUserAsync(sessionId);
 
         Assert.True(store.PromoteCalled);
         Assert.Equal(groupId, store.LastPromotedGroupId);
@@ -326,9 +358,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", batchId, 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var action = () => service.UpdateBatchDetailsForGmAsync(batchId, 1001L, "Updated", "https://example.test/b");
+        var action = () => service.UpdateBatchDetailsForCurrentUserAsync(batchId, "Updated", "https://example.test/b");
 
         await Assert.ThrowsAsync<SessionAccessDeniedException>(action);
         Assert.False(store.UpdateBatchDetailsCalled);
@@ -349,9 +382,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", batchId, 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.UpdateBatchDetailsForGmAsync(batchId, gmId, "Updated", "https://example.test/b");
+        await service.UpdateBatchDetailsForCurrentUserAsync(batchId, "Updated", "https://example.test/b");
 
         Assert.True(store.UpdateBatchDetailsCalled);
         Assert.Equal(batchId, store.LastUpdatedBatchId);
@@ -380,9 +414,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, coGmId, GroupManagerRole.CoGm)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(coGmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.UpdateBatchDetailsForGmAsync(batchId, coGmId, "Updated", "https://example.test/b");
+        await service.UpdateBatchDetailsForCurrentUserAsync(batchId, "Updated", "https://example.test/b");
 
         Assert.True(store.UpdateBatchDetailsCalled);
         Assert.Equal(batchId, store.LastUpdatedBatchId);
@@ -400,9 +435,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, 42, "Alpha", ownerId)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(ownerId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.AddCoGmForOwnerAsync(groupId, ownerId, coGmId, "Assistant GM", "assistant");
+        await service.AddCoGmForOwnerAsync(groupId, "Telegram", coGmId.ToString(), "Assistant GM", "assistant");
 
         Assert.True(store.AddCoGmCalled);
         Assert.Equal(groupId, store.LastAddedCoGmGroupId);
@@ -427,9 +463,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, coGmId, GroupManagerRole.CoGm)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(coGmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var action = () => service.AddCoGmForOwnerAsync(groupId, coGmId, newCoGmId, "Second Assistant", null);
+        var action = () => service.AddCoGmForOwnerAsync(groupId, "Telegram", newCoGmId.ToString(), "Second Assistant", null);
 
         await Assert.ThrowsAsync<SessionAccessDeniedException>(action);
         Assert.False(store.AddCoGmCalled);
@@ -450,9 +487,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, coGmId, GroupManagerRole.CoGm)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(ownerId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.RemoveCoGmForOwnerAsync(groupId, ownerId, coGmId);
+        await service.RemoveCoGmForOwnerAsync(groupId, "Telegram", coGmId.ToString());
 
         Assert.True(store.RemoveCoGmCalled);
         Assert.Equal(groupId, store.LastRemovedCoGmGroupId);
@@ -473,9 +511,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", batchId, 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var action = () => service.UpdateBatchNotificationModeForGmAsync(batchId, 1001L, SessionNotificationMode.GroupOnly);
+        var action = () => service.UpdateBatchNotificationModeForCurrentUserAsync(batchId, SessionNotificationMode.GroupOnly);
 
         await Assert.ThrowsAsync<SessionAccessDeniedException>(action);
         Assert.False(store.UpdateBatchNotificationModeCalled);
@@ -496,9 +535,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", batchId, 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.UpdateBatchNotificationModeForGmAsync(batchId, gmId, SessionNotificationMode.GroupOnly);
+        await service.UpdateBatchNotificationModeForCurrentUserAsync(batchId, SessionNotificationMode.GroupOnly);
 
         Assert.True(store.UpdateBatchNotificationModeCalled);
         Assert.Equal(batchId, store.LastUpdatedNotificationBatchId);
@@ -521,9 +561,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", batchId, 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var action = () => service.RescheduleBatchForGmAsync(batchId, gmId, DateTime.UtcNow.AddDays(7), intervalDays: 0);
+        var action = () => service.RescheduleBatchForCurrentUserAsync(batchId, DateTime.UtcNow.AddDays(7), intervalDays: 0);
 
         await Assert.ThrowsAsync<ArgumentOutOfRangeException>(action);
         Assert.False(store.RescheduleBatchCalled);
@@ -545,9 +586,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", batchId, 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.RescheduleBatchForGmAsync(batchId, gmId, firstScheduledAt, intervalDays: 14);
+        await service.RescheduleBatchForCurrentUserAsync(batchId, firstScheduledAt, intervalDays: 14);
 
         Assert.True(store.RescheduleBatchCalled);
         Assert.Equal(batchId, store.LastRescheduledBatchId);
@@ -571,9 +613,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(Guid.NewGuid(), groupId, "Session A", DateTime.UtcNow, "Planned", "https://example.test/a", batchId, 10, 42, 4, 1, 0)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.CloneBatchForGmAsync(batchId, gmId, BatchCloneInterval.NextWeek);
+        await service.CloneBatchForCurrentUserAsync(batchId, BatchCloneInterval.NextWeek);
 
         Assert.True(store.CloneBatchCalled);
         Assert.Equal(batchId, store.LastClonedBatchId);
@@ -591,11 +634,11 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, 42, "Alpha", gmId)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.CreateCampaignTemplateForGmAsync(
+        await service.CreateCampaignTemplateForCurrentUserAsync(
             groupId,
-            gmId,
             new CreateCampaignTemplateRequest(
                 "  Weekly arc  ",
                 "  Kingmaker  ",
@@ -626,11 +669,11 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, 42, "Alpha", gmId)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.CreateCampaignTemplateForGmAsync(
+        await service.CreateCampaignTemplateForCurrentUserAsync(
             groupId,
-            gmId,
             new CreateCampaignTemplateRequest(
                 "Open table",
                 "West Marches",
@@ -653,11 +696,11 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(groupId, 42, "Alpha", 2002L)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var action = () => service.CreateCampaignTemplateForGmAsync(
+        var action = () => service.CreateCampaignTemplateForCurrentUserAsync(
             groupId,
-            1001L,
             new CreateCampaignTemplateRequest(
                 "Weekly arc",
                 "Kingmaker",
@@ -687,9 +730,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(templateId, groupId, "Weekly arc", "Kingmaker", "https://example.test/kingmaker", 6, 7, 5, SessionNotificationModeExtensions.GroupOnlyValue, DateTime.UtcNow, DateTime.UtcNow)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor(gmId.ToString());
+        var service = new AuthorizedSessionService(store, accessor);
 
-        await service.CreateBatchFromCampaignTemplateForGmAsync(templateId, gmId, firstScheduledAt);
+        await service.CreateBatchFromCampaignTemplateForCurrentUserAsync(templateId, firstScheduledAt);
 
         Assert.True(store.CreateBatchFromTemplateCalled);
         Assert.Equal(templateId, store.LastCreatedBatchTemplateId);
@@ -711,9 +755,10 @@ public sealed class AuthorizedSessionServiceTests
             [
                 new(templateId, groupId, "Weekly arc", "Kingmaker", "https://example.test/kingmaker", 6, 7, 5, SessionNotificationModeExtensions.GroupOnlyValue, DateTime.UtcNow, DateTime.UtcNow)
             ]);
-        var service = new AuthorizedSessionService(store);
+        var accessor = CreateAccessor("1001");
+        var service = new AuthorizedSessionService(store, accessor);
 
-        var action = () => service.CreateBatchFromCampaignTemplateForGmAsync(templateId, 1001L, DateTime.UtcNow.AddDays(3));
+        var action = () => service.CreateBatchFromCampaignTemplateForCurrentUserAsync(templateId, DateTime.UtcNow.AddDays(3));
 
         await Assert.ThrowsAsync<SessionAccessDeniedException>(action);
         Assert.False(store.CreateBatchFromTemplateCalled);
@@ -1019,7 +1064,7 @@ public sealed class AuthorizedSessionServiceTests
 
         public Task LogSessionChangeAsync(Guid sessionId, long actorTelegramId, string actorName, string changeType, string? oldValue, string? newValue)
         {
-            var entry = new SessionAuditLogEntry(Guid.NewGuid(), sessionId, actorTelegramId, actorName, changeType, oldValue, newValue, DateTime.UtcNow);
+            var entry = new SessionAuditLogEntry(Guid.NewGuid(), sessionId, actorTelegramId.ToString(), actorName, changeType, oldValue, newValue, DateTime.UtcNow);
             LogEntries.Add(entry);
             LastLogSessionId = sessionId;
             LastLogActorTelegramId = actorTelegramId;
@@ -1033,12 +1078,62 @@ public sealed class AuthorizedSessionServiceTests
         public Task<List<SessionAuditLogEntry>> GetSessionHistoryAsync(Guid sessionId) =>
             Task.FromResult(LogEntries.Where(e => e.SessionId == sessionId).OrderByDescending(e => e.ChangedAt).ToList());
 
+        public Task<List<WebGameGroup>> GetGroupsForUserAsync(string platform, string externalUserId) =>
+            Task.FromResult(groupsById.Values.Where(group => IsManager(group.Id, externalUserId)).ToList());
+
+        public Task<bool> IsGroupManagerAsync(Guid groupId, string platform, string externalUserId) =>
+            Task.FromResult(IsManager(groupId, externalUserId));
+
+        public Task<bool> IsGroupOwnerAsync(Guid groupId, string platform, string externalUserId) =>
+            Task.FromResult(IsOwner(groupId, externalUserId));
+
+        public Task AddGroupCoGmAsync(Guid groupId, string ownerPlatform, string ownerExternalUserId, string coGmPlatform, string coGmExternalUserId, string displayName, string? externalUsername)
+        {
+            AddCoGmCalled = true;
+            LastAddedCoGmGroupId = groupId;
+            LastAddedCoGmTelegramId = long.TryParse(coGmExternalUserId, out var id) ? id : null;
+            LastAddedCoGmDisplayName = displayName;
+            LastAddedCoGmUsername = externalUsername;
+            return Task.CompletedTask;
+        }
+
+        public Task RemoveGroupCoGmAsync(Guid groupId, string coGmPlatform, string coGmExternalUserId)
+        {
+            RemoveCoGmCalled = true;
+            LastRemovedCoGmGroupId = groupId;
+            LastRemovedCoGmTelegramId = long.TryParse(coGmExternalUserId, out var id) ? id : null;
+            return Task.CompletedTask;
+        }
+
+        public Task LogSessionChangeAsync(Guid sessionId, string actorExternalUserId, string actorName, string changeType, string? oldValue, string? newValue)
+        {
+            var entry = new SessionAuditLogEntry(Guid.NewGuid(), sessionId, actorExternalUserId, actorName, changeType, oldValue, newValue, DateTime.UtcNow);
+            LogEntries.Add(entry);
+            LastLogSessionId = sessionId;
+            LastLogActorTelegramId = long.TryParse(actorExternalUserId, out var id) ? (long?)id : null;
+            LastLogActorName = actorName;
+            LastLogChangeType = changeType;
+            LastLogOldValue = oldValue;
+            LastLogNewValue = newValue;
+            return Task.CompletedTask;
+        }
+
+        public Task UpsertDiscordUserAsync(string discordId, string displayName, string? avatarUrl) =>
+            Task.CompletedTask;
+
         private bool IsManager(Guid groupId, long telegramId) =>
             IsOwner(groupId, telegramId) ||
             managers.Any(manager => manager.GroupId == groupId && manager.TelegramId == telegramId);
 
         private bool IsOwner(Guid groupId, long telegramId) =>
             groupsById.TryGetValue(groupId, out var group) && group.GmTelegramId == telegramId;
+
+        private bool IsManager(Guid groupId, string externalUserId) =>
+            IsOwner(groupId, externalUserId) ||
+            managers.Any(manager => manager.GroupId == groupId && manager.TelegramId.ToString() == externalUserId);
+
+        private bool IsOwner(Guid groupId, string externalUserId) =>
+            groupsById.TryGetValue(groupId, out var group) && group.GmTelegramId.ToString() == externalUserId;
     }
 
     private sealed record FakeGroupManager(Guid GroupId, long TelegramId, GroupManagerRole Role);

tests/GmRelay.Bot.Tests/Web/DiscordAuthServiceTests.cs

@@ -0,0 +1,139 @@
+using System.Net;
+using System.Text.Json;
+using GmRelay.Web;
+using GmRelay.Web.Services;
+using Microsoft.Extensions.Configuration;
+
+namespace GmRelay.Bot.Tests.Web;
+
+public class DiscordAuthServiceTests
+{
+    [Fact]
+    public void BuildAuthorizeUrl_GeneratesCorrectUrl()
+    {
+        var config = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["Discord:ClientId"] = "12345",
+                ["Discord:ClientSecret"] = "secret",
+                ["Discord:RedirectUri"] = "https://example.com/callback"
+            })
+            .Build();
+
+        var service = new DiscordAuthService(new TestHttpClientFactory(), config);
+        var url = service.BuildAuthorizeUrl("state123");
+
+        Assert.Contains("client_id=12345", url);
+        Assert.Contains("response_type=code", url);
+        Assert.Contains("state=state123", url);
+        Assert.Contains("https%3A%2F%2Fexample.com%2Fcallback", url);
+    }
+
+    [Fact]
+    public void BuildAuthorizeUrl_WithMissingConfig_ThrowsInvalidOperationException()
+    {
+        var config = new ConfigurationBuilder().Build();
+        var service = new DiscordAuthService(new TestHttpClientFactory(), config);
+
+        Assert.Throws<InvalidOperationException>(() => service.BuildAuthorizeUrl("state"));
+    }
+
+    [Fact]
+    public async Task ExchangeCodeAsync_WithValidCode_ReturnsUser()
+    {
+        var handler = new TestHttpMessageHandler((request) =>
+        {
+            if (request.RequestUri?.AbsolutePath == "/api/oauth2/token")
+            {
+                var response = new DiscordTokenResponse("access_123", "Bearer", 604800, "identify");
+                return new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent(JsonSerializer.Serialize(response))
+                };
+            }
+
+            if (request.RequestUri?.AbsolutePath == "/api/users/@me")
+            {
+                var user = new DiscordUser("98765", "TestUser", "0", "avatar123", null);
+                return new HttpResponseMessage(HttpStatusCode.OK)
+                {
+                    Content = new StringContent(JsonSerializer.Serialize(user))
+                };
+            }
+
+            return new HttpResponseMessage(HttpStatusCode.NotFound);
+        });
+
+        var config = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["Discord:ClientId"] = "client",
+                ["Discord:ClientSecret"] = "secret",
+                ["Discord:RedirectUri"] = "https://example.com/callback"
+            })
+            .Build();
+
+        var factory = new TestHttpClientFactory(handler);
+        var service = new DiscordAuthService(factory, config);
+
+        var result = await service.ExchangeCodeAsync("valid_code");
+
+        Assert.NotNull(result);
+        Assert.Equal("98765", result.Id);
+        Assert.Equal("TestUser", result.Username);
+        Assert.Equal("https://cdn.discordapp.com/avatars/98765/avatar123.png", result.AvatarUrl);
+    }
+
+    [Fact]
+    public async Task ExchangeCodeAsync_WithInvalidCode_ReturnsNull()
+    {
+        var handler = new TestHttpMessageHandler((request) =>
+        {
+            return new HttpResponseMessage(HttpStatusCode.BadRequest);
+        });
+
+        var config = new ConfigurationBuilder()
+            .AddInMemoryCollection(new Dictionary<string, string?>
+            {
+                ["Discord:ClientId"] = "client",
+                ["Discord:ClientSecret"] = "secret",
+                ["Discord:RedirectUri"] = "https://example.com/callback"
+            })
+            .Build();
+
+        var factory = new TestHttpClientFactory(handler);
+        var service = new DiscordAuthService(factory, config);
+
+        var result = await service.ExchangeCodeAsync("invalid_code");
+
+        Assert.Null(result);
+    }
+
+    private class TestHttpClientFactory : IHttpClientFactory
+    {
+        private readonly HttpMessageHandler? _handler;
+
+        public TestHttpClientFactory(HttpMessageHandler? handler = null)
+        {
+            _handler = handler;
+        }
+
+        public HttpClient CreateClient(string name) =>
+            _handler is not null ? new HttpClient(_handler) : new HttpClient();
+    }
+
+    private class TestHttpMessageHandler : HttpMessageHandler
+    {
+        private readonly Func<HttpRequestMessage, HttpResponseMessage> _handler;
+
+        public TestHttpMessageHandler(Func<HttpRequestMessage, HttpResponseMessage> handler)
+        {
+            _handler = handler;
+        }
+
+        protected override Task<HttpResponseMessage> SendAsync(HttpRequestMessage request, CancellationToken cancellationToken)
+        {
+            return Task.FromResult(_handler(request));
+        }
+    }
+}

tests/GmRelay.Bot.Tests/Web/PlatformIdentityTests.cs

@@ -0,0 +1,114 @@
+using System.Security.Claims;
+using GmRelay.Web.Services;
+
+namespace GmRelay.Bot.Tests.Web;
+
+public class PlatformIdentityTests
+{
+    [Fact]
+    public void TryGetPlatformIdentity_TelegramUser_ReturnsTelegramPlatform()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim(ClaimTypes.NameIdentifier, "12345"),
+            new Claim("TelegramId", "12345")
+        }));
+
+        var result = user.TryGetPlatformIdentity(out var platform, out var externalUserId);
+
+        Assert.True(result);
+        Assert.Equal("Telegram", platform);
+        Assert.Equal("12345", externalUserId);
+    }
+
+    [Fact]
+    public void TryGetPlatformIdentity_TelegramUserWithPlatformClaim_ReturnsTelegramPlatform()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim(ClaimTypes.NameIdentifier, "12345"),
+            new Claim("Platform", "Telegram")
+        }));
+
+        var result = user.TryGetPlatformIdentity(out var platform, out var externalUserId);
+
+        Assert.True(result);
+        Assert.Equal("Telegram", platform);
+        Assert.Equal("12345", externalUserId);
+    }
+
+    [Fact]
+    public void TryGetPlatformIdentity_DiscordUser_ReturnsDiscordPlatform()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim(ClaimTypes.NameIdentifier, "98765"),
+            new Claim("DiscordId", "98765"),
+            new Claim("Platform", "Discord")
+        }));
+
+        var result = user.TryGetPlatformIdentity(out var platform, out var externalUserId);
+
+        Assert.True(result);
+        Assert.Equal("Discord", platform);
+        Assert.Equal("98765", externalUserId);
+    }
+
+    [Fact]
+    public void TryGetPlatformIdentity_UnknownUser_ReturnsFalse()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim(ClaimTypes.Name, "Anonymous")
+        }));
+
+        var result = user.TryGetPlatformIdentity(out _, out _);
+        Assert.False(result);
+    }
+
+    [Fact]
+    public void TryGetDiscordId_DiscordUser_ReturnsTrue()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim("DiscordId", "123")
+        }));
+
+        var result = user.TryGetDiscordId(out var discordId);
+        Assert.True(result);
+        Assert.Equal("123", discordId);
+    }
+
+    [Fact]
+    public void TryGetDiscordId_TelegramUser_ReturnsFalse()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim("TelegramId", "123")
+        }));
+
+        var result = user.TryGetDiscordId(out _);
+        Assert.False(result);
+    }
+
+    [Fact]
+    public void GetAvatarUrl_DiscordUserWithAvatar_ReturnsUrl()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(new[]
+        {
+            new Claim("AvatarUrl", "https://cdn.discordapp.com/avatars/1/abc.png")
+        }));
+
+        var result = user.GetAvatarUrl();
+        Assert.Equal("https://cdn.discordapp.com/avatars/1/abc.png", result);
+    }
+
+    [Fact]
+    public void GetAvatarUrl_UserWithoutAvatar_ReturnsNull()
+    {
+        var user = new ClaimsPrincipal(new ClaimsIdentity(Array.Empty<Claim>()));
+
+        var result = user.GetAvatarUrl();
+        Assert.Null(result);
+    }
+}