feat: support co-gm group delegation

src/GmRelay.Bot/Features/Sessions/CreateSession/CreateSessionHandler.cs

@@ -7,6 +7,8 @@ using Telegram.Bot.Types;
 
 namespace GmRelay.Bot.Features.Sessions.CreateSession;
 
+internal sealed record SessionCreationGroupAccessDto(Guid GroupId, bool CanManage);
+
 public sealed class CreateSessionHandler(
     NpgsqlDataSource dataSource,
     ITelegramBotClient botClient,
@@ -74,16 +76,64 @@ public sealed class CreateSessionHandler(
                 new { TgId = gmId, Name = gmName, Username = gmUsername },
                 transaction);
 
-            var groupId = await connection.ExecuteScalarAsync<Guid>(
+            var existingGroup = await connection.QuerySingleOrDefaultAsync<SessionCreationGroupAccessDto>(
                 """
-                INSERT INTO game_groups (telegram_chat_id, name, gm_telegram_id)
-                VALUES (@ChatId, @ChatName, @GmId)
-                ON CONFLICT (telegram_chat_id) DO UPDATE SET name = EXCLUDED.name
-                RETURNING id;
+                SELECT g.id AS GroupId,
+                       EXISTS (
+                           SELECT 1
+                           FROM group_managers gm
+                           JOIN players p ON p.id = gm.player_id
+                           WHERE gm.group_id = g.id
+                             AND p.telegram_id = @GmId
+                       ) AS CanManage
+                FROM game_groups g
+                WHERE g.telegram_chat_id = @ChatId
                 """,
-                new { ChatId = chatId, ChatName = chatTitle, GmId = gmId },
+                new { ChatId = chatId, GmId = gmId },
                 transaction);
 
+            Guid groupId;
+            if (existingGroup is null)
+            {
+                groupId = await connection.ExecuteScalarAsync<Guid>(
+                    """
+                    INSERT INTO game_groups (telegram_chat_id, name, gm_telegram_id)
+                    VALUES (@ChatId, @ChatName, @GmId)
+                    RETURNING id;
+                    """,
+                    new { ChatId = chatId, ChatName = chatTitle, GmId = gmId },
+                    transaction);
+
+                await connection.ExecuteAsync(
+                    """
+                    INSERT INTO group_managers (group_id, player_id, role)
+                    SELECT @GroupId, p.id, @OwnerRole
+                    FROM players p
+                    WHERE p.telegram_id = @GmId
+                    ON CONFLICT (group_id, player_id) DO NOTHING
+                    """,
+                    new { GroupId = groupId, GmId = gmId, OwnerRole = GroupManagerRoleExtensions.OwnerValue },
+                    transaction);
+            }
+            else
+            {
+                if (!existingGroup.CanManage)
+                {
+                    await transaction.RollbackAsync(cancellationToken);
+                    await botClient.SendMessage(
+                        chatId,
+                        "⛔ Только owner или co-GM этой группы может создавать игровые сессии.",
+                        cancellationToken: cancellationToken);
+                    return;
+                }
+
+                groupId = existingGroup.GroupId;
+                await connection.ExecuteAsync(
+                    "UPDATE game_groups SET name = @ChatName WHERE id = @GroupId",
+                    new { ChatName = chatTitle, GroupId = groupId },
+                    transaction);
+            }
+
             int? messageThreadId = null;
             if (message.Chat.IsForum)
             {