fix(discord): avoid duplicate schedule send after new session

src/GmRelay.DiscordBot/Features/Sessions/DiscordNewSessionHandler.cs

@@ -1,7 +1,6 @@
 using Dapper;
 using GmRelay.DiscordBot.Infrastructure.Discord;
 using GmRelay.Shared.Domain;
-using GmRelay.Shared.Platform;
 using GmRelay.Shared.Rendering;
 using Npgsql;
 
@@ -12,7 +11,6 @@ public sealed record TimeParseResult(bool IsSuccess, DateTimeOffset Value, strin
 public sealed class DiscordNewSessionHandler(
     NpgsqlDataSource dataSource,
     DiscordPermissionChecker permissionChecker,
-    IPlatformMessenger messenger,
     ILogger<DiscordNewSessionHandler> logger)
 {
     public static TimeParseResult ParseTimeInput(string input)
@@ -75,6 +73,7 @@ public sealed class DiscordNewSessionHandler(
         }
 
         await using var transaction = await connection.BeginTransactionAsync(cancellationToken);
+        var transactionCommitted = false;
         try
         {
             await connection.ExecuteAsync(
@@ -125,23 +124,19 @@ public sealed class DiscordNewSessionHandler(
                 transaction);
 
             await transaction.CommitAsync(cancellationToken);
+            transactionCommitted = true;
             logger.LogInformation("Created session {SessionId} in guild {GuildId}", sessionId, guildId);
 
             var sessions = new[] { new SessionBatchDto(sessionId, scheduledAt.UtcDateTime, SessionStatus.Planned, maxPlayers, joinLink ?? string.Empty) };
-            var view = SessionBatchViewBuilder.Build(title, sessions, Array.Empty<ParticipantBatchDto>());
-
-            await messenger.SendScheduleAsync(
-                new PlatformScheduleMessage(
-                    new PlatformGroup(PlatformKind.Discord, guildId, guildId, channelId),
-                    view,
-                    null),
-                cancellationToken);
-
-            return view;
+            return SessionBatchViewBuilder.Build(title, sessions, Array.Empty<ParticipantBatchDto>());
         }
         catch
         {
-            await transaction.RollbackAsync(cancellationToken);
+            if (!transactionCommitted)
+            {
+                await transaction.RollbackAsync(cancellationToken);
+            }
+
             throw;
         }
     }

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

@@ -127,6 +127,18 @@ public sealed class DiscordNewSessionHandlerTests
         Assert.Contains("RollbackAsync", source, StringComparison.Ordinal);
     }
 
+    [Fact]
+    public void Handler_ShouldNotRollbackCommittedTransactionAfterPostCommitFailure()
+    {
+        var repoRoot = GetRepoRoot();
+        var handlerPath = Path.Combine(repoRoot, "src", "GmRelay.DiscordBot", "Features", "Sessions", "DiscordNewSessionHandler.cs");
+        var source = File.ReadAllText(handlerPath);
+
+        Assert.Contains("transactionCommitted = false", source, StringComparison.Ordinal);
+        Assert.Contains("transactionCommitted = true", source, StringComparison.Ordinal);
+        Assert.Contains("if (!transactionCommitted)", source, StringComparison.Ordinal);
+    }
+
     [Fact]
     public void Handler_ShouldRespectCancellationToken()
     {
@@ -148,6 +160,17 @@ public sealed class DiscordNewSessionHandlerTests
         Assert.Contains("message.Embeds = embeds", source, StringComparison.Ordinal);
     }
 
+    [Fact]
+    public void Handler_ShouldLeaveScheduleMessageCreationToInteractionResponse()
+    {
+        var repoRoot = GetRepoRoot();
+        var handlerPath = Path.Combine(repoRoot, "src", "GmRelay.DiscordBot", "Features", "Sessions", "DiscordNewSessionHandler.cs");
+        var source = File.ReadAllText(handlerPath);
+
+        Assert.DoesNotContain("SendScheduleAsync", source, StringComparison.Ordinal);
+        Assert.DoesNotContain("PlatformScheduleMessage", source, StringComparison.Ordinal);
+    }
+
     private static DateTimeOffset FutureDateAt1930()
     {
         var future = DateTimeOffset.UtcNow.AddDays(7);