Add explicit write transactions and deterministic ordering tests

Endpoints/AdminWorkflowService.cs

@@ -13,6 +13,8 @@ internal sealed class AdminWorkflowService(AppDbContext db)
         state.ResultsOpen = request.ResultsOpen;
         state.UpdatedAt = DateTimeOffset.UtcNow;
 
+        await using var tx = await db.Database.BeginTransactionAsync();
+
         if (request.ResultsOpen)
         {
             await db.Players.ExecuteUpdateAsync(p => p.SetProperty(x => x.CurrentPhase, Phase.Results));
@@ -23,6 +25,7 @@ internal sealed class AdminWorkflowService(AppDbContext db)
         }
 
         await db.SaveChangesAsync();
+        await tx.CommitAsync();
         var currentState = await db.AppState.AsNoTracking().FirstAsync();
         return Results.Ok(new
         {
@@ -207,6 +210,8 @@ internal sealed class AdminWorkflowService(AppDbContext db)
 
     public async Task<IResult> ResetAsync()
     {
+        await using var tx = await db.Database.BeginTransactionAsync();
+
         await db.Votes.ExecuteDeleteAsync();
         await db.Suggestions.ExecuteDeleteAsync();
 
@@ -215,6 +220,7 @@ internal sealed class AdminWorkflowService(AppDbContext db)
         state.ResultsOpen = false;
         state.UpdatedAt = DateTimeOffset.UtcNow;
         await db.SaveChangesAsync();
+        await tx.CommitAsync();
 
         return Results.Ok(new
         {

Endpoints/SuggestionWorkflowService.cs

@@ -67,6 +67,8 @@ internal sealed class SuggestionWorkflowService(AppDbContext db, IHttpClientFact
             MaxPlayers = request.MaxPlayers
         };
 
+        await using var tx = await db.Database.BeginTransactionAsync();
+
         db.Suggestions.Add(suggestion);
 
         if (usingJoker)
@@ -76,6 +78,7 @@ internal sealed class SuggestionWorkflowService(AppDbContext db, IHttpClientFact
         }
 
         await db.SaveChangesAsync();
+        await tx.CommitAsync();
 
         return Results.Created($"/api/suggestions/{suggestion.Id}", new { suggestion.Id });
     }
@@ -95,6 +98,8 @@ internal sealed class SuggestionWorkflowService(AppDbContext db, IHttpClientFact
         if (suggestion == null)
             return Results.NotFound(new { error = "Suggestion not found." });
 
+        await using var tx = await db.Database.BeginTransactionAsync();
+
         await db.Suggestions
             .Where(s => s.ParentSuggestionId == suggestion.Id)
             .ExecuteUpdateAsync(s => s.SetProperty(x => x.ParentSuggestionId, (int?)null));
@@ -103,6 +108,7 @@ internal sealed class SuggestionWorkflowService(AppDbContext db, IHttpClientFact
 
         db.Suggestions.Remove(suggestion);
         await db.SaveChangesAsync();
+        await tx.CommitAsync();
         return Results.NoContent();
     }