fix: avoid feedback screenshot concurrency save

backend/src/Socialize.Api/Modules/Feedback/Handlers/AttachMyFeedbackScreenshot.cs

@@ -38,8 +38,7 @@ public class AttachMyFeedbackScreenshotHandler(
         Guid reporterUserId = User.GetUserId();
 
         FeedbackReport? report = await dbContext.FeedbackReports
-            .Include(candidate => candidate.Tags)
-            .Include(candidate => candidate.Screenshot)
+            .AsNoTracking()
             .SingleOrDefaultAsync(
                 candidate => candidate.Id == id && candidate.ReporterUserId == reporterUserId,
                 ct);
@@ -50,7 +49,11 @@ public class AttachMyFeedbackScreenshotHandler(
             return;
         }
 
-        if (report.Screenshot is not null)
+        bool hasScreenshot = await dbContext.FeedbackScreenshots
+            .AsNoTracking()
+            .AnyAsync(candidate => candidate.FeedbackReportId == report.Id, ct);
+
+        if (hasScreenshot)
         {
             AddError("A screenshot is already attached to this feedback report.");
             await SendErrorsAsync(StatusCodes.Status409Conflict, ct);
@@ -94,7 +97,7 @@ public class AttachMyFeedbackScreenshotHandler(
         }
 
         DateTimeOffset now = DateTimeOffset.UtcNow;
-        report.Screenshot = new FeedbackScreenshot
+        FeedbackScreenshot screenshot = new()
         {
             Id = screenshotId,
             FeedbackReportId = report.Id,
@@ -105,10 +108,45 @@ public class AttachMyFeedbackScreenshotHandler(
             BlobName = blobName,
             CreatedAt = now,
         };
-        report.LastActivityAt = now;
 
+        await using Microsoft.EntityFrameworkCore.Storage.IDbContextTransaction transaction =
+            await dbContext.Database.BeginTransactionAsync(ct);
+
+        dbContext.FeedbackScreenshots.Add(screenshot);
+        try
+        {
             await dbContext.SaveChangesAsync(ct);
-        await SendOkAsync(report.ToDto(), ct);
+        }
+        catch (DbUpdateException)
+        {
+            await transaction.RollbackAsync(ct);
+            AddError("A screenshot is already attached to this feedback report.");
+            await SendErrorsAsync(StatusCodes.Status409Conflict, ct);
+            return;
+        }
+
+        int updatedRows = await dbContext.FeedbackReports
+            .Where(candidate => candidate.Id == report.Id && candidate.ReporterUserId == reporterUserId)
+            .ExecuteUpdateAsync(
+                setters => setters.SetProperty(candidate => candidate.LastActivityAt, now),
+                ct);
+
+        if (updatedRows == 0)
+        {
+            await transaction.RollbackAsync(ct);
+            await SendNotFoundAsync(ct);
+            return;
+        }
+
+        await transaction.CommitAsync(ct);
+
+        FeedbackReport responseReport = await dbContext.FeedbackReports
+            .AsNoTracking()
+            .Include(candidate => candidate.Tags)
+            .Include(candidate => candidate.Screenshot)
+            .SingleAsync(candidate => candidate.Id == report.Id, ct);
+
+        await SendOkAsync(responseReport.ToDto(), ct);
     }
 
     private static string NormalizeFileName(string? fileName, string extension)