Asad

public async Task PlaceOrderAsync(PlaceOrderCommand command, CancellationToken ct)
{
    await using var tx = await _db.Database.BeginTransactionAsync(ct);

    var order = new Order(/* ... */);
    _db.Orders.Add(order);

    var evt = new OrderPlacedIntegrationEvent(order.Id, order.CustomerId, order.Total);

    var outboxMessage = OutboxMessage.CreateFrom(evt, aggregateId: order.Id.ToString());
    _db.OutboxMessages.Add(outboxMessage);

    await _db.SaveChangesAsync(ct);
    await tx.CommitAsync(ct);
}

public sealed class OutboxMessage
{
    public Guid Id { get; private set; }
    public string MessageType { get; private set; } = default!;
    public string Payload { get; private set; } = default!;
    public string? Metadata { get; private set; }
    public DateTime CreatedAtUtc { get; private set; }
    public byte Status { get; private set; }

    private OutboxMessage() { } // EF

    public static OutboxMessage CreateFrom(object @event, string? aggregateId = null)
    {
        return new OutboxMessage
        {
            Id = Guid.NewGuid(),
            MessageType = @event.GetType().FullName!,
            Payload = JsonSerializer.Serialize(@event, @event.GetType()),
            Metadata = JsonSerializer.Serialize(new
            {
                AggregateId = aggregateId,
                CorrelationId = Activity.Current?.TraceId.ToString(),
                CausationId = Activity.Current?.SpanId.ToString()
            }),
            CreatedAtUtc = DateTime.UtcNow,
            Status = 0 // Pending
        };
    }
}