// ❌ Direct cross-service DB access → ✅ Use message bus
// ❌ Custom repository interface → ✅ Use platform repo + extensions
// ❌ Manual validation throw → ✅ Use PlatformValidationResult fluent API
// ❌ Side effects in handler → ✅ Use entity event handlers
// ❌ DTO mapping in handler → ✅ DTO owns mapping via MapToObject()/MapToEntity()

public sealed class Save{Entity}Command : PlatformCqrsCommand<Save{Entity}CommandResult>
{
    public string Id { get; set; } = "";
    public string Name { get; set; } = "";

    public override PlatformValidationResult<IPlatformCqrsRequest> Validate()
        => base.Validate().And(_ => Name.IsNotNullOrEmpty(), "Name required");
}

public sealed class Save{Entity}CommandResult : PlatformCqrsCommandResult
{
    public {Entity}Dto Entity { get; set; } = null!;
}

internal sealed class Save{Entity}CommandHandler : PlatformCqrsCommandApplicationHandler<Save{Entity}Command, Save{Entity}CommandResult>
{
    protected override async Task<Save{Entity}CommandResult> HandleAsync(Save{Entity}Command req, CancellationToken ct)
    {
        var entity = req.Id.IsNullOrEmpty()
            ? req.MapToNewEntity().With(e => e.CreatedBy = RequestContext.UserId())
            : await repo.GetByIdAsync(req.Id, ct).Then(e => req.UpdateEntity(e));
        await entity.ValidateAsync(repo, ct).EnsureValidAsync();
        var saved = await repo.CreateOrUpdateAsync(entity, ct);
        return new Save{Entity}CommandResult { Entity = new {Entity}Dto(saved) };
    }
}