Apply DDD tactical patterns in code using entities, value objects, aggregates, repositories, and domain events with explicit invariants.
If detailed checklists are needed, open references/tactical-checklist.md.
class Order {
private status: "draft" | "submitted" = "draft";
submit(itemsCount: number): void {
if (itemsCount === 0) throw new Error("Order cannot be submitted empty");
if (this.status !== "draft") throw new Error("Order already submitted");
this.status = "submitted";
}
}