---
name: ddd-tactical-patterns
description: "Apply DDD tactical patterns in code using entities, value objects, aggregates, repositories, and domain events with explicit invariants."
risk: safe
source: self
tags: "[ddd, tactical, aggregates, value-objects, domain-events]"
date_added: "2026-02-27"
---

# DDD Tactical Patterns

## Use this skill when

- Translating domain rules into code structures.
- Designing aggregate boundaries and invariants.
- Refactoring an anemic model into behavior-rich domain objects.
- Defining repository contracts and domain event boundaries.

## Do not use this skill when

- You are still defining strategic boundaries.
- The task is only API documentation or UI layout.
- Full DDD complexity is not justified.

## Instructions

1. Identify invariants first and design aggregates around them.
2. Model immutable value objects for validated concepts.
3. Keep domain behavior in domain objects, not controllers.
4. Emit domain events for meaningful state transitions.
5. Keep repositories at aggregate root boundaries.

If detailed checklists are needed, open `references/tactical-checklist.md`.

## Example

```typescript
class Order {
  private status: "draft" | "submitted" = "draft";

  submit(itemsCount: number): void {
    if (!Number.isInteger(itemsCount) || itemsCount <= 0) throw new Error("Order cannot be submitted empty");
    if (this.status !== "draft") throw new Error("Order already submitted");
    this.status = "submitted";
  }
}
```

## Limitations

- This skill does not define deployment architecture.
- It does not choose databases or transport protocols.
- It should be paired with testing patterns for invariant coverage.


---
Source attribution: sickn33
Original project: https://github.com/sickn33/agentic-awesome-skills/blob/e8d346bcb691225fb6ae51a49c353bcedb2ef61d/skills/ddd-tactical-patterns/SKILL.md
License: CC-BY-4.0
License information: https://creativecommons.org/licenses/by/4.0/
Original upstream instructions; downloaded from Mega AI Hub.


# Mega AI Hub resource metadata

Creator / publisher: sickn33
Original project: https://github.com/sickn33/agentic-awesome-skills/blob/e8d346bcb691225fb6ae51a49c353bcedb2ef61d/skills/ddd-tactical-patterns/SKILL.md
Attribution basis: Package explicitly declares original/self-authored source

Fields of work: Development & Engineering
Roles: Software Developer
Specialties: Specialty not specified
Tools: Tool not specified
Country applicability: Country not specified
Classification basis: Dave AI task classification from package title, description, and declared metadata
Instruction SHA-256: c8a39611f4e2fbd0215767592ee6c9c0b368c45342be2412d1595a053bbfcdd8
Metadata reviewed: 2026-10-27
This metadata supersedes earlier Mega AI Hub catalog attribution. Original instruction and supporting files are preserved.