Domain-Driven Design: Strategic Design

前置协议

环境检测

# 检测当前项目信息
PROJECT_ROOT=$(git rev-parse --show-toplevel 2>/dev/null || echo "unknown")
BRANCH=$(git branch --show-current 2>/dev/null || echo "unknown")
COMMIT=$(git rev-parse --short HEAD 2>/dev/null || echo "unknown")

echo "PROJECT: $PROJECT_ROOT"
echo "BRANCH: $BRANCH"
echo "COMMIT: $COMMIT"

前置技能检查

benefits-from 检查（推荐但非必须）：

# 检查 goal-oriented 工件
GOAL_ARTIFACT="memory/artifacts/goal-oriented/latest.json"

if [ -f "$GOAL_ARTIFACT" ]; then
  echo "FOUND: goal-oriented artifact"
  # 提取目标信息，确保设计符合目标
fi

# 检查 first-principles 工件
FP_ARTIFACT="memory/artifacts/first-principles/latest.json"

if [ -f "$FP_ARTIFACT" ]; then
  echo "FOUND: first-principles artifact"
  # 提取第一性原理分析结果，用于指导设计
fi

工件目录初始化：

# 确保工件目录存在
mkdir -p memory/artifacts/ddd-strategic

用户意图确认

根据用户消息判断：

检查点：

• [ ] 是否需要设计新系统或重构现有系统
• [ ] 是否涉及多个业务领域或团队
• [ ] 是否需要识别系统边界和上下文关系

意图分类：

1. 新系统设计：从零开始设计系统架构
2. 系统重构：将单体拆分为微服务
3. 架构优化：重新梳理上下文边界
4. 业务建模：梳理业务领域

Overview

Strategic design focuses on defining bounded contexts and their relationships. A bounded context is a boundary within which a domain model is defined and applicable. Inside the boundary, all terms, rules, and logic have a specific, consistent meaning. Different contexts may use the same terms with different meanings.

Why it matters: Without clear boundaries, teams talk past each other. "Customer" means something different to Sales vs Support vs Billing. Strategic design makes these boundaries explicit.

Core principle: Language consistency within a boundary, explicit translation between boundaries.

Tactical design happens within each bounded context. See ddd-tactical-design skill for implementation details.

When to Use

Applicable:

• Starting a new project or system
• Decomposing a monolith into microservices
• Multiple teams working on the same domain
• Domain logic is complex and domain experts are available
• Language confusion across teams (same term, different meanings)

Not applicable:

• Simple CRUD operations with minimal logic
• Single-team small projects (< 3 developers)
• Technical-only domains (no business experts needed)
• Existing well-defined bounded contexts

The Process

digraph strategic_design {
    rankdir=TB;
    "Event Storming" [shape=box, style=filled, fillcolor="#c8e6c9"];
    "Identify Bounded Contexts" [shape=box, style=filled, fillcolor="#bbdefb"];
    "Define Context Map" [shape=box, style=filled, fillcolor="#fff9c4"];
    "Architecture Decisions" [shape=box, style=filled, fillcolor="#f8bbd0"];
    "保存工件" [shape=box, style=filled, fillcolor="#81c784"];

    "Event Storming" -> "Identify Bounded Contexts";
    "Identify Bounded Contexts" -> "Define Context Map";
    "Define Context Map" -> "Architecture Decisions";
    "Architecture Decisions" -> "保存工件";
}

Step 1: Event Storming

Gather domain experts and developers. Use sticky notes to explore the domain:

Domain Events (orange): Something that happened

• "Order Placed", "Payment Processed", "Inventory Reserved"
• Write in past tense

Commands (blue): What triggers events

• "Place Order", "Process Payment", "Reserve Inventory"
• Write in imperative mood

Aggregates (yellow): What handles commands and emits events

• "Order", "Payment", "Inventory"

External Systems (pink): Outside dependencies

• "Payment Gateway", "Email Service"

Actors (green): Who initiates commands

• "Customer", "Admin", "System"

Process: Start with events, work backward to commands, identify what's needed.

Step 2: Identify Bounded Contexts

Group related events, commands, and aggregates into contexts:

Principles:

• Semantic consistency: Same term means same thing within a context
• Independent evolution: Each context can change independently
• Team alignment: One team owns one context (Conway's Law)

Questions to ask:

• Where does language change? (Customer in Sales vs Support)
• Where can we draw a clean boundary?
• What can be deployed independently?
• What team owns this capability?

Start coarse, refine later. Too many contexts = integration complexity. Too few = coupling.

Step 3: Define Context Map

Document relationships between contexts:

Draw the map: Which contexts talk to each other? What patterns apply?

Step 4: Architecture Decisions

Based on context map, decide:

• Team structure: One team per context (ideally)
• Communication: Synchronous (RPC) vs asynchronous (events)
• Data ownership: One context owns data, others subscribe
• Deployment: Monolith or microservices? Start monolith-first.

Thinking Framework

Use this table during Event Storming:

Bounded Context Checklist:

• [ ] Language is consistent within the context
• [ ] Can evolve independently (deployable on own schedule)
• [ ] One team can own it (matches Conway's Law)
• [ ] Clear boundaries with other contexts
• [ ] Defined relationships on context map

Examples

Case 1: E-commerce System

Event Storming reveals:

• Events: OrderPlaced, InventoryReserved, PaymentProcessed, OrderShipped
• Commands: PlaceOrder, ReserveInventory, ProcessPayment, ShipOrder
• Aggregates: Order, Inventory, Payment, Shipment

Bounded Contexts identified:

1. Order Context

• Language: Order, OrderItem, Customer (buyer), OrderStatus
• Team: Order Management Team
• Events: OrderPlaced, OrderCancelled

1. Inventory Context

• Language: Product, Stock, Warehouse, Reservation
• Team: Warehouse Team
• Events: InventoryReserved, StockDepleted

1. Payment Context

• Language: Payment, Transaction, PaymentMethod, Refund
• Team: Finance Team
• Events: PaymentProcessed, PaymentFailed

Context Map:

• Order → Inventory: Customer-Supplier (Order needs Inventory to reserve)
• Order → Payment: Customer-Supplier (Order needs Payment to process)
• Order publishes OrderPlaced event → Inventory subscribes (async)
• Payment publishes PaymentProcessed event → Order subscribes (async)

Architecture: Start as modular monolith. Deploy as microservices if teams scale.

Case 2: Healthcare System

Bounded Contexts:

1. Patient Management Context

• Language: Patient, MedicalRecord, Diagnosis
• Team: Clinical Team

1. Appointment Context

• Language: Appointment, Schedule, Availability, Slot
• Team: Scheduling Team

1. Billing Context

• Language: Invoice, Payment, Insurance, Claim
• Team: Billing Team

Context Map:

• Patient Management → Appointment: Shared Kernel (Patient ID)
• Appointment → Billing: Customer-Supplier (Appointments trigger billing)
• Billing has Anti-Corruption Layer for Insurance Provider's external model

Common Pitfalls

Pitfall 1: Too Fine-Grained Contexts

Mistake: Creating a context for every aggregate or entity.

Problem: Excessive integration complexity. Every change touches multiple contexts.

Solution: Start with fewer, larger contexts. Split only when you feel coupling pain.

Rule of thumb: Can you deploy this independently without coordinating with 3+ other teams? If no, merge contexts.

Pitfall 2: Ignoring Team Structure

Mistake: Designing contexts based on domain purity, ignoring Conway's Law.

Problem: One team owns multiple contexts → coupling. Multiple teams own one context → conflict.

Solution: Align context boundaries with team boundaries. One team, one context.

Pitfall 3: Missing Anti-Corruption Layer

Mistake: Letting upstream context's model leak into downstream context.

Problem: Downstream model becomes polluted with concepts that don't fit its domain.

Solution: Add Anti-Corruption Layer. Translate upstream model to downstream model at the boundary.

Example: External "User" → ACL translates → Internal "AccountHolder" with different attributes.

后置协议

工件输出

保存战略设计结果到工件文件：

# 生成工件文件名
TIMESTAMP=$(date +%Y%m%d-%H%M%S)
ARTIFACT_FILE="memory/artifacts/ddd-strategic/result-$TIMESTAMP.json"

# 写入工件
cat > "$ARTIFACT_FILE" <<EOF
{
  "skill": "ddd-strategic-design",
  "version": "2.0.0",
  "timestamp": "$(date -u +%Y-%m-%dT%H:%M:%SZ)",
  "project": "$PROJECT_ROOT",
  "branch": "$BRANCH",
  "commit": "$COMMIT",
  "input": {
    "user_request": "用户的原始请求"
  },
  "output": {
    "bounded_contexts": [
      {
        "name": "上下文名称",
        "language": ["术语1", "术语2"],
        "team": "团队名称",
        "events": ["Event1", "Event2"]
      }
    ],
    "context_map": {
      "Order → Inventory": "Customer-Supplier",
      "Order → Payment": "Customer-Supplier"
    },
    "architecture_decisions": [
      "Start as modular monolith",
      "Deploy as microservices when teams scale"
    ]
  },
  "next_skills": [
    "ddd-tactical-design",
    "mvp-first"
  ]
}
EOF

echo "ARTIFACT SAVED: $ARTIFACT_FILE"

# 创建 latest.json 符号链接
ln -sf "$ARTIFACT_FILE" memory/artifacts/ddd-strategic/latest.json

目标文件更新

如果存在目标文件，记录设计完成：

# 检查是否有 pending 目标
GOAL_FILE=$(ls -t memory/goals/*.md 2>/dev/null | head -1)

if [ -n "$GOAL_FILE" ]; then
  GOAL_STATUS=$(grep "状态：" "$GOAL_FILE" | awk '{print $2}')

  if [ "$GOAL_STATUS" = "pending" ]; then
    echo "Adding milestone: DDD 战略设计完成"

    # 使用 Edit 工具添加里程碑
  fi
fi

建议后续技能

根据设计结果，推荐后续技能：

推荐格式：

## 后续建议

基于 DDD 战略设计结果，建议继续执行：

**推荐技能链**：
1. /ddd-tactical-design - 在限界上下文内进行战术设计
2. /mvp-first - 进行 MVP 功能筛选

**根据设计阶段选择**：
- **战术实现** → /ddd-tactical-design（设计聚合、实体、值对象）
- **功能规划** → /mvp-first（筛选 MVP 功能）
- **迭代执行** → /pdca-cycle（进入 PDCA 循环）

是否继续执行？
- A) 执行推荐的技能链
- B) 只执行第一个技能
- C) 不继续，结束当前任务

References

• Domain-Driven Design by Eric Evans - The original DDD book
• Implementing Domain-Driven Design by Vaughn Vernon - Practical implementation guide
• Event Storming by Alberto Brandolini - Collaborative domain exploration
• Context Mapping patterns: https://www.infoq.com/articles/ddd-contextmapping/