pact-architecture-patterns

# PACT Architecture Patterns

Design patterns and templates for the Architect phase of PACT. This skill provides
quick references for architectural decisions and links to detailed pattern implementations.

## C4 Model Quick Reference

The C4 model provides four levels of abstraction for system architecture documentation.

### Level 1: System Context

Shows your system as a box surrounded by users and other systems it interacts with.

```
                    +------------------+
                    |   External User  |
                    +--------+---------+
                             |
                             v
+------------------+    +----+----+    +------------------+
| Payment Gateway  |<-->|   Your  |<-->|   Email Service  |
+------------------+    | System  |    +------------------+
                        +---------+
                             ^
                             |
                    +--------+---------+
                    |   Admin User     |
                    +------------------+
```

**What to include:**
- Your system (single box)
- Users/personas
- External systems
- High-level interactions

### Level 2: Container

Shows the high-level technical building blocks (not Docker containers).

```
+----------------------------------------------------------------+
|                         Your System                             |
|  +----------------+     +----------------+     +--------------+ |
|  |   Web App      |     |    API         |     |   Database   | |
|  |   (React)      |---->|    (Node.js)   |---->|   (Postgres) | |
|  +----------------+     +----------------+     +--------------+ |
|                               |                                 |
|                               v                                 |
|                         +----------+                            |
|                         |  Cache   |                            |
|                         | (Redis)  |                            |
|