---
name: mermaid
description: Generate Mermaid overview diagrams for architecture and component visualization. Use when asked to create, generate, or draw Mermaid diagrams, architecture overviews, component diagrams, dependency graphs, or system visualizations. Triggers on "mermaid diagram", "architecture diagram", "component overview", "dependency graph", "draw a diagram", or requests to visualize system structure. Not for sequence diagrams or class diagrams.
---

# Mermaid Overview Diagrams

## Rules

- prefer flowchart (graph) with TD or LR direction
- wrap in ` ```mermaid ` fenced code block
- use stadium-shaped nodes: `([text])`
- use meaningful node IDs reflecting component names
- use `-->` for dependencies, `-.->` for optional/async dependencies
- label arrows only when ambiguous: `Gateway -->|routes| Service`
- visualize only high-level concepts — omit classes, methods, implementation details
- use subgraphs for logical grouping (subsystems)
- write diagram into the target file (e.g. README.md) when context is clear

## BCE Shape Mapping

| Element | Mermaid syntax | Style class |
|---|---|---|
| Business Component (BC) | `Orders([Orders])` | `bc` |
| Subsystem | `subgraph Billing` | `subsystem` |
| External service | `PayGW([Payment Gateway])` | `ext` |
| Boundary layer | `Boundary([Boundary])` | `boundary` |
| Control layer | `Control([Control])` | `control` |
| Entity layer | `Entity([Entity])` | `entity` |

## Style Classes

Define these `classDef` entries at the end of the graph and apply with `class` or `:::`:

```
classDef bc fill:#dae8fc,stroke:#6c8ebf,color:#000
classDef ext fill:#fff2cc,stroke:#d6b656,color:#000,stroke-dasharray:5 5
classDef boundary fill:#d5e8d4,stroke:#82b366,color:#000
classDef control fill:#e1d5e7,stroke:#9673a6,color:#000
classDef entity fill:#fff2cc,stroke:#d6b656,color:#000
```

## Color Palette

- BC blue: fill `#dae8fc`, border `#6c8ebf`
- External yellow: fill `#fff2cc`, border `#d6b656`
- Boundary green: fill `#d5e8d4`, border `#82b366`
- Control purple: fill `#e1d5e7`, border `#9673a6`
- Entity yellow: fill `#fff2cc`, border `#d6b656`

## Example — Between Components

```mermaid
graph LR
    subgraph Billing
        Orders([Orders]) -->|charges| Payments([Payments])
    end
    Orders -.->|async| Notifications([Notifications])
    Payments -->|REST| PayGW([Payment Gateway])

    classDef bc fill:#dae8fc,stroke:#6c8ebf,color:#000
    classDef ext fill:#fff2cc,stroke:#d6b656,color:#000,stroke-dasharray:5 5
    class Orders,Payments,Notifications bc
    class PayGW ext
```