---
name: architecture-1954f90f3190
description: "Use when documenting architecture, understanding system structure, creating diagrams, or analyzing component relationships. Focuses on interfaces and high-level design. Triggers on: 'use architecture mode', 'architecture', 'system design', 'how is this structured', 'document the system', 'create a diagram', 'high-level overview'. Read-only mode."
context: fork
allowed-tools: [Read, Grep, Glob, LSP]
---

# Architecture Mode

High-level design and system understanding.

## Core Constraint

> "Interfaces in; interfaces out. Data in; data out. Major flows, contracts, behaviors, and failure modes only."

If you find yourself describing implementation details, STOP. Zoom out.

## What to Focus On

✅ **Include**:

- System boundaries and contracts
- Data flow between components
- Integration points and APIs
- Error surfaces and failure modes
- Key design decisions and tradeoffs

❌ **Never Include**:

- Implementation details (how functions work internally)
- Line-by-line code analysis
- Minor utility functions
- Specific algorithms (unless architecturally significant)
- Variable names, loop structures, or conditionals
- Database schema details (only mention "stores X in Y")

## Anti-Patterns

| ❌ Don't Do This                        | ✅ Do This Instead                       |
| --------------------------------------- | ---------------------------------------- |
| "The function iterates over items..."   | "Component X transforms input to output" |
| "Line 42 calls the validate method..."  | "Validation happens at the API boundary" |
| "The for loop processes each record..." | "Records flow from A → B → C"            |
| "This uses a HashMap with..."           | "State is cached in memory"              |

## Analysis Framework

### 1. Component Identification

- What are the major components/modules?
- What is each component's single responsibility?
- How are they organized (layers, services, etc.)?

### 2. Interface Analysis

- What are the public APIs?
- What data structures cross boundaries?
- What are the contracts between components?

### 3. Data Flow

- How does data enter the system?
- How does it transform as it moves?
- Where is state stored?

### 4. Integration Points

- What external systems are connected?
- What protocols/formats are used?
- What are the failure modes?

### 5. Quality Attributes

- How is reliability achieved?
- How does it scale?
- What security measures exist?

## Architecture Overview Format

```markdown
## Architecture Overview

### Purpose

[What this system does in 1-2 sentences]

### Components

| Component | Responsibility   | Dependencies |
| --------- | ---------------- | ------------ |
| `api`     | HTTP interface   | auth, db     |
| `auth`    | Authentication   | db           |
| `db`      | Data persistence | -            |

### Data Flow

[Mermaid diagram - see below]

### Key Decisions

| Decision | Rationale | Tradeoffs   |
| -------- | --------- | ----------- |
| [choice] | [why]     | [pros/cons] |
```

## Mermaid Diagrams

### Component Diagram

```mermaid
graph LR
    Client --> API
    API --> Auth
    API --> Service
    Service --> DB
    Service --> Cache
```

### Sequence Diagram

```mermaid
sequenceDiagram
    participant C as Client
    participant A as API
    participant S as Service
    participant D as Database

    C->>A: POST /orders
    A->>S: create_order()
    S->>D: INSERT order
    D-->>S: order_id
    S-->>A: Order
    A-->>C: 201 Created
```

## API Contract Format

````markdown
## API: /orders

### POST /orders

Create a new order.

**Request**:

```json
{
  "items": [{ "sku": "ABC", "qty": 2 }],
  "customer_id": "cust_123"
}
```
````

**Response** (201):

```json
{
  "order_id": "ord_456",
  "status": "pending",
  "total": 49.99
}
```

**Errors**:

- `400 Bad Request` - Invalid input
- `401 Unauthorized` - Missing auth
- `422 Unprocessable Entity` - Business rule violation

```

## Guidelines

- Focus on **what** and **why**, not **how**
- Use diagrams liberally - they communicate structure better than prose
- Document decision rationale, not just the decision
- Identify failure modes and how they're handled
- Keep documentation close to the code it describes
```


---
Source attribution: mcouthon
Original project: https://github.com/mcouthon/agents/blob/a024cab20ec0cc9f51dea87e793fd9a5ecad8f6f/generated/claude/skills/architecture/SKILL.md
License: MIT
License information: https://opensource.org/license/mit
Original upstream instructions; downloaded from Mega AI Hub.

## Upstream license notice

MIT License

Copyright (c) 2025 Pavel Brodsky

Permission is hereby granted, free of charge, to any person obtaining a copy
of this software and associated documentation files (the "Software"), to deal
in the Software without restriction, including without limitation the rights
to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
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The above copyright notice and this permission notice shall be included in all
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THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.



# Mega AI Hub resource metadata

Creator / publisher: mcouthon
Original project: https://github.com/mcouthon/agents/blob/a024cab20ec0cc9f51dea87e793fd9a5ecad8f6f/generated/claude/skills/architecture/SKILL.md
Attribution basis: Source repository record

Fields of work: Data & Analytics, Design, Development & Engineering, Product Management
Roles: Backend Developer, Data Analyst, Product Manager, Technical Product Manager, UX Designer
Specialties: Backend, Cross Platform
Tools: Mermaid
Country applicability: Country not specified
Classification basis: Source catalog labels
Instruction SHA-256: 7e09c4ba78b300c9c9835c7c74e815a6a5cef88a66e2c5477f82fd9f50b16f1a