C4 Context Level: System Context

Use this skill when

• Working on c4 context level: system context tasks or workflows
• Needing guidance, best practices, or checklists for c4 context level: system context

Do not use this skill when

• The task is unrelated to c4 context level: system context
• You need a different domain or tool outside this scope

Instructions

• Clarify goals, constraints, and required inputs.
• Apply relevant best practices and validate outcomes.
• Provide actionable steps and verification.
• If detailed examples are required, open

  resources/implementation-playbook.md

  .

System Overview

Short Description

Long Description

Personas

[Persona Name]

• Type: [Human User / Programmatic User / External System]
• Description: [Who this persona is and what they need]
• Goals: [What this persona wants to achieve]
• Key Features Used: [List of features this persona uses]

System Features

[Feature Name]

• Description: [What this feature does]
• Users: [Which personas use this feature]
• User Journey: [Link to user journey map]

User Journeys

[Feature Name] - [Persona Name] Journey

3. ...

[External System] Integration Journey

2. ...

External Systems and Dependencies

[External System Name]

• Type: [Database, API, Service, Message Queue, etc.]
• Description: [What this external system provides]
• Integration Type: [API, Events, File Transfer, etc.]
• Purpose: [Why the system depends on this]

System Context Diagram

Related Documentation

• Container Documentation
• Component Documentation

## Context Diagram Template

According to the [C4 model](https://c4model.com/diagrams/system-context), a System Context diagram shows the system as a box in the center, surrounded by its users and the other systems that it interacts with. The focus is on **people (actors, roles, personas) and software systems** rather than technologies, protocols, and other low-level details.

Use proper Mermaid C4 syntax:

```mermaid
C4Context
    title System Context Diagram

    Person(user, "User", "Uses the system to accomplish their goals")
    System(system, "System Name", "Provides features X, Y, and Z")
    System_Ext(external1, "External System 1", "Provides service A")
    System_Ext(external2, "External System 2", "Provides service B")
    SystemDb(externalDb, "External Database", "Stores data")

    Rel(user, system, "Uses")
    Rel(system, external1, "Uses", "API")
    Rel(system, external2, "Sends events to")
    Rel(system, externalDb, "Reads from and writes to")

• Focus on people and software systems, not technologies
• Show the system boundary clearly
• Include all users (human and programmatic)
• Include all external systems the system interacts with
• Keep it stakeholder-friendly - understandable by non-technical audiences
• Avoid showing technologies, protocols, or low-level details

Example Interactions

• "Create C4 Context-level documentation for the system"
• "Identify all personas and create user journey maps for key features"
• "Document external systems and create a system context diagram"
• "Analyze system documentation and create comprehensive context documentation"
• "Map user journeys for all key features including programmatic users"

Key Distinctions

• vs C4-Container agent: Provides high-level system view; Container agent focuses on deployment architecture
• vs C4-Component agent: Focuses on system context; Component agent focuses on logical component structure
• vs C4-Code agent: Provides stakeholder-friendly overview; Code agent provides technical code details

Output Examples

• Clear system descriptions (short and long)
• Comprehensive persona documentation (human and programmatic)
• Complete feature lists with descriptions
• Detailed user journey maps for all key features
• Complete external system and dependency documentation
• Mermaid context diagram showing system, users, and external systems
• Links to container and component documentation
• Stakeholder-friendly documentation understandable by non-technical audiences
• Consistent documentation format