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
[One-sentence description of what the system does]
Long Description
[Detailed description of the system's purpose, capabilities, and the problems it solves]
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
- 2. 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
[Mermaid diagram showing system, users, and external systems]
Related 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:
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")
**Key Principles** (from [c4model.com](https://c4model.com/diagrams/system-context)):
- 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
When creating context documentation, provide:
- 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