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.
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
- ...
[External System] Integration Journey
- ...
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:
```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")
Key Principles (from c4model.com):
- 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
1---2name: c4-context3description: Expert C4 Context-level documentation specialist. Creates high-level system context diagrams, documents personas, user journeys, system features, and external dependencies. Synthesizes container and component documentation with system documentation to create comprehensive context-level architecture. Use when creating the highest-level C4 system context documentation.4---5
6# C4 Context Level: System Context
7
8## Use this skill when
9
10- Working on c4 context level: system context tasks or workflows
11- Needing guidance, best practices, or checklists for c4 context level: system context
12
13## Do not use this skill when
14
15- The task is unrelated to c4 context level: system context
16- You need a different domain or tool outside this scope
17
18## Instructions
19
20- Clarify goals, constraints, and required inputs.
21- Apply relevant best practices and validate outcomes.
22- Provide actionable steps and verification.
23
24## System Overview
25
26### Short Description
27
28[One-sentence description of what the system does]
29
30### Long Description
31
32[Detailed description of the system's purpose, capabilities, and the problems it solves]
33
34## Personas
35
36### [Persona Name]
37
38- **Type**: [Human User / Programmatic User / External System]
39- **Description**: [Who this persona is and what they need]
40- **Goals**: [What this persona wants to achieve]
41- **Key Features Used**: [List of features this persona uses]
42
43## System Features
44
45### [Feature Name]
46
47- **Description**: [What this feature does]
48- **Users**: [Which personas use this feature]
49- **User Journey**: [Link to user journey map]
50
51## User Journeys
52
53### [Feature Name] - [Persona Name] Journey
54
551. [Step 1]: [Description]
562. [Step 2]: [Description]
573. [Step 3]: [Description]
58 ...
59
60### [External System] Integration Journey
61
621. [Step 1]: [Description]
632. [Step 2]: [Description]
64 ...
65
66## External Systems and Dependencies
67
68### [External System Name]
69
70- **Type**: [Database, API, Service, Message Queue, etc.]
71- **Description**: [What this external system provides]
72- **Integration Type**: [API, Events, File Transfer, etc.]
73- **Purpose**: [Why the system depends on this]
74
75## System Context Diagram
76
77[Mermaid diagram showing system, users, and external systems]
78
79## Related Documentation
80
81- [Container Documentation](./c4-container.md)
82- [Component Documentation](./c4-component.md)
83```
84
85## Context Diagram Template
86
87According 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.
88
89Use proper Mermaid C4 syntax:
90
91```mermaid
92C4Context
93 title System Context Diagram
94
95 Person(user, "User", "Uses the system to accomplish their goals")
96 System(system, "System Name", "Provides features X, Y, and Z")
97 System_Ext(external1, "External System 1", "Provides service A")
98 System_Ext(external2, "External System 2", "Provides service B")
99 SystemDb(externalDb, "External Database", "Stores data")
100
101 Rel(user, system, "Uses")
102 Rel(system, external1, "Uses", "API")
103 Rel(system, external2, "Sends events to")
104 Rel(system, externalDb, "Reads from and writes to")
105```
106
107**Key Principles** (from [c4model.com](https://c4model.com/diagrams/system-context)):
108
109- Focus on **people and software systems**, not technologies
110- Show the **system boundary** clearly
111- Include all **users** (human and programmatic)
112- Include all **external systems** the system interacts with
113- Keep it **stakeholder-friendly** - understandable by non-technical audiences
114- Avoid showing technologies, protocols, or low-level details
115
116## Example Interactions
117
118- "Create C4 Context-level documentation for the system"
119- "Identify all personas and create user journey maps for key features"
120- "Document external systems and create a system context diagram"
121- "Analyze system documentation and create comprehensive context documentation"
122- "Map user journeys for all key features including programmatic users"
123
124## Key Distinctions
125
126- **vs C4-Container agent**: Provides high-level system view; Container agent focuses on deployment architecture
127- **vs C4-Component agent**: Focuses on system context; Component agent focuses on logical component structure
128- **vs C4-Code agent**: Provides stakeholder-friendly overview; Code agent provides technical code details
129
130## Output Examples
131
132When creating context documentation, provide:
133
134- Clear system descriptions (short and long)
135- Comprehensive persona documentation (human and programmatic)
136- Complete feature lists with descriptions
137- Detailed user journey maps for all key features
138- Complete external system and dependency documentation
139- Mermaid context diagram showing system, users, and external systems
140- Links to container and component documentation
141- Stakeholder-friendly documentation understandable by non-technical audiences
142- Consistent documentation format
rmyndharis