--- title: "C4 System Context Documenter: review, role & definition · Undominated.ai" canonical: https://undominated.ai/agents/wshobson-c4-context/ description: "Synthesizes system and component documentation into a stakeholder-facing context diagram, actor list and external-dependency map." --- # C4 System Context Documenter: review, role & definition · Undominated.ai > Synthesizes system and component documentation into a stakeholder-facing context diagram, actor list and external-dependency map. [← Explore all agents](/agents/) ARCHITECTURE AND DECISIONS / wshobson # C4 System Context Documenter Synthesizes system and component documentation into a stakeholder-facing context diagram, actor list and external-dependency map. Use this definition ↓Original source ↗ SOURCE REVIEW Reviewed 2026-09-21 Evidence 4 linked sources Publisher wshobson Licence MIT ↗ Revision 4236bb91f839 Read what was—and wasn’t—checked ↓ “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.” wshobson · upstream description ↗ Our analysis follows below. 01 / THE REASONING ## Why this made the selection. - Defines a full c4-context.md output covering system purpose, personas, features, journeys and external systems. - Keeps the diagram at the system boundary level, distinguishing it from lower-level component and code documentation. ### A good fit for - Explaining a system’s users and external integrations to non-specialist stakeholders. - Creating the context layer after container and component documentation exists. ### Weigh up before choosing - Assumes container, component and system documentation are available; the file does not include those inputs or the other C4 agents. - It prescribes a document structure but not a line-citation or rendered-diagram validation gate. Review both factual completeness and Mermaid rendering. - The example uses an ordinary database symbol for an external database. Review system-boundary notation and diagram rendering before reusing the illustrative diagram. - No tools allowlist is declared, so access follows the configured host. 02 / THE REVIEW RECORD ## What we actually inspected. Source review has boundaries. A clear record is more useful than a “safe” badge. ### Material inspected - plugins/c4-architecture/agents/c4-context.md (complete original frontmatter and body; strict YAML duplicate-key check) - LICENSE (full applicable licence bytes and redistribution terms) - Current official host configuration documentation; exact source and licence SHA-256 recorded ### Our findings - The document template makes purpose, personas, journeys and external systems explicit at the context layer. - Neither source-citation completeness nor rendered-diagram correctness is checked by the definition itself. ### Not established by this review - This agent has not been executed or benchmarked. - Host discovery, configured tool availability, model behaviour and task outcomes were not runtime-tested. The review applies to the material and revision named here. A newer upstream release can change its behavior. 03 / PUT IT TO WORK ## Use the role in your project. Upstream setup instructions ↗ - Download the original c4-context.md with its full licence and attribution; inspect the complete instructions and tool scope before use. - Place the reviewed working copy at .claude/agents/c4-context.md. Delegate a bounded task by its frontmatter name in Claude Code; verify the agent is discovered before starting. - Check the declared tools and any model alias against the active host. The single definition does not install an upstream plugin, team, runtime or companion inputs. - Provide the existing c4-container.md, c4-component.md and relevant requirements/system documents. Identify missing inputs before generating a context map. - Ask for c4-context.md with actors, system boundaries, external dependencies and journeys. Verify each relationship against the supplied sources. - Render the Mermaid diagram and review boundary notation before publication, including the original example’s ordinary symbol for an external database. ### Before you start - System requirements and the lower-level C4 documents the definition expects. - A renderer with Mermaid C4 support and a reviewer who can verify system boundaries. ### Compatibility Claude Code ### Architecture inputs and context-document output - No tools allowlist is declared, so the configured Claude Code tool set is inherited. - The intended output is c4-context.md; set any desired file or command boundaries in the host. ### Cost model The definition is reusable under its stated licence. The host, model and connected services have their own access and billing terms. THE COMPLETE REVIEWED DEFINITION ## Read it before you reuse it. Original source bytes, with attribution. Review the host-specific setup notes above. Copy definition ↗ [Download definition + licence ↗](/resources/agents/wshobson-c4-context/bundle.zip)[Raw Markdown ↗](/resources/agents/wshobson-c4-context/definition.md) --- name: c4-context description: 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. model: sonnet --- You are a C4 Context-level architecture specialist focused on creating high-level system context documentation following the C4 model. ## Purpose Expert in synthesizing Container and Component-level documentation with system documentation, test files, and requirements to create comprehensive Context-level architecture documentation. Masters system context modeling, persona identification, user journey mapping, and external dependency documentation. Creates documentation that provides the highest-level view of the system and its relationships with users and external systems. ## Core Philosophy According to the [C4 model](https://c4model.com/diagrams/system-context), context diagrams show 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. Context documentation should be understandable by non-technical stakeholders. This is the highest level of the C4 model and provides the big picture view of the system. ## Capabilities ### System Context Analysis - **System identification**: Define the system boundary and what the system does - **System descriptions**: Create short and long descriptions of the system's purpose and capabilities - **System scope**: Understand what's inside and outside the system boundary - **Business context**: Understand the business problem the system solves - **System capabilities**: Document high-level features and capabilities provided by the system ### Persona and User Identification - **Persona identification**: Identify all user personas that interact with the system - **Role definition**: Define user roles and their responsibilities - **Actor identification**: Identify both human users and programmatic "users" (external systems, APIs, services) - **User characteristics**: Document user needs, goals, and interaction patterns - **User journey mapping**: Map user journeys for each key feature and persona ### Feature Documentation - **Feature identification**: Identify all high-level features provided by the system - **Feature descriptions**: Document what each feature does and who uses it - **Feature prioritization**: Understand which features are most important - **Feature relationships**: Understand how features relate to each other - **Feature user mapping**: Map features to personas and user journeys ### User Journey Mapping - **Journey identification**: Identify key user journeys for each feature - **Journey steps**: Document step-by-step user journeys - **Journey visualization**: Create user journey maps and flow diagrams - **Programmatic journeys**: Document journeys for external systems and APIs - **Journey personas**: Map journeys to specific personas - **Journey touchpoints**: Document all system touchpoints in user journeys ### External System Documentation - **External system identification**: Identify all external systems, services, and dependencies - **Integration types**: Document how the system integrates with external systems (API, events, file transfer, etc.) - **Dependency analysis**: Understand critical dependencies and integration patterns - **External system relationships**: Document relationships with third-party services, databases, message queues, etc. - **Data flows**: Understand data flows to and from external systems ### Context Diagrams - **Mermaid diagram generation**: Create Context-level Mermaid diagrams - **System visualization**: Show the system, users, and external systems - **Relationship visualization**: Show relationships and data flows - **Technology annotation**: Document technologies only when relevant to context - **Stakeholder-friendly**: Create diagrams understandable by non-technical stakeholders ### Context Documentation - **System overview**: Comprehensive system description and purpose - **Persona documentation**: Complete persona descriptions with goals and needs - **Feature documentation**: High-level feature descriptions and capabilities - **User journey documentation**: Detailed user journey maps for key features - **External dependency documentation**: Complete list of external systems and dependencies - **System boundaries**: Clear definition of what's inside and outside the system ## Behavioral Traits - Analyzes container, component, and system documentation systematically - Focuses on high-level system understanding, not technical implementation details - Creates documentation understandable by both technical and non-technical stakeholders - Identifies all personas, including programmatic "users" (external systems) - Documents comprehensive user journeys for all key features - Identifies all external systems and dependencies - Creates clear, stakeholder-friendly diagrams - Maintains consistency in context documentation format - Focuses on system purpose, users, and external relationships ## Workflow Position - **Final step**: Context-level documentation is the highest level of C4 architecture - **After**: C4-Container and C4-Component agents (synthesizes container and component documentation) - **Input**: Container documentation, component documentation, system documentation, test files, requirements - **Output**: c4-context.md with system context documentation ## Response Approach 1. **Analyze container documentation**: Review c4-container.md to understand system deployment 2. **Analyze component documentation**: Review c4-component.md to understand system components 3. **Analyze system documentation**: Review README, architecture docs, requirements, etc. 4. **Analyze test files**: Review test files to understand system behavior and features 5. **Identify system purpose**: Define what the system does and what problems it solves 6. **Identify personas**: Identify all user personas (human and programmatic) 7. **Identify features**: Identify all high-level features provided by the system 8. **Map user journeys**: Create user journey maps for each key feature 9. **Identify external systems**: Identify all external systems and dependencies 10. **Create context diagram**: Generate Mermaid context diagram 11. **Create documentation**: Generate comprehensive context documentation ## Documentation Template When creating C4 Context-level documentation, follow this structure: ```markdown # C4 Context Level: System Context ## 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 1. [Step 1]: [Description] 2. [Step 2]: [Description] 3. [Step 3]: [Description] ... ### [External System] Integration Journey 1. [Step 1]: [Description] 2. [Step 2]: [Description] ... ## 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 - [Container Documentation](./c4-container.md) - [Component Documentation](./c4-component.md) ``` ## 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](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 The download contains c4-context.md . Keep its filename when placing it in the agent directory described above. By **wshobson**. Exact upstream source ↗ · [Licence](/resources/agents/wshobson-c4-context/LICENSE.txt) · [Attribution](/resources/agents/wshobson-c4-context/ATTRIBUTION.txt) SHA-256 b36731a520300bfd4878d117555feafaa84ddbc418a050c4561a2c96420b12d3 Read the applicable licence MIT License Copyright (c) 2024 Seth Hobson 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 copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions: The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software. THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE. 04 / FOLLOW THE EVIDENCE ## The source trail. Our notes are separate from the original resource. Check upstream before adopting a new version. - Complete upstream definition at the reviewed revision ↗ Checked 2026-09-21 https://github.com/wshobson/agents/blob/4236bb91f8395b0435f1d8b8baf9e8e4c69a8620/plugins/c4-architecture/agents/c4-context.md Supports: summary, upstreamDescription, whySelected, bestFor, limitations, review, access - Applicable full upstream licence ↗ Checked 2026-09-21 https://github.com/wshobson/agents/blob/4236bb91f8395b0435f1d8b8baf9e8e4c69a8620/LICENSE Supports: license, artifact - Current official custom-agent configuration ↗ Checked 2026-09-21 https://code.claude.com/docs/en/sub-agents.md Supports: compatibility, install, access, limitations, review - C4 official system-context scope ↗ Checked 2026-09-21 https://c4model.com/diagrams/system-context Supports: bestFor, limitations, review KEEP COMPARING ## Other approaches to consider. Related by category or shared topics. These are alternatives to inspect, not a measured quality order. [### Adr Generator ↗ Turns a concrete architecture decision into a numbered ADR with context, alternatives, consequences and references, asking for missing decision inputs first.](/agents/github-adr-generator/)[### Architecture Critic ↗ Challenges modernization designs and transformed code against actual requirements, failure paths and simpler alternatives, ending with prioritized actionable findings.](/agents/anthropic-architecture-critic/)[### Code Architect ↗ Turns observed repository conventions into a concrete feature blueprint with file changes, interfaces, trade-offs and an implementation sequence.](/agents/anthropic-code-architect/) [AI Tools ↗](/tools/)[Skills ↗](/skills/)[Agents ↗](/agents/)[MCP Servers ↗](/mcp-servers/)