# c4-architecture

Runs a bottom-up codebase analysis and writes complete C4 model architecture documentation into C4-Documentation/.

- command · `type=command` · Claude Code, Codex, Cursor · ★ 41823
- Author: Seth Hobson
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/wshobson/agents/tree/HEAD/plugins/c4-architecture/commands/c4-architecture.md
- Updated: 2026-10-24
- HTML: https://affpapa.org/en/nevibecode/commands/c4-architecture

## What it does

The workflow examines the codebase starting from the deepest subdirectories and works upward. For each folder, it invokes the `c4-architecture::c4-code` subagent to record function signatures, parameter types, class structures, and external libraries into individual `c4-code-[directory].md` files. Common non-code folders like `node_modules`, `.git`, `build`, and `dist` are filtered out.

Next, the `c4-architecture::c4-component` subagent aggregates directory-level notes into logical components based on domain and technical boundaries. It maps out interface protocols and creates Mermaid relationship diagrams. The workflow covers four C4 layers: code, component, container, and system context.

On large projects, this workflow generates dozens of Markdown files. It triggers multiple subagent tasks in sequence. All generated artifacts remain inside the root `C4-Documentation/` folder.

## Install

### Claude Code (native platform)

1. **Plugin marketplace**
In the agent chat (not a shell):
```text
/plugin marketplace add wshobson/agents
```
In the agent chat (not a shell):
```text
/plugin install c4-architecture@claude-code-workflows
```

2. **Manually: put the files in place**
- File: `.claude/commands/c4-architecture.md` — Call it with /c4-architecture. For all projects use ~/.claude/commands/

### Codex

**Manually: put the files in place**
- File: `~/.codex/prompts/c4-architecture.md` — Call it with /prompts:c4-architecture. Codex marks this format deprecated in favour of skills

### GitHub Copilot

**Manually: put the files in place**
- File: `.github/prompts/c4-architecture.prompt.md`

### Gemini CLI

**Manually: put the files in place**
- File: `.gemini/commands/c4-architecture.toml` — Gemini stores commands as TOML: the prompt text goes into the prompt field

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/wshobson/agents/tree/HEAD/plugins/c4-architecture/commands/c4-architecture.md

## When to use it
- document functions, classes, and dependencies across all project directories
- synthesize directory-level code notes into logical system components
- generate Mermaid diagrams for module relationships and interfaces
- produce a structured C4 architecture hierarchy in Markdown

## Example prompts
- /c4-architecture
- Analyze this repository and generate complete C4 architecture documentation
- Run the C4 architecture workflow and save output to C4-Documentation

## Source text · c4-architecture.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: 1c5d09f8df7341ea.

BEGIN THIRD-PARTY FILE 1c5d09f8df7341ea
```text
---
description: Generate comprehensive C4 architecture documentation (Context, Container, Component, Code) for a codebase using bottom-up analysis and four coordinated C4 agents.
---

# C4 Architecture Documentation Workflow

Generate comprehensive C4 architecture documentation for an existing repository/codebase using a bottom-up analysis approach.

[Extended thinking: This workflow implements a complete C4 architecture documentation process following the C4 model (Context, Container, Component, Code). It uses a bottom-up approach, starting from the deepest code directories and working upward, ensuring every code element is documented before synthesizing into higher-level abstractions. The workflow coordinates four specialized C4 agents (Code, Component, Container, Context) to create a complete architectural documentation set that serves both technical and non-technical stakeholders.]

## Overview

This workflow creates comprehensive C4 architecture documentation following the [official C4 model](https://c4model.com/diagrams) by:

1. **Code Level**: Analyzing every subdirectory bottom-up to create code-level documentation
2. **Component Level**: Synthesizing code documentation into logical components within containers
3. **Container Level**: Mapping components to deployment containers with API documentation (shows high-level technology choices)
4. **Context Level**: Creating high-level system context with personas and user journeys (focuses on people and software systems, not technologies)

**Note**: According to the [C4 model](https://c4model.com/diagrams), you don't need to use all 4 levels of diagram - the system context and container diagrams are sufficient for most software development teams. This workflow generates all levels for completeness, but teams can choose which levels to use.

All documentation is written to a new `C4-Documentation/` directory in the repository root.

## Phase 1: Code-Level Documentation (Bottom-Up Analysis)

### 1.1 Discover All Subdirectories

- Use codebase search to identify all subdirectories in the repository
- Sort directories by depth (deepest first) for bottom-up processing
- Filter out common non-code directories (node_modules, .git, build, dist, etc.)
- Create list of directories to process

### 1.2 Process Each Directory (Bottom-Up)

For each directory, starting from the deepest:

- Use Task tool with subagent_type="c4-architecture::c4-code"
- Prompt: |
  Analyze the code in directory: [directory_path]

  Create comprehensive C4 Code-level documentation following this structure:
  1. **Overview Section**:
     - Name: [Descriptive name for this code directory]
     - Description: [Short description of what this code does]
     - Location: [Link to actual directory path relative to repo root]
     - Language: [Primary programming language(s) used]
     - Purpose: [What this code accomplishes]
  2. **Code Elements Section**:
     - Document all functions/methods with complete signatures:
       - Function name, parameters (with types), return type
       - Description of what each function does
       - Location (file path and line numbers)
       - Dependencies (what this function depends on)
     - Document all classes/modules:
       - Class name, description, location
       - Methods and their signatures
       - Dependencies
  3. **Dependencies Section**:
     - Internal dependencies (other code in this repo)
     - External dependencies (libraries, frameworks, services)
  4. **Relationships Section**:
     - Optional Mermaid diagram if relationships are complex

  Save the output as: C4-Documentation/c4-code-[directory-name].md
```
END THIRD-PARTY FILE 1c5d09f8df7341ea

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---
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