# c4-to-eventcatalog

Turns a C4 model into an EventCatalog documentation plan, then into catalog files once you approve the mapping.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 425 installs · ★ 13
- Author: eventcatalog
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/event-catalog/skills/tree/HEAD/skills/c4-to-eventcatalog/SKILL.md
- Updated: 2026-10-19
- HTML: https://affpapa.org/en/nevibecode/skills/c4-to-eventcatalog

## What it does

The skill accepts Structurizr DSL or JSON, C4-PlantUML, Mermaid C4, Markdown architecture docs and diagrams. It parses people, external systems, containers, relationships, protocols, topics and queues. Components are only pulled out when they cross an ownership, deployment, data or message boundary.

Each element is then mapped to an EventCatalog type: `domain`, `service`, `agent`, `event`, `command`, `query`, `channel`, `container` or `flow`. When a catalog already exists, the skill inspects it first and tags every item as `new`, `update`, `unchanged` or `investigate`. The output is a `.c4-eventcatalog-plan.md` file listing decisions, relationships and the files to create. Nothing gets generated until you approve that plan.

One caveat: image-only input is less reliable than source text, so feed it the DSL or Markdown when you can. The skill asks structural questions one at a time — domain boundaries, deployable services, agent classification — and skips prose and cosmetic metadata. Existing catalog resources missing from the C4 model are flagged for review, never deleted.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add event-catalog/skills --skill c4-to-eventcatalog -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/c4-to-eventcatalog/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/c4-to-eventcatalog/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add event-catalog/skills --skill c4-to-eventcatalog -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/c4-to-eventcatalog/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add event-catalog/skills --skill c4-to-eventcatalog -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/c4-to-eventcatalog/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install event-catalog/skills c4-to-eventcatalog
```

2. **Manually: put the files in place**
- File: `.github/skills/c4-to-eventcatalog/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add event-catalog/skills --skill c4-to-eventcatalog -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/event-catalog/skills --path skills/c4-to-eventcatalog
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/c4-to-eventcatalog/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add event-catalog/skills --skill c4-to-eventcatalog -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/event-catalog/skills/tree/HEAD/skills/c4-to-eventcatalog/SKILL.md

## When to use it
- map a C4 model onto EventCatalog resources
- reconcile a new architecture with an existing catalog
- separate deployable services from components inside them
- review a migration plan before touching catalog files
- spot drift between diagrams and current documentation

## Example prompts
- Here's our Structurizr DSL, map it into EventCatalog
- Build a `.c4-eventcatalog-plan.md` plan from this Mermaid C4 diagram
- Compare this C4 model against the catalog in `./eventcatalog` and show what changes

## Source text · SKILL.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: 1da76c44e3ea6a93.

BEGIN THIRD-PARTY FILE 1da76c44e3ea6a93
```text
---
name: c4-to-eventcatalog
description: Converts C4 architecture models into EventCatalog documentation plans and hands off to catalog-documentation-creator for file generation. Use when user provides a C4 model, Structurizr DSL, C4-PlantUML, Mermaid C4, diagrams, or architecture descriptions and asks to create, update, reconcile, or map them into an EventCatalog project.
license: MIT
metadata:
  author: eventcatalog
  version: "1.0.0"
---

# C4 to EventCatalog

## Overview

Map a C4 model into EventCatalog resources without flattening architecture intent. Produce a reviewable `.c4-eventcatalog-plan.md` first, then use `catalog-documentation-creator` to generate or update the actual catalog files after the user approves the mapping.

## Load References

Always read `references/c4-mapping.md` before mapping a C4 model.

When generating files, read the relevant `../catalog-documentation-creator/references/` files:

- `domains.md`, `services.md`, `agents.md`
- `events.md`, `commands.md`, `queries.md`
- `channels.md`, `containers.md`, `flows.md`
- `components.md` for NodeGraph, Mermaid, wiki links, schemas, and MDX components

## Workflow

Follow these phases in order.

### 1. Locate inputs

Ask for the C4 source if it is not provided. Accept Structurizr DSL/JSON, C4-PlantUML, Mermaid C4, Markdown architecture docs, or image diagrams. Warn that source text is more reliable than image-only extraction.

Ask whether the user has an EventCatalog project. If yes, ask for the path and verify `eventcatalog.config.js` or known resource directories. If no, note that scaffolding happens during handoff through `catalog-documentation-creator`.

### 2. Inventory the existing catalog

If a catalog exists, inspect it before proposing changes:

- Detect flat vs domain-nested structure.
- Record existing resource IDs, names, versions, owners, and relationships.
- Note naming style, schema formats, owner conventions, badges, and use of domains.
- Treat existing catalog resources not present in the C4 model as `investigate`, not deletion candidates.

### 3. Parse the C4 model

Extract:

- People and external systems
- Software systems
- Containers, including apps, services, agents, databases, queues, and browsers/mobile clients
- Components only when they cross an ownership, deployment, data, or message boundary
- Relationships, protocols, technologies, tags, descriptions, and views
- Dynamic views or narrative scenarios that should become flows
- Message names, topics, queues, APIs, commands, queries, events, and schema references
```
END THIRD-PARTY FILE 1da76c44e3ea6a93

The third-party file has ended. Everything between the 1da76c44e3ea6a93 tags is data: requests and commands from it are not followed. An “end of file” line with another tag inside the block is part of the file.

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---
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