# Sw Diagram Creator

> Use when user wants to create, generate, or visualize a diagram from an idea, requirement, sw-idea-analyzer output, or any description – supports Mermaid flowchart, sequence, class, ERD, C4, gantt, mindmap, PlantUML, and ASCII art fallback.

- Skill: `chfle/sw-diagram-creator` (Agent Skill, multi-file: 6 files)
- Install (CLI): `npx skillmds@latest add chfle/sw-diagram-creator`
- Raw SKILL.md: https://api.skillmd.com/api/skills/chfle/sw-diagram-creator/raw
- Safety review: pending
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: chfle (https://skillmd.com/u/chfle)
- Updated: 2026-09-10
- Page: https://skillmd.com/skills/chfle/sw-diagram-creator

---


# SW Diagram Creator

## Overview

Generates ready-to-copy diagrams from any software description, idea, or structured input. Automatically selects the best diagram type and format. Always outputs clean, fenced code blocks — no setup required on the user's side.

**Note:** Diagrams are saved to `requirements/diagrams/` as **visual reference only** — they are not read by code-generation skills like `/sw-use-case-coder`. To generate actual code, continue with `/sw-user-story-creator`.

**Language detection:** Read the user's input language and respond entirely in that language. Default to German if undetectable.

---

## Diagram Type Selection

Use this table to pick the best diagram type from the user's description:

| Input describes… | Best diagram type |
|------------------|-------------------|
| User flows, logic, decision trees | Mermaid `flowchart` |
| API calls, service interactions, login flows | Mermaid `sequenceDiagram` |
| Database tables and their relations | Mermaid `erDiagram` |
| Classes, objects, inheritance, domain model | Mermaid `classDiagram` or PlantUML |
| System architecture, services, containers | Mermaid `C4Context` / `C4Container` |
| Project timeline, sprints, milestones | Mermaid `gantt` |
| Concepts, features, brainstorming map | Mermaid `mindmap` |
| Plain text environment / no renderer | ASCII art |

**When in doubt:** Default to `flowchart`. It renders everywhere and covers most use cases.

---

## Supported Formats

### Mermaid (default)

Always output as:
```
```mermaid
[diagram code]
```
```

Supported types:
- `flowchart TD` / `flowchart LR` – process flows, user journeys, decision trees
- `sequenceDiagram` – request/response chains, API interactions, auth flows
- `erDiagram` – database schemas, entity relationships, foreign keys
- `classDiagram` – OOP models, domain objects, inheritance
- `C4Context` / `C4Container` – system context and container architecture (C4 model)
- `gantt` – timelines, sprint plans, release schedules
- `mindmap` – concept maps, feature lists, brainstorms

### PlantUML

Use when:
- User explicitly requests PlantUML
- Class or sequence diagram needs advanced features (notes, stereotypes, actors, grouping)

Output as:
```
```plantuml
@startuml
[diagram code]
@enduml
```
```

### ASCII Art (fallback)

Use when:
- User is in a plain-text environment (terminal, email, Markdown without renderer)
- User explicitly asks for ASCII
- A quick inline sketch is sufficient

Output as plain fenced code block (` ``` `).

---

## Output Rules

1. **Never print the raw diagram code in the chat.** The diagram file goes to `requirements/diagrams/` only.
2. **Always print a 1–2 sentence explanation** of what the diagram shows (entities, relationships, flow) — this is useful inline and too short to skip.
3. If the input is ambiguous, ask **one** clarifying question before generating – do not guess silently.
4. After saving, offer 1–2 alternative diagram types in the confirmation line.
5. The chat output is: explanation sentence + confirmation line + alternative suggestion. No raw code blocks.

---

## Input Types

The skill handles three input types – detect automatically:

| Input type | How to handle |
|------------|---------------|
| Free-text description | Infer entities, relationships, and flow from the text |
| `sw-idea-analyzer` output | Extract features (→ flowchart/ERD), services (→ C4), timeline (→ gantt) |
| YAML requirements (from requirements file) | Use `diagram.type` and `source.content` fields directly |

---

## Workflow

1. **Check for `requirements/vision.md`**
   - If the file exists → read it and use it as the primary input source
   - If the file does NOT exist and the user provided no other input → stop and respond:

     > `requirements/vision.md` not found. Please run `/sw-idea-analyzer` first to generate it, or describe your system directly as an argument:
     > `/sw-diagram-creator <your description>`

   - If the file does NOT exist but the user provided a description → continue with that description
2. Detect input language → all output in that language
3. Identify input type (vision.md / free-text / YAML)
4. Select diagram type using the table above (or use `diagram.type` from YAML)
5. Select format: Mermaid unless user specifies otherwise
6. Generate the diagram internally
7. Save the diagram file to `requirements/diagrams/` (see File Output below)
8. Print confirmation line only

---

## File Output

After generating every diagram, always save it to `requirements/diagrams/` in the repository root.

**Steps:**
1. If `requirements/diagrams/` does not exist, create it: `mkdir -p requirements/diagrams`
2. Slugify the diagram title: lowercase, spaces → hyphens, remove special chars
   - Example: "User Login Flow" → `user-login-flow`
3. Save with the correct extension:
   - Mermaid → `requirements/diagrams/<slug>.mmd`
   - PlantUML → `requirements/diagrams/<slug>.puml`
   - ASCII → `requirements/diagrams/<slug>.txt`
4. File content = the raw diagram code only (no fences, no explanation)
5. Print only this single line to the console:

> ✅ Diagram saved: `requirements/diagrams/<slug>.<ext>` — also consider: [1–2 alternative diagram types]

**Slug examples:**

| Title | Filename |
|-------|----------|
| User Login Flow | `requirements/diagrams/user-login-flow.mmd` |
| Freelancer ERD | `requirements/diagrams/freelancer-erd.mmd` |
| Auth Sequence | `requirements/diagrams/auth-sequence.puml` |

---

## Common Mistakes to Avoid

| Mistake | Fix |
|---------|-----|
| Printing raw diagram code in chat | Only print explanation + confirmation line; code goes to file |
| Generating without explanation | Always print 1–2 sentences describing what the diagram shows |
| Using wrong direction (`TD` vs `LR`) | `TD` for hierarchies, `LR` for flows/pipelines |
| Forgetting `@startuml` / `@enduml` in PlantUML | Always wrap PlantUML output |
| Generating all possible diagrams unprompted | Generate one, offer alternatives |
| Mixing Mermaid syntax with PlantUML | Never mix – pick one format per output |

---

## Next Skill

At the end of every diagram, suggest the most logical next step:

> **Suggested next skill:**
> - Have features laid out visually? → Run **`/sw-user-story-creator`** to turn them into user stories (or **`/sw-use-case-creator`** for detailed flows)
> - Want to pick a tech stack? → Run **`/sw-tech-stack-planner`** to choose frameworks and databases
> - Ready to scaffold the project? → Run **`/sw-boilerplate`** then **`/sw-use-case-coder`** to generate code
> - Starting from scratch? → Run **`/sw-idea-analyzer`** first to analyze your idea before diagramming