mermaid

mermaid is a command for Claude Code from Helmi/claude-simone. It costs 0 tokens per session (1,374 once invoked), scanned A, original, MIT.

A command for creating, updating, or maintaining Mermaid diagrams in architecture documentation. Mermaid is a text-based format that describes diagrams such as flows, sequences, and system relationships.

In plain words
What is it for?
Use it to create diagrams from scratch, update them after code changes, or review existing diagrams for accuracy. The diagrams are kept under the project’s architecture documentation directory.
Why use it?
It helps keep architecture diagrams aligned with the project instead of leaving outdated or invalid drawings in the documentation. It also includes syntax, rendering, cross-reference, and style checks.

Command for Claude Code

Written for Claude Code: $ARGUMENTS substitution. Also seen: mentions subagents.

Not installable on its own: it runs a file from its repository that does not travel with it. Clone the repository, or install whatever ships that file. The line is - [Core Classes](./class_diagrams/core_classes.md).

Install

Getting it into your agent

There is no command for this one: it runs only inside a plugin, and the catalogue could not identify which plugin ships it. The source is linked below.

Made for: Claude Code.

Wrote this? Show the measurements

A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.

agentmods badge for mermaid

README.md
[![agentmods](https://agentmods.dev/badge/commands/helmi/claude-simone/mermaid.svg)](https://agentmods.dev/commands/helmi/claude-simone/mermaid)
Your own site
<a href="https://agentmods.dev/commands/helmi/claude-simone/mermaid"><img src="https://agentmods.dev/badge/commands/helmi/claude-simone/mermaid.svg" alt="Measured on agentmods" height="20"></a>
Per session 0 Only the description is in the session, so the agent can decide to use it. The body loads when it is invoked.
When invoked 1,374 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. Scan, not verified.
Origin original No closer match found in the catalogue.
Token cost

What it costs to keep this loaded

Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.

ModelPer sessionOnce invoked
Fable 5.1 $0.00000 $0.01374
Opus 5 $0.00000 $0.00687
Sonnet 5 $0.00000 $0.00275
Haiku 4.5 $0.00000 $0.00137

Measured 6d ago against content hash 0faab8ef3d5d, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-06, from the pricing page.

Security

Grade A, and why

mermaid scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 6d ago.

A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.

Nothing flagged

None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.

Origin

Copies of this mod

1 near-identical copy found in the catalogue:

  • mermaid — 100% identical, 0 lines differ
legacy/.claude/commands/simone/mermaid.md · 252 lines

How it starts

The opening of the file, as written. The whole thing — 252 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Create, Update, and Maintain Mermaid Diagrams

Follow these instructions from top to bottom to generate, update, or maintain mermaid diagrams in the project's architecture documentation.

Create a TODO with EXACTLY these 8 items

  1. Parse arguments and determine action type
  2. Analyze project structure and existing diagrams
  3. Identify diagram scope and requirements
  4. Create or update mermaid diagram code
  5. Validate diagram syntax and rendering
  6. Update cross-references and documentation
  7. Apply diagram standards and styling
  8. Report results and provide next steps

1 · Parse arguments and determine action type

Check <$ARGUMENTS> to determine the requested action:

  • CREATE: Generate new architecture diagrams from scratch
  • UPDATE: Modify existing diagrams based on code changes
  • MAINTAIN: Review and refresh diagrams for accuracy
  • Empty: Analyze project and recommend action

If arguments specify a component/module: Focus on that specific area If arguments are general: Perform comprehensive diagram work

2 · Analyze project structure and existing diagrams

Check existing diagram locations:

All architecture diagrams should be in /docs/architecture/:

docs/architecture/
├── README.md                           # Main architecture overview
├── context_diagram.md                  # System context & data flow
├── module_overview.md                  # Module relationships
└── class_diagrams/
    ├── core_classes.md                 # Database, DAOs, data processing
    ├── data_models.md                  # Domain models & database schema
    └── service_layer.md                # UI architecture & service coordination

Analyze the codebase using PARALLEL SUBAGENTS:

  • SCAN project structure to understand architecture
  • IDENTIFY key components, modules, and services
  • CHECK existing diagrams for outdated information
  • FIND new additions that need documentation

3 · Identify diagram scope and requirements

Based on analysis, determine what diagrams need work:

Read the full file on GitHub · 252 lines

Changes

What this file has done since we first saw it

Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.

  1. 6d ago First seen · 252 lines · 0 tokens per session scan A 0faab8ef3d5d

Subscribe to this mod's changes

mermaid is a command published in the GitHub repository Helmi/claude-simone (557 stars, last pushed 1y ago), licensed MIT. It costs nothing until one of its globs matches a file; then it loads 1,374 tokens. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.