technical-diagrams

technical-diagrams is a skill for Claude Code, Codex from sequenzia/agent-alchemy. It costs 69 tokens per session (3,859 once invoked), scanned A, original, MIT.

A guide to Mermaid, a text format for diagrams that can be stored with code and rendered by documentation tools. It covers syntax, diagram types, and readability styling.

In plain words
What is it for?
Use it to create flowcharts, sequence, class, state, database, architecture, C4, and other technical diagrams in Markdown.
Why use it?
It gives you consistent, reviewable diagrams without relying on image files or separate drawing applications.

Skill for Claude CodeCodex

Installs and runs on its own, but its text points at files inside its plugin — anything it tells you to read at a ${CLAUDE_PLUGIN_ROOT} path is only there once the plugin is installed. Installing the plugin gets both.

Part of the agent-alchemy-core-tools plugin — 6 skills, 4 agents, 1 hook shipped together

Install

Getting it into your agent

One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.

agentmods
npx agentmods add skills/sequenzia/agent-alchemy/technical-diagrams
Any agent
npx skills add sequenzia/agent-alchemy --skill technical-diagrams
Clone the repo
git clone --depth 1 https://github.com/sequenzia/agent-alchemy

Made for: Claude Code, Codex.

Or install agent-alchemy-core-tools, the plugin that ships this one along with the rest of its 6 skills, 4 agents, 1 hook.

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 technical-diagrams

README.md
[![agentmods](https://agentmods.dev/badge/skills/sequenzia/agent-alchemy/technical-diagrams.svg)](https://agentmods.dev/skills/sequenzia/agent-alchemy/technical-diagrams)
Your own site
<a href="https://agentmods.dev/skills/sequenzia/agent-alchemy/technical-diagrams"><img src="https://agentmods.dev/badge/skills/sequenzia/agent-alchemy/technical-diagrams.svg" alt="Measured on agentmods" height="20"></a>
Per session 69 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 3,859 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 $0.00069 $0.03859
Opus 5 $0.00034 $0.01929
Sonnet 5 $0.00014 $0.00772
Haiku 4.5 $0.00007 $0.00386

Measured 5d ago against content hash c79dceef150b, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade A, and why

technical-diagrams 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 5d 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.

claude/core-tools/skills/technical-diagrams/SKILL.md · 406 lines

How it starts

The opening of the file, as written. The whole thing — 406 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Technical Diagrams

Mermaid is the standard for all technical diagrams in this project. It renders natively in GitHub, GitLab, MkDocs (with Material theme), and most modern documentation platforms.

This skill provides:

  • Critical styling rules to ensure readability (especially color contrast)
  • Quick reference examples for common diagram types
  • Reference files for advanced syntax when building complex diagrams

Always wrap Mermaid code in fenced code blocks with the mermaid language identifier.


Why Mermaid

Native rendering — GitHub, GitLab, Notion, MkDocs, and Docusaurus render Mermaid blocks without plugins or build steps. No external image generation tools needed.

Text-based and diffable — Diagrams live alongside code in version control. Changes appear in pull request diffs, making reviews straightforward and history trackable.

No external tools — No Lucidchart exports, no draw.io XML files, no PNG screenshots that go stale. The diagram source is the single source of truth.

Maintainable — Updating a diagram means editing text, not wrestling with a GUI. Refactoring a component name? Find-and-replace works on diagrams too.

Consistent — A shared syntax produces visually consistent diagrams across all documentation, regardless of who authored them.


Critical Styling Rules

This is the most important section. Light text on light backgrounds is the most common Mermaid readability issue. Follow these rules strictly.

Rule 1: Always use dark text on nodes

Every node must have color:#000 (or another dark color like #1a1a1a, #333). Never use white, light gray, or any light-colored text.

Caveat — this assumes a light page. color:#000 is correct for GitHub and MkDocs light mode, but it is not self-sufficient on renderers that auto-switch themes — most notably MkDocs Material's dark (slate) scheme, which flips Mermaid's theme colors and turns this dark text light-on-light. When a diagram will render on a dark-capable site, pair this palette with the dark-mode companion stylesheet in Dark-mode rendering below. Do not "fix" it by switching to light text — that just inverts the problem.

Read the full file on GitHub · 406 lines

Files

What ships with it

6 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.

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. 5d ago First seen · 406 lines · 69 tokens per session scan A c79dceef150b

Subscribe to this mod's changes

technical-diagrams is a skill published in the GitHub repository sequenzia/agent-alchemy (44 stars, last pushed 3mo ago), licensed MIT. It adds 69 tokens to every session and 3,859 once invoked, about $0.0003 per session on Opus 5. 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.

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