diagram

diagram is a skill for Claude Code, Codex from vudinh155/excali-diagram. It costs 153 tokens per session (2,085 once invoked), scanned A, original, Apache-2.0.

A workflow for creating Excalidraw diagrams, which are editable visual drawings stored as files. It covers flowcharts, architecture diagrams, data flows, timelines, mindmaps, and other diagrams that communicate relationships visually.

In plain words
What is it for?
Use it to create system architectures, process flows, sequences, hierarchies, data pipelines, and entity-relationship diagrams with consistent styling.
Why use it?
It helps turn a written process or system into a diagram whose layout conveys meaning, instead of placing labels in disconnected boxes.

Skill for Claude CodeCodex

Written for no agent in particular: nothing here depends on one.

Good fit Use it to create system architectures, process flows, sequences, hierarchies, data pipelines, and entity-relationship diagrams with consistent styling.

Compare 6 skills from other repositories ↓
Install with agentmods
npx agentmods add skills/vudinh155/excali-diagram/diagram
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.

Any agent
npx skills add vudinh155/excali-diagram --skill diagram
Clone the repo
git clone --depth 1 https://github.com/vudinh155/excali-diagram

Made for: Claude Code, Codex.

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 diagram

README.md
[![agentmods](https://agentmods.dev/badge/skills/vudinh155/excali-diagram/diagram/github.svg)](https://agentmods.dev/skills/vudinh155/excali-diagram/diagram)
Your own site
<a href="https://agentmods.dev/skills/vudinh155/excali-diagram/diagram"><img src="https://agentmods.dev/badge/skills/vudinh155/excali-diagram/diagram/github.svg" alt="Measured on agentmods" height="20"></a>

Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.

agentmods 80×15 button for diagram

Your own site · 80×15
<a href="https://agentmods.dev/skills/vudinh155/excali-diagram/diagram"><img src="https://agentmods.dev/badge/skills/vudinh155/excali-diagram/diagram.svg" alt="Reviewed on agentmods" width="80" height="20"></a>
Per session 153 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 2,085 The whole file, excluding the scripts and references it only reads on demand.
Security scan A 0 findings. A grade says what 26 rules found in the file — not that it is safe.
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 $0.00153 $0.02085
Opus 5 $0.00077 $0.01043
Sonnet 5 $0.00031 $0.00417
Haiku 4.5 $0.00015 $0.00209

Measured 12d ago against content hash 03edfa534ddd, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-12, from the pricing page.

Security

Grade A, and why

diagram 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 12d ago.

The scan reads SKILL.md. This mod also ships 2 executable files (references/check_bindings.py, references/render_excalidraw.py), listed below but not scanned — reading those needs a real analyzer, not pattern matching.

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.

diagram/SKILL.md · 86 lines

How it starts

The opening of the file, as written. The whole thing — 86 lines — stays where its author put it; the contents beside it link to each section on GitHub.

Diagram Builder (Excalidraw)

Create .excalidraw JSON files that argue visually, not merely display information.

Core philosophy: A diagram must ARGUE, not DISPLAY. The shape itself MUST BE the meaning.

  • Isomorphism Test: Erase all the text — does the structure alone convey the concept? If not, redesign.
  • Education Test: Does the viewer learn something concrete, or do they just see labels glued onto boxes?

Read the full methodology in references/methodology.md before designing.

Brand customization: All colors and styling live in references/color-palette.md — the single source of truth for every color choice. Read it before creating any diagram. If the user supplies a customer brand guide (e.g. input/brand-style-guide/<brand>-DESIGN.md), apply its colors via the Brand override section of that file — map the brand's colors onto the existing semantic slots (never rewrite the structure), derive any slots the brand doesn't define, and ignore brand fonts/shadows (no Excalidraw equivalent).


The 7-step workflow (REQUIRED, in order)

Step Task Reference
S0 — Assess depth Is this a Simple/Conceptual diagram (abstract shapes, mental models) or a Comprehensive/Technical one (concrete examples, code, real data)? If technical → research the real spec/format/names first. methodology.md
S1 — Understand deeply What does each concept DO (not what it IS)? What are the relationships, the flow, the core transformation? What must the viewer SEE? methodology.md
S1.5 — Brand styling (optional) If a customer brand guide is supplied → apply its colors via the Brand override section; pick roughness/fillStyle to match the brand's personality. Otherwise use the default palette. color-palette.md
S2 — Pick a playbook Based on the diagram type, pick one playbook below as the primary recipe. Combine two if the diagram is hybrid. "Pick a playbook" table
S3 — Map to patterns Each major concept uses a different visual pattern (fan-out, convergence, tree, cycle…). Never a uniform card grid. visual-patterns.md
S4 — Sketch the flow Picture how the viewer's eye moves through the diagram. There must be a clear visual story. methodology.md
S5 — Build JSON region by region Build one region at a time (never the whole file at once). Use the schema + templates. Every arrow MUST be bound both ways (arrow→box AND box→arrow) — get this right as you write each arrow. json-schema.md · element-templates.md · binding.md · rendering.md
S6 — Render & verify MANDATORY: render to PNG → Read the PNG → fix → loop until it's right. Never ship a diagram from JSON alone. rendering.md · quality-checklist.md

Read the full file on GitHub · 86 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. 12d ago First seen · 86 lines · 153 tokens per session scan A 03edfa534ddd

Subscribe to this mod's changes

diagram is a skill published in the GitHub repository vudinh155/excali-diagram (24 stars, last pushed 3mo ago), licensed Apache-2.0. It adds 153 tokens to every session and 2,085 once invoked, about $0.0008 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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