diagrams.net-intellij-plugin: Instructions file for Claude Code

CLAUDE.md

diagrams.net-intellij-plugin CLAUDE.md is an instructions file for Claude Code from docToolchain/diagrams.net-intellij-plugin. It costs 2,102 tokens per session, scanned A, original, Apache-2.0.

A repository guide for developing an IntelliJ plugin that opens diagrams.net files inside JetBrains IDEs. It explains the project, setup requirements, and how to use the required Java version.

In plain words
What is it for?
Use it when building, testing, installing, or changing this diagrams.net editor plugin, especially when running Gradle commands.
Why use it?
It gives a coding agent the project context and prevents setup errors caused by using the wrong Java version or missing the diagrams.net submodule.

Instructions file for Claude Code

Written for Claude Code: the file is CLAUDE.md. Also seen: mentions CLAUDE.md; mentions Claude Code.

This is docToolchain/diagrams.net-intellij-plugin's own configuration. It tells Claude Code how to work on diagrams.net-intellij-plugin itself, so it is not a mod to install elsewhere. Copy it as a starting point and replace the rules that are about this project. Everything diagrams.net-intellij-plugin configures →

Needs its repository: it reads a path above its own folder, which exists only inside the repository. The line is cd ../../...

Reuse

Borrowing it

Nothing to install: this file belongs to docToolchain/diagrams.net-intellij-plugin. Take a copy, put it at the same path in your own repository, and replace the rules that are about this project with yours.

Copy the file
curl -O https://raw.githubusercontent.com/docToolchain/diagrams.net-intellij-plugin/main/CLAUDE.md
Clone the repo
git clone --depth 1 https://github.com/docToolchain/diagrams.net-intellij-plugin

Made for: Claude Code.

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README.md
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Per session 2,102 This file is loaded in full into every session.
When invoked 2,102 The same file — it is already loaded in full.
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 $0.02102 $0.02102
Opus 5 $0.01051 $0.01051
Sonnet 5 $0.00420 $0.00420
Haiku 4.5 $0.00210 $0.00210

Measured 10d ago against content hash fcf4d780c93a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-10, from the pricing page.

Security

Grade A, and why

diagrams.net-intellij-plugin CLAUDE.md 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 10d 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.md · 232 lines

How it starts

The opening of the file, as written. The whole thing — 232 lines — stays where its author put it; the contents beside it link to each section on GitHub.

CLAUDE.md

This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.

Project Overview

This is an IntelliJ Platform plugin that integrates diagrams.net (formerly draw.io) directly into JetBrains IDEs. It provides a JCEF (Java Chromium Embedded Framework) based editor for diagram files with extensions .drawio.(svg|png|xml) and .dio.(svg|png|xml), and auto-detects editable PNGs and SVGs created with diagrams.net.

The plugin uses an offline version of diagrams.net by default, so it works without an internet connection and keeps content local.

Development Setup

Prerequisites

This project uses SDKMAN for Java version management. The required JDK is JDK 21.0.8-tem as specified in .sdkmanrc:

# Install and use the correct JDK (21.0.8-tem)
sdk env install

IMPORTANT: All gradle commands MUST be run with the correct JDK activated:

source ~/.sdkman/bin/sdkman-init.sh && sdk env && ./gradlew <task>

The project requires exactly JDK 21.0.8-tem (Temurin). Using a different JDK version will cause build failures.

Submodule Initialization

The project includes diagrams.net as a git submodule at src/webview/drawio. This must be initialized before building:

git submodule update --init

The build will fail with an error if the submodule is not initialized.

Common Development Commands

Running and Testing

# Run IDE with plugin installed (for development/debugging)
./gradlew runIde

# Build the plugin
./gradlew build

# Run tests
./gradlew test

# Run all checks (verification)
./gradlew check

Plugin-Specific Tasks

# Build plugin ZIP for distribution
./gradlew buildPlugin

# Verify plugin compatibility with target IDE versions
./gradlew verifyPlugin

# Patch plugin.xml with version info
./gradlew patchPluginXml

# Prepare sandbox environment
./gradlew prepareSandbox

# Sign plugin (requires credentials)
./gradlew signPlugin

# Publish to JetBrains Marketplace (requires PUBLISH_TOKEN env var)
./gradlew publishPlugin

Read the full file on GitHub · 232 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. 10d ago First seen · 232 lines · 2,102 tokens per session scan A fcf4d780c93a

Subscribe to this mod's changes

diagrams.net-intellij-plugin CLAUDE.md is an instructions file published in the GitHub repository docToolchain/diagrams.net-intellij-plugin (157 stars, last pushed 14d ago), licensed Apache-2.0. It adds 2,102 tokens to every session, about $0.0105 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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