validate-vst3-editorhost

validate-vst3-editorhost is a skill for Claude Code, Codex from iPlug3/audio-plugin-dev-skills. It costs 78 tokens per session (872 once invoked), scanned B, original, MIT.

A small host application for opening and visually testing VST3 audio-plugin interfaces without a full digital audio workstation. VST3 is a common format for audio effects and instruments.

In plain words
What is it for?
Use it to open a .vst3 bundle, inspect its controls and layout, test host callbacks, open a second editor instance, or select a specific plugin class.
Why use it?
It provides a focused way to check whether a plugin editor appears, lays out correctly, resizes, and supports multiple windows.

Skill for Claude CodeCodex

Part of the audio-plugin-validators plugin — 6 skills 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/iplug3/audio-plugin-dev-skills/validate-vst3-editorhost
Any agent
npx skills add iPlug3/audio-plugin-dev-skills --skill validate-vst3-editorhost
Clone the repo
git clone --depth 1 https://github.com/iPlug3/audio-plugin-dev-skills

Made for: Claude Code, Codex.

Or install audio-plugin-validators, the plugin that ships this one along with the rest of its 6 skills.

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 validate-vst3-editorhost

README.md
[![agentmods](https://agentmods.dev/badge/skills/iplug3/audio-plugin-dev-skills/validate-vst3-editorhost.svg)](https://agentmods.dev/skills/iplug3/audio-plugin-dev-skills/validate-vst3-editorhost)
Your own site
<a href="https://agentmods.dev/skills/iplug3/audio-plugin-dev-skills/validate-vst3-editorhost"><img src="https://agentmods.dev/badge/skills/iplug3/audio-plugin-dev-skills/validate-vst3-editorhost.svg" alt="Measured on agentmods" height="20"></a>
Per session 78 Skills are progressive disclosure: only the name and description are preloaded; the body loads when the skill is used.
When invoked 872 The whole file, excluding the scripts and references it only reads on demand.
Security scan B 1 finding. 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 $0.00078 $0.00872
Opus 5 $0.00039 $0.00436
Sonnet 5 $0.00016 $0.00174
Haiku 4.5 $0.00008 $0.00087

Measured 5d ago against content hash a486bda5022a, method: parsed. Prices are Anthropic first-party input rates as of 2026-09-05, from the pricing page.

Security

Grade B, and why

validate-vst3-editorhost scanned grade B with 1 finding 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.

Asks for rootmediumPrivilege escalation

A mod that escalates privileges can change anything on the machine, not only the project.

sudo apt install libx11-dev libgtkmm-3.0-dev libxcb-util-dev libxcb-cursor-dev libxcb-keysyms1-dev libxcb-xkb-dev
plugins/audio-plugin-validators/skills/validate-vst3-editorhost/SKILL.md · 91 lines

How it starts

The opening of the file, as written. The whole thing — 91 lines — stays where its author put it; the contents beside it link to each section on GitHub.

VST3 EditorHost

Minimal VST3 host for testing plugin UIs without a full DAW.

Plugin Install Locations

editorhost accepts a direct path to a .vst3 bundle.

Platform User Location System Location
macOS ~/Library/Audio/Plug-Ins/VST3/ /Library/Audio/Plug-Ins/VST3/
Windows %LOCALAPPDATA%\Programs\Common\VST3\ C:\Program Files\Common Files\VST3\
Linux ~/.vst3/ /usr/lib/vst3/ or /usr/local/lib/vst3/

Instructions

  1. Build EditorHost from the VST3 SDK if not already built (see Building EditorHost below)
  2. Run: editorhost /path/to/plugin.vst3
  3. The plugin UI window should appear — verify layout, controls, and resizing
  4. Test multiple editor instances with --secondWindow
  5. If the UI doesn't appear, verify the plugin passes validator tests first

Usage

# Basic usage - load plugin and show UI
editorhost /path/to/plugin.vst3

# With component handler (tests host callbacks)
editorhost --componentHandler /path/to/plugin.vst3

# Open second window (tests multiple editor instances)
editorhost --secondWindow /path/to/plugin.vst3

# Specify a particular effect class by UID
editorhost --uid "ABCD1234..." /path/to/plugin.vst3

Binary Locations

Platform Typical Path
macOS <vst3sdk>/build/bin/Release/editorhost.app/Contents/MacOS/editorhost
Windows <vst3sdk>\build\bin\Release\editorhost.exe
Linux <vst3sdk>/build/bin/Release/editorhost

Building EditorHost

Clone the VST3 SDK if you don't have it, then build:

cd <vst3sdk>
cmake -B build -G Ninja -DCMAKE_BUILD_TYPE=Release
cmake --build build --target editorhost

Linux: Requires X11 and GTK3 development libraries:

# Debian/Ubuntu
sudo apt install libx11-dev libgtkmm-3.0-dev libxcb-util-dev libxcb-cursor-dev libxcb-keysyms1-dev libxcb-xkb-dev

# Fedora
sudo dnf install libX11-devel gtkmm3.0-devel xcb-util-devel xcb-util-cursor-devel xcb-util-keysyms-devel libxkbcommon-x11-devel

Read the full file on GitHub · 91 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. 5d ago First seen · 91 lines · 78 tokens per session scan B a486bda5022a

Subscribe to this mod's changes

validate-vst3-editorhost is a skill published in the GitHub repository iPlug3/audio-plugin-dev-skills (90 stars, last pushed 6mo ago), licensed MIT. It adds 78 tokens to every session and 872 once invoked, about $0.0004 per session on Opus 5. A static security scan graded it B with 1 finding (asks for root). No closer match exists in the catalogue, so it is treated as the original; first seen 2026-08-30.

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