validate-vst3 - SKILL.md Agent Skill

name: validate-vst3 description: Validate VST3 plugins (.vst3 bundles) using Steinberg's official validator tool. Use when user says "run VST3 validator", "validate VST3", "test the .vst3", or needs Steinberg-specific test suites. Prefer this over pluginval for multi-bus VST3 plugins. compatibility: macOS, Windows, Linux. Built from VST3 SDK source. metadata: author: Oli Larkin version: 0.0.1

VST3 Validator

Plugin Install Locations

The validator accepts a direct path, but validator -list only scans standard locations.

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

Locate the built .vst3 bundle (in your build output directory or one of the standard locations above)
Locate the validator binary (see Common Binary Locations below)
Run: validator /path/to/plugin.vst3
For thorough testing add -e: validator -e /path/to/plugin.vst3
Check output for FAILED lines — see Common Issues below for fixes

Basic Usage

# Validate a VST3 plugin (validator location depends on your VST3 SDK build)
validator /path/to/plugin.vst3

Common Binary Locations

Platform	Path
macOS	`<vst3sdk>/build/bin/Release/validator` or `/usr/local/bin/validator`
Windows	`<vst3sdk>\build\bin\Release\validator.exe`
Linux	`<vst3sdk>/build/bin/Release/validator`

Options

# Run extensive tests (takes longer but more thorough)
validator -e /path/to/plugin.vst3

# Quiet mode - only print errors
validator -q /path/to/plugin.vst3

# Run only a specific test suite
validator -suite "General Tests" /path/to/plugin.vst3

# Test only a specific processor class ID
validator -cid "ABCD1234..." /path/to/plugin.vst3

# Use local instance per test (isolates tests)
validator -l /path/to/plugin.vst3

Listing Plugins

# List all installed VST3 plugins
validator -list

# List snapshots from all installed plugins
validator -snapshots

Test Suites

Suite	Description
General Tests	Basic plugin loading and info
Single Precision	32-bit audio processing
Double Precision	64-bit audio processing
Bus Activation	Bus enable/disable handling
Bus Arrangement	Channel configuration
Parameters	Parameter handling and automation
State	Preset save/restore
Editor	UI creation/destruction
Process Context	Transport and tempo handling

Building the Validator

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 validator

Common Issues

Plugin Not Loading

Check the binary architecture matches (arm64 vs x86_64 on macOS, x64 vs x86 on Windows)
Verify all dependencies are bundled or available
Check logs: Console.app (macOS), Event Viewer (Windows), or stderr (Linux)

Test Failures

State tests: Ensure getState/setState are implemented correctly
Parameter tests: Check parameter IDs are stable and unique
Bus tests: Verify channel configurations are valid

Extensive Test Failures

The -e flag runs stress tests that may reveal:

Memory leaks
Thread safety issues
Edge cases in parameter handling