Hey @evance I actually figured out the syntax and forgot to update this thread! heres the relevant section, as I have it configured in composer.json:
"require": {
"php": ">=5.6",
"composer/installers": "^1.4",
"vlucas/phpdotenv": "^2.0.1",
"johnpbloch/wordpress": "4.9.4",
"oscarotero/env": "^1.1.0",
"roots/wp-password-bcrypt": "1.0.0",
"roots/soil": "*",
"wpackagist-plugin/wp-retina-2x": "*",
"wpackagist-plugin/wordpress-seo": "*",
"wpackagist-plugin/contact-form-7": "*"
},
"require-dev": {
"squizlabs/php_codesniffer": "^3.0.2"
},
"extra": {
"installer-paths": {
"web/app/mu-plugins/{$name}/": [
"type:wordpress-muplugin", "roots/soil",
"type:wordpress-muplugin", "wpackagist-plugin/wp-retina-2x",
"type:wordpress-muplugin", "wpackagist-plugin/wordpress-seo",
"type:wordpress-muplugin", "wpackagist-plugin/contact-form-7"
],
"web/app/plugins/{$name}/": ["type:wordpress-plugin"],
"web/app/themes/{$name}/": ["type:wordpress-theme"]
},
"wordpress-install-dir": "web/wp"
},
"scripts": {
"post-root-package-install": [
"php -r \"copy('.env.example', '.env');\""
],
"test": [
"phpcs"
]
}
As you can see, the plugins need to be referenced both in require and under installer-paths=>mu-plugins. As well as this, each one must have a preceding “type:wordpress-muplugin” in the array list