depends on the use case, but the most straightforward way to prevent these issues is to ensure plugins that interact with each other are loaded in the same classloader

Is it better to use libraries that depend on the Gradle API?

i.e. rather than developing a Gradle plugin, develop a shared library that makes use of Gradle's API and depend on that library in my plugin, rather than using another plugin

although it definitely depends on what you're trying to do i guess

i don't think it would fix my problem because i'm trying to register and make use of tooling models

if you load plugins (with

apply false

if you don't want them applied there) in a parent project, the same plugins when requested in a child project will be reused from the existing classpath

Oh my gosh that actually worked! I changed my init script from:

initscript {
    repositories {
        mavenLocal()
        mavenCentral()
    }

    dependencies {
        classpath("com.opencastsoftware.gradle:gradle-bsp-plugin:%%BSP_PLUGIN_VERSION%%") // this bit gets find & replaced
    }
}

allprojects {
  apply<com.opencastsoftware.gradle.bsp.BspPlugin>()
}

to:

initscript {
    repositories {
        mavenLocal()
        mavenCentral()
    }

    dependencies {
        classpath("com.opencastsoftware.gradle:gradle-bsp-plugin:%%BSP_PLUGIN_VERSION%%") // this bit gets find & replaced
    }
}

projectsEvaluated {
    rootProject.subprojects {
        apply<com.opencastsoftware.gradle.bsp.BspPlugin>()
    }
}

and this has resolved the issue for the moment. thanks so much for your help with this!

i gotta say though that this whole thing has got me a little bit spooked about the different ways this could go wrong, depending upon whether users apply the plugin manually, what the structure of their project looks like, etc.