Simple mixin hotswap for fabric development (works as far as I know from loom 1.2)

build.gradle

afterEvaluate {
    loom.runs.configureEach {
        // https://fabricmc.net/wiki/tutorial:mixin_hotswaps
        vmArg "-javaagent:${ configurations.compileClasspath.find { it.name.contains("sponge-mixin") } }"
    }
}