diff --git a/SKIE/settings.gradle.kts b/SKIE/settings.gradle.kts
index cf35cc57d..ba9e5b267 100644
--- a/SKIE/settings.gradle.kts
+++ b/SKIE/settings.gradle.kts
@@ -52,6 +52,8 @@ buildSetup {
 
     val gradle by group("skie-gradle") {
         val plugin by module
+        val `plugin-api` by module
+        val `sub-plugin-api` by module
         val `plugin-shim-api` by module
         val `plugin-shim-impl` by module
     }
diff --git a/SKIE/skie-gradle/plugin-api/gradle-plugin-api.gradle.kts b/SKIE/skie-gradle/plugin-api/gradle-plugin-api.gradle.kts
new file mode 100644
index 000000000..3fb3bb2a6
--- /dev/null
+++ b/SKIE/skie-gradle/plugin-api/gradle-plugin-api.gradle.kts
@@ -0,0 +1,21 @@
+plugins {
+    id("skie.gradle")
+    id("skie.publishable")
+}
+
+skiePublishing {
+    name = "SKIE Gradle Plugin API"
+    description = "Public API for SKIE Gradle plugin."
+}
+
+kotlin {
+    sourceSets {
+        val commonMain by getting {
+            dependencies {
+                api(projects.common.configuration.configurationDeclaration)
+
+                implementation(projects.common.util)
+            }
+        }
+    }
+}
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieAnalyticsConfiguration.kt b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieAnalyticsConfiguration.kt
similarity index 100%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieAnalyticsConfiguration.kt
rename to SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieAnalyticsConfiguration.kt
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieBuildConfiguration.kt b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieBuildConfiguration.kt
similarity index 76%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieBuildConfiguration.kt
rename to SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieBuildConfiguration.kt
index 4b212e92d..7eb2508f6 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieBuildConfiguration.kt
+++ b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieBuildConfiguration.kt
@@ -3,8 +3,7 @@
 package co.touchlab.skie.plugin.configuration
 
 import co.touchlab.skie.configuration.SkieConfigurationFlag
-import co.touchlab.skie.plugin.SkieTarget
-import co.touchlab.skie.plugin.configuration.util.takeIf
+import co.touchlab.skie.plugin.util.takeIf
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import javax.inject.Inject
@@ -24,18 +23,11 @@ abstract class SkieBuildConfiguration @Inject constructor(objects: ObjectFactory
     val enableConcurrentSkieCompilation: Property<Boolean> = objects.property(Boolean::class.java).convention(true)
     val enableParallelSkieCompilation: Property<Boolean> = objects.property(Boolean::class.java).convention(true)
 
-    internal fun buildConfigurationFlags(outputKind: SkieTarget.OutputKind): Set<SkieConfigurationFlag> =
+    internal fun buildConfigurationFlags(): Set<SkieConfigurationFlag> =
         setOfNotNull(
-            decideSwiftLibraryEvolutionFlag(outputKind),
+            SkieConfigurationFlag.Build_SwiftLibraryEvolution takeIf enableSwiftLibraryEvolution,
             SkieConfigurationFlag.Build_ParallelSwiftCompilation takeIf enableParallelSwiftCompilation,
             SkieConfigurationFlag.Build_ConcurrentSkieCompilation takeIf enableConcurrentSkieCompilation,
             SkieConfigurationFlag.Build_ParallelSkieCompilation takeIf enableParallelSkieCompilation,
         )
-
-    private fun decideSwiftLibraryEvolutionFlag(outputKind: SkieTarget.OutputKind) =
-        if (outputKind == SkieTarget.OutputKind.XCFramework) {
-            SkieConfigurationFlag.Build_SwiftLibraryEvolution
-        } else {
-            SkieConfigurationFlag.Build_SwiftLibraryEvolution takeIf enableSwiftLibraryEvolution
-        }
 }
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieDebugConfiguration.kt b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieDebugConfiguration.kt
similarity index 97%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieDebugConfiguration.kt
rename to SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieDebugConfiguration.kt
index eb2fe683a..6bc6a158a 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieDebugConfiguration.kt
+++ b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieDebugConfiguration.kt
@@ -3,7 +3,7 @@
 package co.touchlab.skie.plugin.configuration
 
 import co.touchlab.skie.configuration.SkieConfigurationFlag
-import co.touchlab.skie.plugin.configuration.util.takeIf
+import co.touchlab.skie.plugin.util.takeIf
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import javax.inject.Inject
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieExtension.kt b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieExtension.kt
similarity index 59%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieExtension.kt
rename to SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieExtension.kt
index 756c50d5d..c9add06ce 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieExtension.kt
+++ b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieExtension.kt
@@ -3,10 +3,7 @@
 package co.touchlab.skie.plugin.configuration
 
 import co.touchlab.skie.configuration.SkieConfigurationFlag
-import co.touchlab.skie.plugin.SkieTarget
-import co.touchlab.skie.plugin.configuration.util.GradleSkieConfigurationData
 import org.gradle.api.Action
-import org.gradle.api.Project
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import org.gradle.api.provider.SetProperty
@@ -55,26 +52,5 @@ open class SkieExtension @Inject constructor(objects: ObjectFactory) {
         action.execute(migration)
     }
 
-    // Putting these extensions here so that they don't pollute the extension's namespace. They can be used by wrapping in `with(SkieExtension) { ... }`
-    companion object {
-
-        fun createExtension(project: Project): SkieExtension =
-            project.extensions.create("skie", SkieExtension::class.java)
-
-        fun SkieExtension.buildConfiguration(outputKind: SkieTarget.OutputKind): GradleSkieConfigurationData =
-            GradleSkieConfigurationData(
-                enabledConfigurationFlags = (mergeConfigurationSetsFromConfigurations(outputKind) + additionalConfigurationFlags.get()) - suppressedConfigurationFlags.get(),
-                groups = features.buildGroups(),
-            )
-
-        private fun SkieExtension.mergeConfigurationSetsFromConfigurations(outputKind: SkieTarget.OutputKind) =
-            analytics.buildConfigurationFlags() +
-                build.buildConfigurationFlags(outputKind) +
-                debug.buildConfigurationFlags() +
-                features.buildConfigurationFlags() +
-                migration.buildConfigurationFlags()
-    }
+    companion object
 }
-
-internal val Project.skieExtension: SkieExtension
-    get() = project.extensions.getByType(SkieExtension::class.java)
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieFeatureConfiguration.kt b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieFeatureConfiguration.kt
similarity index 75%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieFeatureConfiguration.kt
rename to SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieFeatureConfiguration.kt
index 8fb900eea..0d08535c2 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieFeatureConfiguration.kt
+++ b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieFeatureConfiguration.kt
@@ -1,9 +1,10 @@
+@file:Suppress("MemberVisibilityCanBePrivate")
+
 package co.touchlab.skie.plugin.configuration
 
 import co.touchlab.skie.configuration.ConfigurationKey
 import co.touchlab.skie.configuration.SkieConfigurationFlag
-import co.touchlab.skie.plugin.configuration.util.GradleSkieConfigurationData
-import co.touchlab.skie.plugin.configuration.util.takeIf
+import co.touchlab.skie.plugin.util.takeIf
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import javax.inject.Inject
@@ -25,7 +26,7 @@ abstract class SkieFeatureConfiguration @Inject constructor(objects: ObjectFacto
      */
     val defaultArgumentsInExternalLibraries: Property<Boolean> = objects.property(Boolean::class.java).convention(false)
 
-    private val groupConfigurations = mutableListOf<GroupConfiguration>()
+    internal val groupConfigurations = mutableListOf<GroupConfiguration>()
 
     fun group(targetFqNamePrefix: String = "", overridesAnnotations: Boolean = false, action: GroupConfiguration.() -> Unit) {
         val groupConfiguration = GroupConfiguration(targetFqNamePrefix, overridesAnnotations)
@@ -36,26 +37,17 @@ abstract class SkieFeatureConfiguration @Inject constructor(objects: ObjectFacto
     }
 
     class GroupConfiguration(
-        private val targetFqNamePrefix: String,
-        private val overridesAnnotations: Boolean,
+        internal val targetFqNamePrefix: String,
+        internal val overridesAnnotations: Boolean,
     ) {
 
-        private val items = mutableMapOf<String, String?>()
+        internal val items = mutableMapOf<String, String?>()
 
         operator fun <T> ConfigurationKey<T>.invoke(value: T) {
             items[this.name] = this.serialize(value)
         }
-
-        internal fun build(): GradleSkieConfigurationData.Group = GradleSkieConfigurationData.Group(
-            target = targetFqNamePrefix,
-            overridesAnnotations = overridesAnnotations,
-            items = items.toMap(),
-        )
     }
 
-    internal fun buildGroups(): List<GradleSkieConfigurationData.Group> =
-        groupConfigurations.map { it.build() }
-
     internal fun buildConfigurationFlags(): Set<SkieConfigurationFlag> =
         setOfNotNull(
             SkieConfigurationFlag.Feature_CoroutinesInterop takeIf coroutinesInterop,
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieMigrationConfiguration.kt b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieMigrationConfiguration.kt
similarity index 96%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieMigrationConfiguration.kt
rename to SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieMigrationConfiguration.kt
index 281545ac1..a433461f2 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieMigrationConfiguration.kt
+++ b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/configuration/SkieMigrationConfiguration.kt
@@ -3,7 +3,7 @@
 package co.touchlab.skie.plugin.configuration
 
 import co.touchlab.skie.configuration.SkieConfigurationFlag
-import co.touchlab.skie.plugin.configuration.util.takeIf
+import co.touchlab.skie.plugin.util.takeIf
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.provider.Property
 import javax.inject.Inject
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/util/BooleanProperty.takeIf.kt b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/util/BooleanProperty.takeIf.kt
similarity index 75%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/util/BooleanProperty.takeIf.kt
rename to SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/util/BooleanProperty.takeIf.kt
index 9af47275a..d0937899e 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/util/BooleanProperty.takeIf.kt
+++ b/SKIE/skie-gradle/plugin-api/src/common/kotlin/co/touchlab/skie/plugin/util/BooleanProperty.takeIf.kt
@@ -1,4 +1,4 @@
-package co.touchlab.skie.plugin.configuration.util
+package co.touchlab.skie.plugin.util
 
 import org.gradle.api.provider.Property
 
diff --git a/SKIE/skie-gradle/plugin-shim-api/gradle-plugin-shim-api.gradle.kts b/SKIE/skie-gradle/plugin-shim-api/gradle-plugin-shim-api.gradle.kts
index 1de051ed6..fdbc715f5 100644
--- a/SKIE/skie-gradle/plugin-shim-api/gradle-plugin-shim-api.gradle.kts
+++ b/SKIE/skie-gradle/plugin-shim-api/gradle-plugin-shim-api.gradle.kts
@@ -1,5 +1,3 @@
-import co.touchlab.skie.gradle.version.gradleApiVersionDimension
-
 plugins {
     id("skie.gradle")
     id("skie.publishable")
@@ -14,8 +12,9 @@ kotlin {
     sourceSets {
         val commonMain by getting {
             dependencies {
+                api(projects.gradle.gradlePluginApi)
+
                 implementation(projects.common.util)
-                compileOnly("dev.gradleplugins:gradle-api:${gradleApiVersionDimension().components.min().value}")
             }
         }
     }
diff --git a/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/SkieTarget.kt b/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/SkieTarget.kt
index ea464113f..ddfa2e5bb 100644
--- a/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/SkieTarget.kt
+++ b/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/SkieTarget.kt
@@ -2,6 +2,7 @@ package co.touchlab.skie.plugin
 
 import co.touchlab.skie.plugin.shim.KonanTargetShim
 import co.touchlab.skie.plugin.shim.KotlinSourceSetShim
+import co.touchlab.skie.plugin.util.KotlinCompilerPluginOption
 import co.touchlab.skie.util.directory.SkieBuildDirectory
 import co.touchlab.skie.util.directory.SkieDirectories
 import org.gradle.api.Project
diff --git a/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/KotlinCompilerPluginOption.kt b/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/util/KotlinCompilerPluginOption.kt
similarity index 69%
rename from SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/KotlinCompilerPluginOption.kt
rename to SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/util/KotlinCompilerPluginOption.kt
index 31279af40..a634bfbe1 100644
--- a/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/KotlinCompilerPluginOption.kt
+++ b/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/util/KotlinCompilerPluginOption.kt
@@ -1,4 +1,4 @@
-package co.touchlab.skie.plugin
+package co.touchlab.skie.plugin.util
 
 data class KotlinCompilerPluginOption(
     val key: String,
diff --git a/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/util/KotlinDsl.kt b/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/util/KotlinDsl.kt
index 3bc55d9b6..f845dfaa0 100644
--- a/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/util/KotlinDsl.kt
+++ b/SKIE/skie-gradle/plugin-shim-api/src/common/kotlin/co/touchlab/skie/plugin/util/KotlinDsl.kt
@@ -8,7 +8,7 @@ import org.gradle.api.artifacts.Configuration
 import org.gradle.api.model.ObjectFactory
 import org.gradle.api.tasks.TaskCollection
 
-inline fun <reified S : Any> DomainObjectCollection<in S>.withType() =
+inline fun <reified S : Any> DomainObjectCollection<in S>.withType(): DomainObjectCollection<S> =
     withType(S::class.java)
 
 inline fun <reified S : Any> NamedDomainObjectCollection<in S>.withType(): NamedDomainObjectCollection<S> =
diff --git a/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieArtifactTarget.kt b/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieArtifactTarget.kt
index 9142638e1..76ebdf300 100644
--- a/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieArtifactTarget.kt
+++ b/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieArtifactTarget.kt
@@ -2,6 +2,7 @@ package co.touchlab.skie.plugin
 
 import co.touchlab.skie.plugin.shim.ActualKonanTargetShim
 import co.touchlab.skie.plugin.shim.KonanTargetShim
+import co.touchlab.skie.plugin.util.KotlinCompilerPluginOption
 import co.touchlab.skie.plugin.util.lowerCamelCaseName
 import co.touchlab.skie.util.directory.SkieDirectories
 import org.gradle.api.Project
diff --git a/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieBinaryTarget.kt b/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieBinaryTarget.kt
index 63503f093..86964d917 100644
--- a/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieBinaryTarget.kt
+++ b/SKIE/skie-gradle/plugin-shim-impl/src/kgp_common/gradle_common/kotlin/co/touchlab/skie/plugin/ActualSkieBinaryTarget.kt
@@ -1,10 +1,10 @@
 package co.touchlab.skie.plugin
 
-import co.touchlab.skie.plugin.SkieTarget.OutputKind
 import co.touchlab.skie.plugin.shim.ActualKonanTargetShim
 import co.touchlab.skie.plugin.shim.ActualKotlinSourceSetShim
 import co.touchlab.skie.plugin.shim.KonanTargetShim
 import co.touchlab.skie.plugin.shim.KotlinSourceSetShim
+import co.touchlab.skie.plugin.util.KotlinCompilerPluginOption
 import co.touchlab.skie.util.directory.SkieDirectories
 import org.gradle.api.Project
 import org.gradle.api.file.FileCollection
@@ -20,7 +20,7 @@ class ActualSkieBinaryTarget(
     override val project: Project,
     target: KotlinNativeTarget,
     private val binary: NativeBinary,
-    override val outputKind: OutputKind,
+    override val outputKind: SkieTarget.OutputKind,
 ) : SkieTarget.Binary {
 
     override val konanTarget: KonanTargetShim = ActualKonanTargetShim(target.konanTarget)
diff --git a/SKIE/skie-gradle/plugin/gradle-plugin.gradle.kts b/SKIE/skie-gradle/plugin/gradle-plugin.gradle.kts
index 675c4c75d..b11fa945e 100644
--- a/SKIE/skie-gradle/plugin/gradle-plugin.gradle.kts
+++ b/SKIE/skie-gradle/plugin/gradle-plugin.gradle.kts
@@ -1,6 +1,7 @@
 import co.touchlab.skie.gradle.KotlinCompilerVersion
 import co.touchlab.skie.gradle.publish.dependencyCoordinate
 import co.touchlab.skie.gradle.util.enquoted
+import co.touchlab.skie.gradle.util.gradlePluginApi
 import co.touchlab.skie.gradle.version.gradleApiVersionDimension
 import co.touchlab.skie.gradle.version.kotlinToolingVersionDimension
 
@@ -62,9 +63,12 @@ configurations.configureEach {
 }
 
 dependencies {
-    implementation(projects.gradle.gradlePluginShimApi)
+    api(projects.gradle.gradlePluginApi)
     api(projects.common.configuration.configurationDeclaration)
-    compileOnly("dev.gradleplugins:gradle-api:${gradleApiVersionDimension().components.min().value}")
+    implementation(projects.gradle.gradleSubPluginApi)
+    implementation(projects.gradle.gradlePluginShimApi)
+
+    compileOnly(gradlePluginApi())
     compileOnly(libs.plugin.kotlin.gradle.api)
     compileOnly(libs.plugin.kotlin.gradle)
 
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin-compiler-attribute/co/touchlab/skie/gradle/KotlinCompilerVersion.kt b/SKIE/skie-gradle/plugin/src/main/kotlin-compiler-attribute/co/touchlab/skie/gradle/KotlinCompilerVersion.kt
index aa45ea7a0..a416de20b 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin-compiler-attribute/co/touchlab/skie/gradle/KotlinCompilerVersion.kt
+++ b/SKIE/skie-gradle/plugin/src/main/kotlin-compiler-attribute/co/touchlab/skie/gradle/KotlinCompilerVersion.kt
@@ -5,13 +5,15 @@ import org.gradle.api.artifacts.dsl.DependencyHandler
 import org.gradle.api.attributes.Attribute
 import org.gradle.api.attributes.AttributeDisambiguationRule
 import org.gradle.api.attributes.MultipleCandidatesDetails
+import org.gradle.api.logging.Logger
 import org.gradle.api.logging.Logging
 import javax.inject.Inject
 
 interface KotlinCompilerVersion : Named {
+
     companion object {
 
-        val attribute = Attribute.of("co.touchlab.skie.kotlin.compiler.version", KotlinCompilerVersion::class.java)
+        val attribute: Attribute<KotlinCompilerVersion> = Attribute.of("co.touchlab.skie.kotlin.compiler.version", KotlinCompilerVersion::class.java)
 
         fun registerIn(dependencies: DependencyHandler, currentKotlinVersion: String) {
             dependencies.attributesSchema.attribute(attribute) {
@@ -41,7 +43,7 @@ interface KotlinCompilerVersion : Named {
 
         companion object {
 
-            val log = Logging.getLogger("KotlinCompilerVersion.DisambiguationRule")
+            val log: Logger = Logging.getLogger("KotlinCompilerVersion.DisambiguationRule")
         }
     }
 }
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/SkieGradlePlugin.kt b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/SkieGradlePlugin.kt
index 9312de7d1..d57c410c4 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/SkieGradlePlugin.kt
+++ b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/SkieGradlePlugin.kt
@@ -3,6 +3,7 @@ package co.touchlab.skie.plugin
 import co.touchlab.skie.plugin.analytics.GradleAnalyticsManager
 import co.touchlab.skie.plugin.configuration.CreateSkieConfigurationTask
 import co.touchlab.skie.plugin.configuration.SkieExtension
+import co.touchlab.skie.plugin.configuration.createExtension
 import co.touchlab.skie.plugin.coroutines.addDependencyOnSkieRuntime
 import co.touchlab.skie.plugin.coroutines.configureMinOsVersionIfNeeded
 import co.touchlab.skie.plugin.defaultarguments.disableCachingIfNeeded
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/analytics/GradleAnalyticsManager.kt b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/analytics/GradleAnalyticsManager.kt
index 9f177c62c..8e4d74220 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/analytics/GradleAnalyticsManager.kt
+++ b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/analytics/GradleAnalyticsManager.kt
@@ -7,7 +7,7 @@ import co.touchlab.skie.plugin.analytics.git.getGitRoot
 import co.touchlab.skie.plugin.analytics.hardware.HardwareAnalytics
 import co.touchlab.skie.plugin.analytics.performance.GradlePerformanceAnalytics
 import co.touchlab.skie.plugin.analytics.project.ProjectAnalytics
-import co.touchlab.skie.plugin.configuration.SkieExtension.Companion.buildConfiguration
+import co.touchlab.skie.plugin.configuration.buildConfiguration
 import co.touchlab.skie.plugin.configuration.skieExtension
 import co.touchlab.skie.plugin.directory.createSkieBuildDirectoryTask
 import co.touchlab.skie.plugin.kgpShim
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/CreateSkieConfigurationTask.kt b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/CreateSkieConfigurationTask.kt
index b434ec956..a2a3de62e 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/CreateSkieConfigurationTask.kt
+++ b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/CreateSkieConfigurationTask.kt
@@ -1,8 +1,6 @@
 package co.touchlab.skie.plugin.configuration
 
 import co.touchlab.skie.plugin.SkieTarget
-import co.touchlab.skie.plugin.configuration.SkieExtension.Companion.buildConfiguration
-import co.touchlab.skie.plugin.configuration.util.GradleSkieConfigurationData
 import co.touchlab.skie.plugin.directory.createSkieBuildDirectoryTask
 import co.touchlab.skie.plugin.skieBuildDirectory
 import co.touchlab.skie.plugin.util.registerSkieTargetBasedTask
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/util/GradleSkieConfigurationData.kt b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/GradleSkieConfigurationData.kt
similarity index 91%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/util/GradleSkieConfigurationData.kt
rename to SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/GradleSkieConfigurationData.kt
index e093ce5cd..048397b29 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/util/GradleSkieConfigurationData.kt
+++ b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/GradleSkieConfigurationData.kt
@@ -1,4 +1,4 @@
-package co.touchlab.skie.plugin.configuration.util
+package co.touchlab.skie.plugin.configuration
 
 import co.touchlab.skie.configuration.SkieConfigurationFlag
 import co.touchlab.skie.configuration.UntypedSkieConfigurationData
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieExtensionInternals.kt b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieExtensionInternals.kt
new file mode 100644
index 000000000..a18f5cb0a
--- /dev/null
+++ b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/configuration/SkieExtensionInternals.kt
@@ -0,0 +1,44 @@
+@file:Suppress("MemberVisibilityCanBePrivate", "unused", "invisible_reference", "invisible_member")
+
+package co.touchlab.skie.plugin.configuration
+
+import co.touchlab.skie.configuration.SkieConfigurationFlag
+import co.touchlab.skie.plugin.SkieTarget
+import org.gradle.api.Project
+
+internal fun SkieExtension.Companion.createExtension(project: Project): SkieExtension =
+    project.extensions.create("skie", SkieExtension::class.java)
+
+internal val Project.skieExtension: SkieExtension
+    get() = project.extensions.getByType(SkieExtension::class.java)
+
+internal fun SkieExtension.buildConfiguration(outputKind: SkieTarget.OutputKind): GradleSkieConfigurationData =
+    GradleSkieConfigurationData(
+        enabledConfigurationFlags = (mergeConfigurationSetsFromConfigurations(outputKind) + additionalConfigurationFlags.get()) - suppressedConfigurationFlags.get(),
+        groups = features.buildGroups(),
+    )
+
+private fun SkieExtension.mergeConfigurationSetsFromConfigurations(outputKind: SkieTarget.OutputKind): Set<SkieConfigurationFlag> =
+    analytics.buildConfigurationFlags() +
+        build.buildConfigurationFlags() +
+        debug.buildConfigurationFlags() +
+        features.buildConfigurationFlags() +
+        migration.buildConfigurationFlags() +
+        addSwiftLibraryEvolutionFlagIfNeeded(outputKind)
+
+private fun addSwiftLibraryEvolutionFlagIfNeeded(outputKind: SkieTarget.OutputKind): Set<SkieConfigurationFlag> =
+    if (outputKind == SkieTarget.OutputKind.XCFramework) {
+        setOf(SkieConfigurationFlag.Build_SwiftLibraryEvolution)
+    } else {
+        emptySet()
+    }
+
+private fun SkieFeatureConfiguration.buildGroups(): List<GradleSkieConfigurationData.Group> =
+    groupConfigurations.map { it.build() }
+
+private fun SkieFeatureConfiguration.GroupConfiguration.build(): GradleSkieConfigurationData.Group =
+    GradleSkieConfigurationData.Group(
+        target = targetFqNamePrefix,
+        overridesAnnotations = overridesAnnotations,
+        items = items.toMap(),
+    )
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/util/SkiePluginOptionToKotlinCompilerPluginOption.kt b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/util/SkiePluginOptionToKotlinCompilerPluginOption.kt
index 89da7d395..631896208 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/util/SkiePluginOptionToKotlinCompilerPluginOption.kt
+++ b/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/util/SkiePluginOptionToKotlinCompilerPluginOption.kt
@@ -1,6 +1,5 @@
 package co.touchlab.skie.plugin.util
 
-import co.touchlab.skie.plugin.KotlinCompilerPluginOption
 import co.touchlab.skie.util.plugin.SkiePlugin
 
 internal fun <T> SkiePlugin.Option<T>.toKotlinCompilerPluginOption(value: T): KotlinCompilerPluginOption =
diff --git a/SKIE/skie-gradle/sub-plugin-api/gradle-sub-plugin-api.gradle.kts b/SKIE/skie-gradle/sub-plugin-api/gradle-sub-plugin-api.gradle.kts
new file mode 100644
index 000000000..8960f3519
--- /dev/null
+++ b/SKIE/skie-gradle/sub-plugin-api/gradle-sub-plugin-api.gradle.kts
@@ -0,0 +1,20 @@
+plugins {
+    id("skie.gradle")
+    id("skie.publishable")
+}
+
+skiePublishing {
+    name = "SKIE Gradle Sub Plugin API"
+    description = "API for creating Sub-plugins for SKIE."
+}
+
+kotlin {
+    sourceSets {
+        val commonMain by getting {
+            dependencies {
+                api(projects.gradle.gradlePluginApi)
+                api(projects.gradle.gradlePluginShimApi)
+            }
+        }
+    }
+}
diff --git a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/subplugin/SkieSubplugin.kt b/SKIE/skie-gradle/sub-plugin-api/src/common/kotlin/co/touchlab/skie/plugin/subplugin/SkieSubplugin.kt
similarity index 90%
rename from SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/subplugin/SkieSubplugin.kt
rename to SKIE/skie-gradle/sub-plugin-api/src/common/kotlin/co/touchlab/skie/plugin/subplugin/SkieSubplugin.kt
index f710b3bed..aaa633149 100644
--- a/SKIE/skie-gradle/plugin/src/main/kotlin/co/touchlab/skie/plugin/subplugin/SkieSubplugin.kt
+++ b/SKIE/skie-gradle/sub-plugin-api/src/common/kotlin/co/touchlab/skie/plugin/subplugin/SkieSubplugin.kt
@@ -1,7 +1,7 @@
 package co.touchlab.skie.plugin.subplugin
 
-import co.touchlab.skie.plugin.KotlinCompilerPluginOption
 import co.touchlab.skie.plugin.SkieTarget
+import co.touchlab.skie.plugin.util.KotlinCompilerPluginOption
 import org.gradle.api.Plugin
 import org.gradle.api.Project
 import org.gradle.api.artifacts.Configuration
diff --git a/build-setup/src/main/kotlin/co/touchlab/skie/gradle/util/GradlePluginApiDependency.kt b/build-setup/src/main/kotlin/co/touchlab/skie/gradle/util/GradlePluginApiDependency.kt
new file mode 100644
index 000000000..9bbacc486
--- /dev/null
+++ b/build-setup/src/main/kotlin/co/touchlab/skie/gradle/util/GradlePluginApiDependency.kt
@@ -0,0 +1,7 @@
+package co.touchlab.skie.gradle.util
+
+import co.touchlab.skie.gradle.version.gradleApiVersionDimension
+import org.gradle.api.Project
+
+fun Project.gradlePluginApi(): String =
+    "dev.gradleplugins:gradle-api:${gradleApiVersionDimension().components.min().value}"