diff --git a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SimplePluginRegistrar.kt b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SimplePluginRegistrar.kt
deleted file mode 100644
index 2451839f..00000000
--- a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SimplePluginRegistrar.kt
+++ /dev/null
@@ -1,8 +0,0 @@
-package org.jetbrains.kotlinx.spark.api.compilerPlugin
-
-import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
-
-// Potential future K2 FIR hook
-class SimplePluginRegistrar(private val sparkifyAnnotationFqNames: List<String>) : FirExtensionRegistrar() {
-    override fun ExtensionRegistrarContext.configurePlugin() {}
-}
diff --git a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SparkifyCompilerPluginRegistrar.kt b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SparkifyCompilerPluginRegistrar.kt
index 6390c45f..f2456d50 100644
--- a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SparkifyCompilerPluginRegistrar.kt
+++ b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SparkifyCompilerPluginRegistrar.kt
@@ -3,10 +3,12 @@ package org.jetbrains.kotlinx.spark.api.compilerPlugin
 import org.jetbrains.kotlin.backend.common.extensions.IrGenerationExtension
 import org.jetbrains.kotlin.compiler.plugin.CompilerPluginRegistrar
 import org.jetbrains.kotlin.config.CompilerConfiguration
+import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
+import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrarAdapter
 import org.jetbrains.kotlinx.spark.api.Artifacts
 import org.jetbrains.kotlinx.spark.api.compilerPlugin.ir.SparkifyIrGenerationExtension
 
-open class SparkifyCompilerPluginRegistrar: CompilerPluginRegistrar() {
+open class SparkifyCompilerPluginRegistrar : CompilerPluginRegistrar() {
     init {
         println("SparkifyCompilerPluginRegistrar loaded")
     }
@@ -26,6 +28,15 @@ open class SparkifyCompilerPluginRegistrar: CompilerPluginRegistrar() {
         val productFqNames = // TODO: get from configuration
             listOf("scala.Product")
 
+        // Front end (FIR)
+//        FirExtensionRegistrarAdapter.registerExtension(
+//            SparkifyFirPluginRegistrar(
+//                sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
+//                productFqNames = productFqNames,
+//            )
+//        )
+
+        // Intermediate Representation IR
         IrGenerationExtension.registerExtension(
             SparkifyIrGenerationExtension(
                 sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
diff --git a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SparkifyFirPluginRegistrar.kt b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SparkifyFirPluginRegistrar.kt
new file mode 100644
index 00000000..aca02af7
--- /dev/null
+++ b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/SparkifyFirPluginRegistrar.kt
@@ -0,0 +1,23 @@
+package org.jetbrains.kotlinx.spark.api.compilerPlugin
+
+import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrar
+import org.jetbrains.kotlinx.spark.api.compilerPlugin.fir.DataClassSparkifyFunctionsGenerator
+import org.jetbrains.kotlinx.spark.api.compilerPlugin.fir.DataClassSparkifySuperTypeGenerator
+
+// Potential future K2 FIR hook
+// TODO
+class SparkifyFirPluginRegistrar(
+    private val sparkifyAnnotationFqNames: List<String>,
+    private val productFqNames: List<String>
+) : FirExtensionRegistrar() {
+    override fun ExtensionRegistrarContext.configurePlugin() {
+        +DataClassSparkifySuperTypeGenerator.builder(
+            sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
+            productFqNames = productFqNames,
+        )
+        +DataClassSparkifyFunctionsGenerator.builder(
+            sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
+            productFqNames = productFqNames,
+        )
+    }
+}
diff --git a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/fir/DataClassSparkifyFunctionsGenerator.kt b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/fir/DataClassSparkifyFunctionsGenerator.kt
new file mode 100644
index 00000000..007c6e2c
--- /dev/null
+++ b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/fir/DataClassSparkifyFunctionsGenerator.kt
@@ -0,0 +1,115 @@
+package org.jetbrains.kotlinx.spark.api.compilerPlugin.fir
+
+import org.jetbrains.kotlin.GeneratedDeclarationKey
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.declarations.utils.isData
+import org.jetbrains.kotlin.fir.extensions.FirDeclarationGenerationExtension
+import org.jetbrains.kotlin.fir.extensions.MemberGenerationContext
+import org.jetbrains.kotlin.fir.plugin.createMemberFunction
+import org.jetbrains.kotlin.fir.render
+import org.jetbrains.kotlin.fir.resolve.getSuperTypes
+import org.jetbrains.kotlin.fir.symbols.impl.FirClassSymbol
+import org.jetbrains.kotlin.fir.symbols.impl.FirNamedFunctionSymbol
+import org.jetbrains.kotlin.fir.types.toClassSymbol
+import org.jetbrains.kotlin.name.CallableId
+import org.jetbrains.kotlin.name.Name
+
+class DataClassSparkifyFunctionsGenerator(
+    session: FirSession,
+    private val sparkifyAnnotationFqNames: List<String>,
+    private val productFqNames: List<String>,
+) : FirDeclarationGenerationExtension(session) {
+
+    companion object {
+        fun builder(
+            sparkifyAnnotationFqNames: List<String>,
+            productFqNames: List<String>
+        ): (FirSession) -> FirDeclarationGenerationExtension = {
+            DataClassSparkifyFunctionsGenerator(
+                session = it,
+                sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
+                productFqNames = productFqNames,
+            )
+        }
+
+        // functions to generate
+        val canEqual = Name.identifier("canEqual")
+        val productElement = Name.identifier("productElement")
+        val productArity = Name.identifier("productArity")
+    }
+
+    override fun generateFunctions(
+        callableId: CallableId,
+        context: MemberGenerationContext?
+    ): List<FirNamedFunctionSymbol> {
+        val owner = context?.owner ?: return emptyList()
+
+        val functionName = callableId.callableName
+        val superTypes = owner.getSuperTypes(session)
+        val superProduct = superTypes.first {
+            it.toString().endsWith("Product")
+        }.toClassSymbol(session)!!
+        val superEquals = superTypes.first {
+            it.toString().endsWith("Equals")
+        }.toClassSymbol(session)!!
+
+        val function = when (functionName) {
+            canEqual -> {
+                val func = createMemberFunction(
+                    owner = owner,
+                    key = Key,
+                    name = functionName,
+                    returnType = session.builtinTypes.booleanType.type,
+                ) {
+                    valueParameter(
+                        name = Name.identifier("that"),
+                        type = session.builtinTypes.nullableAnyType.type,
+                    )
+                }
+//                val superFunction = superEquals.declarationSymbols.first {
+//                    it is FirNamedFunctionSymbol && it.name == functionName
+//                } as FirNamedFunctionSymbol
+//                overrides(func, superFunction)
+                func
+            }
+
+            productElement -> {
+                createMemberFunction(
+                    owner = owner,
+                    key = Key,
+                    name = functionName,
+                    returnType = session.builtinTypes.nullableAnyType.type,
+                ) {
+                    valueParameter(
+                        name = Name.identifier("n"),
+                        type = session.builtinTypes.intType.type,
+                    )
+                }
+            }
+
+            productArity -> {
+                createMemberFunction(
+                    owner = owner,
+                    key = Key,
+                    name = functionName,
+                    returnType = session.builtinTypes.intType.type,
+                )
+            }
+
+            else -> {
+                return emptyList()
+            }
+        }
+
+        return listOf(function.symbol)
+    }
+
+    override fun getCallableNamesForClass(classSymbol: FirClassSymbol<*>, context: MemberGenerationContext): Set<Name> =
+        if (classSymbol.isData && classSymbol.annotations.any { "Sparkify" in it.render() }) {
+            setOf(canEqual, productElement, productArity)
+        } else {
+            emptySet()
+        }
+
+    object Key : GeneratedDeclarationKey()
+}
\ No newline at end of file
diff --git a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/fir/DataClassSparkifySuperTypeGenerator.kt b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/fir/DataClassSparkifySuperTypeGenerator.kt
new file mode 100644
index 00000000..339b3269
--- /dev/null
+++ b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/fir/DataClassSparkifySuperTypeGenerator.kt
@@ -0,0 +1,59 @@
+package org.jetbrains.kotlinx.spark.api.compilerPlugin.fir
+
+import org.jetbrains.kotlin.fir.FirSession
+import org.jetbrains.kotlin.fir.declarations.FirClassLikeDeclaration
+import org.jetbrains.kotlin.fir.declarations.utils.isData
+import org.jetbrains.kotlin.fir.extensions.FirSupertypeGenerationExtension
+import org.jetbrains.kotlin.fir.render
+import org.jetbrains.kotlin.fir.resolve.fqName
+import org.jetbrains.kotlin.fir.symbols.impl.ConeClassLikeLookupTagImpl
+import org.jetbrains.kotlin.fir.types.FirResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.builder.buildResolvedTypeRef
+import org.jetbrains.kotlin.fir.types.impl.ConeClassLikeTypeImpl
+import org.jetbrains.kotlin.name.ClassId
+import org.jetbrains.kotlin.name.FqName
+
+/**
+ * This class tells the FIR that all @Sparkify annotated data classes
+ * get [scala.Product] as their super type.
+ */
+class DataClassSparkifySuperTypeGenerator(
+    session: FirSession,
+    private val sparkifyAnnotationFqNames: List<String>,
+    private val productFqNames: List<String>,
+) : FirSupertypeGenerationExtension(session) {
+
+    companion object {
+        fun builder(sparkifyAnnotationFqNames: List<String>, productFqNames: List<String>): (FirSession) -> FirSupertypeGenerationExtension = {
+            DataClassSparkifySuperTypeGenerator(
+                session = it,
+                sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
+                productFqNames = productFqNames,
+            )
+        }
+    }
+
+    context(TypeResolveServiceContainer)
+    override fun computeAdditionalSupertypes(
+        classLikeDeclaration: FirClassLikeDeclaration,
+        resolvedSupertypes: List<FirResolvedTypeRef>
+    ): List<FirResolvedTypeRef> = listOf(
+        buildResolvedTypeRef {
+            val scalaProduct = productFqNames.first().let {
+                ClassId.topLevel(FqName(it))
+            }
+            type = ConeClassLikeTypeImpl(
+                lookupTag = ConeClassLikeLookupTagImpl(scalaProduct),
+                typeArguments = emptyArray(),
+                isNullable = false,
+            )
+        }
+
+    )
+
+    override fun needTransformSupertypes(declaration: FirClassLikeDeclaration): Boolean =
+        declaration.symbol.isData &&
+                declaration.annotations.any {
+                    "Sparkify" in it.render()
+                }
+}
\ No newline at end of file
diff --git a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/DataClassPropertyAnnotationGenerator.kt b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/DataClassSparkifyGenerator.kt
similarity index 99%
rename from compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/DataClassPropertyAnnotationGenerator.kt
rename to compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/DataClassSparkifyGenerator.kt
index 30df9799..0438b42b 100644
--- a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/DataClassPropertyAnnotationGenerator.kt
+++ b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/DataClassSparkifyGenerator.kt
@@ -46,7 +46,7 @@ import org.jetbrains.kotlin.name.FqName
 import org.jetbrains.kotlin.name.Name
 import org.jetbrains.kotlin.name.SpecialNames
 
-class DataClassPropertyAnnotationGenerator(
+class DataClassSparkifyGenerator(
     private val pluginContext: IrPluginContext,
     private val sparkifyAnnotationFqNames: List<String>,
     private val columnNameAnnotationFqNames: List<String>,
diff --git a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/SparkifyIrGenerationExtension.kt b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/SparkifyIrGenerationExtension.kt
index a22cc6f8..d17da71f 100644
--- a/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/SparkifyIrGenerationExtension.kt
+++ b/compiler-plugin/src/main/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/ir/SparkifyIrGenerationExtension.kt
@@ -4,7 +4,6 @@ import org.jetbrains.kotlin.backend.common.extensions.IrGenerationExtension
 import org.jetbrains.kotlin.backend.common.extensions.IrPluginContext
 import org.jetbrains.kotlin.ir.declarations.IrModuleFragment
 import org.jetbrains.kotlin.ir.visitors.acceptChildrenVoid
-import org.jetbrains.kotlinx.spark.api.compilerPlugin.ir.DataClassPropertyAnnotationGenerator
 
 class SparkifyIrGenerationExtension(
     private val sparkifyAnnotationFqNames: List<String>,
@@ -13,7 +12,7 @@ class SparkifyIrGenerationExtension(
 ) : IrGenerationExtension {
     override fun generate(moduleFragment: IrModuleFragment, pluginContext: IrPluginContext) {
         val visitors = listOf(
-            DataClassPropertyAnnotationGenerator(
+            DataClassSparkifyGenerator(
                 pluginContext = pluginContext,
                 sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
                 columnNameAnnotationFqNames = columnNameAnnotationFqNames,
diff --git a/compiler-plugin/src/test-gen/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/runners/DiagnosticTestGenerated.java b/compiler-plugin/src/test-gen/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/runners/DiagnosticTestGenerated.java
new file mode 100644
index 00000000..566db49b
--- /dev/null
+++ b/compiler-plugin/src/test-gen/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/runners/DiagnosticTestGenerated.java
@@ -0,0 +1,28 @@
+
+
+package org.jetbrains.kotlinx.spark.api.compilerPlugin.runners;
+
+import com.intellij.testFramework.TestDataPath;
+import org.jetbrains.kotlin.test.util.KtTestUtil;
+import org.jetbrains.kotlin.test.TestMetadata;
+import org.junit.jupiter.api.Test;
+
+import java.io.File;
+import java.util.regex.Pattern;
+
+/** This class is generated by {@link org.jetbrains.kotlinx.spark.api.compilerPlugin.GenerateTestsKt}. DO NOT MODIFY MANUALLY */
+@SuppressWarnings("all")
+@TestMetadata("/mnt/data/Projects/kotlin-spark-api/compiler-plugin/src/test/resources/testData/diagnostics")
+@TestDataPath("$PROJECT_ROOT")
+public class DiagnosticTestGenerated extends AbstractDiagnosticTest {
+  @Test
+  public void testAllFilesPresentInDiagnostics() {
+    KtTestUtil.assertAllTestsPresentByMetadataWithExcluded(this.getClass(), new File("/mnt/data/Projects/kotlin-spark-api/compiler-plugin/src/test/resources/testData/diagnostics"), Pattern.compile("^(.+)\\.kt$"), null, true);
+  }
+
+  @Test
+  @TestMetadata("dataClassTest.kt")
+  public void testDataClassTest() {
+    runTest("/mnt/data/Projects/kotlin-spark-api/compiler-plugin/src/test/resources/testData/diagnostics/dataClassTest.kt");
+  }
+}
diff --git a/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/GenerateTests.kt b/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/GenerateTests.kt
index a85d0a1b..35eda3b4 100644
--- a/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/GenerateTests.kt
+++ b/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/GenerateTests.kt
@@ -3,6 +3,7 @@ package org.jetbrains.kotlinx.spark.api.compilerPlugin
 import org.jetbrains.kotlin.generators.generateTestGroupSuiteWithJUnit5
 import org.jetbrains.kotlinx.spark.api.Artifacts
 import org.jetbrains.kotlinx.spark.api.compilerPlugin.runners.AbstractBoxTest
+import org.jetbrains.kotlinx.spark.api.compilerPlugin.runners.AbstractDiagnosticTest
 
 fun main() {
     generateTestGroupSuiteWithJUnit5 {
@@ -10,9 +11,9 @@ fun main() {
             testDataRoot = "${Artifacts.projectRoot}/${Artifacts.compilerPluginArtifactId}/src/test/resources/testData",
             testsRoot = "${Artifacts.projectRoot}/${Artifacts.compilerPluginArtifactId}/src/test-gen/kotlin",
         ) {
-//            testClass<AbstractDiagnosticTest> {
-//                model("diagnostics")
-//            }
+            testClass<AbstractDiagnosticTest> {
+                model("diagnostics")
+            }
 
             testClass<AbstractBoxTest> {
                 model("box")
diff --git a/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/services/ExtensionRegistrarConfigurator.kt b/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/services/ExtensionRegistrarConfigurator.kt
index b7942a4e..a48fa81b 100644
--- a/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/services/ExtensionRegistrarConfigurator.kt
+++ b/compiler-plugin/src/test/kotlin/org/jetbrains/kotlinx/spark/api/compilerPlugin/services/ExtensionRegistrarConfigurator.kt
@@ -3,9 +3,11 @@ package org.jetbrains.kotlinx.spark.api.compilerPlugin.services
 import org.jetbrains.kotlin.backend.common.extensions.IrGenerationExtension
 import org.jetbrains.kotlin.compiler.plugin.CompilerPluginRegistrar
 import org.jetbrains.kotlin.config.CompilerConfiguration
+import org.jetbrains.kotlin.fir.extensions.FirExtensionRegistrarAdapter
 import org.jetbrains.kotlin.test.model.TestModule
 import org.jetbrains.kotlin.test.services.EnvironmentConfigurator
 import org.jetbrains.kotlin.test.services.TestServices
+import org.jetbrains.kotlinx.spark.api.compilerPlugin.SparkifyFirPluginRegistrar
 import org.jetbrains.kotlinx.spark.api.compilerPlugin.ir.SparkifyIrGenerationExtension
 
 class ExtensionRegistrarConfigurator(testServices: TestServices) : EnvironmentConfigurator(testServices) {
@@ -16,6 +18,16 @@ class ExtensionRegistrarConfigurator(testServices: TestServices) : EnvironmentCo
         val sparkifyAnnotationFqNames = listOf("foo.bar.Sparkify")
         val columnNameAnnotationFqNames = listOf("foo.bar.ColumnName")
         val productFqNames = listOf("foo.bar.Product")
+
+        // Front end (FIR)
+//        FirExtensionRegistrarAdapter.registerExtension(
+//            SparkifyFirPluginRegistrar(
+//                sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
+//                productFqNames = productFqNames,
+//            )
+//        )
+
+        // Intermediate Representation IR
         IrGenerationExtension.registerExtension(
             SparkifyIrGenerationExtension(
                 sparkifyAnnotationFqNames = sparkifyAnnotationFqNames,
diff --git a/compiler-plugin/src/test/resources/testData/diagnostics/dataClassTest.kt b/compiler-plugin/src/test/resources/testData/diagnostics/dataClassTest.kt
new file mode 100644
index 00000000..4b86f4c1
--- /dev/null
+++ b/compiler-plugin/src/test/resources/testData/diagnostics/dataClassTest.kt
@@ -0,0 +1,28 @@
+package foo.bar
+
+annotation class Sparkify
+annotation class ColumnName(val name: String)
+
+// Fake Equals
+interface Equals {
+    fun canEqual(that: Any?): Boolean
+}
+
+// Fake Product
+interface Product: Equals {
+    fun productElement(n: Int): Any
+    fun productArity(): Int
+}
+
+fun test() {
+    val user = User()
+    user.productArity() // should not be an error
+}
+
+@Sparkify
+data <!ABSTRACT_MEMBER_NOT_IMPLEMENTED!>class User<!>(
+    val name: String = "John Doe",
+    val age: Int = 25,
+    @ColumnName("a") val test: Double = 1.0,
+    @get:ColumnName("b") val test2: Double = 2.0,
+)