diff --git a/build-logic/src/main/kotlin/polaris-java.gradle.kts b/build-logic/src/main/kotlin/polaris-java.gradle.kts
index e3b1767078..68f856a061 100644
--- a/build-logic/src/main/kotlin/polaris-java.gradle.kts
+++ b/build-logic/src/main/kotlin/polaris-java.gradle.kts
@@ -18,6 +18,7 @@
  */
 
 import com.diffplug.spotless.FormatterFunc
+import gradle.kotlin.dsl.accessors._610c9322e0f6ac91715e46c62199c37f.spotless
 import java.io.Serializable
 import net.ltgt.gradle.errorprone.errorprone
 import org.gradle.api.tasks.compile.JavaCompile
@@ -39,20 +40,25 @@ apply<PublishingHelperPlugin>()
 
 tasks.withType(JavaCompile::class.java).configureEach {
   options.compilerArgs.addAll(listOf("-Xlint:unchecked", "-Xlint:deprecation"))
-  options.errorprone.disableAllWarnings = true
-  options.errorprone.disableWarningsInGeneratedCode = true
-  options.errorprone.excludedPaths =
-    ".*/${project.layout.buildDirectory.get().asFile.relativeTo(projectDir)}/generated/.*"
-  options.errorprone.error(
-    "DefaultCharset",
-    "FallThrough",
-    "MissingCasesInEnumSwitch",
-    "MissingOverride",
-    "ModifiedButNotUsed",
-    "OrphanedFormatString",
-    "PatternMatchingInstanceof",
-    "StringCaseLocaleUsage",
-  )
+
+  if (project.extra.has("reused-project-dir")) {
+    options.errorprone.disableAllChecks = true
+  } else {
+    options.errorprone.disableAllWarnings = true
+    options.errorprone.disableWarningsInGeneratedCode = true
+    options.errorprone.excludedPaths =
+      ".*/${project.layout.buildDirectory.get().asFile.relativeTo(projectDir)}/generated/.*"
+    options.errorprone.error(
+      "DefaultCharset",
+      "FallThrough",
+      "MissingCasesInEnumSwitch",
+      "MissingOverride",
+      "ModifiedButNotUsed",
+      "OrphanedFormatString",
+      "PatternMatchingInstanceof",
+      "StringCaseLocaleUsage",
+    )
+  }
 }
 
 tasks.register("compileAll").configure {
@@ -150,42 +156,53 @@ tasks.withType(Jar::class).configureEach {
   }
 }
 
-spotless {
-  java {
-    target("src/*/java/**/*.java")
-    googleJavaFormat()
-    licenseHeaderFile(rootProject.file("codestyle/copyright-header-java.txt"))
-    endWithNewline()
-    custom(
-      "disallowWildcardImports",
-      object : Serializable, FormatterFunc {
-        override fun apply(text: String): String {
-          val regex = "~/import .*\\.\\*;/".toRegex()
-          if (regex.matches(text)) {
-            throw GradleException("Wildcard imports disallowed - ${regex.findAll(text)}")
+if (!project.extra.has("reused-project-dir") && !gradle.ideSyncActive()) {
+  spotless {
+    java {
+      target("src/*/java/**/*.java")
+      googleJavaFormat()
+      licenseHeaderFile(rootProject.file("codestyle/copyright-header-java.txt"))
+      endWithNewline()
+      custom(
+        "disallowWildcardImports",
+        object : Serializable, FormatterFunc {
+          override fun apply(text: String): String {
+            val regex = "~/import .*\\.\\*;/".toRegex()
+            if (regex.matches(text)) {
+              throw GradleException("Wildcard imports disallowed - ${regex.findAll(text)}")
+            }
+            return text
           }
-          return text
-        }
-      },
-    )
-    toggleOffOn()
-  }
-  kotlinGradle {
-    ktfmt().googleStyle()
-    licenseHeaderFile(rootProject.file("codestyle/copyright-header-java.txt"), "$")
-    target("*.gradle.kts")
-  }
-  format("xml") {
-    target("src/**/*.xml", "src/**/*.xsd")
-    targetExclude("codestyle/copyright-header.xml")
-    eclipseWtp(com.diffplug.spotless.extra.wtp.EclipseWtpFormatterStep.XML)
-      .configFile(rootProject.file("codestyle/org.eclipse.wst.xml.core.prefs"))
-    // getting the license-header delimiter right is a bit tricky.
-    // licenseHeaderFile(rootProject.file("codestyle/copyright-header.xml"), '<^[!?].*$')
+        },
+      )
+      toggleOffOn()
+    }
+    scala {
+      scalafmt(requiredDependencyVersion("scalafmt"))
+        .configFile(rootProject.file("codestyle/scalafmt.conf").toString())
+      licenseHeaderFile(
+        rootProject.file("codestyle/copyright-header-java.txt"),
+        "^(package|import) .*$",
+      )
+      target("src/**/scala/**/*.scala")
+    }
+    kotlinGradle {
+      ktfmt().googleStyle()
+      licenseHeaderFile(rootProject.file("codestyle/copyright-header-java.txt"), "$")
+      target("*.gradle.kts")
+    }
+    format("xml") {
+      target("src/**/*.xml", "src/**/*.xsd")
+      targetExclude("codestyle/copyright-header.xml")
+      eclipseWtp(com.diffplug.spotless.extra.wtp.EclipseWtpFormatterStep.XML)
+        .configFile(rootProject.file("codestyle/org.eclipse.wst.xml.core.prefs"))
+      // getting the license-header delimiter right is a bit tricky.
+      // licenseHeaderFile(rootProject.file("codestyle/copyright-header.xml"), '<^[!?].*$')
+    }
   }
 }
 
-dependencies { errorprone(versionCatalogs.named("libs").findLibrary("errorprone").get()) }
+dependencies { errorprone(requiredDependency("errorprone")) }
 
 java {
   withJavadocJar()
diff --git a/build-logic/src/main/kotlin/polaris-root.gradle.kts b/build-logic/src/main/kotlin/polaris-root.gradle.kts
index 96faa07b82..58fabdd95a 100644
--- a/build-logic/src/main/kotlin/polaris-root.gradle.kts
+++ b/build-logic/src/main/kotlin/polaris-root.gradle.kts
@@ -41,7 +41,7 @@ spotless {
   }
 }
 
-if (System.getProperty("idea.sync.active").toBoolean()) {
+if (gradle.ideSyncActive()) {
   idea {
     module {
       isDownloadJavadoc = false // was 'true', but didn't work
diff --git a/build-logic/src/main/kotlin/polaris-scala.gradle.kts b/build-logic/src/main/kotlin/polaris-scala.gradle.kts
new file mode 100644
index 0000000000..f69cd4b0e8
--- /dev/null
+++ b/build-logic/src/main/kotlin/polaris-scala.gradle.kts
@@ -0,0 +1,66 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import org.gradle.api.publish.PublishingExtension
+import org.gradle.api.publish.maven.MavenPublication
+import org.gradle.api.tasks.bundling.Jar
+import org.gradle.api.tasks.scala.ScalaCompile
+import org.gradle.api.tasks.scala.ScalaDoc
+import org.gradle.kotlin.dsl.*
+import org.gradle.language.scala.tasks.KeepAliveMode
+
+plugins {
+  id("polaris-server")
+  scala
+}
+
+tasks.withType<ScalaCompile>().configureEach {
+  options.release = 21
+  scalaCompileOptions.additionalParameters.add("-release:21")
+  sourceCompatibility = "21"
+  targetCompatibility = "21"
+}
+
+tasks.withType<ScalaCompile>().configureEach {
+  scalaCompileOptions.keepAliveMode = KeepAliveMode.DAEMON
+  scalaCompileOptions.encoding = "UTF-8"
+}
+
+val scaladoc = tasks.named<ScalaDoc>("scaladoc")
+val scaladocJar = tasks.register<Jar>("scaladocJar")
+
+scaladocJar.configure {
+  dependsOn(scaladoc)
+  val baseJar = tasks.getByName<Jar>("jar")
+  from(scaladoc.get().destinationDir)
+  destinationDirectory = baseJar.destinationDirectory
+  archiveClassifier = "scaladoc"
+}
+
+tasks.named("assemble").configure { dependsOn(scaladocJar) }
+
+configure<PublishingExtension> {
+  publications {
+    withType(MavenPublication::class.java) {
+      if (name == "maven") {
+        artifact(scaladocJar)
+      }
+    }
+  }
+}
diff --git a/build-logic/src/main/kotlin/polaris-spark.gradle.kts b/build-logic/src/main/kotlin/polaris-spark.gradle.kts
new file mode 100644
index 0000000000..9e166c0b81
--- /dev/null
+++ b/build-logic/src/main/kotlin/polaris-spark.gradle.kts
@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+plugins {
+  id("polaris-client")
+  scala
+}
+
+tasks.withType<ScalaCompile>().configureEach {
+  options.release = 11
+  scalaCompileOptions.additionalParameters.add("-release:11")
+  sourceCompatibility = "11"
+  targetCompatibility = "11"
+}
+
+tasks.withType<ScalaCompile>().configureEach {
+  scalaCompileOptions.keepAliveMode = KeepAliveMode.DAEMON
+  scalaCompileOptions.encoding = "UTF-8"
+}
+
+val scaladoc = tasks.named<ScalaDoc>("scaladoc")
+val scaladocJar = tasks.register<Jar>("scaladocJar")
+
+scaladocJar.configure {
+  dependsOn(scaladoc)
+  val baseJar = tasks.getByName<Jar>("jar")
+  from(scaladoc.get().destinationDir)
+  destinationDirectory = baseJar.destinationDirectory
+  archiveClassifier = "scaladoc"
+}
+
+tasks.named("assemble").configure { dependsOn(scaladocJar) }
+
+configure<PublishingExtension> {
+  publications {
+    withType(MavenPublication::class.java) {
+      if (name == "maven") {
+        artifact(scaladocJar)
+      }
+    }
+  }
+}
+
+val versions = sparkScalaVersionsForProject()
+
+scala { scalaVersion.set(versions.scalaFullVersion) }
diff --git a/build-logic/src/main/kotlin/spark-scala.kt b/build-logic/src/main/kotlin/spark-scala.kt
new file mode 100644
index 0000000000..79b7a10cc9
--- /dev/null
+++ b/build-logic/src/main/kotlin/spark-scala.kt
@@ -0,0 +1,162 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.lang.IllegalArgumentException
+import org.gradle.api.Project
+import org.gradle.api.artifacts.Dependency
+import org.gradle.api.artifacts.ExternalModuleDependency
+import org.gradle.api.artifacts.ModuleDependency
+import org.gradle.api.tasks.testing.Test
+import org.gradle.kotlin.dsl.exclude
+
+fun Project.prepareSparkScalaProject(): SparkScalaVersions {
+  val versions = sparkScalaVersionsForProject()
+
+  forceJavaVersionForTests(versions.runtimeJavaVersion)
+  addSparkJvmOptions()
+  return versions
+}
+
+fun Project.prepareScalaProject(): SparkScalaVersions {
+  return sparkScalaVersionsForProject()
+}
+
+/** Resolves the Spark and Scala major/minor versions from the Gradle project name. */
+fun Project.sparkScalaVersionsForProject(): SparkScalaVersions {
+  val matchScala = ".*_(\\d+[.]\\d+)".toRegex().matchEntire(project.name)!!
+  val matchSpark = ".*-(\\d+[.]\\d+)_\\d+[.]\\d+".toRegex().matchEntire(project.name)
+
+  val sparkMajorMinorVersion = if (matchSpark != null) matchSpark.groups[1]!!.value else ""
+  val scalaMajorMinorVersion = matchScala.groups[1]!!.value
+
+  project.layout.buildDirectory.set(layout.buildDirectory.dir(scalaMajorMinorVersion).get())
+
+  return SparkScalaVersions(
+    sparkMajorMinorVersion,
+    scalaMajorMinorVersion,
+    if (sparkMajorMinorVersion.isNotBlank())
+      resolveFullSparkVersion(sparkMajorMinorVersion, scalaMajorMinorVersion)
+    else "",
+    resolveFullScalaVersion(scalaMajorMinorVersion),
+    if (sparkMajorMinorVersion.isNotBlank()) javaVersionForSpark(sparkMajorMinorVersion) else 0,
+  )
+}
+
+/**
+ * Apply the `sparkFullVersion` as a `strictly` version constraint and apply [withSparkExcludes] on
+ * the current [Dependency].
+ */
+fun ModuleDependency.sparkDependencyAndExcludes(sparkScala: SparkScalaVersions): ModuleDependency {
+  val dep = this as ExternalModuleDependency
+  dep.version { strictly(sparkScala.sparkFullVersion) }
+  return this.withSparkExcludes()
+}
+
+/** Apply a bunch of common dependency-exclusion to the current Spark [Dependency]. */
+fun ModuleDependency.withSparkExcludes(): ModuleDependency {
+  return this.exclude("commons-logging", "commons-logging")
+    .exclude("log4j", "log4j")
+    .exclude("org.slf4j", "slf4j-log4j12")
+    .exclude("org.slf4j", "slf4j-reload4j")
+    .exclude("org.eclipse.jetty", "jetty-util")
+    .exclude("org.apache.avro", "avro")
+    .exclude("org.apache.arrow", "arrow-vector")
+    .exclude("org.apache.logging.log4j", "log4j-slf4j2-impl")
+}
+
+/**
+ * Resolve the full Spark version for the given major/minor Spark + Scala versions from the
+ * `spark*-sql-scala*` dependency.
+ */
+fun Project.resolveFullSparkVersion(
+  sparkMajorMinorVersion: String,
+  scalaMajorMinorVersion: String,
+): String {
+  val dotRegex = "[.]".toRegex()
+  val sparkVerTrimmed = sparkMajorMinorVersion.replace(dotRegex, "")
+  val scalaVerTrimmed = scalaMajorMinorVersion.replace(dotRegex, "")
+  return requiredDependencyPreferredVersion("spark$sparkVerTrimmed-sql-scala$scalaVerTrimmed")
+}
+
+/**
+ * Resolve the full Scala version for the given major/minor Scala version from the
+ * `scala*-lang-library` dependency.
+ */
+fun Project.resolveFullScalaVersion(scalaMajorMinorVersion: String): String {
+  val dotRegex = "[.]".toRegex()
+  val scalaVerTrimmed = scalaMajorMinorVersion.replace(dotRegex, "")
+  return requiredDependencyPreferredVersion("scala$scalaVerTrimmed-lang-library")
+}
+
+/**
+ * Get the Java LTS version, that is lower than or equal to the currently running Java version, for
+ * a given Spark version to be used in tests.
+ */
+fun javaVersionForSpark(sparkVersion: String): Int {
+  return when (sparkVersion) {
+    "3.4",
+    "3.5" -> 21
+    else ->
+      throw IllegalArgumentException("Do not know which Java version Spark $sparkVersion supports")
+  }
+}
+
+class SparkScalaVersions(
+  /** Spark major/minor version. */
+  val sparkMajorMinorVersion: String,
+  /** Scala major/minor version. */
+  val scalaMajorMinorVersion: String,
+  /** Full Spark version, including the patch version, for dependencies. */
+  val sparkFullVersion: String,
+  /** Full Scala version, including the patch version, for dependencies. */
+  val scalaFullVersion: String,
+  /** Java runtime version to be used in tests. */
+  val runtimeJavaVersion: Int,
+)
+
+/**
+ * Adds the JPMS options required for Spark to run on Java 17, taken from the
+ * `DEFAULT_MODULE_OPTIONS` constant in `org.apache.spark.launcher.JavaModuleOptions`.
+ */
+fun Project.addSparkJvmOptions() {
+  tasks.withType(Test::class.java).configureEach {
+    jvmArgs =
+      jvmArgs +
+        listOf(
+          "-XX:+IgnoreUnrecognizedVMOptions",
+          "--add-opens=java.base/java.lang=ALL-UNNAMED",
+          "--add-opens=java.base/java.lang.invoke=ALL-UNNAMED",
+          "--add-opens=java.base/java.lang.reflect=ALL-UNNAMED",
+          "--add-opens=java.base/java.io=ALL-UNNAMED",
+          "--add-opens=java.base/java.net=ALL-UNNAMED",
+          "--add-opens=java.base/java.nio=ALL-UNNAMED",
+          "--add-opens=java.base/java.util=ALL-UNNAMED",
+          "--add-opens=java.base/java.util.concurrent=ALL-UNNAMED",
+          "--add-opens=java.base/java.util.concurrent.atomic=ALL-UNNAMED",
+          "--add-opens=java.base/sun.nio.ch=ALL-UNNAMED",
+          "--add-opens=java.base/sun.nio.cs=ALL-UNNAMED",
+          "--add-opens=java.base/sun.security.action=ALL-UNNAMED",
+          "--add-opens=java.base/sun.util.calendar=ALL-UNNAMED",
+          "--add-opens=java.security.jgss/sun.security.krb5=ALL-UNNAMED",
+          "-Djdk.reflect.useDirectMethodHandle=false",
+          // Required for Java 23+ if Hadoop stuff is used
+          "-Djava.security.manager=allow",
+        )
+  }
+}
diff --git a/build-logic/src/main/kotlin/util.kt b/build-logic/src/main/kotlin/util.kt
new file mode 100644
index 0000000000..971b82bc42
--- /dev/null
+++ b/build-logic/src/main/kotlin/util.kt
@@ -0,0 +1,71 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+import java.lang.IllegalStateException
+import org.gradle.api.JavaVersion
+import org.gradle.api.Project
+import org.gradle.api.artifacts.MinimalExternalModuleDependency
+import org.gradle.api.artifacts.VersionCatalogsExtension
+import org.gradle.api.invocation.Gradle
+import org.gradle.api.tasks.testing.Test
+import org.gradle.jvm.toolchain.JavaLanguageVersion
+import org.gradle.jvm.toolchain.JavaToolchainService
+import org.gradle.kotlin.dsl.getByType
+
+fun Gradle.ideSyncActive(): Boolean =
+  System.getProperty("idea.sync.active").toBoolean() ||
+    System.getProperty("eclipse.product") != null ||
+    startParameter.taskNames.any { it.startsWith("eclipse") }
+
+fun Project.requiredDependencyVersion(dependencyName: String): String =
+  requiredDependency(dependencyName).version!!
+
+fun Project.requiredDependencyPreferredVersion(dependencyName: String): String =
+  requiredDependency(dependencyName).versionConstraint.preferredVersion
+
+fun Project.requiredDependency(dependencyName: String): MinimalExternalModuleDependency {
+  val versionCatalog = extensions.getByType<VersionCatalogsExtension>().named("libs")
+  val dependency =
+    versionCatalog.findLibrary(dependencyName).orElseThrow {
+      IllegalStateException("No library '$dependencyName' defined in version catalog 'libs'")
+    }
+  return dependency.get()
+}
+
+/** Forces all [Test] tasks to use the given Java version. */
+fun Project.forceJavaVersionForTests(requestedJavaVersion: Int) {
+  if (requestedJavaVersion > 0) {
+    tasks.withType(Test::class.java).configureEach {
+      val currentJavaVersion = JavaVersion.current().majorVersion.toInt()
+      if (requestedJavaVersion != currentJavaVersion) {
+        useJavaVersion(requestedJavaVersion)
+      }
+    }
+  }
+}
+
+fun Test.useJavaVersion(requestedJavaVersion: Int) {
+  val javaToolchains = project.extensions.findByType(JavaToolchainService::class.java)
+  logger.info("Configuring Java $requestedJavaVersion for $path test execution")
+  javaLauncher.set(
+    javaToolchains!!.launcherFor {
+      languageVersion.set(JavaLanguageVersion.of(requestedJavaVersion))
+    }
+  )
+}
diff --git a/codestyle/scalafmt.conf b/codestyle/scalafmt.conf
new file mode 100644
index 0000000000..d02567b9ae
--- /dev/null
+++ b/codestyle/scalafmt.conf
@@ -0,0 +1,42 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+version = 3.9.4
+runner.dialect = scala213
+
+maxColumn = 100
+
+preset = default
+align.preset = some
+
+assumeStandardLibraryStripMargin = true
+align.stripMargin = true
+
+rewrite.rules = [
+  AvoidInfix
+  RedundantBraces
+  RedundantParens
+  SortModifiers
+  PreferCurlyFors
+  Imports
+]
+
+rewrite.imports.sort = original
+docstrings.style = Asterisk
+docstrings.wrap = fold
diff --git a/gradle/libs.versions.toml b/gradle/libs.versions.toml
index 4e569e27dd..f70ad6e28a 100644
--- a/gradle/libs.versions.toml
+++ b/gradle/libs.versions.toml
@@ -23,8 +23,7 @@ iceberg = "1.7.1"
 quarkus = "3.19.3"
 immutables = "2.10.1"
 picocli = "4.7.6"
-scala212 = "2.12.19"
-spark35 = "3.5.5"
+scalafmt = "3.9.4"
 slf4j = "2.0.17"
 swagger = "1.6.15"
 
@@ -82,19 +81,29 @@ picocli-codegen = { module = "info.picocli:picocli-codegen", version.ref = "pico
 postgresql = { module = "org.postgresql:postgresql", version = "42.7.5" }
 prometheus-metrics-exporter-servlet-jakarta = { module = "io.prometheus:prometheus-metrics-exporter-servlet-jakarta", version = "1.3.6" }
 quarkus-bom = { module = "io.quarkus.platform:quarkus-bom", version.ref = "quarkus" }
-scala212-lang-library = { module = "org.scala-lang:scala-library", version.ref = "scala212" }
-scala212-lang-reflect = { module = "org.scala-lang:scala-reflect", version.ref = "scala212" }
+scalafmt = { module = "org.scalameta:scalafmt-core_2.13", version = "3.9.4" }
 s3mock-testcontainers = { module = "com.adobe.testing:s3mock-testcontainers", version = "3.12.0" }
 slf4j-api = { module = "org.slf4j:slf4j-api", version.ref = "slf4j" }
 smallrye-common-annotation = { module = "io.smallrye.common:smallrye-common-annotation", version = "2.10.0" }
 smallrye-config-core = { module = "io.smallrye.config:smallrye-config-core", version = "3.12.3" }
-spark35-sql-scala212 = { module = "org.apache.spark:spark-sql_2.12", version.ref = "spark35" }
 spotbugs-annotations = { module = "com.github.spotbugs:spotbugs-annotations", version = "4.9.3" }
 swagger-annotations = { module = "io.swagger:swagger-annotations", version.ref = "swagger" }
 swagger-jaxrs = { module = "io.swagger:swagger-jaxrs", version.ref = "swagger" }
 testcontainers-bom = { module = "org.testcontainers:testcontainers-bom", version = "1.20.6" }
 threeten-extra = { module = "org.threeten:threeten-extra", version = "1.8.0" }
 
+# Scala 2.12
+scala212-lang-library = { module = "org.scala-lang:scala-library", version = { strictly = "[2.12, 2.13[", prefer = "2.12.20" }}
+scala212-lang-reflect = { module = "org.scala-lang:scala-reflect", version = { strictly = "[2.12, 2.13[", prefer = "2.12.20" }}
+# Scala 2.13
+scala213-lang-library = { module = "org.scala-lang:scala-library", version = { strictly = "[2.13, 2.14[", prefer = "2.13.16" }}
+scala213-lang-reflect = { module = "org.scala-lang:scala-reflect", version = { strictly = "[2.13, 2.14[", prefer = "2.13.16" }}
+# Spark deps
+spark34-sql-scala212 = { module = "org.apache.spark:spark-sql_2.12", version = { strictly = "[3.4, 3.5[", prefer = "3.4.4"}}
+spark34-sql-scala213 = { module = "org.apache.spark:spark-sql_2.13", version = { strictly = "[3.4, 3.5[", prefer = "3.4.4"}}
+spark35-sql-scala212 = { module = "org.apache.spark:spark-sql_2.12", version = { strictly = "[3.5, 3.6[", prefer = "3.5.5"}}
+spark35-sql-scala213 = { module = "org.apache.spark:spark-sql_2.13", version = { strictly = "[3.5, 3.6[", prefer = "3.5.5"}}
+
 [plugins]
 jandex = { id = "org.kordamp.gradle.jandex", version = "2.1.0" }
 openapi-generator = { id = "org.openapi.generator", version = "7.12.0" }
diff --git a/integrations/demo/build.gradle.kts b/integrations/demo/build.gradle.kts
new file mode 100644
index 0000000000..b7ba6ab695
--- /dev/null
+++ b/integrations/demo/build.gradle.kts
@@ -0,0 +1,22 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+plugins { id("polaris-spark") }
+
+val scalaVersions = prepareScalaProject()
diff --git a/integrations/demo/src/main/scala/org/apache/polaris/scalademo/SomeScala.scala b/integrations/demo/src/main/scala/org/apache/polaris/scalademo/SomeScala.scala
new file mode 100644
index 0000000000..b27f81ff3e
--- /dev/null
+++ b/integrations/demo/src/main/scala/org/apache/polaris/scalademo/SomeScala.scala
@@ -0,0 +1,21 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.scalademo
+
+class SomeScala {}
diff --git a/integrations/spark-scala.properties b/integrations/spark-scala.properties
new file mode 100644
index 0000000000..49909cbae1
--- /dev/null
+++ b/integrations/spark-scala.properties
@@ -0,0 +1,35 @@
+#
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+#
+
+sparkVersions=3.5,3.4
+
+# Hint: the first Scala version in the list(s) is the one used in IDEs
+sparkVersion-3.4-scalaVersions=2.12,2.13
+sparkVersion-3.5-scalaVersions=2.12,2.13
+# Scala versions for non-Spark Scala projects
+allScalaVersions=2.12,2.13
+
+# Spark+Scala projects (comma separated)
+sparkProjects=spark
+# Non-Spark Scala projects (comma separated)
+scalaProjects=demo
+
+# Artifact IDs for the above projects
+project.demo.artifact-id-prefix=polaris-scala-demo
+project.spark.artifact-id-prefix=polaris-spark-plugin
diff --git a/integrations/spark/build.gradle.kts b/integrations/spark/build.gradle.kts
new file mode 100644
index 0000000000..18f631e04b
--- /dev/null
+++ b/integrations/spark/build.gradle.kts
@@ -0,0 +1,37 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+
+plugins {
+    id("polaris-spark")
+}
+
+val sparkScala = prepareSparkScalaProject()
+
+dependencies {
+  compileOnly("org.apache.spark:spark-sql_${sparkScala.scalaMajorMinorVersion}") { sparkDependencyAndExcludes(sparkScala) }
+
+  implementation(platform(libs.iceberg.bom))
+  implementation("org.apache.iceberg:iceberg-spark-runtime-${sparkScala.sparkMajorMinorVersion}_${sparkScala.scalaMajorMinorVersion}")
+
+  implementation(project(":polaris-scala-demo_${sparkScala.scalaMajorMinorVersion}"))
+
+  compileOnly("org.apache.iceberg:iceberg-spark-${sparkScala.sparkMajorMinorVersion}_${sparkScala.scalaMajorMinorVersion}")
+
+  testImplementation("org.apache.spark:spark-sql_${sparkScala.scalaMajorMinorVersion}") { sparkDependencyAndExcludes(sparkScala) }
+}
diff --git a/integrations/spark/v3.4/src/main/java/org/apache/polaris/sparkplugin/JavaStuff.java b/integrations/spark/v3.4/src/main/java/org/apache/polaris/sparkplugin/JavaStuff.java
new file mode 100644
index 0000000000..018ad1cf90
--- /dev/null
+++ b/integrations/spark/v3.4/src/main/java/org/apache/polaris/sparkplugin/JavaStuff.java
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import org.apache.polaris.scalademo.SomeScala;
+
+public class JavaStuff {
+  public SomeScala someScala = new SomeScala();
+}
diff --git a/integrations/spark/v3.4/src/main/java/org/apache/polaris/sparkplugin/SparkCatalog.java b/integrations/spark/v3.4/src/main/java/org/apache/polaris/sparkplugin/SparkCatalog.java
new file mode 100644
index 0000000000..c9329c5eb1
--- /dev/null
+++ b/integrations/spark/v3.4/src/main/java/org/apache/polaris/sparkplugin/SparkCatalog.java
@@ -0,0 +1,161 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import com.google.common.collect.ImmutableSet;
+import java.util.Map;
+import java.util.Set;
+import org.apache.iceberg.exceptions.NoSuchTableException;
+import org.apache.spark.sql.catalyst.analysis.*;
+import org.apache.spark.sql.connector.catalog.*;
+import org.apache.spark.sql.connector.expressions.Transform;
+import org.apache.spark.sql.types.StructType;
+import org.apache.spark.sql.util.CaseInsensitiveStringMap;
+
+public class SparkCatalog implements TableCatalog, SupportsNamespaces, ViewCatalog {
+  private static final Set<String> DEFAULT_NS_KEYS = ImmutableSet.of(TableCatalog.PROP_OWNER);
+  private String catalogName = null;
+  private org.apache.iceberg.spark.SparkCatalog icebergsSparkCatalog = null;
+
+  // TODO: Add Polaris Specific REST Catalog
+
+  @Override
+  public String name() {
+    return catalogName;
+  }
+
+  @Override
+  public void initialize(String name, CaseInsensitiveStringMap options) {
+    this.catalogName = name;
+  }
+
+  @Override
+  public Table loadTable(Identifier ident) throws NoSuchTableException {
+    throw new UnsupportedOperationException("loadTable");
+  }
+
+  @Override
+  public Table createTable(
+      Identifier ident, StructType schema, Transform[] transforms, Map<String, String> properties)
+      throws TableAlreadyExistsException {
+    throw new UnsupportedOperationException("createTable");
+  }
+
+  @Override
+  public Table alterTable(Identifier ident, TableChange... changes) throws NoSuchTableException {
+    throw new UnsupportedOperationException("alterTable");
+  }
+
+  @Override
+  public boolean dropTable(Identifier ident) {
+    throw new UnsupportedOperationException("dropTable");
+  }
+
+  @Override
+  public void renameTable(Identifier from, Identifier to)
+      throws NoSuchTableException, TableAlreadyExistsException {
+    throw new UnsupportedOperationException("renameTable");
+  }
+
+  @Override
+  public Identifier[] listTables(String[] namespace) {
+    throw new UnsupportedOperationException("listTables");
+  }
+
+  @Override
+  public String[] defaultNamespace() {
+    throw new UnsupportedOperationException("defaultNamespace");
+  }
+
+  @Override
+  public String[][] listNamespaces() {
+    throw new UnsupportedOperationException("listNamespaces");
+  }
+
+  @Override
+  public String[][] listNamespaces(String[] namespace) throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("listNamespaces");
+  }
+
+  @Override
+  public Map<String, String> loadNamespaceMetadata(String[] namespace)
+      throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("loadNamespaceMetadata");
+  }
+
+  @Override
+  public void createNamespace(String[] namespace, Map<String, String> metadata)
+      throws NamespaceAlreadyExistsException {
+    throw new UnsupportedOperationException("createNamespace");
+  }
+
+  @Override
+  public void alterNamespace(String[] namespace, NamespaceChange... changes)
+      throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("alterNamespace");
+  }
+
+  @Override
+  public boolean dropNamespace(String[] namespace, boolean cascade)
+      throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("dropNamespace");
+  }
+
+  @Override
+  public Identifier[] listViews(String... namespace) {
+    throw new UnsupportedOperationException("listViews");
+  }
+
+  @Override
+  public View loadView(Identifier ident) throws NoSuchViewException {
+    throw new UnsupportedOperationException("loadView");
+  }
+
+  @Override
+  public View createView(
+      Identifier ident,
+      String sql,
+      String currentCatalog,
+      String[] currentNamespace,
+      StructType schema,
+      String[] queryColumnNames,
+      String[] columnAliases,
+      String[] columnComments,
+      Map<String, String> properties)
+      throws ViewAlreadyExistsException, NoSuchNamespaceException {
+    throw new UnsupportedOperationException("createView");
+  }
+
+  @Override
+  public View alterView(Identifier ident, ViewChange... changes)
+      throws NoSuchViewException, IllegalArgumentException {
+    throw new UnsupportedOperationException("alterView");
+  }
+
+  @Override
+  public boolean dropView(Identifier ident) {
+    throw new UnsupportedOperationException("dropView");
+  }
+
+  @Override
+  public void renameView(Identifier fromIdentifier, Identifier toIdentifier)
+      throws NoSuchViewException, ViewAlreadyExistsException {
+    throw new UnsupportedOperationException("renameView");
+  }
+}
diff --git a/integrations/spark/v3.4/src/main/scala/org/apache/polaris/sparkplugin/ScalaStuff.scala b/integrations/spark/v3.4/src/main/scala/org/apache/polaris/sparkplugin/ScalaStuff.scala
new file mode 100644
index 0000000000..e3af3ebba0
--- /dev/null
+++ b/integrations/spark/v3.4/src/main/scala/org/apache/polaris/sparkplugin/ScalaStuff.scala
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin
+
+import org.apache.polaris.scalademo.SomeScala
+
+class ScalaStuff {
+  new SomeScala()
+}
diff --git a/integrations/spark/v3.4/src/test/java/org/apache/polaris/sparkplugin/SparkCatalogTest.java b/integrations/spark/v3.4/src/test/java/org/apache/polaris/sparkplugin/SparkCatalogTest.java
new file mode 100644
index 0000000000..57666468f8
--- /dev/null
+++ b/integrations/spark/v3.4/src/test/java/org/apache/polaris/sparkplugin/SparkCatalogTest.java
@@ -0,0 +1,97 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import static org.apache.iceberg.CatalogProperties.CATALOG_IMPL;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.Map;
+import java.util.UUID;
+import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.spark.sql.connector.catalog.Identifier;
+import org.apache.spark.sql.types.StructType;
+import org.apache.spark.sql.util.CaseInsensitiveStringMap;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+public class SparkCatalogTest {
+  private SparkCatalog catalog;
+  private String catalogName;
+
+  @BeforeEach
+  public void setup() {
+    catalogName = "test_" + UUID.randomUUID();
+    Map<String, String> catalogConfig = Maps.newHashMap();
+    catalogConfig.put(CATALOG_IMPL, "org.apache.iceberg.inmemory.InMemoryCatalog");
+    catalogConfig.put("cache-enabled", "false");
+    catalog = new SparkCatalog();
+    catalog.initialize(catalogName, new CaseInsensitiveStringMap(catalogConfig));
+  }
+
+  @Test
+  public void testUnsupportedOperations() {
+    String[] namespace = new String[] {"ns1"};
+    Identifier identifier = Identifier.of(namespace, "table1");
+    Identifier new_identifier = Identifier.of(namespace, "table2");
+    // table methods
+    assertThatThrownBy(() -> catalog.loadTable(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(
+            () -> catalog.createTable(identifier, Mockito.mock(StructType.class), null, null))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.alterTable(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.dropTable(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.renameTable(identifier, new_identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.listTables(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+
+    // namespace methods
+    assertThatThrownBy(() -> catalog.loadNamespaceMetadata(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.listNamespaces())
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.listNamespaces(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.createNamespace(namespace, null))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.alterNamespace(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.dropNamespace(namespace, false))
+        .isInstanceOf(UnsupportedOperationException.class);
+
+    // view methods
+    assertThatThrownBy(() -> catalog.listViews(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.loadView(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(
+            () -> catalog.createView(identifier, null, null, null, null, null, null, null, null))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.alterView(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.dropView(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.renameView(identifier, new_identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+  }
+}
diff --git a/integrations/spark/v3.4/src/test/java/org/apache/polaris/sparkplugin/TestStuff.java b/integrations/spark/v3.4/src/test/java/org/apache/polaris/sparkplugin/TestStuff.java
new file mode 100644
index 0000000000..ffee405ae4
--- /dev/null
+++ b/integrations/spark/v3.4/src/test/java/org/apache/polaris/sparkplugin/TestStuff.java
@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import org.junit.jupiter.api.Test;
+
+public class TestStuff {
+  @Test
+  public void javaStuff() {
+    new JavaStuff();
+  }
+
+  @Test
+  public void scalaStuff() {
+    new ScalaStuff();
+  }
+}
diff --git a/integrations/spark/v3.5/src/main/java/org/apache/polaris/sparkplugin/JavaStuff.java b/integrations/spark/v3.5/src/main/java/org/apache/polaris/sparkplugin/JavaStuff.java
new file mode 100644
index 0000000000..018ad1cf90
--- /dev/null
+++ b/integrations/spark/v3.5/src/main/java/org/apache/polaris/sparkplugin/JavaStuff.java
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import org.apache.polaris.scalademo.SomeScala;
+
+public class JavaStuff {
+  public SomeScala someScala = new SomeScala();
+}
diff --git a/integrations/spark/v3.5/src/main/java/org/apache/polaris/sparkplugin/SparkCatalog.java b/integrations/spark/v3.5/src/main/java/org/apache/polaris/sparkplugin/SparkCatalog.java
new file mode 100644
index 0000000000..c9329c5eb1
--- /dev/null
+++ b/integrations/spark/v3.5/src/main/java/org/apache/polaris/sparkplugin/SparkCatalog.java
@@ -0,0 +1,161 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import com.google.common.collect.ImmutableSet;
+import java.util.Map;
+import java.util.Set;
+import org.apache.iceberg.exceptions.NoSuchTableException;
+import org.apache.spark.sql.catalyst.analysis.*;
+import org.apache.spark.sql.connector.catalog.*;
+import org.apache.spark.sql.connector.expressions.Transform;
+import org.apache.spark.sql.types.StructType;
+import org.apache.spark.sql.util.CaseInsensitiveStringMap;
+
+public class SparkCatalog implements TableCatalog, SupportsNamespaces, ViewCatalog {
+  private static final Set<String> DEFAULT_NS_KEYS = ImmutableSet.of(TableCatalog.PROP_OWNER);
+  private String catalogName = null;
+  private org.apache.iceberg.spark.SparkCatalog icebergsSparkCatalog = null;
+
+  // TODO: Add Polaris Specific REST Catalog
+
+  @Override
+  public String name() {
+    return catalogName;
+  }
+
+  @Override
+  public void initialize(String name, CaseInsensitiveStringMap options) {
+    this.catalogName = name;
+  }
+
+  @Override
+  public Table loadTable(Identifier ident) throws NoSuchTableException {
+    throw new UnsupportedOperationException("loadTable");
+  }
+
+  @Override
+  public Table createTable(
+      Identifier ident, StructType schema, Transform[] transforms, Map<String, String> properties)
+      throws TableAlreadyExistsException {
+    throw new UnsupportedOperationException("createTable");
+  }
+
+  @Override
+  public Table alterTable(Identifier ident, TableChange... changes) throws NoSuchTableException {
+    throw new UnsupportedOperationException("alterTable");
+  }
+
+  @Override
+  public boolean dropTable(Identifier ident) {
+    throw new UnsupportedOperationException("dropTable");
+  }
+
+  @Override
+  public void renameTable(Identifier from, Identifier to)
+      throws NoSuchTableException, TableAlreadyExistsException {
+    throw new UnsupportedOperationException("renameTable");
+  }
+
+  @Override
+  public Identifier[] listTables(String[] namespace) {
+    throw new UnsupportedOperationException("listTables");
+  }
+
+  @Override
+  public String[] defaultNamespace() {
+    throw new UnsupportedOperationException("defaultNamespace");
+  }
+
+  @Override
+  public String[][] listNamespaces() {
+    throw new UnsupportedOperationException("listNamespaces");
+  }
+
+  @Override
+  public String[][] listNamespaces(String[] namespace) throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("listNamespaces");
+  }
+
+  @Override
+  public Map<String, String> loadNamespaceMetadata(String[] namespace)
+      throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("loadNamespaceMetadata");
+  }
+
+  @Override
+  public void createNamespace(String[] namespace, Map<String, String> metadata)
+      throws NamespaceAlreadyExistsException {
+    throw new UnsupportedOperationException("createNamespace");
+  }
+
+  @Override
+  public void alterNamespace(String[] namespace, NamespaceChange... changes)
+      throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("alterNamespace");
+  }
+
+  @Override
+  public boolean dropNamespace(String[] namespace, boolean cascade)
+      throws NoSuchNamespaceException {
+    throw new UnsupportedOperationException("dropNamespace");
+  }
+
+  @Override
+  public Identifier[] listViews(String... namespace) {
+    throw new UnsupportedOperationException("listViews");
+  }
+
+  @Override
+  public View loadView(Identifier ident) throws NoSuchViewException {
+    throw new UnsupportedOperationException("loadView");
+  }
+
+  @Override
+  public View createView(
+      Identifier ident,
+      String sql,
+      String currentCatalog,
+      String[] currentNamespace,
+      StructType schema,
+      String[] queryColumnNames,
+      String[] columnAliases,
+      String[] columnComments,
+      Map<String, String> properties)
+      throws ViewAlreadyExistsException, NoSuchNamespaceException {
+    throw new UnsupportedOperationException("createView");
+  }
+
+  @Override
+  public View alterView(Identifier ident, ViewChange... changes)
+      throws NoSuchViewException, IllegalArgumentException {
+    throw new UnsupportedOperationException("alterView");
+  }
+
+  @Override
+  public boolean dropView(Identifier ident) {
+    throw new UnsupportedOperationException("dropView");
+  }
+
+  @Override
+  public void renameView(Identifier fromIdentifier, Identifier toIdentifier)
+      throws NoSuchViewException, ViewAlreadyExistsException {
+    throw new UnsupportedOperationException("renameView");
+  }
+}
diff --git a/integrations/spark/v3.5/src/main/scala/org/apache/polaris/sparkplugin/ScalaStuff.scala b/integrations/spark/v3.5/src/main/scala/org/apache/polaris/sparkplugin/ScalaStuff.scala
new file mode 100644
index 0000000000..e3af3ebba0
--- /dev/null
+++ b/integrations/spark/v3.5/src/main/scala/org/apache/polaris/sparkplugin/ScalaStuff.scala
@@ -0,0 +1,25 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin
+
+import org.apache.polaris.scalademo.SomeScala
+
+class ScalaStuff {
+  new SomeScala()
+}
diff --git a/integrations/spark/v3.5/src/test/java/org/apache/polaris/sparkplugin/SparkCatalogTest.java b/integrations/spark/v3.5/src/test/java/org/apache/polaris/sparkplugin/SparkCatalogTest.java
new file mode 100644
index 0000000000..57666468f8
--- /dev/null
+++ b/integrations/spark/v3.5/src/test/java/org/apache/polaris/sparkplugin/SparkCatalogTest.java
@@ -0,0 +1,97 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import static org.apache.iceberg.CatalogProperties.CATALOG_IMPL;
+import static org.assertj.core.api.Assertions.assertThatThrownBy;
+
+import java.util.Map;
+import java.util.UUID;
+import org.apache.iceberg.relocated.com.google.common.collect.Maps;
+import org.apache.spark.sql.connector.catalog.Identifier;
+import org.apache.spark.sql.types.StructType;
+import org.apache.spark.sql.util.CaseInsensitiveStringMap;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+public class SparkCatalogTest {
+  private SparkCatalog catalog;
+  private String catalogName;
+
+  @BeforeEach
+  public void setup() {
+    catalogName = "test_" + UUID.randomUUID();
+    Map<String, String> catalogConfig = Maps.newHashMap();
+    catalogConfig.put(CATALOG_IMPL, "org.apache.iceberg.inmemory.InMemoryCatalog");
+    catalogConfig.put("cache-enabled", "false");
+    catalog = new SparkCatalog();
+    catalog.initialize(catalogName, new CaseInsensitiveStringMap(catalogConfig));
+  }
+
+  @Test
+  public void testUnsupportedOperations() {
+    String[] namespace = new String[] {"ns1"};
+    Identifier identifier = Identifier.of(namespace, "table1");
+    Identifier new_identifier = Identifier.of(namespace, "table2");
+    // table methods
+    assertThatThrownBy(() -> catalog.loadTable(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(
+            () -> catalog.createTable(identifier, Mockito.mock(StructType.class), null, null))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.alterTable(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.dropTable(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.renameTable(identifier, new_identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.listTables(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+
+    // namespace methods
+    assertThatThrownBy(() -> catalog.loadNamespaceMetadata(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.listNamespaces())
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.listNamespaces(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.createNamespace(namespace, null))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.alterNamespace(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.dropNamespace(namespace, false))
+        .isInstanceOf(UnsupportedOperationException.class);
+
+    // view methods
+    assertThatThrownBy(() -> catalog.listViews(namespace))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.loadView(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(
+            () -> catalog.createView(identifier, null, null, null, null, null, null, null, null))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.alterView(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.dropView(identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+    assertThatThrownBy(() -> catalog.renameView(identifier, new_identifier))
+        .isInstanceOf(UnsupportedOperationException.class);
+  }
+}
diff --git a/integrations/spark/v3.5/src/test/java/org/apache/polaris/sparkplugin/TestStuff.java b/integrations/spark/v3.5/src/test/java/org/apache/polaris/sparkplugin/TestStuff.java
new file mode 100644
index 0000000000..ffee405ae4
--- /dev/null
+++ b/integrations/spark/v3.5/src/test/java/org/apache/polaris/sparkplugin/TestStuff.java
@@ -0,0 +1,33 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one
+ * or more contributor license agreements.  See the NOTICE file
+ * distributed with this work for additional information
+ * regarding copyright ownership.  The ASF licenses this file
+ * to you under the Apache License, Version 2.0 (the
+ * "License"); you may not use this file except in compliance
+ * with the License.  You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.apache.polaris.sparkplugin;
+
+import org.junit.jupiter.api.Test;
+
+public class TestStuff {
+  @Test
+  public void javaStuff() {
+    new JavaStuff();
+  }
+
+  @Test
+  public void scalaStuff() {
+    new ScalaStuff();
+  }
+}
diff --git a/settings.gradle.kts b/settings.gradle.kts
index 707592ead1..04d04fff80 100644
--- a/settings.gradle.kts
+++ b/settings.gradle.kts
@@ -44,19 +44,82 @@ fun loadProperties(file: File): Properties {
   return props
 }
 
-fun polarisProject(name: String, directory: File) {
+fun listFromProperty(props: Properties, key: String): List<String> {
+  val prop = props[key]
+  return prop.toString().split(',').filter { it.isNotBlank() }.map { it.trim() }
+}
+
+fun polarisProject(name: String, directory: File): ProjectDescriptor {
   include(name)
   val prj = project(":${name}")
   prj.name = name
   prj.projectDir = file(directory)
+  return prj
 }
 
-val projects = Properties()
-
 loadProperties(file("gradle/projects.main.properties")).forEach { name, directory ->
   polarisProject(name as String, file(directory as String))
 }
 
+val ideSyncActive =
+  System.getProperty("idea.sync.active").toBoolean() ||
+    System.getProperty("eclipse.product") != null ||
+    gradle.startParameter.taskNames.any { it.startsWith("eclipse") }
+
+// Setup Spark/Scala projects
+
+val projectsWithReusedSourceDirs = mutableSetOf<String>()
+val sparkScala = loadProperties(file("integrations/spark-scala.properties"))
+
+val sparkVersions = listFromProperty(sparkScala, "sparkVersions")
+
+for (sparkVersion in sparkVersions) {
+  val scalaVersions =
+    sparkScala["sparkVersion-${sparkVersion}-scalaVersions"].toString().split(",").map { it.trim() }
+  var first = true
+  for (scalaVersion in scalaVersions) {
+    for (prj in listFromProperty(sparkScala, "sparkProjects")) {
+      val artifactIdPrefix = sparkScala["project.$prj.artifact-id-prefix"].toString()
+      val artifactId = "$artifactIdPrefix-${sparkVersion}_$scalaVersion"
+      if (first) {
+        first = false
+      } else {
+        projectsWithReusedSourceDirs.add(":$artifactId")
+      }
+      polarisProject(artifactId, file("integrations/$prj/v${sparkVersion}")).buildFileName =
+        "../build.gradle.kts"
+    }
+    if (ideSyncActive) {
+      break
+    }
+  }
+}
+
+// Setup Spark/Scala and "pure" Scala projects
+
+val allScalaVersions = listFromProperty(sparkScala, "allScalaVersions")
+
+var first = true
+
+for (scalaVersion in allScalaVersions) {
+  for (prj in listFromProperty(sparkScala, "scalaProjects")) {
+    val name = sparkScala["project.$prj.artifact-id-prefix"].toString()
+    val artifactId = "${name}_$scalaVersion"
+    if (!first) {
+      projectsWithReusedSourceDirs.add(":$artifactId")
+    }
+    polarisProject(artifactId, file("integrations/$prj"))
+  }
+  if (first) {
+    first = false
+  }
+  if (ideSyncActive) {
+    break
+  }
+}
+
+// Plugin, dependency management, etc
+
 pluginManagement {
   repositories {
     mavenCentral() // prefer Maven Central, in case Gradle's repo has issues
@@ -75,4 +138,9 @@ dependencyResolutionManagement {
 gradle.beforeProject {
   version = baseVersion
   group = "org.apache.polaris"
+
+  // Mark projects that reuse source directories, so those do not re-run spotless, errorprone, etc
+  if (projectsWithReusedSourceDirs.contains(this.path)) {
+    project.extra["reused-project-dir"] = true
+  }
 }