diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index e1b891487..30f9a2af8 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -168,7 +168,7 @@ jobs:
         echo "-Xmx2g" > .mill-jvm-opts
         cat .mill-jvm-opts.bak | grep -v Xmx >> .mill-jvm-opts
         # sometimes running into memory issues when attempting __.publishLocal upfront
-        for SV in $(./mill scalaVersions); do
+        for SV in $(./mill dev.scalaVersions); do
           ./mill -i '__['"$SV"'].compile'
           ./mill -i '__['"$SV"'].docJar'
           ./mill -i '__['"$SV"'].publishLocal'
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 55471dbfe..7db8f481b 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -27,13 +27,13 @@ jobs:
         mv .mill-jvm-opts .mill-jvm-opts.bak
         cat .mill-jvm-opts.bak | grep -v Xmx > .mill-jvm-opts
         # sometimes running into memory issues when attempting __.publishLocal or __.publishArtifacts upfront
-        for SV in $(./mill scalaVersions); do
+        for SV in $(./mill dev.scalaVersions); do
           ./mill -i '__['"$SV"'].compile'
           ./mill -i '__['"$SV"'].docJar'
           ./mill -i '__['"$SV"'].publishLocal'
         done
         ./mill -i __.publishLocal
-        ./mill -i publishSonatype __.publishArtifacts
+        ./mill -i ci.publishSonatype __.publishArtifacts
       shell: bash
       env:
         PGP_PASSWORD: ${{ secrets.PUBLISH_SECRET_KEY_PASSWORD }}
diff --git a/build.sc b/build.sc
index 04eec3c90..e2e1c9fed 100644
--- a/build.sc
+++ b/build.sc
@@ -3,7 +3,7 @@ import $ivy.`io.get-coursier.util::get-cs:0.1.1`
 import $ivy.`com.github.lolgab::mill-mima::0.0.24`
 import $ivy.`io.github.alexarchambault.mill::mill-native-image-upload:0.1.24`
 
-import $file.project.deps, deps.{Deps, DepOps, ScalaVersions}
+import $file.project.deps, deps.{Deps, DepOps, ScalaVersions, Versions}
 import $file.project.jupyterserver, jupyterserver.{jupyterConsole => jupyterConsole0, jupyterServer}
 import $file.scripts.website0.Website, Website.Relativize
 import $file.project.settings, settings.{
@@ -33,17 +33,19 @@ import _root_.scala.concurrent.duration._
 import _root_.scala.util.Properties
 
 // Tell mill modules are under modules/
-implicit def millModuleBasePath: define.BasePath =
-  define.BasePath(super.millModuleBasePath.value / "modules")
+implicit def millModuleBasePath: define.Ctx.BasePath =
+  define.Ctx.BasePath(super.millModuleBasePath.value / "modules")
 
-class LoggerScala2Macros(val crossScalaVersion: String) extends AlmondModule {
+trait LoggerScala2Macros extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def ivyDeps = T {
     val sv = scalaVersion()
     Agg(Deps.scalaReflect(sv))
   }
 }
 
-class Logger(val crossScalaVersion: String) extends AlmondModule {
+trait Logger extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def supports3 = true
   def moduleDeps = Seq(
     shared.`logger-scala2-macros`()
@@ -55,10 +57,11 @@ class Logger(val crossScalaVersion: String) extends AlmondModule {
       else Agg(ivy"org.scala-lang:scala3-library_3:${scalaVersion()}")
     scalaReflect
   }
-  object test extends Tests with AlmondTestModule
+  object test extends CrossSbtModuleTests with AlmondTestModule
 }
 
-class Channels(val crossScalaVersion: String) extends AlmondModule with Mima {
+trait Channels extends Cross.Module[String] with AlmondModule with Mima {
+  def crossScalaVersion = crossValue
   def moduleDeps = Seq(
     shared.logger()
   )
@@ -66,10 +69,11 @@ class Channels(val crossScalaVersion: String) extends AlmondModule with Mima {
     Deps.fs2(crossScalaVersion),
     Deps.jeromq
   )
-  object test extends Tests with AlmondTestModule
+  object test extends CrossSbtModuleTests with AlmondTestModule
 }
 
-class Protocol(val crossScalaVersion: String) extends AlmondModule {
+trait Protocol extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def moduleDeps = Seq(
     shared.channels()
   )
@@ -80,12 +84,15 @@ class Protocol(val crossScalaVersion: String) extends AlmondModule {
     Deps.scalaReflect(scalaVersion()),
     Deps.jsoniterScalaMacros.withConfiguration("provided")
   )
-  object test extends Tests with AlmondTestModule
+  object test extends CrossSbtModuleTests with AlmondTestModule
 }
 
-class InterpreterApi(val crossScalaVersion: String) extends AlmondModule with Mima
+trait InterpreterApi extends Cross.Module[String] with AlmondModule with Mima {
+  def crossScalaVersion = crossValue
+}
 
-class Interpreter(val crossScalaVersion: String) extends AlmondModule {
+trait Interpreter extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def moduleDeps = Seq(
     shared.`interpreter-api`(),
     shared.protocol()
@@ -96,10 +103,11 @@ class Interpreter(val crossScalaVersion: String) extends AlmondModule {
     Deps.scalatags.applyBinaryVersion213_3(scalaVersion()),
     Deps.slf4jNop
   )
-  object test extends Tests with AlmondTestModule
+  object test extends CrossSbtModuleTests with AlmondTestModule
 }
 
-class Kernel(val crossScalaVersion: String) extends AlmondModule {
+trait Kernel extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def moduleDeps = Seq(
     shared.interpreter()
   )
@@ -112,7 +120,7 @@ class Kernel(val crossScalaVersion: String) extends AlmondModule {
     Deps.coursierApi,
     Deps.fs2(crossScalaVersion)
   )
-  object test extends Tests with AlmondTestModule {
+  object test extends CrossSbtModuleTests with AlmondTestModule {
     def moduleDeps = super.moduleDeps ++ Seq(
       shared.interpreter().test,
       shared.`test-kit`()
@@ -120,13 +128,15 @@ class Kernel(val crossScalaVersion: String) extends AlmondModule {
   }
 }
 
-class Test(val crossScalaVersion: String) extends AlmondModule {
+trait Test extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def moduleDeps = Seq(
     shared.`interpreter-api`()
   )
 }
 
-class JupyterApi(val crossScalaVersion: String) extends AlmondModule with Mima {
+trait JupyterApi extends Cross.Module[String] with AlmondModule with Mima {
+  def crossScalaVersion = crossValue
   def moduleDeps = Seq(
     shared.`interpreter-api`()
   )
@@ -135,8 +145,9 @@ class JupyterApi(val crossScalaVersion: String) extends AlmondModule with Mima {
   )
 }
 
-class ScalaKernelApi(val crossScalaVersion: String) extends AlmondModule with DependencyListResource
+trait ScalaKernelApi extends Cross.Module[String] with AlmondModule with DependencyListResource
     with ExternalSources with PropertyFile with Mima with Bloop.Module {
+  def crossScalaVersion = crossValue
   def skipBloop             = !ScalaVersions.binaries.contains(crossScalaVersion)
   def crossFullScalaVersion = true
   def moduleDeps =
@@ -184,7 +195,8 @@ class ScalaKernelApi(val crossScalaVersion: String) extends AlmondModule with De
   }
 }
 
-class ScalaInterpreter(val crossScalaVersion: String) extends AlmondModule with Bloop.Module {
+trait ScalaInterpreter extends Cross.Module[String] with AlmondModule with Bloop.Module {
+  def crossScalaVersion = crossValue
   def skipBloop             = !ScalaVersions.binaries.contains(crossScalaVersion)
   def crossFullScalaVersion = true
   def supports3             = true
@@ -234,7 +246,7 @@ class ScalaInterpreter(val crossScalaVersion: String) extends AlmondModule with
       else Nil
     scala213Options
   }
-  object test extends Tests with AlmondTestModule {
+  object test extends CrossSbtModuleTests with AlmondTestModule {
     def moduleDeps = {
       val rx =
         if (crossScalaVersion.startsWith("2.12.")) Seq(scala.`almond-rx`())
@@ -269,8 +281,9 @@ class ScalaInterpreter(val crossScalaVersion: String) extends AlmondModule with
   }
 }
 
-class ScalaKernel(val crossScalaVersion: String) extends AlmondModule with ExternalSources
+trait ScalaKernel extends Cross.Module[String] with AlmondModule with ExternalSources
     with BootstrapLauncher with Bloop.Module {
+  def crossScalaVersion = crossValue
   def skipBloop             = !ScalaVersions.binaries.contains(crossScalaVersion)
   def crossFullScalaVersion = true
   def moduleDeps =
@@ -289,7 +302,7 @@ class ScalaKernel(val crossScalaVersion: String) extends AlmondModule with Exter
     Deps.classPathUtil,
     Deps.scalafmtDynamic.withDottyCompat(crossScalaVersion)
   )
-  object test extends Tests with AlmondTestModule {
+  object test extends CrossSbtModuleTests with AlmondTestModule {
     def moduleDeps = super.moduleDeps ++ Seq(
       scala.`scala-interpreter`().test
     )
@@ -357,7 +370,8 @@ class ScalaKernel(val crossScalaVersion: String) extends AlmondModule with Exter
 // depend on the more complex 2.13-targeting-scala-3 module like
 // scala-kernel-cross-3.0.2_2.13.7. The former follows the same name pattern
 // as their Scala 2 counterparts, and are more convenient to write down for end users.
-class ScalaKernelHelper(val crossScalaVersion: String) extends AlmondModule with Bloop.Module {
+trait ScalaKernelHelper extends Cross.Module[String] with AlmondModule with Bloop.Module {
+  def crossScalaVersion = crossValue
   def skipBloop             = !ScalaVersions.binaries.contains(crossScalaVersion)
   def crossFullScalaVersion = true
   def supports3             = true
@@ -367,7 +381,8 @@ class ScalaKernelHelper(val crossScalaVersion: String) extends AlmondModule with
   )
 }
 
-class CoursierLogger(val crossScalaVersion: String) extends AlmondModule {
+trait CoursierLogger extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def supports3 = true
   def moduleDeps = super.moduleDeps ++ Seq(
     shared.`interpreter-api`(),
@@ -379,7 +394,8 @@ class CoursierLogger(val crossScalaVersion: String) extends AlmondModule {
   )
 }
 
-class SharedDirectives(val crossScalaVersion: String) extends AlmondModule {
+trait SharedDirectives extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def supports3 = true
   def ivyDeps = super.ivyDeps() ++ Agg(
     Deps.directiveHandler,
@@ -422,8 +438,9 @@ trait Launcher extends AlmondSimpleModule with BootstrapLauncher with PropertyFi
   }
 }
 
-class ScalaKernelApiHelper(val crossScalaVersion: String) extends AlmondModule with ExternalSources
+trait ScalaKernelApiHelper extends Cross.Module[String] with AlmondModule with ExternalSources
     with Bloop.Module {
+  def crossScalaVersion = crossValue
   def skipBloop             = !ScalaVersions.binaries.contains(crossScalaVersion)
   def crossFullScalaVersion = true
   def supports3             = true
@@ -433,7 +450,8 @@ class ScalaKernelApiHelper(val crossScalaVersion: String) extends AlmondModule w
   )
 }
 
-class AlmondScalaPy(val crossScalaVersion: String) extends AlmondModule with Mima {
+trait AlmondScalaPy extends Cross.Module[String] with AlmondModule with Mima {
+  def crossScalaVersion = crossValue
   def ivyDeps = Agg(
     Deps.jvmRepr
   )
@@ -442,7 +460,8 @@ class AlmondScalaPy(val crossScalaVersion: String) extends AlmondModule with Mim
   )
 }
 
-class AlmondRx(val crossScalaVersion: String) extends AlmondModule with Mima {
+trait AlmondRx extends Cross.Module[String] with AlmondModule with Mima {
+  def crossScalaVersion = crossValue
   def compileModuleDeps = Seq(
     scala.`scala-kernel-api`()
   )
@@ -451,7 +470,8 @@ class AlmondRx(val crossScalaVersion: String) extends AlmondModule with Mima {
   )
 }
 
-class Echo(val crossScalaVersion: String) extends AlmondModule {
+trait Echo extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def moduleDeps = Seq(
     shared.kernel()
   )
@@ -459,14 +479,15 @@ class Echo(val crossScalaVersion: String) extends AlmondModule {
     Deps.caseApp.withDottyCompat(crossScalaVersion)
   )
   def propertyFilePath = "almond/echo.properties"
-  object test extends Tests with AlmondTestModule {
+  object test extends this.CrossSbtModuleTests with AlmondTestModule {
     def moduleDeps = super.moduleDeps ++ Seq(
       shared.test()
     )
   }
 }
 
-class ToreeHooks(val crossScalaVersion: String) extends AlmondModule {
+trait ToreeHooks extends Cross.Module[String] with AlmondModule {
+  def crossScalaVersion = crossValue
   def supports3 = true
   def compileModuleDeps = super.compileModuleDeps ++ Seq(
     scala.`scala-kernel-api`(ScalaVersions.binary(crossScalaVersion))
@@ -474,40 +495,40 @@ class ToreeHooks(val crossScalaVersion: String) extends AlmondModule {
 }
 
 object shared extends Module {
-  object `logger-scala2-macros` extends Cross[LoggerScala2Macros](ScalaVersions.binaries: _*)
-  object logger                 extends Cross[Logger](ScalaVersions.binaries: _*)
-  object channels               extends Cross[Channels](ScalaVersions.binaries: _*)
-  object protocol               extends Cross[Protocol](ScalaVersions.binaries: _*)
-  object `interpreter-api`      extends Cross[InterpreterApi](ScalaVersions.binaries: _*)
-  object interpreter            extends Cross[Interpreter](ScalaVersions.binaries: _*)
-  object kernel                 extends Cross[Kernel](ScalaVersions.binaries: _*)
-  object test                   extends Cross[Test](ScalaVersions.binaries: _*)
-  object `test-kit`             extends Cross[TestKit](ScalaVersions.all: _*)
+  object `logger-scala2-macros` extends Cross[LoggerScala2Macros](ScalaVersions.binaries)
+  object logger                 extends Cross[Logger](ScalaVersions.binaries)
+  object channels               extends Cross[Channels](ScalaVersions.binaries)
+  object protocol               extends Cross[Protocol](ScalaVersions.binaries)
+  object `interpreter-api`      extends Cross[InterpreterApi](ScalaVersions.binaries)
+  object interpreter            extends Cross[Interpreter](ScalaVersions.binaries)
+  object kernel                 extends Cross[Kernel](ScalaVersions.binaries)
+  object test                   extends Cross[Test](ScalaVersions.binaries)
+  object `test-kit`             extends Cross[TestKit](ScalaVersions.all)
 }
 
 // FIXME Can't use 'scala' because of macro hygiene issues in some mill macros
 object scala extends Module {
-  implicit def millModuleBasePath: define.BasePath =
-    define.BasePath(super.millModuleBasePath.value / os.up / "scala")
-  object `jupyter-api`      extends Cross[JupyterApi](ScalaVersions.binaries: _*)
-  object `scala-kernel-api` extends Cross[ScalaKernelApi](ScalaVersions.all: _*)
+  implicit def millModuleBasePath: define.Ctx.BasePath =
+    define.Ctx.BasePath(super.millModuleBasePath.value / os.up / "scala")
+  object `jupyter-api`      extends Cross[JupyterApi](ScalaVersions.binaries)
+  object `scala-kernel-api` extends Cross[ScalaKernelApi](ScalaVersions.all)
   object `scala-kernel-api-helper`
-      extends Cross[ScalaKernelApiHelper](ScalaVersions.all.filter(_.startsWith("3.")): _*)
-  object `scala-interpreter` extends Cross[ScalaInterpreter](ScalaVersions.all: _*)
-  object `scala-kernel`      extends Cross[ScalaKernel](ScalaVersions.all: _*)
+      extends Cross[ScalaKernelApiHelper](ScalaVersions.all.filter(_.startsWith("3.")))
+  object `scala-interpreter` extends Cross[ScalaInterpreter](ScalaVersions.all)
+  object `scala-kernel`      extends Cross[ScalaKernel](ScalaVersions.all)
   object `scala-kernel-helper`
-      extends Cross[ScalaKernelHelper](ScalaVersions.all.filter(_.startsWith("3.")): _*)
-  object `coursier-logger` extends Cross[CoursierLogger](ScalaVersions.binaries: _*)
+      extends Cross[ScalaKernelHelper](ScalaVersions.all.filter(_.startsWith("3.")))
+  object `coursier-logger` extends Cross[CoursierLogger](ScalaVersions.binaries)
   object `shared-directives`
-      extends Cross[SharedDirectives]("2.12.15" +: ScalaVersions.binaries: _*)
+      extends Cross[SharedDirectives]("2.12.15" +: ScalaVersions.binaries)
   object launcher         extends Launcher
-  object `almond-scalapy` extends Cross[AlmondScalaPy](ScalaVersions.binaries: _*)
-  object `almond-rx`      extends Cross[AlmondRx](ScalaVersions.scala212, ScalaVersions.scala213)
+  object `almond-scalapy` extends Cross[AlmondScalaPy](ScalaVersions.binaries)
+  object `almond-rx`      extends Cross[AlmondRx](Seq(ScalaVersions.scala212, ScalaVersions.scala213))
 
-  object `toree-hooks` extends Cross[ToreeHooks](ScalaVersions.binaries: _*)
+  object `toree-hooks` extends Cross[ToreeHooks](ScalaVersions.binaries)
 
-  object `test-definitions` extends Cross[TestDefinitions](ScalaVersions.all: _*)
-  object `local-repo`       extends Cross[KernelLocalRepo](ScalaVersions.all: _*)
+  object `test-definitions` extends Cross[TestDefinitions](ScalaVersions.all)
+  object `local-repo`       extends Cross[KernelLocalRepo](ScalaVersions.all)
   object integration        extends Integration
 
   object examples extends Examples
@@ -517,7 +538,7 @@ trait Examples extends SbtModule {
   private def examplesScalaVersion = "2.12.12"
   private def baseRepoRoot         = os.rel / "out" / "repo"
   def scalaVersion                 = ScalaVersions.scala3Latest
-  object test extends Tests {
+  object test extends SbtModuleTests {
     def testFramework = "munit.Framework"
     def ivyDeps = T {
       super.ivyDeps() ++ Agg(
@@ -542,7 +563,8 @@ trait Examples extends SbtModule {
   }
 }
 
-class TestKit(val crossScalaVersion: String) extends CrossSbtModule with Bloop.Module {
+trait TestKit extends Cross.Module[String] with CrossSbtModule with Bloop.Module {
+  def crossScalaVersion = crossValue
   def skipBloop = !ScalaVersions.binaries.contains(crossScalaVersion)
   def moduleDeps =
     if (crossScalaVersion.startsWith("3."))
@@ -560,7 +582,8 @@ class TestKit(val crossScalaVersion: String) extends CrossSbtModule with Bloop.M
   )
 }
 
-class TestDefinitions(val crossScalaVersion: String) extends CrossSbtModule with Bloop.Module {
+trait TestDefinitions extends Cross.Module[String] with CrossSbtModule with Bloop.Module {
+  def crossScalaVersion = crossValue
   def skipBloop = !ScalaVersions.binaries.contains(crossScalaVersion)
 
   def moduleDeps = super.moduleDeps ++ Seq(
@@ -574,7 +597,8 @@ class TestDefinitions(val crossScalaVersion: String) extends CrossSbtModule with
   }
 }
 
-class KernelLocalRepo(val testScalaVersion: String) extends LocalRepo {
+trait KernelLocalRepo extends Cross.Module[String] with LocalRepo {
+  def testScalaVersion = crossValue
   def stubsModules = {
     val extra =
       if (testScalaVersion.startsWith("2.")) Nil
@@ -625,7 +649,7 @@ trait Integration extends SbtModule {
     Deps.pprint
   )
 
-  object test extends Tests with TestCommand {
+  object test extends SbtModuleTests with TestCommand {
     def testFramework = "munit.Framework"
     def forkArgs = T {
       scala.`local-repo`(ScalaVersions.scala212).localRepo()
@@ -651,7 +675,7 @@ trait Integration extends SbtModule {
   }
 }
 
-object echo extends Cross[Echo](ScalaVersions.binaries: _*)
+object echo extends Cross[Echo](ScalaVersions.binaries)
 
 object docs extends ScalaModule with AlmondRepositories {
   private def scalaVersion0 = ScalaVersions.scala213
@@ -759,89 +783,76 @@ object docs extends ScalaModule with AlmondRepositories {
   }
 }
 
-def jupyter0(args: Seq[String], fast: Boolean, console: Boolean = false) = {
-  val (sv, args0) = args match {
-    case Seq(sv, rem @ _*) if sv.startsWith("2.") || sv.startsWith("3.") =>
-      (sv, rem)
-    case _ => (ScalaVersions.scala213, args)
-  }
-  val launcher =
-    if (fast) scala.`scala-kernel`(sv).fastLauncher
-    else scala.`scala-kernel`(sv).launcher
-  val specialLauncher =
-    if (fast) scala.launcher.fastLauncher
-    else scala.launcher.launcher
-  T.command {
-    val jupyterDir       = T.ctx().dest / "jupyter"
-    val launcher0        = launcher().path.toNIO
-    val specialLauncher0 = specialLauncher().path.toNIO
-    if (console)
-      jupyterConsole0(launcher0, specialLauncher0, jupyterDir.toNIO, args0)
-    else
-      jupyterServer(launcher0, specialLauncher0, jupyterDir.toNIO, args0)
-  }
-}
+object dev extends Module {
 
-def jupyter(args: String*) =
-  jupyter0(args, fast = false)
+  def jupyter0(args: Seq[String], fast: Boolean, console: Boolean = false) = {
+    val (sv, args0) = args match {
+      case Seq(sv, rem @ _*) if sv.startsWith("2.") || sv.startsWith("3.") =>
+        (sv, rem)
+      case _ => (ScalaVersions.scala213, args)
+    }
+    val launcher =
+      if (fast) scala.`scala-kernel`(sv).fastLauncher
+      else scala.`scala-kernel`(sv).launcher
+    val specialLauncher =
+      if (fast) scala.launcher.fastLauncher
+      else scala.launcher.launcher
+    T.command {
+      val jupyterDir       = T.ctx().dest / "jupyter"
+      val launcher0        = launcher().path.toNIO
+      val specialLauncher0 = specialLauncher().path.toNIO
+      if (console)
+        jupyterConsole0(launcher0, specialLauncher0, jupyterDir.toNIO, args0)
+      else
+        jupyterServer(launcher0, specialLauncher0, jupyterDir.toNIO, args0)
+    }
+  }
 
-def jupyterFast(args: String*) =
-  jupyter0(args, fast = true)
+  def jupyter(args: String*) =
+    jupyter0(args, fast = false)
 
-def jupyterConsole(args: String*) =
-  jupyter0(args, fast = false, console = true)
+  def jupyterFast(args: String*) =
+    jupyter0(args, fast = true)
 
-def jupyterConsoleFast(args: String*) =
-  jupyter0(args, fast = true, console = true)
+  def jupyterConsole(args: String*) =
+    jupyter0(args, fast = false, console = true)
 
-def publishSonatype(tasks: mill.main.Tasks[PublishModule.PublishData]) =
-  T.command {
-    val timeout     = 10.minutes
-    val credentials = sys.env("SONATYPE_USERNAME") + ":" + sys.env("SONATYPE_PASSWORD")
-    val pgpPassword = sys.env("PGP_PASSWORD")
-    val data        = T.sequence(tasks.value)()
+  def jupyterConsoleFast(args: String*) =
+    jupyter0(args, fast = true, console = true)
 
-    settings.publishSonatype(
-      credentials = credentials,
-      pgpPassword = pgpPassword,
-      data = data,
-      timeout = timeout,
-      log = T.ctx().log
-    )
+  def scala212() = T.command {
+    println(ScalaVersions.scala212)
+  }
+  def scala213() = T.command {
+    println(ScalaVersions.scala213)
+  }
+  def scala3() = T.command {
+    println(ScalaVersions.scala3Latest)
+  }
+  def scalaVersions() = T.command {
+    for (sv <- ScalaVersions.all)
+      println(sv)
   }
 
-def scala212() = T.command {
-  println(ScalaVersions.scala212)
-}
-def scala213() = T.command {
-  println(ScalaVersions.scala213)
-}
-def scala3() = T.command {
-  println(ScalaVersions.scala3Latest)
-}
-def scalaVersions() = T.command {
-  for (sv <- ScalaVersions.all)
-    println(sv)
-}
-
-def launcher(scalaVersion: String = ScalaVersions.scala213) = T.command {
-  val launcher = scala.`scala-kernel`(scalaVersion).launcher().path.toNIO
-  println(launcher)
-}
+  def launcher(scalaVersion: String = ScalaVersions.scala213) = T.command {
+    val launcher = scala.`scala-kernel`(scalaVersion).launcher().path.toNIO
+    println(launcher)
+  }
 
-def specialLauncher(scalaVersion: String = ScalaVersions.scala213) = T.command {
-  val launcher = scala.launcher.launcher().path.toNIO
-  println(launcher)
-}
+  def specialLauncher(scalaVersion: String = ScalaVersions.scala213) = T.command {
+    val launcher = scala.launcher.launcher().path.toNIO
+    println(launcher)
+  }
 
-def launcherFast(scalaVersion: String = ScalaVersions.scala213) = T.command {
-  val launcher = scala.`scala-kernel`(scalaVersion).fastLauncher().path.toNIO
-  println(launcher)
-}
+  def launcherFast(scalaVersion: String = ScalaVersions.scala213) = T.command {
+    val launcher = scala.`scala-kernel`(scalaVersion).fastLauncher().path.toNIO
+    println(launcher)
+  }
 
-def specialLauncherFast(scalaVersion: String = ScalaVersions.scala213) = T.command {
-  val launcher = scala.launcher.fastLauncher().path.toNIO
-  println(launcher)
+  def specialLauncherFast(scalaVersion: String = ScalaVersions.scala213) = T.command {
+    val launcher = scala.launcher.fastLauncher().path.toNIO
+    println(launcher)
+  }
 }
 
 def ghOrg  = "almond-sh"
@@ -883,6 +894,22 @@ object ci extends Module {
       launchers: _*
     )
   }
+
+  def publishSonatype(tasks: mill.main.Tasks[PublishModule.PublishData]) =
+    T.command {
+      val timeout     = 10.minutes
+      val credentials = sys.env("SONATYPE_USERNAME") + ":" + sys.env("SONATYPE_PASSWORD")
+      val pgpPassword = sys.env("PGP_PASSWORD")
+      val data        = T.sequence(tasks.value)()
+
+      settings.publishSonatype(
+        credentials = credentials,
+        pgpPassword = pgpPassword,
+        data = data,
+        timeout = timeout,
+        log = T.ctx().log
+      )
+    }
 }
 
 object dummy extends Module {
diff --git a/docs/pages/dev-from-sources.md b/docs/pages/dev-from-sources.md
index 49e7bc603..747946639 100644
--- a/docs/pages/dev-from-sources.md
+++ b/docs/pages/dev-from-sources.md
@@ -35,7 +35,7 @@ We list below useful commands, to help get you started using mill to build almon
 ## Run a Jupyter notebook server without installing a kernel
 
 ```text
-$ ./mill -i jupyterFast
+$ ./mill -i dev.jupyterFast
 ```
 
 This should
@@ -46,16 +46,16 @@ From the JupyterLab instance, select the kernel "Scala (sources)".
 
 Optionally, pass a Scala version and / or JupyterLab options, like
 ```text
-$ ./mill -i jupyterFast 2.12.13
-$ ./mill -i jupyterFast --ip=192.168.0.1
-$ ./mill -i jupyterFast 2.12.13 --ip=192.168.0.1
+$ ./mill -i dev.jupyterFast 2.12.13
+$ ./mill -i dev.jupyterFast --ip=192.168.0.1
+$ ./mill -i dev.jupyterFast 2.12.13 --ip=192.168.0.1
 ```
 (If specified, the Scala version needs to be passed first.)
 
 ## Build a kernel launcher
 
 ```text
-$ ./mill launcherFast
+$ ./mill dev.launcherFast
 ```
 
 Once done building, this should print the path to the kernel launcher, like
@@ -63,7 +63,7 @@ Once done building, this should print the path to the kernel launcher, like
 
 Optionally, pass a Scala version, like
 ```text
-$ ./mill launcherFast 2.12.13
+$ ./mill dev.launcherFast 2.12.13
 ```
 
 You can then run that launcher to install it on your system:
@@ -76,18 +76,18 @@ Pass `--help` or see [this page](install-options.md) for the available options.
 
 You can re-build a launcher upon source changes with
 ```text
-$ ./mill -w launcherFast
+$ ./mill -w dev.launcherFast
 ```
 
 If you [ran a JupyterLab server from the almond sources](#run-a-jupyter-notebook-server-without-installing-a-kernel),
 you can restart the kernel from a notebook via JupyterLab to pick a newly built launcher. If you passed a Scala
-version to `./mill jupyter`, beware to pass the same version to `./mill -w launcher`.
+version to `./mill dev.jupyter`, beware to pass the same version to `./mill -w dev.launcher`.
 
 ## Useful commands
 
 ### List available Scala versions
 ```text
-$ ./mill scalaVersions
+$ ./mill dev.scalaVersions
 2.13.4
 2.13.3
 …
@@ -95,13 +95,13 @@ $ ./mill scalaVersions
 
 ### Print the latest supported Scala 2.13 version
 ```text
-$ ./mill scala213
+$ ./mill dev.scala213
 2.13.4
 ```
 
 ### Print the latest supported Scala 2.12 version
 ```text
-$ ./mill scala212
+$ ./mill dev.scala212
 2.12.13
 ```
 
diff --git a/project/settings.sc b/project/settings.sc
index 81add5b0b..dc883d326 100644
--- a/project/settings.sc
+++ b/project/settings.sc
@@ -8,6 +8,7 @@ import java.nio.file.{Files, Path}
 import java.util.{Arrays, Properties}
 
 import mill._, scalalib.{CrossSbtModule => _, _}
+import mill.scalalib.api.ZincWorkerUtil
 
 import scala.annotation.tailrec
 import scala.concurrent.duration._
@@ -34,20 +35,27 @@ lazy val buildVersion = {
 }
 
 // Adapted from https://github.com/lihaoyi/mill/blob/0.9.3/scalalib/src/MiscModule.scala/#L80-L100
+// and https://github.com/com-lihaoyi/mill/blob/c75e29c78cfc3c1e04776978bfc8e5697f8ca1aa/scalalib/src/mill/scalalib/CrossSbtModule.scala#L7
 // Compared to the original code, we ensure `scalaVersion()` rather than `crossScalaVersion` is
 // used when computing paths, as the former is always a valid Scala version,
 // while the latter can be a 3.x version while we compile using Scala 2.x
 // (and later rely on dotty compatibility to mix Scala 2 / Scala 3 modules).
 trait CrossSbtModule extends mill.scalalib.SbtModule with mill.scalalib.CrossModuleBase { outer =>
 
-  override def sources = T.sources {
-    super.sources() ++
-      mill.scalalib.CrossModuleBase.scalaVersionPaths(
-        scalaVersion(),
-        s => millSourcePath / 'src / 'main / s"scala-$s"
+  def sources = T.sources {
+    super.sources() ++ scalaVersionDirectoryNames.map(s =>
+      PathRef(millSourcePath / "src" / "main" / s"scala-$s")
+    )
+  }
+  trait CrossSbtModuleTests extends SbtModuleTests {
+    override def millSourcePath = outer.millSourcePath
+    def sources = T.sources {
+      super.sources() ++ scalaVersionDirectoryNames.map(s =>
+        PathRef(millSourcePath / "src" / "test" / s"scala-$s")
       )
-
+    }
   }
+  trait Tests extends CrossSbtModuleTests
 }
 
 trait AlmondRepositories extends CoursierModule {
@@ -74,9 +82,9 @@ trait AlmondPublishModule extends PublishModule {
 }
 
 trait ExternalSources extends CrossSbtModule {
-  def allIvyDeps = T(transitiveIvyDeps() ++ scalaLibraryIvyDeps())
+  // def allIvyDeps = T((transitiveIvyDeps(): Agg[Dep]) ++ (scalaLibraryIvyDeps(): Agg[Dep]))
   def externalSources = T {
-    resolveDeps(allIvyDeps, sources = true)()
+    resolveDeps(T.task { transitiveCompileIvyDeps() ++ transitiveIvyDeps() }, sources = true)()
   }
 }
 
@@ -152,11 +160,12 @@ trait AlmondArtifactName extends SbtModule {
 trait AlmondScala2Or3Module extends CrossSbtModule {
   def crossScalaVersion: String
   def supports3: Boolean = false
-  def scalaVersion = T {
+  private def actualScalaVersion = {
     if (crossScalaVersion.startsWith("3.") && !supports3)
       ScalaVersions.cross2_3Version(crossScalaVersion)
     else crossScalaVersion
   }
+  def scalaVersion = T(actualScalaVersion)
   def useCrossSuffix = T {
     crossScalaVersion.startsWith("3.") && !scalaVersion().startsWith("3.")
   }
@@ -170,6 +179,8 @@ trait AlmondScala2Or3Module extends CrossSbtModule {
       else Nil
     tastyReaderOptions
   }
+  override def scalaVersionDirectoryNames =
+    ZincWorkerUtil.matchingVersions(actualScalaVersion)
 }
 
 trait AlmondScalacOptions extends ScalaModule {
@@ -234,27 +245,10 @@ trait AlmondModule
   }
   def transitiveIvyDeps = T {
     super.transitiveIvyDeps().map { dep =>
-      def isScala3Lib =
-        dep.dep.module.organization.value == "org.scala-lang" &&
-        dep.dep.module.name.value == "scala3-library" &&
-        (dep.cross match {
-          case _: CrossVersion.Binary => true
-          case _                      => false
-        })
-      def isScala3JarWithSuffix =
+      val isScala3JarWithSuffix =
         dep.dep.module.organization.value == "org.scala-lang" &&
         dep.dep.module.name.value.startsWith("scala3-")
-      if (isScala3Lib)
-        dep.copy(
-          dep = dep.dep.withModule(
-            dep.dep.module.withName(
-              coursier.ModuleName(dep.dep.module.name.value + "_3")
-            )
-          ),
-          cross = CrossVersion.empty(dep.cross.platformed),
-          force = false
-        )
-      else if (isScala3JarWithSuffix)
+      if (isScala3JarWithSuffix)
         dep.copy(force = false)
       else dep
     }
@@ -296,39 +290,14 @@ trait AlmondTestModule
   }
   def transitiveIvyDeps = T {
     super.transitiveIvyDeps().map { dep =>
-      def isScala3Lib =
-        dep.dep.module.organization.value == "org.scala-lang" &&
-        dep.dep.module.name.value == "scala3-library" &&
-        (dep.cross match {
-          case _: CrossVersion.Binary => true
-          case _                      => false
-        })
-      def isScala3JarWithSuffix =
+      val isScala3JarWithSuffix =
         dep.dep.module.organization.value == "org.scala-lang" &&
         dep.dep.module.name.value.startsWith("scala3-")
-      if (isScala3Lib)
-        dep.copy(
-          dep = dep.dep.withModule(
-            dep.dep.module.withName(
-              coursier.ModuleName(dep.dep.module.name.value + "_3")
-            )
-          ),
-          cross = CrossVersion.empty(dep.cross.platformed),
-          force = false
-        )
-      else if (isScala3JarWithSuffix)
+      if (isScala3JarWithSuffix)
         dep.copy(force = false)
       else dep
     }
   }
-
-  def sources = T.sources {
-    super.sources() ++
-      mill.scalalib.CrossModuleBase.scalaVersionPaths(
-        scalaVersion(),
-        s => millSourcePath / "src" / "test" / s"scala-$s"
-      )
-  }
 }
 
 trait BootstrapLauncher extends SbtModule {
@@ -516,9 +485,10 @@ trait DependencyListResource extends CrossSbtModule {
   def depResourcesDir = T.persistent {
     val (_, res) = Lib.resolveDependenciesMetadata(
       repositoriesTask(),
-      resolveCoursierDependency().apply(_),
       transitiveIvyDeps(),
-      Some(mapDependencies())
+      Some(mapDependencies()),
+      customizer = resolutionCustomizer(),
+      coursierCacheCustomizer = coursierCacheCustomizer()
     )
     val content = res
       .orderedDependencies
@@ -712,7 +682,7 @@ trait TestCommand extends TestModule {
       import mill.testrunner.TestRunner
 
       val globSelectors = Nil
-      val outputPath    = os.pwd / "test-output.json"
+      val outputPath    = T.dest / "out.json"
       val useArgsFile   = testUseArgsFile()
 
       val (jvmArgs, props: Map[String, String]) =
@@ -732,34 +702,31 @@ trait TestCommand extends TestModule {
         else
           forkArgs() -> Map()
 
-      os.remove(outputPath)
-
-      val testArgs = TestRunner.TestArgs(
+      val testArgs = mill.testrunner.TestArgs(
         framework = testFramework(),
-        classpath = runClasspath().map(_.path.toString()),
+        classpath = runClasspath().map(_.path),
         arguments = args,
         sysProps = props,
-        outputPath = outputPath.toString(),
+        outputPath = outputPath,
         colored = T.log.colored,
-        testCp = compile().classes.path.toString(),
-        homeStr = T.home.toString(),
+        testCp = compile().classes.path,
+        home = T.home,
         globSelectors = globSelectors
       )
 
-      val mainArgs =
-        if (useArgsFile) {
-          val argsFile = T.dest / "testargs"
-          Seq(testArgs.writeArgsFile(argsFile))
-        }
-        else
-          testArgs.toArgsSeq
+      val testRunnerClasspathArg = zincWorker().scalalibClasspath()
+        .map(_.path.toNIO.toUri.toURL)
+        .mkString(",")
 
-      val envArgs    = forkEnv()
+      val argsFile = T.dest / "testargs"
+      os.write(argsFile, upickle.default.write(testArgs))
+      val mainArgs = Seq(testRunnerClasspathArg, argsFile.toString)
+      val envArgs  = forkEnv()
       val workingDir = forkWorkingDir()
 
       val args0 = jvmSubprocessCommand(
-        mainClass = "mill.testrunner.TestRunner",
-        classPath = zincWorker.scalalibClasspath().map(_.path),
+        mainClass = "mill.testrunner.entrypoint.TestRunnerMain",
+        classPath = (runClasspath() ++ zincWorker().testrunnerEntrypointClasspath()).map(_.path),
         jvmArgs = jvmArgs,
         envArgs = envArgs,
         mainArgs = mainArgs,
diff --git a/scripts/update-docker-images.sh b/scripts/update-docker-images.sh
index f7c0c55f1..a5db07864 100755
--- a/scripts/update-docker-images.sh
+++ b/scripts/update-docker-images.sh
@@ -3,9 +3,9 @@ set -eu
 
 # TODO Convert to a mill task
 
-SCALA212_VERSION="$(./mill scala212)"
-SCALA213_VERSION="$(./mill scala213)"
-SCALA3_VERSION="$(./mill scala3)"
+SCALA212_VERSION="$(./mill dev.scala212)"
+SCALA213_VERSION="$(./mill dev.scala213)"
+SCALA3_VERSION="$(./mill dev.scala3)"
 
 DOCKER_REPO=almondsh/almond