diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index b6b94b636..243f8705f 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -28,7 +28,7 @@ jobs:
     strategy:
       matrix:
         os: [ubuntu-latest]
-        scala: [2.13, 2.12]
+        scala: [per-project-matrix]
         java: [temurin@8]
     runs-on: ${{ matrix.os }}
     timeout-minutes: 60
@@ -108,22 +108,12 @@ jobs:
         if: matrix.java == 'temurin@8' && steps.setup-java-temurin-8.outputs.cache-hit == 'false'
         run: sbt +update
 
-      - name: Download target directories (2.13)
+      - name: Download target directories (per-project-matrix)
         uses: actions/download-artifact@v4
         with:
-          name: target-${{ matrix.os }}-${{ matrix.java }}-2.13
+          name: target-${{ matrix.os }}-${{ matrix.java }}-per-project-matrix
 
-      - name: Inflate target directories (2.13)
-        run: |
-          tar xf targets.tar
-          rm targets.tar
-
-      - name: Download target directories (2.12)
-        uses: actions/download-artifact@v4
-        with:
-          name: target-${{ matrix.os }}-${{ matrix.java }}-2.12
-
-      - name: Inflate target directories (2.12)
+      - name: Inflate target directories (per-project-matrix)
         run: |
           tar xf targets.tar
           rm targets.tar
diff --git a/.mergify.yml b/.mergify.yml
index da3d98937..efc7fc616 100644
--- a/.mergify.yml
+++ b/.mergify.yml
@@ -12,8 +12,7 @@ pull_request_rules:
   - or:
     - body~=labels:.*early-semver-patch
     - body~=labels:.*early-semver-minor
-  - status-success=Build and Test (ubuntu-latest, 2.13, temurin@8)
-  - status-success=Build and Test (ubuntu-latest, 2.12, temurin@8)
+  - status-success=Build and Test (ubuntu-latest, per-project-matrix, temurin@8)
   - status-success=Validate Steward Config (ubuntu-latest, temurin@11)
   actions:
     merge: {}
diff --git a/.sbtopts b/.sbtopts
index 1ca6d0b39..2b63e3b2d 100644
--- a/.sbtopts
+++ b/.sbtopts
@@ -1 +1 @@
--J-Xmx2G
+-J-Xmx4G
diff --git a/build.sbt b/build.sbt
index b0e0d41ec..5d94415d4 100644
--- a/build.sbt
+++ b/build.sbt
@@ -1,28 +1,3 @@
-ThisBuild / organization := "com.dwolla"
-ThisBuild / homepage := Some(url("https://github.com/Dwolla/async-utils"))
-ThisBuild / licenses := Seq(License.MIT)
-ThisBuild / developers := List(
-  Developer(
-    "bpholt",
-    "Brian Holt",
-    "bholt+async-utils@dwolla.com",
-    url("https://dwolla.com")
-  ),
-)
-ThisBuild / startYear := Option(2021)
-ThisBuild / tlSonatypeUseLegacyHost := true
-ThisBuild / tlBaseVersion := "1.1"
-ThisBuild / githubWorkflowScalaVersions := Seq("2.13", "2.12")
-ThisBuild / tlCiReleaseBranches := Seq("main")
-ThisBuild / mergifyRequiredJobs ++= Seq("validate-steward")
-ThisBuild / mergifyStewardConfig ~= { _.map(_.copy(
-  author = "dwolla-oss-scala-steward[bot]",
-  mergeMinors = true,
-))}
-ThisBuild / tlJdkRelease := Option(8)
-
-ThisBuild / scalaVersion := "2.13.10"
-
 lazy val `async-utils-root` = (project in file("."))
   .aggregate(allProjects.map(_.project) *)
   .settings(
diff --git a/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/TracedThriftClient.scala b/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/TracedThriftClient.scala
index 25661bb35..0f61aa73e 100644
--- a/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/TracedThriftClient.scala
+++ b/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/TracedThriftClient.scala
@@ -1,18 +1,16 @@
 package com.dwolla.util.async.finagle
 
-import cats.data._
+import cats.data.*
 import cats.effect.std.Env
-import cats.effect.syntax.all._
-import cats.effect.{Trace => _, tracing => _, _}
-import cats.syntax.all._
-import cats.tagless._
+import cats.effect.syntax.all.*
+import cats.effect.{Trace as _, tracing as _, *}
+import cats.syntax.all.*
+import cats.tagless.*
 import com.dwolla.util.async.finagle.ThriftClient.initialAcquire
-import com.dwolla.util.async.twitter._
+import com.dwolla.util.async.twitter.*
 import com.twitter.util.{Closable, Future}
 import natchez.Trace
 
-import scala.language.reflectiveCalls
-
 /**
  * Build a Finagle Thrift client using the given Thrift
  * method-per-endpoint algebra and the given destination. Optionally,
@@ -40,6 +38,7 @@ object TracedThriftClient {
    */
   def apply[Alg[_[_]] <: AnyRef {def asClosable: Closable}] = new PartiallyAppliedThriftClient[Alg]()
 
+  @annotation.nowarn("msg=dubious usage of method hashCode with unit value")
   class PartiallyAppliedThriftClient[Alg[_[_]] <: AnyRef {def asClosable: Closable}] private[TracedThriftClient](val dummy: Unit = ()) extends AnyVal {
     /**
      * @param name the local service name to be set on the Zipkin tracer
diff --git a/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/ZipkinTracer.scala b/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/ZipkinTracer.scala
index 6f93873b8..a831b2ffa 100644
--- a/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/ZipkinTracer.scala
+++ b/finagle-natchez/src/main/scala/com/dwolla/util/async/finagle/ZipkinTracer.scala
@@ -3,8 +3,8 @@ package com.dwolla.util.async.finagle
 import cats.Functor
 import cats.effect.Sync
 import cats.effect.std.Env
-import cats.syntax.all._
-import com.comcast.ip4s._
+import cats.syntax.all.*
+import com.comcast.ip4s.*
 import com.dwolla.util.async.finagle.ZipkinTracer.alwaysSample
 import com.twitter.finagle.stats.NullStatsReceiver
 import com.twitter.finagle.tracing.Tracer
@@ -35,7 +35,7 @@ object ZipkinTracerConfig {
       }
 }
 
-class ZipkinTracerConfig(val host: SocketAddress[_],
+class ZipkinTracerConfig(val host: SocketAddress[?],
                          val initialSampleRate: Float,
                          val tlsEnabled: Boolean,
                          val localServiceName: String,
@@ -47,14 +47,14 @@ class ZipkinTracerConfig(val host: SocketAddress[_],
     this(
       SocketAddress(host"127.0.0.1", port"9411"),
       alwaysSample,
-      false,
+      tlsEnabled = false,
       localServiceName,
-      true,
+      compressionEnabled = true,
       "zipkin",
       "/api/v2/spans"
     )
 
-  def withHost(update: SocketAddress[_]): ZipkinTracerConfig =
+  def withHost(update: SocketAddress[?]): ZipkinTracerConfig =
     new ZipkinTracerConfig(update, initialSampleRate, tlsEnabled, localServiceName, compressionEnabled, hostHeader, path)
 
   private[finagle] def build(): HttpZipkinTracer.Config =
diff --git a/project/AsyncUtilsBuildPlugin.scala b/project/AsyncUtilsBuildPlugin.scala
index 3af6cb41b..73d5926e1 100644
--- a/project/AsyncUtilsBuildPlugin.scala
+++ b/project/AsyncUtilsBuildPlugin.scala
@@ -6,7 +6,13 @@ import org.scalajs.jsenv.JSEnv
 import org.scalajs.jsenv.nodejs.NodeJSEnv
 import org.scalajs.sbtplugin.ScalaJSPlugin.autoImport.*
 import org.typelevel.sbt.TypelevelMimaPlugin.autoImport.*
+import org.typelevel.sbt.TypelevelSettingsPlugin
+import org.typelevel.sbt.TypelevelSettingsPlugin.autoImport.*
+import org.typelevel.sbt.TypelevelSonatypeCiReleasePlugin.autoImport.*
+import org.typelevel.sbt.TypelevelSonatypePlugin.autoImport.*
+import org.typelevel.sbt.TypelevelVersioningPlugin.autoImport.*
 import org.typelevel.sbt.gha.GenerativePlugin.autoImport.*
+import org.typelevel.sbt.gha.GitHubActionsPlugin.autoImport.*
 import org.typelevel.sbt.mergify.MergifyPlugin
 import org.typelevel.sbt.mergify.MergifyPlugin.autoImport.*
 import sbt.*
@@ -21,7 +27,7 @@ object AsyncUtilsBuildPlugin extends AutoPlugin {
   override def trigger = noTrigger
 
   override def requires: Plugins =
-    ProjectMatrixPlugin && ScalafixPlugin && MimaPlugin && MergifyPlugin
+    ProjectMatrixPlugin && ScalafixPlugin && MimaPlugin && MergifyPlugin && TypelevelSettingsPlugin && WarnNonUnitStatements
 
   object autoImport {
     lazy val allProjects: Seq[Project] =
@@ -57,8 +63,8 @@ object AsyncUtilsBuildPlugin extends AutoPlugin {
 
   private val supportedVersions = (currentTwitterVersion :: oldVersions).sorted.reverse
 
-  private val SCALA_2_13: String = "2.13.12"
-  private val SCALA_2_12 = "2.12.18"
+  private val SCALA_2_13: String = "2.13.13"
+  private val SCALA_2_12 = "2.12.19"
   private val Scala2Versions: Seq[String] = Seq(SCALA_2_13, SCALA_2_12)
 
   private val CatsEffect3V = "3.5.4"
@@ -304,7 +310,6 @@ object AsyncUtilsBuildPlugin extends AutoPlugin {
       .dependsOn(`async-utils-finagle`)
 
   override def buildSettings: Seq[Def.Setting[?]] = Seq(
-    scalaVersion := SCALA_2_13,
     mergifyLabelPaths :=
       List(
         "core",
@@ -318,22 +323,34 @@ object AsyncUtilsBuildPlugin extends AutoPlugin {
         .map(x => x -> file(x))
         .toMap,
 
-    /* this is misleading, because we're actually running the build for all supported
-     * scala versions, but unfortunately this seems to be our best option until
-     * sbt-typelevel 0.5.
-     *
-     * sbt-projectmatrix creates separate projects for each crossed Scala version
-     * setting githubWorkflowScalaVersions to a single (ignored) version minimizes
-     * the build matrix, and setting githubWorkflowBuildSbtStepPreamble to an empty
-     * list ensures that the build phase ignores the scala version set in
-     * githubWorkflowScalaVersions.
-     *
-     * '++ ${{ matrix.scala }}' will still be used in the Publish stage, but it
-     * sounds like the tlCiRelease will do the right thing anyway.
-     */
-    githubWorkflowScalaVersions := Seq("2.13"),
+    githubWorkflowScalaVersions := Seq("per-project-matrix"),
     githubWorkflowBuildSbtStepPreamble := Nil,
 
+    organization := "com.dwolla",
+    homepage := Some(url("https://github.com/Dwolla/async-utils")),
+    licenses := Seq(License.MIT),
+    developers := List(
+      Developer(
+        "bpholt",
+        "Brian Holt",
+        "bholt+async-utils@dwolla.com",
+        url("https://dwolla.com")
+      ),
+    ),
+    startYear := Option(2021),
+    tlSonatypeUseLegacyHost := true,
+    tlBaseVersion := "1.1",
+    tlCiReleaseBranches := Seq("main"),
+    mergifyRequiredJobs ++= Seq("validate-steward"),
+    mergifyStewardConfig ~= {
+      _.map(_.copy(
+        author = "dwolla-oss-scala-steward[bot]",
+        mergeMinors = true,
+      ))
+    },
+    tlJdkRelease := Option(8),
+    tlFatalWarnings := githubIsWorkflowBuild.value,
+
     nodeExecutable :=
       scala.util.Try {
         import scala.sys.process.*
@@ -357,3 +374,18 @@ object AsyncUtilsBuildPlugin extends AutoPlugin {
   private lazy val nvmJsEnv: TaskKey[JSEnv] = taskKey("use nvm to find node")
   private lazy val nodeExecutable: TaskKey[Option[File]] = taskKey("path to Node executable for JS tasks")
 }
+
+object WarnNonUnitStatements extends AutoPlugin {
+  override def trigger = allRequirements
+
+  override def projectSettings: Seq[Def.Setting[?]] = Seq(
+    scalacOptions ++= {
+      if (scalaVersion.value.startsWith("2.13"))
+        Seq("-Wnonunit-statement")
+      else if (scalaVersion.value.startsWith("2.12"))
+        Seq()
+      else
+        Nil
+    },
+  )
+}
diff --git a/project/plugins.sbt b/project/plugins.sbt
index 98d0ba87e..5c4ac68a7 100644
--- a/project/plugins.sbt
+++ b/project/plugins.sbt
@@ -3,5 +3,5 @@ addSbtPlugin("org.typelevel" % "sbt-typelevel-ci-release" % "0.6.7")
 addSbtPlugin("org.typelevel" % "sbt-typelevel-mergify" % "0.6.7")
 addSbtPlugin("org.typelevel" % "sbt-typelevel-settings" % "0.6.7")
 addSbtPlugin("org.scala-js" % "sbt-scalajs" % "1.15.0")
-addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.11.1")
+addSbtPlugin("ch.epfl.scala" % "sbt-scalafix" % "0.12.0")
 addSbtPlugin("com.eed3si9n" % "sbt-projectmatrix" % "0.10.0")
diff --git a/scalafix/rules/src/main/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstances.scala b/scalafix/rules/src/main/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstances.scala
index 4c40e7452..2d2946990 100644
--- a/scalafix/rules/src/main/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstances.scala
+++ b/scalafix/rules/src/main/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstances.scala
@@ -1,16 +1,18 @@
 package com.dwolla.scrooge.scalafix
 
-import com.dwolla.scrooge.scalafix.AddCatsTaglessInstances._
-import scalafix.v1._
+import com.dwolla.scrooge.scalafix.AddCatsTaglessInstances.*
+import scalafix.v1.*
 
-import scala.meta._
+import scala.meta.*
 import scala.meta.tokens.Token.Ident
 import GuardedPatchBuilder.toGuardedPatch
 
+import scala.meta.Type.ParamClause
+
 object ThriftServiceTrait {
   def unapply(subtree: Tree): Option[(String, Defn.Trait)] =
     PartialFunction.condOpt(subtree) {
-      case term@Defn.Trait(_, Type.Name(name), Nil, _, ExtendsThriftService(_)) => (name, term)
+      case term@Defn.Trait.After_4_6_0(_, Type.Name(name), ParamClause(Nil), _, ExtendsThriftService(_)) => (name, term)
     }
 }
 
@@ -43,7 +45,7 @@ object TemplateExtends {
     }
 
     PartialFunction.condOpt(subtree) {
-      case t@Template(_, TemplateInitsContainName(_), _, _) => t
+      case t@Template.After_4_4_0(_, TemplateInitsContainName(_), _, _, _) => t
     }
   }
 }
@@ -100,14 +102,14 @@ case class ThriftServiceTrait(private val generatedThriftServiceObject: Defn.Obj
     }
       .map(Patch.replaceToken(_, s"${generatedThriftServiceObject.name.value}[F[_]]"))
       .onlyIfMissing {
-        case Defn.Trait(_, Type.Name(name), _, _, _) if name == generatedThriftServiceObject.name.value => ()
+        case Defn.Trait.After_4_6_0(_, Type.Name(name), _, _, _) if name == generatedThriftServiceObject.name.value => ()
       }
       .in(generatedThriftServiceObject)
 
   private val addServiceCompanionObjectWithImplicits: Patch =
     Patch.addRight(methodPerEndpointTrait, companionObjectWithImplicits)
       .onlyIfMissing {
-        case Defn.Object(_, Term.Name(name), Template(_, List(), _, _)) if name == generatedThriftServiceObject.name.value => ()
+        case Defn.Object(_, Term.Name(name), Template.After_4_4_0(_, List(), _, _, _)) if name == generatedThriftServiceObject.name.value => ()
       }
       .in(generatedThriftServiceObject)
 
@@ -116,7 +118,7 @@ case class ThriftServiceTrait(private val generatedThriftServiceObject: Defn.Obj
       s"""
          |  trait MethodPerEndpoint extends ${generatedThriftServiceObject.name.value}[Future]""".stripMargin)
       .onlyIfMissing {
-        case Defn.Trait(_, Type.Name("MethodPerEndpoint"), _, _, ExtendsServiceTrait(_)) => ()
+        case Defn.Trait.After_4_6_0(_, Type.Name("MethodPerEndpoint"), _, _, ExtendsServiceTrait(_)) => ()
       }
       .in(generatedThriftServiceObject)
 
@@ -138,7 +140,7 @@ case class ThriftServiceTrait(private val generatedThriftServiceObject: Defn.Obj
           t.parent.fold(Patch.empty) {
             Patch.replaceToken(t.tokens.head, "F")
               .onlyIfMissing {
-                case Type.Apply(Type.Name(name), _) if name == generatedThriftServiceObject.name.value => ()
+                case Type.Apply.After_4_6_0(Type.Name(name), _) if name == generatedThriftServiceObject.name.value => ()
               }
               .in(_)
           }
@@ -163,8 +165,8 @@ case class ThriftServiceTrait(private val generatedThriftServiceObject: Defn.Obj
               methodPerEndpointTrait
                 .templ
                 .collect {
-                  case d@Decl.Def(_, name, _, paramss, _) =>
-                    s"override ${d.toString()} = fa.$name${invokeEachParamList(paramss)}"
+                  case d@Decl.Def.After_4_7_3(_, name, paramss, _) =>
+                    s"override ${d.toString()} = fa.$name${invokeEachParamList(paramss.flatMap(_.paramClauses.map(_.values)))}"
                 }
 
             val code =
@@ -182,7 +184,7 @@ case class ThriftServiceTrait(private val generatedThriftServiceObject: Defn.Obj
     modifyMethodPerEndpointTrait ++ modifyMethodPerEndpointCompanionObject
 }
 
-class GuardedPatch(private val tuple: (Patch, PartialFunction[Tree, _])) extends AnyVal {
+class GuardedPatch(private val tuple: (Patch, PartialFunction[Tree, ?])) extends AnyVal {
   def in(tree: Tree): Patch = {
     val empty = tree.collect(tuple._2).isEmpty
     if (empty) tuple._1
@@ -191,7 +193,7 @@ class GuardedPatch(private val tuple: (Patch, PartialFunction[Tree, _])) extends
 }
 
 class GuardedPatchBuilder(private val patch: Patch) extends AnyVal {
-  def onlyIfMissing(pf: PartialFunction[Tree, _]) = new GuardedPatch(patch -> pf)
+  def onlyIfMissing(pf: PartialFunction[Tree, ?]) = new GuardedPatch(patch -> pf)
 }
 
 object GuardedPatchBuilder {
@@ -210,13 +212,13 @@ case class Unapplied(patch: Patch) extends IdempotentPatch
 object IdempotentPatch {
   def apply(patch: Patch)
            (tree: Tree)
-           (pf: PartialFunction[Tree, _]): IdempotentPatch =
+           (pf: PartialFunction[Tree, ?]): IdempotentPatch =
     if (tree.collect(pf).nonEmpty) AlreadyApplied
     else Unapplied(patch)
 
   def apply(patch: Option[Patch])
            (tree: Tree)
-           (pf: PartialFunction[Tree, _]): IdempotentPatch =
+           (pf: PartialFunction[Tree, ?]): IdempotentPatch =
     IdempotentPatch(patch.getOrElse(Patch.empty))(tree)(pf)
 }
 
diff --git a/scalafix/rules/src/test/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstancesTest.scala b/scalafix/rules/src/test/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstancesTest.scala
index cbd953323..feedc8a88 100644
--- a/scalafix/rules/src/test/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstancesTest.scala
+++ b/scalafix/rules/src/test/scala/com/dwolla/scrooge/scalafix/AddCatsTaglessInstancesTest.scala
@@ -55,21 +55,21 @@ class AddCatsTaglessInstancesTest extends FunSuite {
 
   test("rename MethodPerEndpoint to SimpleService[F[_]]") {
     val expectedPatchContent =
-      s"Add(MethodPerEndpoint, MethodPerEndpoint [${range("MethodPerEndpoint")(input.indexOf)}), SimpleService[F[_]])"
+      s"Add(MethodPerEndpoint, Ident(MethodPerEndpoint) [${range("MethodPerEndpoint")(input.indexOf)}), SimpleService[F[_]])"
 
     expect(patch.toString.contains(expectedPatchContent))
   }
 
   test("replace Future[*] with F[*]") {
     val expectedPatchContent =
-      s"Add(Future, Future [${range("Future")(input.indexOf)}), F)"
+      s"Add(Future, Ident(Future) [${range("Future")(input.indexOf)}), F)"
 
     expect(patch.toString.contains(expectedPatchContent))
   }
 
   test("add SimpleService companion object with implicits") {
     val expectedPatchContent =
-      """Add(}, } [467..468), }
+      """Add(}, RightBrace(}) [467..468), }
         |
         |  object SimpleService {
         |    implicit def SimpleServiceInReaderT[F[_]]: SimpleService[({type Λ[β0] = _root_.cats.data.ReaderT[F, SimpleService[F], β0]})#Λ] =
@@ -92,7 +92,7 @@ class AddCatsTaglessInstancesTest extends FunSuite {
 
   test("add replacement MethodPerEndpoint that extends SimpleService[Future]") {
     val expectedPatchContent =
-      """Add(}, } [467..468), }
+      """Add(}, RightBrace(}) [467..468), }
         |  trait MethodPerEndpoint extends SimpleService[Future])""".stripMargin
 
     expect(patch.toString.contains(expectedPatchContent))
diff --git a/twitter-finagle/src/main/scala/com/dwolla/util/async/finagle/ThriftClient.scala b/twitter-finagle/src/main/scala/com/dwolla/util/async/finagle/ThriftClient.scala
index bdcf6ccfe..63626d598 100644
--- a/twitter-finagle/src/main/scala/com/dwolla/util/async/finagle/ThriftClient.scala
+++ b/twitter-finagle/src/main/scala/com/dwolla/util/async/finagle/ThriftClient.scala
@@ -1,18 +1,17 @@
 package com.dwolla.util.async.finagle
 
-import cats.data._
-import cats.effect._
-import cats.syntax.all._
-import cats.tagless._
-import com.dwolla.util.async.twitter._
+import cats.data.*
+import cats.effect.*
+import cats.syntax.all.*
+import cats.tagless.*
+import com.dwolla.util.async.twitter.*
 import com.twitter.finagle.Thrift
 import com.twitter.util.{Closable, Future}
 
-import scala.language.reflectiveCalls
-
 object ThriftClient {
   def apply[Alg[_[_]] <: AnyRef {def asClosable: Closable}] = new PartiallyAppliedThriftClient[Alg]()
 
+  @annotation.nowarn("msg=dubious usage of method hashCode with unit value")
   class PartiallyAppliedThriftClient[Alg[_[_]] <: AnyRef {def asClosable: Closable}] private[ThriftClient] (val dummy: Unit = ()) extends AnyVal {
     def apply[G[_] : Async](dest: String)
                            (implicit