diff --git a/build.sbt b/build.sbt
index d1ebb4a..ef4cf06 100644
--- a/build.sbt
+++ b/build.sbt
@@ -57,18 +57,35 @@ lazy val testSettings = Seq(
 lazy val `gs-test` = project
   .in(file("."))
   .aggregate(
-    `api-definition`,
-    `api-execution`
+    `test-support`,
+    api,
+    runtime
   )
   .settings(noPublishSettings)
   .settings(name := s"${gsProjectName.value}-v${semVerMajor.value}")
 
-lazy val `api-definition` = project
-  .in(file("modules/api-definition"))
+lazy val `test-support` = project
+  .in(file("modules/test-support"))
+  .settings(sharedSettings)
+  .settings(testSettings)
+  .settings(noPublishSettings)
+  .settings(
+    name := s"${gsProjectName.value}-test-support"
+  )
+  .settings(
+    libraryDependencies ++= Seq(
+      Deps.Cats.Core,
+      Deps.Cats.Effect
+    )
+  )
+
+lazy val api = project
+  .in(file("modules/api"))
+  .dependsOn(`test-support` % "test->test")
   .settings(sharedSettings)
   .settings(testSettings)
   .settings(
-    name := s"${gsProjectName.value}-api-definition-v${semVerMajor.value}"
+    name := s"${gsProjectName.value}-api-v${semVerMajor.value}"
   )
   .settings(
     libraryDependencies ++= Seq(
@@ -78,13 +95,14 @@ lazy val `api-definition` = project
     )
   )
 
-lazy val `api-execution` = project
-  .in(file("modules/api-execution"))
-  .dependsOn(`api-definition`)
+lazy val runtime = project
+  .in(file("modules/runtime"))
+  .dependsOn(`test-support` % "test->test")
+  .dependsOn(api)
   .settings(sharedSettings)
   .settings(testSettings)
   .settings(
-    name := s"${gsProjectName.value}-api-execution-v${semVerMajor.value}"
+    name := s"${gsProjectName.value}-runtime-v${semVerMajor.value}"
   )
   .settings(
     libraryDependencies ++= Seq(
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineResult.scala b/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineResult.scala
deleted file mode 100644
index c6dc613..0000000
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineResult.scala
+++ /dev/null
@@ -1,7 +0,0 @@
-package gs.test.v0.execution.engine
-
-import gs.test.v0.execution.SuiteExecution
-
-final class EngineResult(
-  val suiteExecution: SuiteExecution
-)
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/Assertion.scala b/modules/api/src/main/scala/gs/test/v0/api/Assertion.scala
similarity index 95%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/Assertion.scala
rename to modules/api/src/main/scala/gs/test/v0/api/Assertion.scala
index 7424602..31dbb90 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/Assertion.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/Assertion.scala
@@ -1,6 +1,5 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
-import gs.test.v0.definition.pos.SourcePosition
 import scala.reflect.*
 
 sealed abstract class Assertion(val name: String)
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/Check.scala b/modules/api/src/main/scala/gs/test/v0/api/Check.scala
similarity index 97%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/Check.scala
rename to modules/api/src/main/scala/gs/test/v0/api/Check.scala
index befdc90..758599e 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/Check.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/Check.scala
@@ -1,7 +1,6 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.effect.Sync
-import gs.test.v0.definition.pos.SourcePosition
 import scala.reflect.ClassTag
 
 /** Opaque type used to check candidate values against expected values.
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/Marker.scala b/modules/api/src/main/scala/gs/test/v0/api/Marker.scala
similarity index 94%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/Marker.scala
rename to modules/api/src/main/scala/gs/test/v0/api/Marker.scala
index f80104c..a4c28ff 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/Marker.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/Marker.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 /** Enumeration for _Markers_, special tokens which "mark" a test to change
   * execution functionality.
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/PermanentId.scala b/modules/api/src/main/scala/gs/test/v0/api/PermanentId.scala
similarity index 97%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/PermanentId.scala
rename to modules/api/src/main/scala/gs/test/v0/api/PermanentId.scala
index cffc197..a74935e 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/PermanentId.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/PermanentId.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.Show
 
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/pos/SourcePosition.scala b/modules/api/src/main/scala/gs/test/v0/api/SourcePosition.scala
similarity index 97%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/pos/SourcePosition.scala
rename to modules/api/src/main/scala/gs/test/v0/api/SourcePosition.scala
index f52ee4b..4ff7d16 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/pos/SourcePosition.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/SourcePosition.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition.pos
+package gs.test.v0.api
 
 import scala.quoted.*
 
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/Tag.scala b/modules/api/src/main/scala/gs/test/v0/api/Tag.scala
similarity index 92%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/Tag.scala
rename to modules/api/src/main/scala/gs/test/v0/api/Tag.scala
index ee232b4..dc8f55f 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/Tag.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/Tag.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.Show
 
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestDefinition.scala b/modules/api/src/main/scala/gs/test/v0/api/TestDefinition.scala
similarity index 95%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/TestDefinition.scala
rename to modules/api/src/main/scala/gs/test/v0/api/TestDefinition.scala
index 88f2325..41ef204 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestDefinition.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/TestDefinition.scala
@@ -1,7 +1,6 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.Show
-import gs.test.v0.definition.pos.SourcePosition
 
 /** Each instance of this class indicates the _definition_ of some test.
   *
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestFailure.scala b/modules/api/src/main/scala/gs/test/v0/api/TestFailure.scala
similarity index 94%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/TestFailure.scala
rename to modules/api/src/main/scala/gs/test/v0/api/TestFailure.scala
index 186dadf..35f00e4 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestFailure.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/TestFailure.scala
@@ -1,6 +1,4 @@
-package gs.test.v0.definition
-
-import gs.test.v0.definition.pos.SourcePosition
+package gs.test.v0.api
 
 /** Base trait for all failures recognized by gs-test.
   */
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestGroup.scala b/modules/api/src/main/scala/gs/test/v0/api/TestGroup.scala
similarity index 99%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/TestGroup.scala
rename to modules/api/src/main/scala/gs/test/v0/api/TestGroup.scala
index 3caaace..1e15638 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestGroup.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/TestGroup.scala
@@ -1,9 +1,8 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.data.EitherT
 import cats.effect.Async
 import cats.syntax.all.*
-import gs.test.v0.definition.pos.SourcePosition
 import java.util.concurrent.ConcurrentHashMap
 import scala.collection.mutable.ListBuffer
 import scala.jdk.CollectionConverters.*
@@ -14,7 +13,7 @@ import scala.jdk.CollectionConverters.*
   * ## Example
   *
   * {{{
-  * import gs.test.v0.definition.*
+  * import gs.test.v0.api.*
   *
   * final class MyTestGroup extends TestGroup.IO:
   *   override def name: String = "My Test Group"
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestGroupDefinition.scala b/modules/api/src/main/scala/gs/test/v0/api/TestGroupDefinition.scala
similarity index 98%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/TestGroupDefinition.scala
rename to modules/api/src/main/scala/gs/test/v0/api/TestGroupDefinition.scala
index eaedab6..db99eea 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestGroupDefinition.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/TestGroupDefinition.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.Show
 import cats.effect.Async
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestIterations.scala b/modules/api/src/main/scala/gs/test/v0/api/TestIterations.scala
similarity index 97%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/TestIterations.scala
rename to modules/api/src/main/scala/gs/test/v0/api/TestIterations.scala
index 01cff55..2256f14 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestIterations.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/TestIterations.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.Show
 
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestSuite.scala b/modules/api/src/main/scala/gs/test/v0/api/TestSuite.scala
similarity index 94%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/TestSuite.scala
rename to modules/api/src/main/scala/gs/test/v0/api/TestSuite.scala
index 97f2a7b..40c7b00 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/TestSuite.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/TestSuite.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 /** The Test Suite is the primary unit of organization within `gs-test` -- each
   * execution _typically_ runs a single test suite. For example, the unit tests
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/UnitOfWork.scala b/modules/api/src/main/scala/gs/test/v0/api/UnitOfWork.scala
similarity index 99%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/UnitOfWork.scala
rename to modules/api/src/main/scala/gs/test/v0/api/UnitOfWork.scala
index 6911b00..d64ce31 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/UnitOfWork.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/UnitOfWork.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.~>
 import cats.Applicative
diff --git a/modules/api-definition/src/main/scala/gs/test/v0/definition/syntax.scala b/modules/api/src/main/scala/gs/test/v0/api/syntax.scala
similarity index 94%
rename from modules/api-definition/src/main/scala/gs/test/v0/definition/syntax.scala
rename to modules/api/src/main/scala/gs/test/v0/api/syntax.scala
index 81e3b9f..b20128f 100644
--- a/modules/api-definition/src/main/scala/gs/test/v0/definition/syntax.scala
+++ b/modules/api/src/main/scala/gs/test/v0/api/syntax.scala
@@ -1,10 +1,9 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.Applicative
 import cats.data.EitherT
 import cats.effect.Sync
 import cats.syntax.all.*
-import gs.test.v0.definition.pos.SourcePosition
 
 /** Type alias for test results. Test results are either a [[TestFailure]] or a
   * unit value (indicating success).
@@ -15,7 +14,7 @@ type TestResult = Either[TestFailure, Unit]
   * instances.
   *
   * {{{
-  * import gs.test.v0.definition.*
+  * import gs.test.v0.api.*
   * val tag1: TestDefinition.Tag = tag"example"
   * }}}
   */
@@ -25,7 +24,7 @@ extension (sc: StringContext) def tag(args: Any*): Tag = Tag(sc.s(args*))
   * [[PermanentId]] instances.
   *
   * {{{
-  * import gs.test.v0.definition.*
+  * import gs.test.v0.api.*
   * val permanentId: PermanentId = pid"example"
   * }}}
   */
@@ -82,7 +81,7 @@ def failT[F[_]: Applicative](
   * ## Example
   *
   * {{{
-  * import gs.test.v0.definition.*
+  * import gs.test.v0.api.*
   *
   * final class Example extends TestGroup.IO:
   *   override def name: String = "example"
@@ -100,7 +99,7 @@ def pass(): Either[TestFailure, Unit] = Right(())
   * ## Example
   *
   * {{{
-  * import gs.test.v0.definition.*
+  * import gs.test.v0.api.*
   *
   * final class Example extends TestGroup.IO:
   *   override def name: String = "example"
@@ -119,7 +118,7 @@ def passF[F[_]: Applicative](): F[Either[TestFailure, Unit]] =
   * ## Example
   *
   * {{{
-  * import gs.test.v0.definition.*
+  * import gs.test.v0.api.*
   *
   * final class Example extends TestGroup.IO:
   *   override def name: String = "example"
diff --git a/modules/api-definition/src/test/scala/gs/test/v0/definition/GroupImplementationTests.scala b/modules/api/src/test/scala/gs/test/v0/api/GroupImplementationTests.scala
similarity index 98%
rename from modules/api-definition/src/test/scala/gs/test/v0/definition/GroupImplementationTests.scala
rename to modules/api/src/test/scala/gs/test/v0/api/GroupImplementationTests.scala
index 8274105..2b962c3 100644
--- a/modules/api-definition/src/test/scala/gs/test/v0/definition/GroupImplementationTests.scala
+++ b/modules/api/src/test/scala/gs/test/v0/api/GroupImplementationTests.scala
@@ -1,9 +1,9 @@
-package gs.test.v0.definition
+package gs.test.v0.api
 
 import cats.data.Kleisli
 import cats.effect.Async
 import cats.effect.IO
-import gs.test.v0.definition.{Tag => GsTag}
+import gs.test.v0.api.{Tag => GsTag}
 import munit.*
 import natchez.Span
 
diff --git a/modules/api-definition/src/test/scala/gs/test/v0/definition/pos/SourcePositionTests.scala b/modules/api/src/test/scala/gs/test/v0/api/SourcePositionTests.scala
similarity index 91%
rename from modules/api-definition/src/test/scala/gs/test/v0/definition/pos/SourcePositionTests.scala
rename to modules/api/src/test/scala/gs/test/v0/api/SourcePositionTests.scala
index e85dfe6..638c37a 100644
--- a/modules/api-definition/src/test/scala/gs/test/v0/definition/pos/SourcePositionTests.scala
+++ b/modules/api/src/test/scala/gs/test/v0/api/SourcePositionTests.scala
@@ -1,14 +1,14 @@
-package gs.test.v0.definition.pos
+package gs.test.v0.api
 
 import cats.effect.IO
 import cats.effect.kernel.Resource
-import gs.test.v0.IOSuite
-import gs.test.v0.definition.*
+import gs.test.v0.api.*
 import munit.*
 import natchez.EntryPoint
 import natchez.Kernel
 import natchez.Span
 import natchez.Span.Options
+import support.IOSuite
 
 /** These tests are sensitive to changes, even in formatting! They are looking
   * for specific line numbers in this source code, so any sort of newline that
@@ -87,12 +87,12 @@ object SourcePositionTests:
     override def name: String = "G2"
 
     test(pid"t2", "pos").pure {
-      gs.test.v0.definition.fail("Expected Failure")
+      gs.test.v0.api.fail("Expected Failure")
     }
 
   end G2
 
   val SourceFileName: String =
-    "modules/api-definition/src/test/scala/gs/test/v0/definition/pos/SourcePositionTests.scala"
+    "modules/api/src/test/scala/gs/test/v0/api/SourcePositionTests.scala"
 
 end SourcePositionTests
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/SuiteExecution.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/SuiteExecution.scala
similarity index 91%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/SuiteExecution.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/SuiteExecution.scala
index a691ecd..a6d0531 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/SuiteExecution.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/SuiteExecution.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.execution
+package gs.test.v0.runtime
 
 import gs.uuid.v0.UUID
 import java.time.Instant
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/TestExecution.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/TestExecution.scala
similarity index 98%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/TestExecution.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/TestExecution.scala
index 8cce39f..61ceafd 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/TestExecution.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/TestExecution.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.execution
+package gs.test.v0.runtime
 
 import cats.Show
 import gs.test.v0.definition.Marker
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/ConcurrencySetting.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/ConcurrencySetting.scala
similarity index 91%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/engine/ConcurrencySetting.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/engine/ConcurrencySetting.scala
index 128dbee..690cf19 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/ConcurrencySetting.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/ConcurrencySetting.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.execution.engine
+package gs.test.v0.runtime.engine
 
 sealed abstract class ConcurrencySetting(val name: String):
   def toInt(): Int
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineConfiguration.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineConfiguration.scala
similarity index 92%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineConfiguration.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineConfiguration.scala
index e7d4f49..af41202 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineConfiguration.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineConfiguration.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.execution.engine
+package gs.test.v0.runtime.engine
 
 /** Used to control the behavior of some [[TestEngine]]
   *
diff --git a/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineResult.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineResult.scala
new file mode 100644
index 0000000..2b19bdc
--- /dev/null
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineResult.scala
@@ -0,0 +1,7 @@
+package gs.test.v0.runtime.engine
+
+import gs.test.v0.runtime.SuiteExecution
+
+final class EngineResult(
+  val suiteExecution: SuiteExecution
+)
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineStats.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineStats.scala
similarity index 95%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineStats.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineStats.scala
index 1156823..9fa5093 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/EngineStats.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/EngineStats.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.execution.engine
+package gs.test.v0.runtime.engine
 
 import cats.effect.Async
 import cats.effect.Ref
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/GroupResult.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/GroupResult.scala
similarity index 77%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/engine/GroupResult.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/engine/GroupResult.scala
index 300b81a..049b91f 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/GroupResult.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/GroupResult.scala
@@ -1,7 +1,7 @@
-package gs.test.v0.execution.engine
+package gs.test.v0.runtime.engine
 
 import gs.test.v0.definition.TestGroupDefinition
-import gs.test.v0.execution.TestExecution
+import gs.test.v0.runtime.TestExecution
 import scala.concurrent.duration.FiniteDuration
 
 final class GroupResult(
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/MaximumConcurrency.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/MaximumConcurrency.scala
similarity index 92%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/engine/MaximumConcurrency.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/engine/MaximumConcurrency.scala
index b73300a..17ca7ae 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/MaximumConcurrency.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/MaximumConcurrency.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.execution.engine
+package gs.test.v0.runtime.engine
 
 opaque type MaximumConcurrency = Int
 
diff --git a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/TestEngine.scala b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/TestEngine.scala
similarity index 97%
rename from modules/api-execution/src/main/scala/gs/test/v0/execution/engine/TestEngine.scala
rename to modules/runtime/src/main/scala/gs/test/v0/runtime/engine/TestEngine.scala
index 0a36455..c07a1fa 100644
--- a/modules/api-execution/src/main/scala/gs/test/v0/execution/engine/TestEngine.scala
+++ b/modules/runtime/src/main/scala/gs/test/v0/runtime/engine/TestEngine.scala
@@ -1,4 +1,4 @@
-package gs.test.v0.execution.engine
+package gs.test.v0.runtime.engine
 
 import cats.effect.Async
 import cats.syntax.all.*
@@ -6,8 +6,8 @@ import gs.test.v0.definition.TestDefinition
 import gs.test.v0.definition.TestFailure
 import gs.test.v0.definition.TestGroupDefinition
 import gs.test.v0.definition.TestSuite
-import gs.test.v0.execution.SuiteExecution
-import gs.test.v0.execution.TestExecution
+import gs.test.v0.runtime.SuiteExecution
+import gs.test.v0.runtime.TestExecution
 import gs.timing.v0.Timing
 import gs.uuid.v0.UUID
 import java.time.Clock
diff --git a/modules/api-definition/src/test/scala/gs/test/v0/IOSuite.scala b/modules/test-support/src/test/scala/support/IOSuite.scala
similarity index 94%
rename from modules/api-definition/src/test/scala/gs/test/v0/IOSuite.scala
rename to modules/test-support/src/test/scala/support/IOSuite.scala
index 86d771e..1fc7f44 100644
--- a/modules/api-definition/src/test/scala/gs/test/v0/IOSuite.scala
+++ b/modules/test-support/src/test/scala/support/IOSuite.scala
@@ -1,4 +1,4 @@
-package gs.test.v0
+package support
 
 import cats.effect.IO
 import cats.effect.unsafe.IORuntime