diff --git a/main/src/main/scala/sbt/Defaults.scala b/main/src/main/scala/sbt/Defaults.scala
index bfd867aaf..05f5d1fd9 100644
--- a/main/src/main/scala/sbt/Defaults.scala
+++ b/main/src/main/scala/sbt/Defaults.scala
@@ -420,6 +420,7 @@ object Defaults extends BuildCommon {
       terminal := Def.uncached(state.value.get(terminalKey).getOrElse(Terminal(ITerminal.get))),
       InstallSbtn.installSbtn := InstallSbtn.installSbtnImpl.evaluated,
       InstallSbtn.installSbtn / aggregate := false,
+      checkBuildSources / pollInterval :== CheckBuildSources.defaultPollInterval,
     ) ++ LintUnused.lintSettings
       ++ DefaultBackgroundJobService.backgroundJobServiceSettings
       ++ RemoteCache.globalSettings
@@ -555,8 +556,6 @@ object Defaults extends BuildCommon {
     sourceManaged := target.value / "src_managed",
     resourceManaged := target.value / "resource_managed",
     // Adds subproject build.sbt files to the global list of build files to monitor
-    Scope.Global / checkBuildSources / pollInterval :==
-      new FiniteDuration(Int.MinValue, TimeUnit.MILLISECONDS),
     Scope.Global / checkBuildSources / fileInputs ++= {
       if ((Scope.Global / onChangedBuildSource).value != IgnoreSourceChanges)
         Seq(baseDirectory.value.toGlob / "*.sbt")
diff --git a/main/src/main/scala/sbt/internal/Load.scala b/main/src/main/scala/sbt/internal/Load.scala
index 8ca8d88d2..bc7e6c040 100755
--- a/main/src/main/scala/sbt/internal/Load.scala
+++ b/main/src/main/scala/sbt/internal/Load.scala
@@ -73,10 +73,10 @@ private[sbt] object Load {
     val launcher = scalaProvider.launcher
     val stagingDirectory = getStagingDirectory(state, globalBase).getCanonicalFile
     val javaHome = Util.javaHome
-    val out = baseDirectory.toPath.resolve("target").resolve("out")
+    val out = app.baseDirectory.toPath.resolve("target").resolve("out")
     val rootPaths = Map(
       "OUT" -> out,
-      "BASE" -> baseDirectory.toPath,
+      "BASE" -> app.baseDirectory.toPath,
       "SBT_BOOT" -> launcher.bootDirectory.toPath,
       "IVY_HOME" -> launcher.ivyHome.toPath,
       "JAVA_HOME" -> javaHome,
@@ -119,7 +119,9 @@ private[sbt] object Load {
     )
     val evalPluginDef: (BuildStructure, State) => PluginData = EvaluateTask.evalPluginDef
     val delegates = defaultDelegates
-    val pluginMgmt = PluginManagement(loader)
+    import sbt.ProjectExtra.projectReturn
+    val pluginContext = PluginManagement.Context(false, Project.projectReturn(state).size - 1)
+    val pluginMgmt = PluginManagement(loader, pluginContext)
     val inject = InjectSettings(injectGlobal(state), Nil, const(Nil))
     SysProp.setSwovalTempDir()
     SysProp.setIpcSocketTempDir()
diff --git a/main/src/main/scala/sbt/internal/PluginManagement.scala b/main/src/main/scala/sbt/internal/PluginManagement.scala
index 0a9c94980..e551b3c44 100644
--- a/main/src/main/scala/sbt/internal/PluginManagement.scala
+++ b/main/src/main/scala/sbt/internal/PluginManagement.scala
@@ -54,12 +54,15 @@ object PluginManagement {
   val emptyContext: Context = Context(false, 0)
 
   def apply(initialLoader: ClassLoader): PluginManagement =
+    PluginManagement(initialLoader, emptyContext)
+
+  def apply(initialLoader: ClassLoader, context: Context): PluginManagement =
     PluginManagement(
       Set.empty,
       Set.empty,
       new PluginClassLoader(initialLoader),
       initialLoader,
-      emptyContext
+      context
     )
 
   def extractOverrides(classpath: Classpath): Set[ModuleID] =
diff --git a/main/src/main/scala/sbt/nio/CheckBuildSources.scala b/main/src/main/scala/sbt/nio/CheckBuildSources.scala
index 7b3bde263..1a39546d3 100644
--- a/main/src/main/scala/sbt/nio/CheckBuildSources.scala
+++ b/main/src/main/scala/sbt/nio/CheckBuildSources.scala
@@ -10,6 +10,7 @@ package sbt
 package internal.nio
 
 import java.nio.file.Path
+import java.util.concurrent.TimeUnit
 import java.util.concurrent.atomic.{ AtomicBoolean, AtomicReference }
 import sbt.BasicCommandStrings.{ RebootCommand, Shutdown, TerminateAction }
 import sbt.Keys.{ baseDirectory, pollInterval, state }
@@ -65,7 +66,9 @@ private[sbt] class CheckBuildSources extends AutoCloseable {
   }
   private def reset(state: State): Unit = {
     val extracted = Project.extract(state)
-    val interval = extracted.get(checkBuildSources / pollInterval)
+    val interval = extracted
+      .getOpt(checkBuildSources / pollInterval)
+      .getOrElse(CheckBuildSources.defaultPollInterval)
     val newSources = extracted.get(Global / checkBuildSources / fileInputs).distinct
     if (interval >= 0.seconds || "polling" == SysProp.watchMode) {
       Option(repository.getAndSet(null)).foreach(_.close())
@@ -174,7 +177,9 @@ private[sbt] class CheckBuildSources extends AutoCloseable {
   override def close(): Unit = {}
 }
 
-private[sbt] object CheckBuildSources {
+private[sbt] object CheckBuildSources:
+  val defaultPollInterval: FiniteDuration = FiniteDuration(Int.MinValue, TimeUnit.MILLISECONDS)
+
   private[sbt] val CheckBuildSourcesKey =
     AttributeKey[CheckBuildSources]("check-build-source", "", KeyRanks.Invisible)
   /*
@@ -219,4 +224,4 @@ private[sbt] object CheckBuildSources {
       projectGlobs(projectDir, baseDir.toGlob / "*.sbt" :: Nil)
     } else Nil
   }
-}
+end CheckBuildSources
diff --git a/sbt-app/src/sbt-test/project-load/metabuild/project/FooPlugin.scala b/sbt-app/src/sbt-test/project-load/metabuild/project/FooPlugin.scala
new file mode 100644
index 000000000..5633f3307
--- /dev/null
+++ b/sbt-app/src/sbt-test/project-load/metabuild/project/FooPlugin.scala
@@ -0,0 +1,24 @@
+package example
+
+import sbt.*
+import Keys.*
+import complete.DefaultParsers.{ *, given }
+
+object FooPlugin extends AutoPlugin:
+  override def requires = empty
+  override def trigger = allRequirements
+
+  lazy object autoImport:
+    @transient
+    lazy val foo = taskKey[Unit]("foo")
+    lazy val check = inputKey[Unit]("check")
+
+  import autoImport.*
+  override def projectSettings: Seq[Def.Setting[?]] = Seq(
+    foo := println("foo"),
+    check := {
+      val args = spaceDelimited("<arg>").parsed
+      assert(name.value.endsWith(args.head), s"${name.value} does not end with ${args.head}")
+    },
+  )
+end FooPlugin
diff --git a/sbt-app/src/sbt-test/project-load/metabuild/project/project/FooPlugin.scala b/sbt-app/src/sbt-test/project-load/metabuild/project/project/FooPlugin.scala
new file mode 100644
index 000000000..5633f3307
--- /dev/null
+++ b/sbt-app/src/sbt-test/project-load/metabuild/project/project/FooPlugin.scala
@@ -0,0 +1,24 @@
+package example
+
+import sbt.*
+import Keys.*
+import complete.DefaultParsers.{ *, given }
+
+object FooPlugin extends AutoPlugin:
+  override def requires = empty
+  override def trigger = allRequirements
+
+  lazy object autoImport:
+    @transient
+    lazy val foo = taskKey[Unit]("foo")
+    lazy val check = inputKey[Unit]("check")
+
+  import autoImport.*
+  override def projectSettings: Seq[Def.Setting[?]] = Seq(
+    foo := println("foo"),
+    check := {
+      val args = spaceDelimited("<arg>").parsed
+      assert(name.value.endsWith(args.head), s"${name.value} does not end with ${args.head}")
+    },
+  )
+end FooPlugin
diff --git a/sbt-app/src/sbt-test/project-load/metabuild/test b/sbt-app/src/sbt-test/project-load/metabuild/test
new file mode 100644
index 000000000..68aec72a2
--- /dev/null
+++ b/sbt-app/src/sbt-test/project-load/metabuild/test
@@ -0,0 +1,9 @@
+> foo
+> reload plugins
+> check -build
+> foo
+> reload plugins
+> reload return
+> reload return
+> compile
+> foo