Don't apply platform substitution to %

core/src/main/scala/sbt/librarymanagement/ScalaArtifacts.scala

@@ -57,12 +57,12 @@ object ScalaArtifacts {
 
   def libraryDependency(version: String): ModuleID = libraryDependency(Organization, version)
 
-  def libraryDependency(org: String, version: String): ModuleID = {
-    if (isScala3(version))
-      ModuleID(org, Scala3LibraryID, version).withCrossVersion(CrossVersion.binary)
-    else
-      ModuleID(org, LibraryID, version)
-  }
+  def libraryDependency(org: String, version: String): ModuleID =
+    if isScala3(version) then
+      ModuleID(org, Scala3LibraryID, version)
+        .withCrossVersion(CrossVersion.binary)
+        .platform(Platform.jvm)
+    else ModuleID(org, LibraryID, version).platform(Platform.jvm)
 
   private[sbt] def docToolDependencies(
       org: String,
@@ -79,6 +79,7 @@ object ScalaArtifacts {
         ModuleID(org, ScaladocID, version)
           .withConfigurations(Some(Configurations.ScalaDocTool.name + "->default(compile)"))
           .withCrossVersion(CrossVersion.binary)
+          .platform(Platform.jvm)
       )
     else Seq.empty
 
@@ -91,6 +92,7 @@ object ScalaArtifacts {
         ModuleID(org, Scala3CompilerID, version)
           .withConfigurations(Some(Configurations.ScalaTool.name + "->default(compile)"))
           .withCrossVersion(CrossVersion.binary)
+          .platform(Platform.jvm)
       )
     else
       Seq(
@@ -99,9 +101,11 @@ object ScalaArtifacts {
       )
 
   private[this] def scala2ToolDependency(org: String, id: String, version: String): ModuleID =
-    ModuleID(org, id, version).withConfigurations(
-      Some(Configurations.ScalaTool.name + "->default,optional(default)")
-    )
+    ModuleID(org, id, version)
+      .withConfigurations(
+        Some(Configurations.ScalaTool.name + "->default,optional(default)")
+      )
+      .platform(Platform.jvm)
 }
 
 object SbtArtifacts {

ivy/src/main/scala/sbt/internal/librarymanagement/Ivy.scala

@@ -742,10 +742,13 @@ private[sbt] object IvySbt {
         case "" | Platform.jvm => m
         case _                 => m.withName(s"${m.name}_$platformName")
     (m: ModuleID) =>
-      (platform, m.platformOpt) match
-        case (Some(p), None) => addSuffix(m, p)
-        case (_, Some(p))    => addSuffix(m, p)
-        case _               => m
+      m.crossVersion match
+        case _: Disabled => m
+        case _ =>
+          (platform, m.platformOpt) match
+            case (Some(p), None) => addSuffix(m, p)
+            case (_, Some(p))    => addSuffix(m, p)
+            case _               => m
   }
 
   private def toIvyArtifact(

ivy/src/test/scala/sbt/internal/librarymanagement/PlatformResolutionSpec.scala

@@ -27,6 +27,20 @@ object PlatformResolutionSpec extends BaseIvySpecification {
     )
   }
 
+  test("sjs1 platform resolves % as JVM") {
+    cleanCache()
+    val m = module(
+      exampleModuleId("0.6.0"),
+      deps = Vector(junit),
+      Some(scala2_13),
+      platform = Some(sjs1),
+    )
+    assert(
+      update(m).configurations.head.modules.map(_.toString).mkString
+        contains "junit:junit:4.13.1"
+    )
+  }
+
   test("None platform can specify .platform(sjs1) depenency") {
     cleanCache()
     val m = module(
@@ -64,6 +78,7 @@ object PlatformResolutionSpec extends BaseIvySpecification {
 
   def exampleModuleId(v: String): ModuleID = ("com.example" % "foo" % v % Compile)
   def scopt = ("com.github.scopt" %% "scopt" % "4.1.0" % Compile)
+  def junit = ("junit" % "junit" % "4.13.1" % Compile)
   override val resolvers = Vector(
     Resolver.mavenCentral,
   )