diff --git a/platformUI/build.gradle.kts b/platformUI/build.gradle.kts
index 5f13799..9ad06af 100644
--- a/platformUI/build.gradle.kts
+++ b/platformUI/build.gradle.kts
@@ -15,7 +15,6 @@
  */
 
 import com.github.gradle.node.yarn.task.YarnTask
-import org.gradle.api.logging.LogLevel.INFO
 
 node {
     // Retrieve tested versions of Node, Npm and Yarn from the version catalog (see gradle/libs.versions.toml)
@@ -41,11 +40,7 @@ dependencies {
 
 // TODO: Future webapp improvement; implement a parallel NPM / package-lock based approach. Yarn does not like having a package lock in the same build.
 internal val gui = project.file("gui")
-internal val buildDirs = arrayOf("gui/node_modules", "gui_dist", "gui/.quasar")
-
-val compileXtc by tasks.existing {
-    dependsOn(yarnQuasarBuild)
-}
+internal val buildDirs = arrayOf("gui/node_modules", "gui/dist", "gui/.quasar")
 
 /**
  * By adding the gui/dist folder as a resource directory, the build will also treat
@@ -57,26 +52,34 @@ val compileXtc by tasks.existing {
 sourceSets.main {
     xtc {
         resources {
-            srcDir(file("gui/dist/"))
+            srcDir(files("gui/dist/"))
         }
     }
 }
 
 val clean by tasks.existing {
-    delete(layout.files(*buildDirs))
+    doLast {
+        for (buildDir in buildDirs) {
+            logger.info("Want to clean build dir: $buildDir")
+            delete(layout.files(buildDir))
+        }
+    }
 }
 
-// The yarnSetup task is just referenced here for type safety. We can also refer to it by name below,
-// instead of to the variable "yarnSetup", but that is more brittle, and if we rename the task, any references
-// to it might accidentally be forgotten.
-val yarnSetup by tasks.existing
-
-val yarnAddQuasar by tasks.registering(YarnTask::class) {
-    dependsOn(yarnSetup)
+/**
+ * Task that will make sure yarn updates all node_modules.
+ */
+val yarnAddDependencies by tasks.registering(YarnTask::class) {
     workingDir = gui
+    dependsOn(tasks.yarnSetup)
+
     // Tag this task as a producer of the "node_modules" directory, implicitly ensuring that any changes
     // to the resolved node_modules will make its dependents rebuild properly.
-    outputs.file("node_modules")
+    outputs.dir("gui/node_modules")
+
+    // Add a dependency to quasar. If one exists in the yarn/lock file, it may be used instead, so
+    // if the state of global/local installation changed, that may still rebuild, though, if it's
+    // not installed in both places.
     val quasarGlobal = providers.gradleProperty("org.xtclang.platform.quasarGlobal")
     args = buildList {
         add("add")
@@ -88,27 +91,67 @@ val yarnAddQuasar by tasks.registering(YarnTask::class) {
     }
 
     doFirst {
-        logger.lifecycle("Task '$name' installing Quasar (${if (quasarGlobal.isPresent && quasarGlobal.get().toBoolean()) "globally" else "locally, only for ${rootProject.name}"}.")
-        printTaskOutputs(INFO)
+        logger.lifecycle("Task '$name' installing Quasar (${if (quasarGlobal.isPresent && quasarGlobal.get().toBoolean()) "globally" else "locally, only for ${rootProject.name})"}.")
+        printTaskInputsAndOutputs(LogLevel.INFO)
     }
 }
 
+/**
+ * Task that defines the inputs and outputs for the Quasar webapp, and builds it. This means that the task
+ * should detect, e.g. if someone changes index.html or a single Vue file, and then rerun the task. Otherwise
+ * the task will be treated as "up to date".
+ */
 val yarnQuasarBuild by tasks.registering(YarnTask::class) {
-    dependsOn(yarnAddQuasar)
     workingDir = gui
-    outputs.files()
-    args = listOf("--ignore-engines", "quasar", "build")
+    dependsOn(yarnAddDependencies)
+
+    inputs.files("gui/public")
+    inputs.files("gui/index.html", "gui/src")
+    outputs.dir("gui/.quasar")
+    outputs.dir("gui/dist/spa") // Declare output file collection, even though empty, or we can never cache the yarnQuasarBuild task.
+    args = listOf("quasar", "build")
     doLast {
-        printTaskOutputs(INFO)
+        printTaskInputsAndOutputs(LogLevel.INFO)
     }
 }
 
-internal fun Task.printTaskOutputs(level: LogLevel = LogLevel.LIFECYCLE) {
+/**
+ * Compile the XTC PlatformUI Module.
+ */
+val compileXtc by tasks.existing {
+    dependsOn(verifySourceSets)
+    dependsOn(yarnQuasarBuild)
+}
+
+val processResources by tasks.existing {
+    dependsOn(yarnQuasarBuild)
+}
+
+val verifySourceSets by tasks.registering {
+    dependsOn(processResources)
+    mustRunAfter(yarnQuasarBuild)
+    sourceSets.forEach {
+        logger.info("*** Source Set: $it")
+        it.resources.files.forEach {
+            logger.info("** Resource: $it")
+        }
+    }
+}
+
+private fun Task.printTaskInputsAndOutputs(level: LogLevel = LogLevel.LIFECYCLE) {
+    val inputFiles = inputs.files.asFileTree
+    logger.log(level, "Inputs: $name: ${inputFiles.toList()}")
     val outputFiles = outputs.files.asFileTree
-    val n = outputFiles.count()
+    logger.log(level, "Outputs: $name: ${outputFiles.toList()}")
+    val ni = inputFiles.count()
+    val no = outputFiles.count()
     logger.log(level, "${project.name} Task '$name' finished.")
-    logger.log(level, "${project.name}     Outputs (count: $n):")
+    logger.log(level, "${project.name}     Inputs (count: $no):")
+    inputs.files.asFileTree.forEachIndexed {
+            i, it -> logger.log(level, "${project.name}     '$name' input $i (of $ni): $it")
+    }
+    logger.log(level, "${project.name}     Outputs (count: $no):")
     outputs.files.asFileTree.forEachIndexed {
-        i, it -> logger.log(level, "${project.name}     '$name' output $i (of $n): $it")
+            i, it -> logger.log(level, "${project.name}     '$name' output $i (of $no): $it")
     }
 }
diff --git a/platformUI/gui/src/App.vue b/platformUI/gui/src/App.vue
index 5a2ae0d..38442ee 100644
--- a/platformUI/gui/src/App.vue
+++ b/platformUI/gui/src/App.vue
@@ -8,4 +8,4 @@ import { defineComponent } from 'vue'
 export default defineComponent({
   name: 'App'
 })
-</script>
\ No newline at end of file
+</script>