Detect plugins lazily when loading a site from disk

update/org.eclipse.update.configurator.tests/META-INF/MANIFEST.MF

@@ -14,4 +14,5 @@ Export-Package: org.eclipse.update.configurator.tests,
  org.eclipse.update.internal.configurator.tests
 Eclipse-BundleShape: dir
 Import-Package: org.junit.jupiter.api;version="[5.14.0,6.0.0)",
+ org.junit.jupiter.api.io;version="[5.14.0,6.0.0)",
  org.junit.platform.suite.api;version="[1.14.0,2.0.0)"

update/org.eclipse.update.configurator.tests/src/org/eclipse/update/configurator/tests/AutomatedConfiguratorSuite.java

@@ -14,6 +14,7 @@
 package org.eclipse.update.configurator.tests;
 
 import org.eclipse.update.internal.configurator.tests.FeatureEntryTests;
+import org.eclipse.update.internal.configurator.tests.SiteEntryTests;
 import org.junit.platform.suite.api.SelectClasses;
 import org.junit.platform.suite.api.Suite;
 
@@ -25,6 +26,7 @@
 @Suite
 @SelectClasses({ //
 		FeatureEntryTests.class, //
+		SiteEntryTests.class, //
 })
 public class AutomatedConfiguratorSuite {
 

update/org.eclipse.update.configurator.tests/src/org/eclipse/update/internal/configurator/tests/SiteEntryTests.java

@@ -0,0 +1,95 @@
+/*******************************************************************************
+ * Copyright (c) 2026 Lars Vogel and others.
+ *
+ *  This program and the accompanying materials
+ *  are made available under the terms of the Eclipse Public License 2.0
+ *  which accompanies this distribution, and is available at
+ *  https://www.eclipse.org/legal/epl-2.0/
+ *
+ *  SPDX-License-Identifier: EPL-2.0
+ *
+ *  Contributors:
+ *     Lars Vogel <Lars.Vogel@vogella.com> - initial API and implementation
+ *******************************************************************************/
+package org.eclipse.update.internal.configurator.tests;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import java.io.OutputStream;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.jar.Attributes;
+import java.util.jar.JarOutputStream;
+import java.util.jar.Manifest;
+
+import org.eclipse.update.internal.configurator.Configuration;
+import org.eclipse.update.internal.configurator.FeatureEntry;
+import org.eclipse.update.internal.configurator.PluginEntry;
+import org.eclipse.update.internal.configurator.SiteEntry;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.io.TempDir;
+
+@SuppressWarnings("restriction")
+public class SiteEntryTests {
+
+	@TempDir
+	Path siteRoot;
+
+	@Test
+	public void testLoadFromDiskDetectsFeaturesWithoutScanningPlugins() throws Exception {
+		createFeature("test.feature", "1.0.0");
+		Path pluginJar = createPluginJar("test.plugin", "1.0.0");
+
+		SiteEntry site = createSite();
+		site.loadFromDisk(0);
+
+		FeatureEntry[] features = site.getFeatureEntries();
+		assertEquals(1, features.length);
+		assertEquals("test.feature", features[0].getFeatureIdentifier());
+
+		// the jar is untouched so far, deleting it now leaves an eager scan nothing to have found
+		Files.delete(pluginJar);
+		assertEquals(0, site.getAllPluginEntries().length);
+	}
+
+	@Test
+	public void testPluginsAreDetectedOnFirstAccess() throws Exception {
+		createFeature("test.feature", "1.0.0");
+		createPluginJar("test.plugin", "1.0.0");
+
+		SiteEntry site = createSite();
+		site.loadFromDisk(0);
+
+		PluginEntry[] plugins = site.getAllPluginEntries();
+		assertEquals(1, plugins.length);
+		assertEquals("test.plugin", plugins[0].getPluginIdentifier());
+		assertEquals("1.0.0", plugins[0].getPluginVersion());
+	}
+
+	private SiteEntry createSite() throws Exception {
+		SiteEntry site = new SiteEntry(siteRoot.toUri().toURL());
+		site.setConfig(new Configuration());
+		return site;
+	}
+
+	private void createFeature(String id, String version) throws Exception {
+		Path featureDir = Files.createDirectories(siteRoot.resolve("features").resolve(id + "_" + version));
+		Files.writeString(featureDir.resolve("feature.xml"), "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n" //
+				+ "<feature id=\"" + id + "\" version=\"" + version + "\"/>\n");
+	}
+
+	private Path createPluginJar(String id, String version) throws Exception {
+		Path pluginsDir = Files.createDirectories(siteRoot.resolve("plugins"));
+		Path jar = pluginsDir.resolve(id + "_" + version + ".jar");
+		Manifest manifest = new Manifest();
+		Attributes attributes = manifest.getMainAttributes();
+		attributes.put(Attributes.Name.MANIFEST_VERSION, "1.0");
+		attributes.putValue("Bundle-ManifestVersion", "2");
+		attributes.putValue("Bundle-SymbolicName", id);
+		attributes.putValue("Bundle-Version", version);
+		try (OutputStream out = Files.newOutputStream(jar); JarOutputStream jarOut = new JarOutputStream(out, manifest)) {
+			// the manifest written by the stream is all the detection needs
+		}
+		return jar;
+	}
+}

update/org.eclipse.update.configurator/src/org/eclipse/update/internal/configurator/SiteEntry.java

@@ -674,7 +674,7 @@ public void loadFromDisk(long lastChange) throws CoreException{
 		featuresChangeStamp = lastChange;
 		pluginsChangeStamp = lastChange;
 		detectFeatures();
-		detectPlugins();
+		// plugins are detected on first access, the scan opens every jar on the site
 	}
 
 	/**