fix(libraries): keep External Libraries in a stable order and reload after a build sync (#3077)

External Libraries groups were listed in detection order, which differed between the streamed and final results; they are now sorted SDKs first, then libraries by name. A Maven sync that changed dependency versions without touching a manifest left old versions listed; every successful build sync now emits projectRootsChanged (Gradle already did) and External Libraries reloads on it.

crates/ide-host/src/ops/build.rs

@@ -313,10 +313,11 @@ pub async fn build_sync(
     if tool == BuildTool::Gradle {
         // The sync may report project folders outside the project (`includeFlat`): index and list them.
         project.refresh_index_scope();
-        project.sink.emit(ide_core::IdeEvent::ProjectRootsChanged { root: project.root.clone().into() });
         let p = project.clone();
         tokio::task::spawn_blocking(move || p.refresh_repositories());
     }
+    // New source folders and dependency versions: the Project view and External Libraries reload.
+    project.sink.emit(ide_core::IdeEvent::ProjectRootsChanged { root: project.root.clone().into() });
     if tool == BuildTool::Maven
         && model.maven.is_some()
         && let Some(bridge) = &project.kotlin_bridge

src/features/libraries/index.ts

@@ -83,6 +83,14 @@ export function touchesManifest(paths: readonly string[]): boolean {
   );
 }
 
+/** IDEA's order, whatever order the ecosystems were detected in: SDKs first, then libraries, each by name. */
+function sortedGroups(groups: readonly LibraryGroup[]): LibraryGroup[] {
+  const rank = (g: LibraryGroup) => (SDK_KINDS.has(g.kind) ? 0 : 1);
+  return [...groups].sort(
+    (a, b) => rank(a) - rank(b) || a.name.localeCompare(b.name, undefined, { sensitivity: "base", numeric: true }),
+  );
+}
+
 /** The "External Libraries" node for `groups` (`< Python 3.12 (.venv) >` › `python3.12`, `site-packages`). */
 export function librariesRoot(groups: readonly LibraryGroup[]): ProjectViewRootContribution | null {
   if (!groups.length) return null;
@@ -93,7 +101,7 @@ export function librariesRoot(groups: readonly LibraryGroup[]): ProjectViewRootC
     // After the project, before Scratches and Consoles (IDEA's order).
     order: 5,
     readOnly: true,
-    children: groups.map((g) => ({
+    children: sortedGroups(groups).map((g) => ({
       label: SDK_KINDS.has(g.kind) ? `< ${g.name} >` : g.name,
       icon: GROUP_ICONS[g.kind] ?? "library",
       children: g.roots.map((r) => ({
@@ -192,12 +200,18 @@ export function activate(): () => void {
     clearTimeout(timer);
     timer = setTimeout(refresh, MANIFEST_REFRESH_DELAY);
   });
+  // A Maven / Gradle sync changes the dependency versions without touching a manifest.
+  const unsubRoots = onIdeEvent("projectRootsChanged", () => {
+    clearTimeout(timer);
+    timer = setTimeout(refresh, MANIFEST_REFRESH_DELAY);
+  });
   return () => {
     seq++;
     if (request !== undefined) void commands.cancelRequest(request).catch(() => {});
     clearTimeout(timer);
     unsub();
     unsubFs();
+    unsubRoots();
     disposeActions();
     clear();
   };

src/features/libraries/libraries.test.ts

@@ -37,18 +37,46 @@ describe("External Libraries", () => {
         }),
       ),
     )!;
-    expect(root.children?.map((g) => g.icon)).toEqual([
-      "file-java",
-      "file-js",
-      "file-npm",
-      "file-rust",
-      "file-cargo",
-      "file-go",
-      "file-gomod",
-      "maven-project",
-      "file-gradle",
-      "library",
+    expect(Object.fromEntries(root.children!.map((g) => [g.label, g.icon]))).toEqual({
+      "< jdk >": "file-java",
+      nodeCore: "file-js",
+      nodeModules: "file-npm",
+      "< rust >": "file-rust",
+      cargo: "file-cargo",
+      "< go >": "file-go",
+      goModules: "file-gomod",
+      maven: "maven-project",
+      gradle: "file-gradle",
+      other: "library",
+    });
+  });
+
+  it("lists SDKs first, then libraries by name, whatever order they were detected in", () => {
+    const group = (name: string, kind: string) => ({ name, kind, roots: [{ name: "r", path: `/libs/${name}` }] });
+    const detected = [
+      group("Maven: org.junit:junit:4.13", "maven"),
+      group("temurin-21", "jdk"),
+      group("node_modules", "nodeModules"),
+      group("Python 3.14", "python"),
+      group("Cargo dependencies", "cargo"),
+      group("Gradle: com.acme:lib:1.0", "gradle"),
+      group("Go SDK 1.27.4", "go"),
+      group("Maven: com.acme:core:2.1.27", "maven"),
+      group("Node.js Core", "nodeCore"),
+    ];
+    const labels = (groups: typeof detected) => librariesRoot(groups)!.children!.map((g) => g.label);
+    expect(labels(detected)).toEqual([
+      "< Go SDK 1.27.4 >",
+      "< Python 3.14 >",
+      "< temurin-21 >",
+      "Cargo dependencies",
+      "Gradle: com.acme:lib:1.0",
+      "Maven: com.acme:core:2.1.27",
+      "Maven: org.junit:junit:4.13",
+      "node_modules",
+      "Node.js Core",
     ]);
+    expect(labels([...detected].reverse())).toEqual(labels(detected));
   });
 
   it("lists archives (src.zip, dependency jars) as browsable roots", () => {