diff --git a/zeppelin-web-angular/AGENTS.md b/zeppelin-web-angular/AGENTS.md
index c6fbaf21ba1..fa2280ffeb3 100644
--- a/zeppelin-web-angular/AGENTS.md
+++ b/zeppelin-web-angular/AGENTS.md
@@ -84,6 +84,10 @@ A spec with no assertion, or one whose assertion sits inside an `if`, passes by
 
 The e2e suite gets the same protection from `eslint-plugin-playwright`.
 
+## monaco-editor and path aliases in specs
+
+`vitest.shell.config.mts` mirrors the `paths` block in `tsconfig.base.json`, which Vite does not read; add an alias there when you add a path. Eleven files under `src/` import `monaco-editor`, two behind the `@zeppelin/services` barrel, so a spec that reaches the editor or notebook area loads it: a few seconds on first import and a `marked.umd.js.map` sourcemap warning, both monaco's, not ours. Mock it with `vi.mock('monaco-editor', ...)` when the spec only needs to assert the editor was called. The runner resolves monaco to `editor.api`, which skips the language registrations `editor.main` performs, so do not assert that a built-in language is registered.
+
 ## Determinism
 
 No clock, no randomness, no network. A spec that reads `Date.now()` or fetches will eventually fail for reasons unrelated to the code under test.
diff --git a/zeppelin-web-angular/src/app/services/array-ordering.service.spec.ts b/zeppelin-web-angular/src/app/services/array-ordering.service.spec.ts
new file mode 100644
index 00000000000..0508814f40d
--- /dev/null
+++ b/zeppelin-web-angular/src/app/services/array-ordering.service.spec.ts
@@ -0,0 +1,77 @@
+/*
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { beforeEach, describe, expect, it } from 'vitest';
+import { NodeItem } from '@zeppelin/interfaces';
+// Through the barrel, not the neighbouring file:
+// that is what walks the alias chain to monaco and @zeppelin/sdk,
+// so this spec fails if either stops resolving.
+import { ArrayOrderingService } from '@zeppelin/services';
+
+const TRASH_FOLDER_ID = '~Trash';
+
+const note = (id: string, title: string, children?: NodeItem[]): NodeItem => ({ id, title, children }) as NodeItem;
+
+describe('ArrayOrderingService', () => {
+  let service: ArrayOrderingService;
+
+  beforeEach(() => {
+    service = new ArrayOrderingService(TRASH_FOLDER_ID);
+  });
+
+  describe('getNoteName', () => {
+    it('returns the title when it has one', () => {
+      expect(service.getNoteName(note('a1', 'My note'))).toBe('My note');
+    });
+
+    it('falls back to the id when the title is blank', () => {
+      expect(service.getNoteName(note('a1', '   '))).toBe('Note a1');
+    });
+  });
+
+  describe('noteListOrdering', () => {
+    it('sorts the trash folder last by returning the highest code point', () => {
+      expect(service.noteListOrdering(note(TRASH_FOLDER_ID, 'Trash'))).toBe('￿');
+    });
+
+    it('orders every other node by its display name', () => {
+      expect(service.noteListOrdering(note('a1', 'My note'))).toBe('My note');
+    });
+  });
+
+  describe('noteComparator', () => {
+    it('puts the trash folder after anything else, whichever side it is on', () => {
+      const trash = note(TRASH_FOLDER_ID, 'Trash');
+      const other = note('a1', 'My note');
+
+      expect(service.noteComparator(trash, other)).toBe(1);
+      expect(service.noteComparator(other, trash)).toBe(-1);
+    });
+
+    it('puts folders before notes', () => {
+      const folder = note('f1', 'Folder', []);
+      const leaf = note('a1', 'Note');
+
+      expect(service.noteComparator(leaf, folder)).toBe(1);
+      expect(service.noteComparator(folder, leaf)).toBe(-1);
+    });
+
+    it('compares two nodes of the same kind by display name', () => {
+      expect(service.noteComparator(note('a1', 'Alpha'), note('a2', 'Beta'))).toBeLessThan(0);
+    });
+
+    it('uses the id fallback when a title is blank', () => {
+      // 'Note a1' sorts before 'Zebra', which the raw empty title would not.
+      expect(service.noteComparator(note('a1', ''), note('a2', 'Zebra'))).toBeLessThan(0);
+    });
+  });
+});
diff --git a/zeppelin-web-angular/vitest.shell.config.mts b/zeppelin-web-angular/vitest.shell.config.mts
index 0c035c2b2b6..a85648ced89 100644
--- a/zeppelin-web-angular/vitest.shell.config.mts
+++ b/zeppelin-web-angular/vitest.shell.config.mts
@@ -11,9 +11,42 @@
  */
 
 // vite is pinned in package.json: the React remote keeps its own lockfile and drifted to a different minor.
+import { fileURLToPath } from 'node:url';
 import { defineConfig } from 'vitest/config';
 
 export default defineConfig({
+  // Mirrors the `paths` block in tsconfig.base.json, which Vite does not read.
+  // The two library aliases resolve to source, not `dist/`, so a unit run does not wait on a build.
+  resolve: {
+    alias: [
+      // monaco-editor ships no `main` and no `exports` (microsoft/monaco-editor#4848).
+      // `module` names editor.main, which boots the full editor and dies in jsdom.
+      // 0.55 restores resolution but still points there, so revisit rather than drop.
+      {
+        find: /^monaco-editor$/,
+        replacement: fileURLToPath(new URL('./node_modules/monaco-editor/esm/vs/editor/editor.api.js', import.meta.url))
+      },
+      { find: /^@zeppelin\/sdk$/, replacement: fileURLToPath(new URL('./projects/zeppelin-sdk/src', import.meta.url)) },
+      {
+        find: /^@zeppelin\/sdk\/(.*)$/,
+        replacement: `${fileURLToPath(new URL('./projects/zeppelin-sdk/src', import.meta.url))}/$1`
+      },
+      {
+        find: /^@zeppelin\/visualization$/,
+        replacement: fileURLToPath(new URL('./projects/zeppelin-visualization/src', import.meta.url))
+      },
+      {
+        find: /^@zeppelin\/visualization\/(.*)$/,
+        replacement: `${fileURLToPath(new URL('./projects/zeppelin-visualization/src', import.meta.url))}/$1`
+      },
+      // `@zeppelin/*` falls back to src/environments in tsconfig; Vite aliases do not.
+      {
+        find: /^@zeppelin\/environment$/,
+        replacement: fileURLToPath(new URL('./src/environments/environment.ts', import.meta.url))
+      },
+      { find: /^@zeppelin\/(.*)$/, replacement: `${fileURLToPath(new URL('./src/app', import.meta.url))}/$1` }
+    ]
+  },
   // oxc does not apply the decorator options from tsconfig.base.json to specs,
   // which src/tsconfig.json excludes. Undeclared, a decorated spec fails to
   // parse with "Invalid or unexpected token".