diff --git a/apps/web/src/components/editor/NoteLinkSuggestion.test.mjs b/apps/web/src/components/editor/NoteLinkSuggestion.test.mjs
index f93f9d2a..85090ff9 100644
--- a/apps/web/src/components/editor/NoteLinkSuggestion.test.mjs
+++ b/apps/web/src/components/editor/NoteLinkSuggestion.test.mjs
@@ -1,6 +1,7 @@
 import { describe, expect, test } from "bun:test";
 import { Editor } from "@tiptap/core";
 import StarterKit from "@tiptap/starter-kit";
+import { ensureTestWindowDom } from "../../lib/restore-test-global.mjs";
 import {
   filterNoteLinkSuggestions,
   insertSuggestedNoteLink,
@@ -31,6 +32,7 @@ describe("note link suggestion", () => {
   });
 
   test("replaces the @ query with the existing internal-note link format", () => {
+    ensureTestWindowDom();
     const editor = new Editor({
       extensions: [StarterKit],
       content: {
@@ -64,6 +66,7 @@ describe("note link suggestion", () => {
   });
 
   test("uses the untitled fallback for an empty title", () => {
+    ensureTestWindowDom();
     const editor = new Editor({
       extensions: [StarterKit],
       content: {
diff --git a/apps/web/src/components/editor/attachment-editor-range.test.mjs b/apps/web/src/components/editor/attachment-editor-range.test.mjs
index d434b6ae..19f14caf 100644
--- a/apps/web/src/components/editor/attachment-editor-range.test.mjs
+++ b/apps/web/src/components/editor/attachment-editor-range.test.mjs
@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test";
 import { Editor } from "@tiptap/core";
 import StarterKit from "@tiptap/starter-kit";
 import { FileAttachment, PdfAttachment } from "@edgeever/shared";
+import { ensureTestWindowDom } from "../../lib/restore-test-global.mjs";
 import { findAttachmentRange, removeAttachmentAt, renameAttachmentAt } from "./attachment-editor-range.ts";
 
 const videoUrl = "edgeever-resource://resource/res_video";
@@ -35,10 +36,13 @@ const pdfNode = (url, filename) => ({
 
 const paragraph = (...content) => ({ type: "paragraph", content });
 
-const makeEditor = (content) => new Editor({
-  extensions: [StarterKit, FileAttachment, PdfAttachment],
-  content: { type: "doc", content },
-});
+const makeEditor = (content) => {
+  ensureTestWindowDom();
+  return new Editor({
+    extensions: [StarterKit, FileAttachment, PdfAttachment],
+    content: { type: "doc", content },
+  });
+};
 
 describe("attachment editor range", () => {
   test("removes a video file-attachment node whose hover URL is the API blob path", () => {
diff --git a/apps/web/src/components/editor/math-formula.test.mjs b/apps/web/src/components/editor/math-formula.test.mjs
index 10e9951a..316b1b12 100644
--- a/apps/web/src/components/editor/math-formula.test.mjs
+++ b/apps/web/src/components/editor/math-formula.test.mjs
@@ -2,6 +2,7 @@ import { describe, expect, test } from "bun:test";
 import { Editor } from "@tiptap/core";
 import { createEdgeEverDocumentExtensions } from "@edgeever/shared";
 import { createEdgeEverMathematics } from "@edgeever/shared/mathematics";
+import { ensureTestWindowDom } from "../../lib/restore-test-global.mjs";
 import {
   applyMathFormula,
   deleteMathFormula,
@@ -9,12 +10,15 @@ import {
   selectedTextAsLatex,
 } from "./math-formula.ts";
 
-const createEditor = (content) => new Editor({
-  extensions: createEdgeEverDocumentExtensions({
-    mathematics: createEdgeEverMathematics(),
-  }),
-  content,
-});
+const createEditor = (content) => {
+  ensureTestWindowDom();
+  return new Editor({
+    extensions: createEdgeEverDocumentExtensions({
+      mathematics: createEdgeEverMathematics(),
+    }),
+    content,
+  });
+};
 
 describe("math formula commands", () => {
   test("inserts inline math at the caret", () => {
diff --git a/apps/web/src/components/pdf/pdf-document-source.test.mjs b/apps/web/src/components/pdf/pdf-document-source.test.mjs
index 20e49f47..793ce2f9 100644
--- a/apps/web/src/components/pdf/pdf-document-source.test.mjs
+++ b/apps/web/src/components/pdf/pdf-document-source.test.mjs
@@ -20,9 +20,16 @@ describe("PDF document sources", () => {
   });
 
   test("recovers leaked desktop resource URLs in the web runtime", async () => {
-    await expect(loadPdfDocumentSource("edgeever-resource://resource/res_web", undefined)).resolves.toEqual({
-      url: "/api/v1/resources/res_web/blob",
-    });
+    const current = globalThis.window;
+    const previousBridge = current?.edgeeverDesktop;
+    if (current) current.edgeeverDesktop = undefined;
+    try {
+      await expect(loadPdfDocumentSource("edgeever-resource://resource/res_web")).resolves.toEqual({
+        url: "/api/v1/resources/res_web/blob",
+      });
+    } finally {
+      if (current) current.edgeeverDesktop = previousBridge;
+    }
   });
 
   test("loads synced desktop resources through the native bridge", async () => {
diff --git a/apps/web/src/lib/restore-test-global.mjs b/apps/web/src/lib/restore-test-global.mjs
index 53b5416f..7f145639 100644
--- a/apps/web/src/lib/restore-test-global.mjs
+++ b/apps/web/src/lib/restore-test-global.mjs
@@ -1,4 +1,20 @@
 const restoreUnconditionally = Symbol("restore-unconditionally");
+const noop = () => {};
+
+// Linux Bun exposes `document` without a `window` binding. Test files then
+// install plain objects. ProseMirror and TipTap read `window.MutationObserver`
+// and `window.addEventListener` from that object, so a leftover stub needs
+// those methods. Do not create a window when none is installed: assigning one
+// is unnecessary on hosts whose editor already resolves `window` elsewhere.
+export const ensureTestWindowDom = () => {
+  const current = globalThis.window;
+  if (!current || typeof current !== "object") return;
+  if (typeof current.addEventListener !== "function") current.addEventListener = noop;
+  if (typeof current.removeEventListener !== "function") current.removeEventListener = noop;
+  if (typeof current.getComputedStyle !== "function") current.getComputedStyle = () => ({ listStyle: "" });
+  if (typeof current.setTimeout !== "function") current.setTimeout = globalThis.setTimeout.bind(globalThis);
+  if (typeof current.clearTimeout !== "function") current.clearTimeout = globalThis.clearTimeout.bind(globalThis);
+};
 
 export const restoreTestGlobal = (key, original, installed = restoreUnconditionally) => {
   if (installed !== restoreUnconditionally && globalThis[key] !== installed) return;
@@ -6,10 +22,12 @@ export const restoreTestGlobal = (key, original, installed = restoreUnconditiona
     globalThis[key] = original;
     return;
   }
-  // Linux Bun provides document without a window binding. Assigning
-  // undefined shadows it, and deleting it makes ProseMirror throw
-  // `window is not defined` while reading MutationObserver. Keep the
-  // stub object when there was no previous window.
-  if (key === "window") return;
+  // Assigning undefined shadows the host binding, and deleting window makes
+  // ProseMirror throw `window is not defined`. Keep the stub and make it
+  // safe for a later editor test.
+  if (key === "window") {
+    ensureTestWindowDom();
+    return;
+  }
   delete globalThis[key];
 };
diff --git a/apps/web/src/lib/restore-test-global.test.mjs b/apps/web/src/lib/restore-test-global.test.mjs
index 97cfb39f..7e8f64cf 100644
--- a/apps/web/src/lib/restore-test-global.test.mjs
+++ b/apps/web/src/lib/restore-test-global.test.mjs
@@ -1,5 +1,5 @@
 import { expect, test } from "bun:test";
-import { restoreTestGlobal } from "./restore-test-global.mjs";
+import { ensureTestWindowDom, restoreTestGlobal } from "./restore-test-global.mjs";
 
 test("restoreTestGlobal keeps a window object when nothing was there before", () => {
   const descriptor = Object.getOwnPropertyDescriptor(globalThis, "window");
@@ -8,6 +8,8 @@ test("restoreTestGlobal keeps a window object when nothing was there before", ()
   globalThis.window = stub;
   restoreTestGlobal("window", undefined, stub);
   expect(globalThis.window).toBe(stub);
+  expect(typeof globalThis.window.addEventListener).toBe("function");
+  expect(typeof globalThis.window.removeEventListener).toBe("function");
   if (descriptor) Object.defineProperty(globalThis, "window", descriptor);
   else delete globalThis.window;
 });
@@ -23,3 +25,16 @@ test("restoreTestGlobal leaves a global that another file replaced", () => {
   if (descriptor) Object.defineProperty(globalThis, "document", descriptor);
   else delete globalThis.document;
 });
+
+test("ensureTestWindowDom fills event methods on a leftover window", () => {
+  const descriptor = Object.getOwnPropertyDescriptor(globalThis, "window");
+  const stub = { edgeeverDesktop: { isAvailable: true } };
+  globalThis.window = stub;
+  ensureTestWindowDom();
+  expect(typeof stub.addEventListener).toBe("function");
+  expect(typeof stub.getComputedStyle).toBe("function");
+  expect(stub.edgeeverDesktop.isAvailable).toBe(true);
+  ensureTestWindowDom();
+  if (descriptor) Object.defineProperty(globalThis, "window", descriptor);
+  else delete globalThis.window;
+});