diff --git a/apps/desktop/src/docx-contract.ts b/apps/desktop/src/docx-contract.ts
index 7f8aad0..cff84b4 100644
--- a/apps/desktop/src/docx-contract.ts
+++ b/apps/desktop/src/docx-contract.ts
@@ -31,6 +31,18 @@ export type DesktopDocxExportOutcome =
 
 export type DesktopDocxCapability = DocxCapability;
 
+function readSafeDesktopMediaDetail(error: DocxExportServiceError) {
+  const cause = error.cause;
+  if (!(cause instanceof Error)) {
+    return undefined;
+  }
+  return /^桌面 DOCX (?:媒体布局超过 \d+ms|第 \d+\/\d+ 个媒体（(?:image|mermaid|echarts)）PNG 捕获超过 \d+ms)$/u.test(
+    cause.message
+  )
+    ? cause.message
+    : undefined;
+}
+
 export function toDesktopDocxExportFailure(
   error: unknown
 ): DesktopDocxExportFailure {
@@ -54,10 +66,11 @@ export function toDesktopDocxExportFailure(
     };
   }
   if (error instanceof DocxExportServiceError) {
+    const detail = readSafeDesktopMediaDetail(error);
     return {
       ok: false,
       error: error.code,
-      message: error.message,
+      message: detail ? `${error.message}：${detail}` : error.message,
       retryable: error.retryable
     };
   }
diff --git a/apps/desktop/src/electron-docx-media-capture.ts b/apps/desktop/src/electron-docx-media-capture.ts
index bb2ffb1..69df713 100644
--- a/apps/desktop/src/electron-docx-media-capture.ts
+++ b/apps/desktop/src/electron-docx-media-capture.ts
@@ -9,6 +9,51 @@ interface CaptureScreenshotResult {
   data: string;
 }
 
+export interface ElectronDocxMediaCaptureTimeouts {
+  renderMs: number;
+  screenshotMs: number;
+}
+
+const DEFAULT_CAPTURE_TIMEOUTS: ElectronDocxMediaCaptureTimeouts = {
+  renderMs: 30_000,
+  screenshotMs: 20_000
+};
+
+function withTimeout<T>(
+  operation: Promise<T>,
+  timeoutMs: number,
+  message: string,
+  signal?: AbortSignal
+) {
+  return new Promise<T>((resolve, reject) => {
+    let settled = false;
+    const finish = (callback: () => void) => {
+      if (settled) {
+        return;
+      }
+      settled = true;
+      clearTimeout(timeout);
+      signal?.removeEventListener("abort", abort);
+      callback();
+    };
+    const abort = () =>
+      finish(() => reject(signal?.reason ?? new Error("操作已取消")));
+    const timeout = setTimeout(
+      () => finish(() => reject(new Error(message))),
+      timeoutMs
+    );
+    signal?.addEventListener("abort", abort, { once: true });
+    if (signal?.aborted) {
+      abort();
+      return;
+    }
+    operation.then(
+      (value) => finish(() => resolve(value)),
+      (error) => finish(() => reject(error))
+    );
+  });
+}
+
 function createRenderScript(request: DocxMediaCaptureRequest) {
   const serialized = JSON.stringify(request);
   return `(async () => {
@@ -24,12 +69,15 @@ function createRenderScript(request: DocxMediaCaptureRequest) {
 export async function captureDocxMediaWithElectronWebContents(
   webContents: WebContents,
   request: DocxMediaCaptureRequest,
-  signal?: AbortSignal
+  signal?: AbortSignal,
+  timeouts: ElectronDocxMediaCaptureTimeouts = DEFAULT_CAPTURE_TIMEOUTS
 ) {
   signal?.throwIfAborted();
-  const plan = (await webContents.executeJavaScript(
-    createRenderScript(request),
-    true
+  const plan = (await withTimeout(
+    webContents.executeJavaScript(createRenderScript(request), true),
+    timeouts.renderMs,
+    `桌面 DOCX 媒体布局超过 ${timeouts.renderMs}ms`,
+    signal
   )) as DocxMediaCapturePlan;
   signal?.throwIfAborted();
   const ownsDebugger = !webContents.debugger.isAttached();
@@ -41,20 +89,25 @@ export async function captureDocxMediaWithElectronWebContents(
     const captures = [];
     for (const target of plan.targets) {
       signal?.throwIfAborted();
-      const result = (await webContents.debugger.sendCommand(
-        "Page.captureScreenshot",
-        {
-          format: "png",
-          fromSurface: true,
-          captureBeyondViewport: true,
-          clip: {
-            x: target.captureX,
-            y: target.captureY,
-            width: target.captureWidthPx,
-            height: target.captureHeightPx,
-            scale: target.rasterScale
+      const result = (await withTimeout(
+        webContents.debugger.sendCommand(
+          "Page.captureScreenshot",
+          {
+            format: "png",
+            fromSurface: true,
+            captureBeyondViewport: true,
+            clip: {
+              x: target.captureX,
+              y: target.captureY,
+              width: target.captureWidthPx,
+              height: target.captureHeightPx,
+              scale: target.rasterScale
+            }
           }
-        }
+        ),
+        timeouts.screenshotMs,
+        `桌面 DOCX 第 ${target.ordinal}/${plan.targets.length} 个媒体（${target.kind}）PNG 捕获超过 ${timeouts.screenshotMs}ms`,
+        signal
       )) as CaptureScreenshotResult;
       captures.push({
         id: target.id,
diff --git a/apps/desktop/src/electron-docx-media-engine.ts b/apps/desktop/src/electron-docx-media-engine.ts
index 4b02b33..d523ea9 100644
--- a/apps/desktop/src/electron-docx-media-engine.ts
+++ b/apps/desktop/src/electron-docx-media-engine.ts
@@ -18,6 +18,25 @@ export interface ElectronDocxMediaEngineOptions {
   renderUrl: string;
 }
 
+export async function withActiveDocxCaptureSurface<T>(
+  window: Pick<
+    BrowserWindow,
+    "showInactive" | "hide" | "isDestroyed"
+  >,
+  operation: () => Promise<T>,
+  settleMs = 50
+) {
+  window.showInactive();
+  await new Promise((resolve) => setTimeout(resolve, settleMs));
+  try {
+    return await operation();
+  } finally {
+    if (!window.isDestroyed()) {
+      window.hide();
+    }
+  }
+}
+
 export class ElectronDocxMediaEngine
   implements DocxMediaCaptureAdapter, DocxThemeStyleCaptureAdapter
 {
@@ -98,10 +117,14 @@ export class ElectronDocxMediaEngine
     };
     signal?.addEventListener("abort", abort, { once: true });
     try {
-      return await captureDocxMediaWithElectronWebContents(
-        window.webContents,
-        request,
-        signal
+      return await withActiveDocxCaptureSurface(
+        window,
+        () =>
+          captureDocxMediaWithElectronWebContents(
+            window.webContents,
+            request,
+            signal
+          )
       );
     } finally {
       signal?.removeEventListener("abort", abort);
diff --git a/apps/desktop/tests/docx-contract.test.ts b/apps/desktop/tests/docx-contract.test.ts
index 5575c57..0164ee9 100644
--- a/apps/desktop/tests/docx-contract.test.ts
+++ b/apps/desktop/tests/docx-contract.test.ts
@@ -41,6 +41,40 @@ describe("Desktop DOCX IPC 契约", () => {
     });
   });
 
+  it("仅透传格式受控的桌面媒体超时详情", () => {
+    expect(
+      toDesktopDocxExportFailure(
+        new DocxExportServiceError(
+          500,
+          "DOCX_GENERATION_FAILED",
+          "DOCX 导出失败",
+          false,
+          { cause: new Error("桌面 DOCX 媒体布局超过 30000ms") }
+        )
+      )
+    ).toMatchObject({
+      message: "DOCX 导出失败：桌面 DOCX 媒体布局超过 30000ms"
+    });
+    expect(
+      toDesktopDocxExportFailure(
+        new DocxExportServiceError(
+          500,
+          "DOCX_GENERATION_FAILED",
+          "DOCX 导出失败",
+          false,
+          {
+            cause: new Error(
+              "桌面 DOCX 第 2/7 个媒体（echarts）PNG 捕获超过 20000ms"
+            )
+          }
+        )
+      )
+    ).toMatchObject({
+      message:
+        "DOCX 导出失败：桌面 DOCX 第 2/7 个媒体（echarts）PNG 捕获超过 20000ms"
+    });
+  });
+
   it("保留 Front Matter 解析错误", () => {
     expect(
       toDesktopDocxExportFailure(
diff --git a/apps/desktop/tests/electron-docx-media-capture.test.ts b/apps/desktop/tests/electron-docx-media-capture.test.ts
index c66ef8e..fa35032 100644
--- a/apps/desktop/tests/electron-docx-media-capture.test.ts
+++ b/apps/desktop/tests/electron-docx-media-capture.test.ts
@@ -104,4 +104,52 @@ describe("Electron DOCX 媒体捕获", () => {
     );
     expect(detach).toHaveBeenCalledOnce();
   });
+
+  it("媒体布局永久不返回时报告局部超时", async () => {
+    const webContents = {
+      executeJavaScript: vi.fn(() => new Promise(() => undefined)),
+      debugger: {
+        isAttached: vi.fn(() => false)
+      }
+    } as unknown as WebContents;
+
+    await expect(
+      captureDocxMediaWithElectronWebContents(
+        webContents,
+        request,
+        undefined,
+        { renderMs: 10, screenshotMs: 10 }
+      )
+    ).rejects.toThrow("桌面 DOCX 媒体布局超过 10ms");
+  });
+
+  it("单个 PNG 永久不返回时报告媒体编号和类型", async () => {
+    let attached = false;
+    const detach = vi.fn(() => {
+      attached = false;
+    });
+    const webContents = {
+      executeJavaScript: vi.fn(async () => plan),
+      debugger: {
+        isAttached: vi.fn(() => attached),
+        attach: vi.fn(() => {
+          attached = true;
+        }),
+        detach,
+        sendCommand: vi.fn(() => new Promise(() => undefined))
+      }
+    } as unknown as WebContents;
+
+    await expect(
+      captureDocxMediaWithElectronWebContents(
+        webContents,
+        request,
+        undefined,
+        { renderMs: 10, screenshotMs: 10 }
+      )
+    ).rejects.toThrow(
+      "桌面 DOCX 第 1/1 个媒体（image）PNG 捕获超过 10ms"
+    );
+    expect(detach).toHaveBeenCalledOnce();
+  });
 });
diff --git a/apps/desktop/tests/electron-docx-media-engine.test.ts b/apps/desktop/tests/electron-docx-media-engine.test.ts
new file mode 100644
index 0000000..b79bca0
--- /dev/null
+++ b/apps/desktop/tests/electron-docx-media-engine.test.ts
@@ -0,0 +1,47 @@
+import { describe, expect, it, vi } from "vitest";
+import { withActiveDocxCaptureSurface } from "../src/electron-docx-media-engine.js";
+
+function createWindow() {
+  let destroyed = false;
+  return {
+    showInactive: vi.fn(),
+    hide: vi.fn(),
+    isDestroyed: vi.fn(() => destroyed),
+    destroy: () => {
+      destroyed = true;
+    }
+  };
+}
+
+describe("Electron DOCX 捕获合成表面", () => {
+  it("截图期间无焦点显示窗口并在完成后隐藏", async () => {
+    const window = createWindow();
+    const operation = vi.fn(async () => "captured");
+
+    await expect(
+      withActiveDocxCaptureSurface(window, operation, 0)
+    ).resolves.toBe("captured");
+
+    expect(window.showInactive).toHaveBeenCalledOnce();
+    expect(operation).toHaveBeenCalledOnce();
+    expect(window.hide).toHaveBeenCalledOnce();
+  });
+
+  it("窗口在失败期间销毁时不再隐藏", async () => {
+    const window = createWindow();
+
+    await expect(
+      withActiveDocxCaptureSurface(
+        window,
+        async () => {
+          window.destroy();
+          throw new Error("capture failed");
+        },
+        0
+      )
+    ).rejects.toThrow("capture failed");
+
+    expect(window.showInactive).toHaveBeenCalledOnce();
+    expect(window.hide).not.toHaveBeenCalled();
+  });
+});
diff --git a/apps/web/src/hidden-window-animation-frame.ts b/apps/web/src/hidden-window-animation-frame.ts
new file mode 100644
index 0000000..e70c61f
--- /dev/null
+++ b/apps/web/src/hidden-window-animation-frame.ts
@@ -0,0 +1,16 @@
+export async function withHiddenWindowAnimationFrames<T>(
+  windowRef: Window,
+  operation: () => Promise<T>
+) {
+  const requestAnimationFrame = windowRef.requestAnimationFrame;
+  windowRef.requestAnimationFrame = (callback) =>
+    windowRef.setTimeout(
+      () => callback(windowRef.performance.now()),
+      0
+    );
+  try {
+    return await operation();
+  } finally {
+    windowRef.requestAnimationFrame = requestAnimationFrame;
+  }
+}
diff --git a/apps/web/src/paged-preview-frame.ts b/apps/web/src/paged-preview-frame.ts
index b73c331..e85a72e 100644
--- a/apps/web/src/paged-preview-frame.ts
+++ b/apps/web/src/paged-preview-frame.ts
@@ -15,6 +15,7 @@ import {
   beginPreviewFrameRender,
   completePreviewFrameRender
 } from "./preview-frame-visibility";
+import { withHiddenWindowAnimationFrames } from "./hidden-window-animation-frame";
 
 function getPreviewRoot() {
   const element = document.querySelector<HTMLElement>("#preview-root");
@@ -139,22 +140,24 @@ window.__mdToPdfRender = async (
   return result;
 };
 window.__mdToPdfRenderDocxMedia = (payload, dimensions) =>
-  renderDocxMediaCapturePlan(
-    runtime,
-    previewRoot,
-    payload,
-    dimensions
+  withHiddenWindowAnimationFrames(window, () =>
+    renderDocxMediaCapturePlan(
+      runtime,
+      previewRoot,
+      payload,
+      dimensions
+    )
   );
 document.documentElement.dataset.runtimeReady = "true";
 
 const desktopPdfBridge = window.__mdToPdfDesktopPdf;
 if (desktopPdfBridge) {
   desktopPdfBridge.onRender(async (requestId, payload) => {
-    const requestAnimationFrame = window.requestAnimationFrame;
-    window.requestAnimationFrame = (callback) =>
-      window.setTimeout(() => callback(performance.now()), 0);
     try {
-      const result = await window.__mdToPdfRender?.(payload, "pdf");
+      const result = await withHiddenWindowAnimationFrames(
+        window,
+        async () => window.__mdToPdfRender?.(payload, "pdf")
+      );
       if (!result) {
         throw new Error("PDF 分页运行时不可用");
       }
@@ -164,8 +167,6 @@ if (desktopPdfBridge) {
         requestId,
         reason instanceof Error ? reason.message : "PDF 分页失败"
       );
-    } finally {
-      window.requestAnimationFrame = requestAnimationFrame;
     }
   });
   desktopPdfBridge.ready();
diff --git a/apps/web/tests/hidden-window-animation-frame.test.ts b/apps/web/tests/hidden-window-animation-frame.test.ts
new file mode 100644
index 0000000..9980fd5
--- /dev/null
+++ b/apps/web/tests/hidden-window-animation-frame.test.ts
@@ -0,0 +1,36 @@
+// @vitest-environment happy-dom
+
+import { describe, expect, it, vi } from "vitest";
+import { withHiddenWindowAnimationFrames } from "../src/hidden-window-animation-frame";
+
+describe("隐藏窗口动画帧调度", () => {
+  it("使用定时器驱动动画帧并在成功后恢复", async () => {
+    const original = window.requestAnimationFrame;
+    const callback = vi.fn();
+
+    await withHiddenWindowAnimationFrames(window, async () => {
+      expect(window.requestAnimationFrame).not.toBe(original);
+      await new Promise<void>((resolve) => {
+        window.requestAnimationFrame((timestamp) => {
+          callback(timestamp);
+          resolve();
+        });
+      });
+    });
+
+    expect(callback).toHaveBeenCalledOnce();
+    expect(window.requestAnimationFrame).toBe(original);
+  });
+
+  it("操作失败后仍恢复原动画帧函数", async () => {
+    const original = window.requestAnimationFrame;
+
+    await expect(
+      withHiddenWindowAnimationFrames(window, async () => {
+        throw new Error("render failed");
+      })
+    ).rejects.toThrow("render failed");
+
+    expect(window.requestAnimationFrame).toBe(original);
+  });
+});
diff --git a/docs/PROGRESS.md b/docs/PROGRESS.md
index 79c85ed..e056160 100644
--- a/docs/PROGRESS.md
+++ b/docs/PROGRESS.md
@@ -101,6 +101,14 @@ WOFF2 可用，生产 DOCX 含 5 个字体部件。当前镜像大小为 711,082
 字节；Desktop 主安装器为 140,279,447 字节，独立字体安装器为
 24,488,770 字节，字体 ZIP 为 29,186,293 字节。
 
+`v0.6.0` 发布前 Desktop DOCX 媒体捕获超时修复已完成。共享图片等待
+逻辑消除了 `decode()` 与加载事件之间的竞态，并增加有界超时；隐藏窗口
+中的媒体渲染使用定时器驱动帧调度，Electron 捕获阶段临时激活合成表面，
+同时为布局与单媒体截图提供可诊断的独立超时。Windows 目录版使用默认
+10 页示例完成真实导出，12 个媒体全部生成 PNG，最终 DOCX 为 8,937,824
+字节、包含 12 个媒体部件和 5 个字体部件；单元测试、类型检查、生产构建
+及 `git diff --check` 均通过。
+
 `v0.6.0` 阶段 3 已完成 DOCX 共享协议：`packages/core` 统一定义请求
 Schema、资源、Pandoc capability、错误码、结果、诊断、耗时、MIME 和
 安全文件名；`packages/application` 新增 `prepareDocxExport()`，复用
diff --git a/packages/preview-engine/src/paged-document-runtime.ts b/packages/preview-engine/src/paged-document-runtime.ts
index 6f24c91..5aeb077 100644
--- a/packages/preview-engine/src/paged-document-runtime.ts
+++ b/packages/preview-engine/src/paged-document-runtime.ts
@@ -74,24 +74,55 @@ export interface PreviewEngineStyles {
   echartsCss: string;
 }
 
-function waitForImages(container: ParentNode) {
-  const images = Array.from(container.querySelectorAll("img"));
-  return Promise.all(
-    images.map(async (image) => {
-      if (image.complete) {
+export const DEFAULT_IMAGE_READY_TIMEOUT_MS = 10_000;
+
+function waitForImage(
+  image: HTMLImageElement,
+  timeoutMs: number
+) {
+  if (image.complete) {
+    return Promise.resolve();
+  }
+
+  return new Promise<void>((resolve) => {
+    let settled = false;
+    const finish = () => {
+      if (settled) {
         return;
       }
+      settled = true;
+      clearTimeout(timeout);
+      image.removeEventListener("load", finish);
+      image.removeEventListener("error", finish);
+      resolve();
+    };
+    const timeout = window.setTimeout(finish, timeoutMs);
 
-      try {
-        await image.decode();
-      } catch {
-        await new Promise<void>((resolve) => {
-          image.addEventListener("load", () => resolve(), { once: true });
-          image.addEventListener("error", () => resolve(), { once: true });
-        });
+    // 先监听事件，再检查 complete 和调用 decode，避免 Electron 中图片
+    // 已经失败后才注册 error 监听器而永久等待。
+    image.addEventListener("load", finish, { once: true });
+    image.addEventListener("error", finish, { once: true });
+    if (image.complete) {
+      finish();
+      return;
+    }
+
+    void image.decode().then(finish, () => {
+      // decode 失败时仍允许尚未到达的 load/error 事件完成等待；若事件
+      // 已经发生，complete 会立即结束。最终由有界超时兜底。
+      if (image.complete) {
+        finish();
       }
-    })
-  );
+    });
+  });
+}
+
+export function waitForImages(
+  container: ParentNode,
+  timeoutMs = DEFAULT_IMAGE_READY_TIMEOUT_MS
+) {
+  const images = Array.from(container.querySelectorAll("img"));
+  return Promise.all(images.map((image) => waitForImage(image, timeoutMs)));
 }
 
 function stylesheet(
diff --git a/packages/preview-engine/tests/image-ready.test.ts b/packages/preview-engine/tests/image-ready.test.ts
new file mode 100644
index 0000000..bfd419a
--- /dev/null
+++ b/packages/preview-engine/tests/image-ready.test.ts
@@ -0,0 +1,60 @@
+// @vitest-environment happy-dom
+
+import { describe, expect, it, vi } from "vitest";
+import { waitForImages } from "../src/index.js";
+
+function createPendingImage() {
+  const image = document.createElement("img");
+  Object.defineProperty(image, "complete", {
+    configurable: true,
+    get: () => false
+  });
+  return image;
+}
+
+describe("文档图片就绪等待", () => {
+  it("图片正常加载后立即完成", async () => {
+    const image = createPendingImage();
+    image.decode = vi.fn(() => new Promise(() => undefined));
+    document.body.replaceChildren(image);
+
+    const waiting = waitForImages(document, 1_000);
+    image.dispatchEvent(new Event("load"));
+
+    await expect(waiting).resolves.toEqual([undefined]);
+  });
+
+  it("decode 拒绝且图片已经失败时不会错过 error 状态", async () => {
+    let complete = false;
+    const image = document.createElement("img");
+    Object.defineProperty(image, "complete", {
+      configurable: true,
+      get: () => complete
+    });
+    image.decode = vi.fn(async () => {
+      complete = true;
+      throw new Error("decode failed");
+    });
+    document.body.replaceChildren(image);
+
+    await expect(waitForImages(document, 1_000)).resolves.toEqual([
+      undefined
+    ]);
+  });
+
+  it("图片永不响应时由局部超时结束等待", async () => {
+    vi.useFakeTimers();
+    try {
+      const image = createPendingImage();
+      image.decode = vi.fn(() => new Promise(() => undefined));
+      document.body.replaceChildren(image);
+
+      const waiting = waitForImages(document, 25);
+      await vi.advanceTimersByTimeAsync(25);
+
+      await expect(waiting).resolves.toEqual([undefined]);
+    } finally {
+      vi.useRealTimers();
+    }
+  });
+});