From fefdc4f1b15d4b8f5e952f35c6ef9cbfbf5d7b3b Mon Sep 17 00:00:00 2001
From: Julius Marminge <51714798+juliusmarminge@users.noreply.github.com>
Date: Wed, 11 Nov 2026 13:04:41 -0800
Subject: [PATCH] ci: split web tests over two runners so every run finishes
 sooner

Test Web gated every CI run (p50 211s on main). Browser tests are bound by
the Vite server transforming modules for each file, not by Chromium, so a
second runner with its own Vite server cuts the job by about 35-40%.

AttachmentFilePreview.browser.test.tsx then became the longest file in its
shard, so its Office tests move to their own file and run in parallel.

Server shards restore Vitest's content-keyed module cache, saved from main,
instead of re-transforming every import in each per-file process.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
---
 .github/workflows/ci.yml                      |   30 +-
 .github/workflows/release.yml                 |    9 +-
 .../AttachmentFilePreview.browser.test.tsx    | 1043 +---------------
 ...achmentFilePreview.office.browser.test.tsx | 1086 +++++++++++++++++
 4 files changed, 1121 insertions(+), 1047 deletions(-)
 create mode 100644 apps/web/src/components/files/AttachmentFilePreview.office.browser.test.tsx

diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
index f5770c1f4516b..ba1e1e612e6d3 100644
--- a/.github/workflows/ci.yml
+++ b/.github/workflows/ci.yml
@@ -355,16 +355,22 @@ jobs:
 
   # The web suite is the largest outside the server. In the shared Test job it
   # started last and ran alone for about 40s after everything else finished.
-  # release.yml mirrors this test, test_web, and test_server split.
+  # Browser tests are bound by the Vite server transforming modules for each
+  # file, not by Chromium, so a second runner (and Vite server) halves the job
+  # that gated every run. release.yml mirrors this test, test_web, and test_server split.
   test_web:
     permissions:
       contents: read
       id-token: write
-    name: Test Web
+    name: Test Web ${{ matrix.shard }}
     needs: changes
     if: ${{ !cancelled() && needs.changes.outputs.test_web != 'false' }}
     runs-on: blacksmith-8vcpu-ubuntu-2404
     timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        shard: [1, 2]
     steps:
       - name: Checkout
         uses: actions/checkout@v6
@@ -406,7 +412,7 @@ jobs:
           fi
 
       - name: Test
-        run: vp run --filter @t3tools/web test
+        run: vp run --filter @t3tools/web test --shard ${{ matrix.shard }}/${{ strategy.job-total }}
 
   # apps/server sets `fileParallelism: false`, so its test files run strictly
   # one at a time. Sharding spreads them over separate runners instead of
@@ -481,6 +487,17 @@ jobs:
             node apps/server/node_modules/playwright-core/cli.js install-deps chromium
           fi
 
+      # Each server test file runs in its own Vitest process, and a fresh install starts
+      # Vitest's content-keyed module cache empty, so every file re-transformed its imports.
+      # Only pushes to main save it, so pull requests never evict each other's entries.
+      - name: Restore Vitest module cache
+        if: steps.changes.outputs.test_server != 'false'
+        uses: actions/cache/restore@v6
+        with:
+          path: node_modules/.vitest-cache
+          key: vitest-modules-server-${{ matrix.shard }}-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}-${{ github.sha }}
+          restore-keys: vitest-modules-server-${{ matrix.shard }}-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}-
+
       - name: Test
         if: steps.changes.outputs.test_server != 'false'
         env:
@@ -491,6 +508,13 @@ jobs:
           --uncached apps/server/integration/transferBudgetV2.integration.test.ts
           --verify-hits 1 apps/server
 
+      - name: Save Vitest module cache
+        if: github.event_name == 'push' && steps.changes.outputs.test_server != 'false'
+        uses: actions/cache/save@v6
+        with:
+          path: node_modules/.vitest-cache
+          key: vitest-modules-server-${{ matrix.shard }}-${{ runner.os }}-${{ hashFiles('pnpm-lock.yaml') }}-${{ github.sha }}
+
       # integration/transferBudgetV2.integration.test.ts writes the report; exactly one shard
       # produces these files. Gating the upload on their presence keeps a
       # single `thread-transfer-results` artifact per run, which is the name
diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index 84acc7c74f865..8827876b3829f 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -300,11 +300,15 @@ jobs:
   # Web browser tests time out when they share a runner with the other package
   # suites: Chromium gets too little CPU and diff workers miss their 10s start budget.
   test_web:
-    name: Release web tests
+    name: Release web tests ${{ matrix.shard }}
     needs: [preflight]
     if: ${{ !failure() && !cancelled() && needs.preflight.result == 'success' }}
     runs-on: blacksmith-8vcpu-ubuntu-2404
     timeout-minutes: 10
+    strategy:
+      fail-fast: false
+      matrix:
+        shard: [1, 2]
     steps:
       - name: Checkout
         uses: actions/checkout@v6
@@ -344,10 +348,11 @@ jobs:
           fi
 
       - name: Test
-        run: vp run --filter @t3tools/web test
+        run: vp run --filter @t3tools/web test --shard ${{ matrix.shard }}/${{ strategy.job-total }}
 
       # Browser tests run source modules; this boots the production chunk graph.
       - name: Boot the built web client
+        if: matrix.shard == 1
         run: |
           vp run --filter @t3tools/web build
           node apps/web/scripts/verify-built-boot.ts
diff --git a/apps/web/src/components/files/AttachmentFilePreview.browser.test.tsx b/apps/web/src/components/files/AttachmentFilePreview.browser.test.tsx
index 4ecc965f6fe32..285032b5b6a0a 100644
--- a/apps/web/src/components/files/AttachmentFilePreview.browser.test.tsx
+++ b/apps/web/src/components/files/AttachmentFilePreview.browser.test.tsx
@@ -78,6 +78,7 @@ import { decodeImagePreview } from "./decodeImagePreview";
 import type { BinaryWorkerResult } from "./binaryPreviewProtocol";
 import type { TextPreviewResult } from "./largeTextProtocol";
 import type { ReactElement } from "react";
+import type { OfficeWorkerResult } from "./officePreviewProtocol";
 
 // Real worker imports and WASM initialization can exceed waitFor's default second
 // when the full browser project runs concurrently on CI.
@@ -481,8 +482,6 @@ describe("bounded binary previews", () => {
     }
   });
 });
-import { OFFICE_PREVIEW_MAX_COLUMNS, type OfficeWorkerResult } from "./officePreviewProtocol";
-import { WORD_LIMITS } from "./officeArchive";
 
 describe("large text preview recovery", () => {
   it("retains the workspace viewer across URL renewals and reloads revisions and manual refreshes", async () => {
@@ -921,1046 +920,6 @@ describe("large text preview recovery", () => {
     await vi.waitFor(() => expect(load).toHaveBeenCalledWith(0));
   });
 });
-it.each(["<w:body/>", "<w:body></w:body>"])(
-  "opens an empty Word document with %s",
-  async (body) => {
-    const { default: JSZip } = await import("jszip");
-    const { prepareOffice } = await import("./officeArchive");
-    const archive = new JSZip().file(
-      "word/document.xml",
-      `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">${body}</w:document>`,
-    );
-    const prepared = await prepareOffice(
-      await archive.generateAsync({ type: "arraybuffer" }),
-      "docx",
-    );
-    const result = await JSZip.loadAsync(prepared.bytes);
-    const xml = new DOMParser().parseFromString(
-      await result.file("word/document.xml")!.async("string"),
-      "application/xml",
-    );
-    expect(xml.querySelector("parsererror")).toBeNull();
-    expect(
-      xml.getElementsByTagNameNS(
-        "http://schemas.openxmlformats.org/wordprocessingml/2006/main",
-        "body",
-      ),
-    ).toHaveLength(1);
-  },
-);
-
-it.each([false, true])(
-  "rejects excessive archive entries before JSZip (directories: %s)",
-  async (directories) => {
-    const { default: JSZip } = await import("jszip");
-    const { prepareOffice } = await import("./officeArchive");
-    const archive = new JSZip();
-    for (let i = 0; i < 4096; i++)
-      archive.file(`entry-${i}${directories ? "/" : ".txt"}`, "", { dir: directories });
-    const bytes = await archive.generateAsync({ type: "arraybuffer" });
-    const load = vi.spyOn(JSZip, "loadAsync");
-    try {
-      await expect(prepareOffice(bytes, "docx")).rejects.toThrow("2,048 entries");
-      expect(load).not.toHaveBeenCalled();
-      // The actual central-directory records must also be bounded if EOCD lies.
-      const view = new DataView(bytes);
-      view.setUint16(bytes.byteLength - 22 + 8, 1, true);
-      view.setUint16(bytes.byteLength - 22 + 10, 1, true);
-      await expect(prepareOffice(bytes, "docx")).rejects.toThrow("2,048 entries");
-      expect(load).not.toHaveBeenCalled();
-    } finally {
-      load.mockRestore();
-    }
-  },
-);
-
-it("rejects oversized embedded images before decoding pixels and retains ordinary images", async () => {
-  const { officeImageBitmap } = await import("./office/image-bitmap");
-  const canvas = new OffscreenCanvas(2, 3);
-  canvas.getContext("2d");
-  const blob = await canvas.convertToBlob({ type: "image/png" });
-  const bytes = await blob.arrayBuffer();
-  new DataView(bytes).setUint32(16, 12000);
-  new DataView(bytes).setUint32(20, 12000);
-  const decode = vi.spyOn(globalThis, "createImageBitmap");
-  try {
-    await expect(officeImageBitmap(new Blob([bytes]))).rejects.toThrow("pixel limit");
-    expect(decode).not.toHaveBeenCalled();
-    const bitmap = await officeImageBitmap(blob);
-    expect([bitmap.width, bitmap.height]).toEqual([2, 3]);
-    bitmap.close();
-  } finally {
-    decode.mockRestore();
-  }
-});
-
-it.each(["utf-16le", "utf-16be", "windows-1252"])(
-  "preserves %s Office XML and safe hyperlink targets",
-  async (encoding) => {
-    const { default: JSZip } = await import("jszip");
-    const { prepareOffice } = await import("./officeArchive");
-    const archive = new JSZip();
-    const encode = (text: string) => {
-      const xml = `<?xml version="1.0" encoding="${encoding}"?>${text}`;
-      if (encoding === "windows-1252") return Uint8Array.from(xml, (char) => char.charCodeAt(0));
-      const bytes = new Uint8Array(2 + xml.length * 2);
-      const view = new DataView(bytes.buffer);
-      const little = encoding === "utf-16le";
-      view.setUint16(0, 0xfeff, little);
-      for (let i = 0; i < xml.length; i++) view.setUint16(2 + i * 2, xml.charCodeAt(i), little);
-      return bytes;
-    };
-    archive.file(
-      "word/document.xml",
-      encode(
-        '<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body><w:p><w:r><w:t>café</w:t></w:r></w:p></w:body></w:document>',
-      ),
-    );
-    archive.file(
-      "word/_rels/document.xml.rels",
-      encode(
-        `<Relationships>${["https://example.com/page", "http://example.com", "mailto:maria@example.com", "javascript:alert(1)", "file:///tmp/private"].map((target, i) => `<Relationship Id="r${i}" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/hyperlink" TargetMode="External" Target="${target}"/>`).join("")}</Relationships>`,
-      ),
-    );
-    const prepared = await prepareOffice(
-      await archive.generateAsync({ type: "arraybuffer" }),
-      "docx",
-    );
-    const result = await JSZip.loadAsync(prepared.bytes);
-    expect(await result.file("word/document.xml")!.async("string")).toContain("café");
-    const links = await result.file("word/_rels/document.xml.rels")!.async("string");
-    expect(links).toContain('encoding="UTF-8"');
-    expect(links).toContain("https://example.com/page");
-    expect(links).toContain("http://example.com");
-    expect(links).toContain("mailto:maria@example.com");
-    expect(links).not.toContain("javascript:");
-    expect(links).not.toContain("file:");
-  },
-);
-
-it.each([
-  ["", "worksheets/./sheet1.xml", false, false],
-  ["x:", "../xl/worksheets/sheet1.xml", false, false],
-  ["", "/xl/worksheets/sheet1.xml", true, false],
-  ["", "worksheets/sheet1.xml", false, true],
-  ["", "worksheets/sheet1.xml", true, true],
-])(
-  "preserves %sworksheet metadata with relationship target %s",
-  async (prefix, target, empty, localPrefix) => {
-    const { default: JSZip } = await import("jszip");
-    const archive = new JSZip();
-    const ns = "http://schemas.openxmlformats.org/spreadsheetml/2006/main";
-    archive.file(
-      "xl/workbook.xml",
-      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Chart" sheetId="2" r:id="c"/><sheet name="Sheet" sheetId="1" r:id="s"/></sheets></workbook>',
-    );
-    archive.file(
-      "xl/_rels/workbook.xml.rels",
-      `<Relationships><Relationship Id="s" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="${target}"/><Relationship Id="c" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/chartsheet" Target="chartsheets/sheet1.xml"/></Relationships>`,
-    );
-    archive.file(
-      "xl/worksheets/sheet1.xml",
-      `<${prefix}worksheet xmlns${prefix ? ":x" : ""}="${ns}"><${prefix}dimension ref="XFD1048576"/><${prefix}sheetViews><${prefix}sheetView showGridLines="0"/></${prefix}sheetViews><${prefix}sheetFormatPr defaultColWidth="30"/><${prefix}cols><${prefix}col min="${OFFICE_PREVIEW_MAX_COLUMNS - 1}" max="${OFFICE_PREVIEW_MAX_COLUMNS + 10}" width="20"/><${prefix}col min="${OFFICE_PREVIEW_MAX_COLUMNS + 1}" max="${OFFICE_PREVIEW_MAX_COLUMNS + 30}" hidden="1"/></${prefix}cols><${prefix}sheetData><${prefix}row ht="42" customHeight="1" hidden="1"><${prefix}c r="A50" t="inlineStr"><${prefix}is><${prefix}t>${"value".repeat(1000)}</${prefix}t></${prefix}is></${prefix}c></${prefix}row></${prefix}sheetData><${prefix}mergeCells><${prefix}mergeCell ref="XFD1048576"/></${prefix}mergeCells></${prefix}worksheet>`
-        .replace(
-          /<((?:x:)?(?:col|dimension|mergeCell))\b([^>]*)\/>/g,
-          prefix ? "<$1$2></$1>" : "$&",
-        )
-        .replace(/<sheetData>[\s\S]*?<\/sheetData>/, (data) => (empty ? "<sheetData/>" : data))
-        .replace(/<(\/?)sheetData\b/g, (tag, closing: string) =>
-          localPrefix ? `<${closing}x:sheetData${closing ? "" : ` xmlns:x="${ns}"`}` : tag,
-        )
-        .replace(/="([^"]*)"/g, (attribute, value: string) =>
-          prefix || empty
-            ? ` = '${value.replace(/\d/g, (digit) => `&#${digit.charCodeAt(0)};`)}'`
-            : attribute,
-        ),
-    );
-    const bytes = await archive.generateAsync({ type: "arraybuffer" });
-    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
-      type: "module",
-    });
-    try {
-      const result = await new Promise<OfficeWorkerResult>((resolve) => {
-        worker.addEventListener(
-          "message",
-          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
-          { once: true },
-        );
-        worker.postMessage({ type: "open", kind: "xlsx", bytes }, [bytes]);
-      });
-      expect(result.type).toBe("xlsx");
-      if (result.type !== "xlsx") throw new Error("Expected bounded workbook");
-      // The engine counts the chart sheet before it.
-      expect(result.view?.hiddenGridlines).toEqual([1]);
-      const bounded = await JSZip.loadAsync(result.bytes);
-      const sheet = new DOMParser().parseFromString(
-        await bounded.file("xl/worksheets/sheet1.xml")!.async("string"),
-        "application/xml",
-      );
-      expect(sheet.querySelector("parsererror")).toBeNull();
-      const row = sheet.getElementsByTagNameNS(ns, "row")[0];
-      if (empty) expect(row).toBeUndefined();
-      else {
-        expect(row!.getAttribute("ht")).toBe("42");
-        expect(row!.getAttribute("hidden")).toBe("1");
-        expect(row!.getElementsByTagNameNS(ns, "c")[0]!.getAttribute("r")).toBe("A50");
-        expect(row!.getElementsByTagNameNS(ns, "t")[0]!.textContent).toHaveLength(4096);
-      }
-      expect(sheet.getElementsByTagNameNS(ns, "dimension")).toHaveLength(0);
-      expect(sheet.getElementsByTagNameNS(ns, "mergeCell")).toHaveLength(0);
-      const columns = [...sheet.getElementsByTagNameNS(ns, "col")].map((column) =>
-        ["min", "max", "width"].map((name) => column.getAttribute(name)),
-      );
-      // The engine ignores `defaultColWidth`, so the columns it sizes are spelled out.
-      expect(columns).toEqual([
-        [String(OFFICE_PREVIEW_MAX_COLUMNS - 1), String(OFFICE_PREVIEW_MAX_COLUMNS), "20"],
-        // Hidden columns keep their span past the limit, so they stay hidden.
-        [String(OFFICE_PREVIEW_MAX_COLUMNS + 1), String(OFFICE_PREVIEW_MAX_COLUMNS + 30), null],
-        ["1", String(OFFICE_PREVIEW_MAX_COLUMNS - 2), "30"],
-      ]);
-    } finally {
-      worker.terminate();
-    }
-  },
-);
-
-it("reports the final slide at maximum scroll after page visibility changes", async () => {
-  const { OfficePages } = await import("./office/OfficePages");
-  const changed = vi.fn();
-  const container = document.createElement("div");
-  container.style.cssText = "display:flex;flex-direction:column;width:400px;height:400px";
-  await using screen = await render(
-    <OfficePages
-      pages={Array.from({ length: 6 }, () => ({ width: 400, height: 240 }))}
-      label="Slide"
-      paint={async () => undefined}
-      onPageChange={changed}
-      onError={(error) => {
-        throw error;
-      }}
-    />,
-    { container },
-  );
-  const scroller = screen.container.querySelector<HTMLElement>("[data-office-pages]")!;
-  await vi.waitFor(() => expect(scroller.scrollHeight).toBeGreaterThan(scroller.clientHeight));
-  await act(() => {
-    scroller.scrollTop = scroller.scrollHeight;
-  });
-  await vi.waitFor(() => expect(changed).toHaveBeenLastCalledWith(5));
-  await act(() => {
-    scroller.scrollTop = 10;
-  });
-  await vi.waitFor(() => expect(changed).toHaveBeenLastCalledWith(0));
-});
-
-it("preserves merged text across tile clears", async () => {
-  const { paintFrame } = await import("./office/sheet-frame");
-  const canvas = new OffscreenCanvas(400, 80);
-  const context = canvas.getContext("2d")!;
-  paintFrame(
-    context,
-    {
-      viewport: { x: 0, y: 0, width: 400, height: 80 },
-      list: { width: 400, height: 80, commands: [] },
-      tiles: [
-        {
-          x: 0,
-          y: 0,
-          clipX: 0,
-          clipY: 0,
-          list: {
-            width: 208,
-            height: 80,
-            commands: [
-              {
-                op: "text",
-                x: 2,
-                y: 40,
-                text: "MMMMMMMMMMMMMMMMMMMMMMMM",
-                fontSize: 20,
-                color: "#000",
-                clip: { x: 0, y: 0, w: 400, h: 80 },
-              },
-            ],
-          },
-        },
-        { x: 192, y: 0, clipX: 200, clipY: 0, list: { width: 208, height: 80, commands: [] } },
-      ],
-    },
-    { ratio: 1, origin: { x: 0, y: 0 } },
-  );
-  const pixels = context.getImageData(240, 15, 100, 35).data;
-  expect(pixels.some((value, index) => index % 4 === 3 && value > 0)).toBe(true);
-});
-
-it.each([
-  "paragraphs",
-  "runs",
-  "tables",
-  "auxiliary XML",
-  "XML bytes",
-  "renamed XML",
-  "section after prefix",
-  "oversized section",
-])("bounds excessive Word %s before rendering DOM", async (scenario) => {
-  const { default: JSZip } = await import("jszip");
-  const archive = new JSZip();
-  const body = ["paragraphs", "section after prefix", "oversized section"].includes(scenario)
-    ? "<w:p><w:r><w:t>x</w:t></w:r></w:p>".repeat(200_000)
-    : scenario === "runs"
-      ? `<w:p>${"<w:r><w:t>x</w:t></w:r>".repeat(50_001)}</w:p>`
-      : scenario === "tables"
-        ? "<w:tbl/>".repeat(2 * WORD_LIMITS.bodyElements)
-        : scenario === "XML bytes"
-          ? `<w:p><w:r><w:t>${"x".repeat(2 * 1024 * 1024)}</w:t></w:r></w:p>`
-          : "<w:p/>";
-  const section =
-    '<w:sectPr><w:pgSz w:w="16838" w:h="11906" w:orient="landscape"/><w:pgMar w:top="1440" w:left="1440" w:bottom="1440" w:right="1440"/></w:sectPr>';
-  archive.file(
-    "word/document.xml",
-    `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body>${body}${scenario === "section after prefix" ? '<w:p xmlns:s="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:pPr><s:sectPr><s:pgSz s:w="11906" s:h="16838"/></s:sectPr></w:pPr></w:p>' : ""}${scenario === "oversized section" ? `<w:sectPr>${"<w:cols/>".repeat(2_001)}</w:sectPr>` : section}</w:body></w:document>`,
-  );
-  if (scenario === "auxiliary XML" || scenario === "renamed XML")
-    archive.file(
-      scenario === "renamed XML" ? "word/footnotes.dat" : "word/footnotes.xml",
-      `<w:footnotes>${"<w:p/>".repeat(WORD_LIMITS.auxiliaryMarkup + 1)}</w:footnotes>`,
-    );
-  const file = await archive.generateAsync({ type: "blob", compression: "DEFLATE" });
-  const src = URL.createObjectURL(file);
-  try {
-    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
-      type: "module",
-    });
-    try {
-      const result = await new Promise<OfficeWorkerResult>((resolve) => {
-        worker.addEventListener(
-          "message",
-          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
-          { once: true },
-        );
-        void file
-          .arrayBuffer()
-          .then((bytes) => worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]));
-      });
-      if (
-        scenario === "auxiliary XML" ||
-        scenario === "renamed XML" ||
-        scenario === "oversized section"
-      ) {
-        expect(result).toMatchObject({
-          type: "error",
-          message: expect.stringContaining("Preview limited"),
-        });
-      } else {
-        expect(result.type).toBe("docx");
-        if (result.type !== "docx") throw new Error("Expected a Word prefix");
-        expect(result.truncated).toBe(true);
-        const bounded = await JSZip.loadAsync(result.bytes);
-        const markup = await bounded.file("word/document.xml")!.async("string");
-        {
-          const xml = markup;
-          const document = new DOMParser().parseFromString(xml, "application/xml");
-          expect(document.querySelector("parsererror")).toBeNull();
-          const bodies = document.getElementsByTagNameNS("*", "body");
-          expect(bodies).toHaveLength(1);
-          const section = bodies[0]!.lastElementChild!;
-          expect(section.localName).toBe("sectPr");
-          const size = section.getElementsByTagNameNS("*", "pgSz")[0]!;
-          expect(size.getAttributeNS(section.namespaceURI, "w")).toBe(
-            scenario === "section after prefix" ? "11906" : "16838",
-          );
-          expect(size.getAttributeNS(section.namespaceURI, "orient")).toBe(
-            scenario === "section after prefix" ? null : "landscape",
-          );
-        }
-        expect(markup.length).toBeLessThan(body.length);
-        expect(markup.length).toBeLessThanOrEqual(WORD_LIMITS.bodyBytes);
-        expect(markup.match(/<(?![!?/])/g)!.length).toBeLessThanOrEqual(WORD_LIMITS.bodyTags);
-      }
-    } finally {
-      worker.terminate();
-    }
-  } finally {
-    URL.revokeObjectURL(src);
-  }
-});
-
-it.each([
-  "relationship markup",
-  "relationship bytes",
-  "content type",
-  "metadata type",
-  "deep XML",
-  "query path",
-])("bounds XML hidden in media by %s", async (scenario) => {
-  const { default: JSZip } = await import("jszip");
-  const archive = new JSZip();
-  const path = `word/media/payload.png${scenario === "query path" ? "?xml" : ""}`;
-  archive.file(
-    "word/document.xml",
-    '<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body><w:p/></w:body></w:document>',
-  );
-  archive.file(
-    "[Content_Types].xml",
-    `<Types><Override PartName="/${path}" ContentType="${scenario === "content type" ? "application/vnd.openxmlformats-officedocument.wordprocessingml.styles+xml" : "image/png"}"/>${scenario === "metadata type" ? '<Default Extension="rels" ContentType="image/png"/>' : ""}</Types>`,
-  );
-  archive.file(
-    "word/_rels/document.xml.rels",
-    `<Relationships>${scenario === "content type" ? "" : `<Relationship Id="style" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="${path.slice(5)}"/>`}${scenario === "metadata type" ? "<unused/>".repeat(WORD_LIMITS.auxiliaryMarkup + 1) : ""}</Relationships>`,
-  );
-  archive.file(
-    path,
-    scenario === "relationship bytes"
-      ? `<styles>${"x".repeat(WORD_LIMITS.auxiliaryPartBytes)}</styles>`
-      : scenario === "deep XML"
-        ? `${"<styles>".repeat(65)}${"</styles>".repeat(65)}`
-        : `<styles>${"<style/>".repeat(WORD_LIMITS.auxiliaryMarkup + 1)}</styles>`,
-  );
-  const bytes = await archive.generateAsync({ type: "arraybuffer", compression: "DEFLATE" });
-  const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
-    type: "module",
-  });
-  try {
-    const result = await new Promise<OfficeWorkerResult>((resolve) => {
-      worker.addEventListener(
-        "message",
-        (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
-        { once: true },
-      );
-      worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]);
-    });
-    expect(result).toMatchObject({
-      type: "error",
-      message: expect.stringContaining("Preview limited"),
-    });
-  } finally {
-    worker.terminate();
-  }
-});
-
-const EXPANDED_WORD_ROLES = [
-  "footnotes",
-  "note roots",
-  "endnotes",
-  "header",
-  "footer",
-  "comments",
-  "styles",
-  "style chain",
-  "style count",
-  "style visits",
-  "numbering",
-  "picture numbering",
-] as const;
-
-async function expandedWordFixture(role: (typeof EXPANDED_WORD_ROLES)[number]) {
-  const archive = new JSZip();
-  const ns = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
-  const type = role.startsWith("style")
-    ? "styles"
-    : role === "picture numbering"
-      ? "numbering"
-      : role === "note roots"
-        ? "footnotes"
-        : role;
-  archive.file(
-    "_rels/.rels",
-    '<Relationships><Relationship Id="doc" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/></Relationships>',
-  );
-  const text = (value: string) => `<w:p><w:r><w:t>${value}</w:t></w:r></w:p>`;
-  // Each copy of the 2,000-paragraph payload costs 6,000 markup units, so enough
-  // references (or pages) exceed the expansion budget.
-  const copies = Math.ceil(WORD_LIMITS.expandedMarkup / 6_000) + 1;
-  archive.file(
-    "word/document.xml",
-    `<w:document xmlns:w="${ns}" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><w:body>${text("body retained")}${Array.from({ length: copies }, () => `<w:p><w:r><w:footnoteReference w:id="1"/><w:endnoteReference w:id="1"/><w:commentReference w:id="1"/><w:br w:type="page"/></w:r></w:p>`).join("")}<w:sectPr><w:headerReference w:type="default" r:id="aux"/><w:footerReference w:type="default" r:id="aux"/></w:sectPr></w:body></w:document>`,
-  );
-  archive.file(
-    "word/_rels/document.xml.rels",
-    `<Relationships><Relationship Id="aux" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/${type}" Target="media/aux.xml"/></Relationships>`,
-  );
-  const xml =
-    role === "style chain" || role === "style count" || role === "style visits"
-      ? `<w:styles xmlns:w="${ns}">${Array.from({ length: role === "style count" ? WORD_LIMITS.styles + 1 : role === "style visits" ? Math.ceil(WORD_LIMITS.styleVisits / 30) + 1 : 1_000 }, (_, i) => `<w:style w:styleId="s${i}" w:type="paragraph">${i ? `<w:basedOn w:val="s${role === "style visits" && i >= 30 ? 29 : i - 1}"/>` : ""}<w:pPr><w:spacing w:after="120"/></w:pPr></w:style>`).join("")}</w:styles>`
-      : role === "styles"
-        ? `<w:styles xmlns:w="${ns}">${Array.from({ length: 100 }, (_, i) => `<w:style w:styleId="${"s".repeat(2_000)}${i}" w:type="paragraph"><w:basedOn w:val="s0"/><w:pPr><w:spacing w:after="120"/></w:pPr></w:style>`).join("")}</w:styles>`
-        : role.includes("numbering")
-          ? `<w:numbering xmlns:w="${ns}">${role === "picture numbering" ? '<w:numPicBullet w:numPicBulletId="1"/>' : ""}<w:abstractNum w:abstractNumId="1">${Array.from({ length: 9 }, (_, i) => `<w:lvl w:ilvl="${i}"><w:lvlText w:val="%1."/></w:lvl>`).join("")}</w:abstractNum>${Array.from({ length: WORD_LIMITS.numberingReferences + 1 }, (_, i) => `<w:num w:numId="${i}"><w:abstractNumId w:val="1"/></w:num>`).join("")}</w:numbering>`
-          : role === "header" || role === "footer"
-            ? `<w:${role === "header" ? "hdr" : "ftr"} xmlns:w="${ns}">${text("omitted payload").repeat(2_000)}</w:${role === "header" ? "hdr" : "ftr"}>`
-            : `<w:${role} xmlns:w="${ns}"><w:${role.slice(0, -1)} w:id="1">${text("omitted payload").repeat(2_000)}</w:${role.slice(0, -1)}></w:${role}>`;
-  archive.file("word/media/aux.xml", xml);
-  if (role === "note roots") {
-    // Each note's XML repeats the 32 KB root, which the expansion budget charges twice.
-    const notes = Math.ceil(WORD_LIMITS.expandedBytes / 64_000) + 1;
-    archive.file(
-      "word/document.xml",
-      `<w:document xmlns:w="${ns}"><w:body>${text("body retained")}${Array.from({ length: notes }, (_, id) => `<w:p><w:r><w:footnoteReference w:id="${id}"/></w:r></w:p>`).join("")}</w:body></w:document>`,
-    );
-    archive.file(
-      "word/media/aux.xml",
-      `<w:footnotes xmlns:w="${ns}" padding="${"x".repeat(32_000)}">${Array.from({ length: notes }, (_, id) => `<w:footnote w:id="${id}">${text("omitted payload")}</w:footnote>`).join("")}</w:footnotes>`,
-    );
-  }
-  return archive.generateAsync({ type: "blob", compression: "DEFLATE" });
-}
-
-// Rendering starts a Word engine worker per case, which compiles about 30 MB of WebAssembly and
-// took 10-17 s per test on loaded CI runners. Omission and retention are prepareOffice decisions,
-// so they are checked there.
-it.each(EXPANDED_WORD_ROLES)(
-  "keeps the body and omits expanded %s from the prepared document",
-  async (role) => {
-    const file = await expandedWordFixture(role);
-    const { SaxesParser } = await import("saxes");
-    const { prepareOffice } = await import("./officeArchive");
-    const parse = vi.spyOn(SaxesParser.prototype, "write");
-    try {
-      const prepared = await prepareOffice(await file.arrayBuffer(), "docx");
-      expect(prepared.truncated).toBe(true);
-      if (role === "note roots")
-        expect(
-          parse.mock.calls.reduce(
-            (sum, [chunk]) => sum + (typeof chunk === "string" ? chunk.length : 0),
-            0,
-          ),
-        ).toBeLessThan(WORD_LIMITS.expandedBytes + 4 * 1024 * 1024);
-      const bounded = await JSZip.loadAsync(prepared.bytes);
-      const markup = await bounded.file("word/document.xml")!.async("string");
-      expect(markup).toContain("body retained");
-      expect(bounded.file("word/media/aux.xml")).toBeNull();
-      // A dangling header or footer reference makes the engine reject the whole body.
-      expect(markup).not.toMatch(/<w:(header|footer)Reference/);
-      for (const entry of Object.values(bounded.files))
-        if (!entry.dir) expect(await entry.async("string")).not.toContain("omitted payload");
-    } finally {
-      parse.mockRestore();
-    }
-  },
-);
-
-it.each([
-  "ordinary parts",
-  "unused parts",
-  "independent styles",
-  "inherited styles",
-  "python-docx package",
-  "default template styles",
-  "binary package properties",
-])("retains Word %s without a limit warning", async (scenario) => {
-  const { default: JSZip } = await import("jszip");
-  const archive = new JSZip();
-  const ns = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
-  const r = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
-  const text = (value: string) => `<w:p><w:r><w:t>${value}</w:t></w:r></w:p>`;
-  archive.file(
-    "_rels/.rels",
-    `<Relationships><Relationship Id="doc" Type="${r}/officeDocument" Target="word/document.xml"/></Relationships>`,
-  );
-  if (scenario === "python-docx package" || scenario === "binary package properties") {
-    const packageRelationships = "http://schemas.openxmlformats.org/package/2006/relationships";
-    archive.file(
-      "_rels/.rels",
-      `<Relationships xmlns="${packageRelationships}"><Relationship Id="doc" Type="${r}/officeDocument" Target="word/document.xml"/><Relationship Id="thumbnail" Type="${packageRelationships}/metadata/thumbnail" Target="docProps/thumbnail.jpeg"/><Relationship Id="core" Type="${packageRelationships}/metadata/core-properties" Target="docProps/core.xml"/><Relationship Id="app" Type="${r}/extended-properties" Target="docProps/app.xml"/><Relationship Id="custom" Type="${r}/custom-properties" Target="docProps/custom.xml"/><Relationship Id="signature" Type="${packageRelationships}/digital-signature/origin" Target="_xmlsignatures/origin.sigs"/></Relationships>`,
-    );
-    archive.file(
-      "[Content_Types].xml",
-      '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types"><Default Extension="jpeg" ContentType="image/jpeg"/><Default Extension="xml" ContentType="application/xml"/><Default Extension="sigs" ContentType="application/vnd.openxmlformats-package.digital-signature-origin"/></Types>',
-    );
-    archive.file(
-      "docProps/thumbnail.jpeg",
-      new Uint8Array([255, 216, 255, 224, 0, 16, 74, 70, 73, 70]),
-    );
-    archive.file("_xmlsignatures/origin.sigs", new Uint8Array());
-    for (const part of ["core", "app", "custom"])
-      archive.file(`docProps/${part}.xml`, '<properties xmlns="urn:properties"/>');
-    if (scenario === "binary package properties") {
-      const roles = [
-        `${packageRelationships}/metadata/core-properties`,
-        `${r}/extended-properties`,
-        `${packageRelationships}/metadata/custom-properties`,
-        `${packageRelationships}/digital-signature/signature`,
-      ];
-      archive.file(
-        "_rels/.rels",
-        `<Relationships><Relationship Id="doc" Type="${r}/officeDocument" Target="word/document.xml"/>${roles.map((role, i) => `<Relationship Id="metadata${i}" Type="${role}" Target="docProps/metadata${i}.dat"/>`).join("")}</Relationships>`,
-      );
-      for (const i of roles.keys())
-        archive.file(`docProps/metadata${i}.dat`, new Uint8Array([255, 216, 255, 0]));
-    }
-  }
-  const ordinary = scenario === "ordinary parts";
-  archive.file(
-    "word/document.xml",
-    `<w:document xmlns:w="${ns}" xmlns:r="${r}"><w:body>${text("ordinary body")}<w:p><w:pPr><w:pStyle w:val="s19"/></w:pPr><w:r><w:t>styled body</w:t>${ordinary ? '<w:footnoteReference w:id="1"/><w:footnoteReference w:id="1"/><w:endnoteReference w:id="1"/><w:commentReference w:id="1"/>' : ""}</w:r></w:p><w:sectPr>${ordinary ? '<w:headerReference w:type="default" r:id="header"/><w:footerReference w:type="default" r:id="footer"/>' : ""}</w:sectPr></w:body></w:document>`,
-  );
-  archive.file(
-    "word/_rels/document.xml.rels",
-    `<Relationships>${["header", "footer", "footnotes", "endnotes", "comments", "fontTable", "styles"].map((role) => `<Relationship Id="${role}" Type="${r}/${role}" Target="${role}.xml"/>`).join("")}</Relationships>`,
-  );
-  for (const [role, root] of [
-    ["header", "hdr"],
-    ["footer", "ftr"],
-  ])
-    archive.file(
-      `word/${role}.xml`,
-      `<w:${root} xmlns:w="${ns}">${text(`${role} retained`)}</w:${root}>`,
-    );
-  for (const role of ["footnotes", "endnotes", "comments"])
-    archive.file(
-      `word/${role}.xml`,
-      `<w:${role} xmlns:w="${ns}"><w:${role.slice(0, -1)} w:id="1" w:author="reviewer" w:date="2026-10-01T00:00:00Z">${text(`${role} retained`)}</w:${role.slice(0, -1)}></w:${role}>`,
-    );
-  archive.file(
-    "word/fontTable.xml",
-    `<w:fonts xmlns:w="${ns}"><w:font w:name="unused"/></w:fonts>`,
-  );
-  archive.file(
-    "word/styles.xml",
-    `<w:styles xmlns:w="${ns}"><w:docDefaults/><w:style w:type="paragraph" w:styleId="base"><w:rPr><w:b/></w:rPr></w:style>${Array.from({ length: 20 }, (_, i) => `<w:style w:styleId="s${i}" w:type="paragraph">${scenario === "inherited styles" ? '<w:basedOn w:val="base"/>' : ""}<w:rPr><w:color w:val="123456"/></w:rPr></w:style>`).join("")}</w:styles>`,
-  );
-  if (scenario === "default template styles") {
-    const heading =
-      '<w:style w:type="paragraph" w:styleId="s19"><w:basedOn w:val="Normal"/><w:link w:val="HeadingChar"/><w:pPr><w:spacing w:after="120"/></w:pPr><w:rPr><w:b/><w:sz w:val="32"/><w:color w:val="123456"/></w:rPr></w:style>';
-    const conditions = [
-      "wholeTable",
-      "firstRow",
-      "lastRow",
-      "firstCol",
-      "lastCol",
-      "band1Horz",
-      "band2Horz",
-      "band1Vert",
-      "band2Vert",
-    ];
-    archive.file(
-      "word/styles.xml",
-      `<w:styles xmlns:w="${ns}"><w:docDefaults><w:rPrDefault><w:rPr><w:sz w:val="22"/></w:rPr></w:rPrDefault></w:docDefaults><w:latentStyles>${Array.from({ length: 276 }, (_, i) => `<w:lsdException w:name="latent ${i}" w:semiHidden="0" w:uiPriority="99"/>`).join("")}</w:latentStyles><w:style w:type="paragraph" w:styleId="Normal"/><w:style w:type="character" w:styleId="HeadingChar"><w:rPr><w:b/></w:rPr></w:style>${heading}${Array.from({ length: 61 }, (_, i) => `<w:style w:type="paragraph" w:styleId="p${i}"><w:basedOn w:val="Normal"/><w:pPr><w:spacing w:after="120"/></w:pPr><w:rPr><w:color w:val="123456"/></w:rPr></w:style>`).join("")}${Array.from({ length: 100 }, (_, i) => `<w:style w:type="table" w:styleId="Table${i}">${i ? '<w:basedOn w:val="Table0"/>' : ""}<w:tblPr><w:tblCellMar><w:top w:w="0"/><w:left w:w="108"/><w:bottom w:w="0"/><w:right w:w="108"/></w:tblCellMar></w:tblPr>${conditions.map((type) => `<w:tblStylePr w:type="${type}"><w:pPr><w:spacing w:after="0"/></w:pPr><w:rPr><w:b/><w:color w:val="123456"/></w:rPr><w:tcPr><w:shd w:fill="D9E2F3"/></w:tcPr></w:tblStylePr>`).join("")}</w:style>`).join("")}</w:styles>`,
-    );
-    archive.file(
-      "word/_rels/document.xml.rels",
-      (await archive.file("word/_rels/document.xml.rels")!.async("string")).replace(
-        "</Relationships>",
-        `<Relationship Id="numbering" Type="${r}/numbering" Target="numbering.xml"/></Relationships>`,
-      ),
-    );
-    archive.file(
-      "word/numbering.xml",
-      `<w:numbering xmlns:w="${ns}">${Array.from({ length: 9 }, (_, i) => `<w:abstractNum w:abstractNumId="${i}"><w:multiLevelType w:val="singleLevel"/><w:lvl w:ilvl="0"><w:start w:val="1"/><w:numFmt w:val="decimal"/><w:lvlText w:val="%1."/><w:lvlJc w:val="left"/><w:pPr><w:tabs><w:tab w:val="num" w:pos="720"/></w:tabs><w:ind w:left="720" w:hanging="360"/></w:pPr></w:lvl></w:abstractNum><w:num w:numId="${i + 1}"><w:abstractNumId w:val="${i}"/></w:num>`).join("")}</w:numbering>`,
-    );
-    const document = await archive.file("word/document.xml")!.async("string");
-    archive.file(
-      "word/document.xml",
-      document.replace(
-        "<w:sectPr>",
-        '<w:tbl><w:tblPr><w:tblStyle w:val="Table99"/></w:tblPr><w:tblGrid><w:gridCol w:w="2000"/></w:tblGrid><w:tr><w:tc><w:p><w:r><w:t>styled cell</w:t></w:r></w:p></w:tc></w:tr></w:tbl><w:sectPr>',
-      ),
-    );
-  }
-  const { prepareOffice } = await import("./officeArchive");
-  const prepared = await prepareOffice(
-    await archive.generateAsync({ type: "arraybuffer", compression: "DEFLATE" }),
-    "docx",
-  );
-  expect(prepared.truncated).toBe(false);
-  const bounded = await JSZip.loadAsync(prepared.bytes);
-  const markup = await bounded.file("word/document.xml")!.async("string");
-  expect(markup).toContain("ordinary body");
-  expect(markup).toContain("styled body");
-  expect(bounded.file("word/styles.xml")).not.toBeNull();
-  if (scenario === "default template styles") {
-    expect(markup).toContain("styled cell");
-    expect(await bounded.file("word/styles.xml")!.async("string")).toContain('w:styleId="Table99"');
-  }
-  if (ordinary) {
-    expect(markup).toMatch(/<w:headerReference/);
-    expect(markup).toMatch(/<w:footerReference/);
-    for (const role of ["header", "footer", "footnotes", "endnotes", "comments"])
-      expect(await bounded.file(`word/${role}.xml`)!.async("string")).toContain(`${role} retained`);
-  }
-});
-
-it.each([false, true])(
-  "bounds shared-string text including CDATA %s per cell and across sheets in the worker",
-  async (cdata) => {
-    const { default: JSZip } = await import("jszip");
-    const archive = new JSZip();
-    archive.file(
-      "xl/workbook.xml",
-      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="one" sheetId="1" r:id="s"/><sheet name="two" sheetId="2" r:id="s"/></sheets></workbook>',
-    );
-    archive.file(
-      "xl/_rels/workbook.xml.rels",
-      '<Relationships><Relationship Id="s" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/></Relationships>',
-    );
-    const sharedPath = cdata ? "customStrings.xml" : "sharedStrings.xml";
-    archive.file(
-      "xl/_rels/workbook.xml.rels",
-      (await archive.file("xl/_rels/workbook.xml.rels")!.async("string")).replace(
-        "</Relationships>",
-        `<Relationship Id="strings" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/sharedStrings" Target="${sharedPath}"/></Relationships>`,
-      ),
-    );
-    const content = "x".repeat(32_767);
-    archive.file(
-      `xl/${sharedPath}`,
-      `<sst><si><t>${cdata ? `<![CDATA[${content}]]>` : content}</t></si></sst>`,
-    );
-    archive.file(
-      "xl/worksheets/sheet1.xml",
-      `<worksheet><sheetData>${Array.from({ length: 500 }, (_, i) => `<row r="${i + 1}">${Array.from({ length: 50 }, (_, j) => `<c r="${j < 26 ? String.fromCharCode(65 + j) : "A" + String.fromCharCode(65 + j - 26)}${i + 1}" t="s"><v>${cdata ? "<![CDATA[0]]>" : "0"}</v></c>`).join("")}</row>`).join("")}</sheetData></worksheet>`.replace(
-        '<c r="A1" t="s"><v><![CDATA[0]]></v></c>',
-        `<c r="A1" t="inlineStr"><is><t><![CDATA[${content}]]></t></is></c>`,
-      ),
-    );
-    const file = await archive.generateAsync({ type: "blob", compression: "DEFLATE" });
-    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
-      type: "module",
-    });
-    try {
-      const result = await new Promise<OfficeWorkerResult>((resolve) => {
-        worker.addEventListener(
-          "message",
-          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
-          { once: true },
-        );
-        void file
-          .arrayBuffer()
-          .then((bytes) => worker.postMessage({ type: "open", kind: "xlsx", bytes }, [bytes]));
-      });
-      expect(result.type).toBe("xlsx");
-      if (result.type !== "xlsx") throw new Error("Expected bounded workbook");
-      const bounded = await JSZip.loadAsync(result.bytes);
-      const sheet = new DOMParser().parseFromString(
-        await bounded.file("xl/worksheets/sheet1.xml")!.async("string"),
-        "application/xml",
-      );
-      const cells = [...sheet.getElementsByTagName("t")].map((cell) => cell.textContent ?? "");
-      expect(cells.reduce((total, cell) => total + cell.length, 0)).toBe(1024 * 1024);
-      expect(Math.max(...cells.map((cell) => cell.length))).toBe(4096);
-      expect(result.truncated).toBe(true);
-    } finally {
-      worker.terminate();
-    }
-  },
-);
-
-// A body just over the read limit once each paragraph repeats its text this often.
-it.each([1, Math.ceil(WORD_LIMITS.bodyBytes / 5_000 / 4)])(
-  "counts shared Word settings once with %s text repetitions",
-  async (repetitions) => {
-    const { default: JSZip } = await import("jszip");
-    const archive = new JSZip();
-    const ns = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
-    archive.file(
-      "word/document.xml",
-      `<w:document xmlns:w="${ns}"><w:body>${`<w:p><w:r><w:t>${"body".repeat(repetitions)}</w:t></w:r></w:p>`.repeat(5_000)}</w:body></w:document>`,
-    );
-    archive.file(
-      "word/_rels/document.xml.rels",
-      '<Relationships><Relationship Id="settings" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/settings" Target="settings.xml"/></Relationships>',
-    );
-    const settings = `<w:settings xmlns:w="${ns}"><w:unused>${"s".repeat(120_000)}</w:unused></w:settings>`;
-    archive.file("word/settings.xml", settings);
-    const bytes = await archive.generateAsync({ type: "arraybuffer" });
-    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
-      type: "module",
-    });
-    try {
-      const result = await new Promise<OfficeWorkerResult>((resolve) => {
-        worker.addEventListener(
-          "message",
-          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
-          { once: true },
-        );
-        worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]);
-      });
-      expect(result.type).toBe("docx");
-      if (result.type !== "docx") throw new Error("Expected a Word prefix");
-      expect(result.truncated).toBe(repetitions > 1);
-      const bounded = await JSZip.loadAsync(result.bytes);
-      const document = await bounded.file("word/document.xml")!.async("string");
-      const retainedSettings = await bounded.file("word/settings.xml")!.async("string");
-      expect(document.match(/<w:p>/g)!.length).toBeGreaterThan(100);
-      expect(document.length).toBeLessThanOrEqual(WORD_LIMITS.bodyBytes);
-      expect(retainedSettings).toBe(settings);
-    } finally {
-      worker.terminate();
-    }
-  },
-);
-
-it.each(["repeated binary", "XML relationship alias", "duplicate relationship ID"])(
-  "bounds Word image expansion for %s",
-  async (scenario) => {
-    const { default: JSZip } = await import("jszip");
-    const archive = new JSZip();
-    archive.file(
-      "[Content_Types].xml",
-      '<Types><Default Extension="png" ContentType="image/png"/></Types>',
-    );
-    archive.file(
-      "word/_rels/document.xml.rels",
-      `<Relationships><Relationship Id="image" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/${scenario === "XML relationship alias" ? "styles" : "image"}" Target="media/payload.png"/>${scenario === "duplicate relationship ID" ? '<Relationship Id="image" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="media/tiny.png"/>' : ""}</Relationships>`,
-    );
-    archive.file(
-      "word/media/payload.png",
-      scenario === "XML relationship alias" ? "<styles/>" : new Uint8Array(8 * 1024 * 1024),
-    );
-    if (scenario === "duplicate relationship ID")
-      archive.file("word/media/tiny.png", new Uint8Array(1));
-    archive.file(
-      "word/document.xml",
-      `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main" xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><w:body><w:p>${'<w:r><a:blip r:embed="image"/></w:r>'.repeat(7)}</w:p></w:body></w:document>`,
-    );
-    const bytes = await archive.generateAsync({ type: "arraybuffer", compression: "DEFLATE" });
-    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
-      type: "module",
-    });
-    try {
-      const result = await new Promise<OfficeWorkerResult>((resolve) => {
-        worker.addEventListener(
-          "message",
-          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
-          { once: true },
-        );
-        worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]);
-      });
-      expect(result).toMatchObject({
-        type: "error",
-        message: expect.stringContaining("expanded markup"),
-      });
-    } finally {
-      worker.terminate();
-    }
-  },
-);
-
-it.each(["XFD200", "XFD300", "XFD1048576", "AX500", "AZ9999999"])(
-  "bounds spreadsheet cells at %s before padding",
-  async (ref) => {
-    const { default: JSZip } = await import("jszip");
-    const archive = new JSZip();
-    archive.file(
-      "xl/workbook.xml",
-      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Sheet" sheetId="1" r:id="rId1"/></sheets></workbook>',
-    );
-    // A nonstandard relationship target must get the same bounds.
-    archive.file(
-      "xl/_rels/workbook.xml.rels",
-      '<Relationships><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="custom.xml"/></Relationships>',
-    );
-    archive.file(
-      "xl/custom.xml",
-      `<worksheet><dimension ref="A1:${ref}"/><sheetData><row r="1"><c r="A1"><v>7</v></c></row><row r="${ref.replace(/\D/g, "")}">${ref === "XFD300" ? `<c r="${ref}" s="1"/>` : `<c r="${ref}"><v>9</v></c>`}</row></sheetData></worksheet>`,
-    );
-    const bytes = await archive.generateAsync({ type: "arraybuffer" });
-    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
-      type: "module",
-    });
-    try {
-      const result = await new Promise<OfficeWorkerResult>((resolve) => {
-        worker.addEventListener(
-          "message",
-          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
-          { once: true },
-        );
-        worker.postMessage({ type: "open", kind: "xlsx", bytes }, [bytes]);
-      });
-      if (ref === "AZ9999999" || ref === "XFD1048576") {
-        expect(result).toMatchObject({
-          type: "error",
-          message: expect.stringContaining(ref === "AZ9999999" ? "invalid" : "preview limit"),
-        });
-      } else {
-        expect(result.type).toBe("xlsx");
-        if (result.type !== "xlsx") throw new Error("Expected workbook values");
-        const bounded = await JSZip.loadAsync(result.bytes);
-        const sheet = new DOMParser().parseFromString(
-          await bounded.file("xl/custom.xml")!.async("string"),
-          "application/xml",
-        );
-        expect(sheet.querySelector('c[r="A1"] v')?.textContent).toBe("7");
-        expect(sheet.querySelectorAll("row").length).toBeLessThanOrEqual(500);
-        expect(result.truncated).toBe(ref === "XFD200" || ref === "XFD300");
-        if (ref === "AX500") expect(sheet.querySelector('c[r="AX500"] v')?.textContent).toBe("9");
-        else expect(sheet.querySelector('c[r="' + ref + '"]')).toBeNull();
-      }
-    } finally {
-      worker.terminate();
-    }
-  },
-);
-
-it.each(['<u val="double"/>', '<u val="double"></u>'])(
-  "shows workbook formats and underline %s",
-  async (underline) => {
-    const { default: JSZip } = await import("jszip");
-    const archive = new JSZip();
-    archive.file(
-      "xl/workbook.xml",
-      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Styles" sheetId="1" r:id="rId1"/></sheets></workbook>',
-    );
-    archive.file(
-      "xl/_rels/workbook.xml.rels",
-      '<Relationships><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/></Relationships>',
-    );
-    archive.file(
-      "xl/styles.xml",
-      `<styleSheet><numFmts count="4"><numFmt numFmtId="164" formatCode="0.000"/><numFmt numFmtId="65535" formatCode="0.0000"/><numFmt numFmtId="007" formatCode="&quot;￥&quot;#,##0.00"/><numFmt numFmtId="82" formatCode="[$-010409]dd-mmm-yyyy"/></numFmts><fonts count="2"><font><sz val="11"/></font><font>${underline}<sz val="11"/></font></fonts><cellXfs count="4"><xf numFmtId="0" fontId="0"/><xf numFmtId="7" fontId="0"/><xf numFmtId="82" fontId="0"/><xf numFmtId="0" fontId="1"/></cellXfs></styleSheet>`,
-    );
-    archive.file(
-      "xl/worksheets/sheet1.xml",
-      '<worksheet><sheetData><row r="1"><c r="A1" s="1"><v>100</v></c><c r="B1" s="2"><v>44986</v></c><c r="C1" s="3" t="inlineStr"><is><t>Total</t></is></c></row></sheetData></worksheet>',
-    );
-    const { prepareOffice } = await import("./officeArchive");
-    const prepared = await prepareOffice(
-      await archive.generateAsync({ type: "arraybuffer" }),
-      "xlsx",
-    );
-    const styles = await (
-      await JSZip.loadAsync(prepared.bytes)
-    )
-      .file("xl/styles.xml")!
-      .async("string");
-    expect(styles).toContain("<font><u/>");
-    const worker = new Worker(new URL("./office/spreadsheet.worker.ts", import.meta.url), {
-      type: "module",
-    });
-    try {
-      const { createWorkerClient } = await import("./office/worker-rpc");
-      const client = createWorkerClient<import("./office/sheet-protocol").SheetMethods>(worker);
-      const bytes = prepared.bytes;
-      await client.call("open", { bytes, view: prepared.view! }, { transfer: [bytes] });
-      const cells = await client.call("cells", {
-        sheet: 0,
-        range: { top: 0, bottom: 0, left: 0, right: 1 },
-      });
-      // Ids under 164 that a workbook defines keep its formats, not Excel's built-in ones.
-      expect(cells[0]).toEqual(["￥100.00", "01-Mar-2023"]);
-    } finally {
-      worker.terminate();
-    }
-    archive.file("xl/styles.xml", "<styleSheet><numFmts/><numFmts/></styleSheet>");
-    await expect(
-      prepareOffice(await archive.generateAsync({ type: "arraybuffer" }), "xlsx"),
-    ).rejects.toThrow("duplicate stylesheet blocks");
-  },
-);
-
-it("keeps spreadsheet dates on their calendar day west of UTC", async () => {
-  const { default: JSZip } = await import("jszip");
-  const archive = new JSZip();
-  archive.file(
-    "xl/workbook.xml",
-    '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Dates" sheetId="1" r:id="rId1"/></sheets></workbook>',
-  );
-  archive.file(
-    "xl/_rels/workbook.xml.rels",
-    '<Relationships><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/></Relationships>',
-  );
-  archive.file(
-    "xl/styles.xml",
-    '<styleSheet><cellXfs><xf numFmtId="0"/><xf numFmtId="14"/></cellXfs></styleSheet>',
-  );
-  archive.file(
-    "xl/worksheets/sheet1.xml",
-    '<worksheet><sheetData><row r="1"><c r="A1" s="1"><v>46023</v></c></row></sheetData></worksheet>',
-  );
-  const bytes = await archive.generateAsync({ type: "arraybuffer" });
-  const workerModule = new URL(
-    "./office/spreadsheet.worker.ts?worker_file&type=module",
-    import.meta.url,
-  ).href;
-  // Give the worker a west-of-UTC default while preserving explicit format options.
-  const bootstrap = URL.createObjectURL(
-    new Blob(
-      [
-        `
-    const NativeURL = URL;
-    globalThis.URL = class extends NativeURL {
-      constructor(input, base) { super(input, base?.startsWith("blob:") ? ${JSON.stringify(location.href)} : base); }
-    };
-    const format = Date.prototype.toLocaleDateString;
-    Date.prototype.toLocaleDateString = function(locale, options) {
-      return format.call(this, "en-US", { timeZone: "America/Los_Angeles", ...options });
-    };
-    await import(${JSON.stringify(workerModule)});
-    postMessage({ type: "ready" });
-  `,
-      ],
-      { type: "text/javascript" },
-    ),
-  );
-  const worker = new Worker(bootstrap, { type: "module" });
-  try {
-    await new Promise<void>((resolve, reject) => {
-      worker.addEventListener(
-        "message",
-        (event) => {
-          if (event.data.type === "ready") resolve();
-        },
-        { once: true },
-      );
-      worker.addEventListener("error", (event) => reject(new Error(event.message)), { once: true });
-    });
-    const { createWorkerClient } = await import("./office/worker-rpc");
-    const client = createWorkerClient<import("./office/sheet-protocol").SheetMethods>(worker);
-    await client.call(
-      "open",
-      {
-        bytes,
-        view: { hiddenGridlines: [], themeFonts: { major: "Calibri Light", minor: "Calibri" } },
-      },
-      { transfer: [bytes] },
-    );
-    const cells = await client.call("cells", {
-      sheet: 0,
-      range: { top: 0, bottom: 0, left: 0, right: 0 },
-    });
-    expect(cells[0]![0]).toMatch(/^1\/1\/(26|2026)$/);
-  } finally {
-    worker.terminate();
-    URL.revokeObjectURL(bootstrap);
-  }
-});
-
-it.each([60, 100])("prepares all %i pages of a table-heavy Word report", async (pages) => {
-  const { default: JSZip } = await import("jszip");
-  const archive = new JSZip();
-  const paragraph = (text: string) =>
-    `<w:p><w:pPr><w:spacing w:after="120"/><w:jc w:val="left"/></w:pPr><w:r><w:rPr><w:rFonts w:ascii="Calibri"/><w:sz w:val="22"/></w:rPr><w:t>${text}</w:t></w:r></w:p>`;
-  archive.file(
-    "word/document.xml",
-    `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body>${Array.from({ length: pages }, (_, page) => paragraph(`page ${page + 1}`) + `<w:tbl>${Array.from({ length: 10 }, () => `<w:tr>${Array.from({ length: 5 }, () => `<w:tc><w:tcPr><w:tcW w:w="1800"/></w:tcPr>${paragraph("report entry")}</w:tc>`).join("")}</w:tr>`).join("")}</w:tbl>`).join("")}</w:body></w:document>`,
-  );
-  archive.file(
-    "_rels/.rels",
-    '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/></Relationships>',
-  );
-  archive.file(
-    "[Content_Types].xml",
-    '<Types><Default Extension="png" ContentType="image/png"/></Types>',
-  );
-  // Binary media must not consume the document's markup budget.
-  archive.file("word/media/image.png", new Uint8Array(2_500_000));
-  const file = await archive.generateAsync({ type: "blob", compression: "DEFLATE" });
-  await using screen = await render(
-    <AttachmentFilePreview
-      name="report.docx"
-      mimeType="application/octet-stream"
-      file={file}
-      sizeBytes={file.size}
-    />,
-  );
-  // The first Office preview in the file loads the lazy viewer chain and the preparation worker.
-  await vi.waitFor(() => expect(screen.container.textContent).toContain("page " + pages), {
-    timeout: 10_000,
-  });
-  expect(screen.container.textContent).not.toContain("Preview limited");
-  expect(screen.container.querySelector('[role="alert"]')).toBeNull();
-});
-
 describe("standalone Mermaid previews", () => {
   it.each([
     'A@{ "img": "//attacker.invalid/pixel.png" }',
diff --git a/apps/web/src/components/files/AttachmentFilePreview.office.browser.test.tsx b/apps/web/src/components/files/AttachmentFilePreview.office.browser.test.tsx
new file mode 100644
index 0000000000000..c628075ed86bb
--- /dev/null
+++ b/apps/web/src/components/files/AttachmentFilePreview.office.browser.test.tsx
@@ -0,0 +1,1086 @@
+import { act, render } from "../../../test/render";
+import { expect, it, vi } from "vite-plus/test";
+import "~/index.css";
+
+const { refresh, assetUrlState } = vi.hoisted(() => ({
+  refresh: vi.fn<() => Promise<string | null>>(),
+  assetUrlState: vi.fn<() => import("~/assets/assetUrls").AssetUrlState>(),
+}));
+
+vi.mock(import("~/assets/assetUrls"), async (original) => ({
+  ...(await original()),
+  useAssetUrlRefresh: () => refresh,
+  useAssetUrlState: assetUrlState,
+}));
+// The real source view highlights through a worker pool; the text it receives is what matters here.
+// Never load the original: its highlighter graph can outlast waitFor on a cold CI browser.
+vi.mock(import("./ReadOnlySourcePreview"), () => ({
+  default: ({ text, wordWrap }: { text: string; wordWrap?: boolean }) => (
+    <pre data-word-wrap={String(wordWrap)}>{text}</pre>
+  ),
+}));
+
+// The Word engine compiles about 30 MB of WebAssembly in a fresh worker per document, which took
+// 10-17 s per test on loaded CI runners. These tests cover fetching, preparation and remounts, so
+// the stand-in shows the prepared body's text instead of laying it out.
+vi.mock(import("./office/WordDocument"), async () => {
+  const { use } = await import("react");
+  const { default: Zip } = await import("jszip");
+  const texts = new WeakMap<ArrayBuffer, Promise<string>>();
+  const read = (bytes: ArrayBuffer) =>
+    Zip.loadAsync(bytes)
+      .then((zip) => zip.file("word/document.xml")!.async("string"))
+      .then((xml) => xml.replace(/<[^>]+>/g, " "));
+  return {
+    default: ({ bytes }: { bytes: ArrayBuffer }) => {
+      let text = texts.get(bytes);
+      if (!text) texts.set(bytes, (text = read(bytes)));
+      return <pre>{use(text)}</pre>;
+    },
+  };
+});
+
+import { AttachmentFilePreview } from "./AttachmentFilePreview";
+import JSZip from "jszip";
+import { OFFICE_PREVIEW_MAX_COLUMNS, type OfficeWorkerResult } from "./officePreviewProtocol";
+import { WORD_LIMITS } from "./officeArchive";
+
+it.each(["<w:body/>", "<w:body></w:body>"])(
+  "opens an empty Word document with %s",
+  async (body) => {
+    const { default: JSZip } = await import("jszip");
+    const { prepareOffice } = await import("./officeArchive");
+    const archive = new JSZip().file(
+      "word/document.xml",
+      `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main">${body}</w:document>`,
+    );
+    const prepared = await prepareOffice(
+      await archive.generateAsync({ type: "arraybuffer" }),
+      "docx",
+    );
+    const result = await JSZip.loadAsync(prepared.bytes);
+    const xml = new DOMParser().parseFromString(
+      await result.file("word/document.xml")!.async("string"),
+      "application/xml",
+    );
+    expect(xml.querySelector("parsererror")).toBeNull();
+    expect(
+      xml.getElementsByTagNameNS(
+        "http://schemas.openxmlformats.org/wordprocessingml/2006/main",
+        "body",
+      ),
+    ).toHaveLength(1);
+  },
+);
+
+it.each([false, true])(
+  "rejects excessive archive entries before JSZip (directories: %s)",
+  async (directories) => {
+    const { default: JSZip } = await import("jszip");
+    const { prepareOffice } = await import("./officeArchive");
+    const archive = new JSZip();
+    for (let i = 0; i < 4096; i++)
+      archive.file(`entry-${i}${directories ? "/" : ".txt"}`, "", { dir: directories });
+    const bytes = await archive.generateAsync({ type: "arraybuffer" });
+    const load = vi.spyOn(JSZip, "loadAsync");
+    try {
+      await expect(prepareOffice(bytes, "docx")).rejects.toThrow("2,048 entries");
+      expect(load).not.toHaveBeenCalled();
+      // The actual central-directory records must also be bounded if EOCD lies.
+      const view = new DataView(bytes);
+      view.setUint16(bytes.byteLength - 22 + 8, 1, true);
+      view.setUint16(bytes.byteLength - 22 + 10, 1, true);
+      await expect(prepareOffice(bytes, "docx")).rejects.toThrow("2,048 entries");
+      expect(load).not.toHaveBeenCalled();
+    } finally {
+      load.mockRestore();
+    }
+  },
+);
+
+it("rejects oversized embedded images before decoding pixels and retains ordinary images", async () => {
+  const { officeImageBitmap } = await import("./office/image-bitmap");
+  const canvas = new OffscreenCanvas(2, 3);
+  canvas.getContext("2d");
+  const blob = await canvas.convertToBlob({ type: "image/png" });
+  const bytes = await blob.arrayBuffer();
+  new DataView(bytes).setUint32(16, 12000);
+  new DataView(bytes).setUint32(20, 12000);
+  const decode = vi.spyOn(globalThis, "createImageBitmap");
+  try {
+    await expect(officeImageBitmap(new Blob([bytes]))).rejects.toThrow("pixel limit");
+    expect(decode).not.toHaveBeenCalled();
+    const bitmap = await officeImageBitmap(blob);
+    expect([bitmap.width, bitmap.height]).toEqual([2, 3]);
+    bitmap.close();
+  } finally {
+    decode.mockRestore();
+  }
+});
+
+it.each(["utf-16le", "utf-16be", "windows-1252"])(
+  "preserves %s Office XML and safe hyperlink targets",
+  async (encoding) => {
+    const { default: JSZip } = await import("jszip");
+    const { prepareOffice } = await import("./officeArchive");
+    const archive = new JSZip();
+    const encode = (text: string) => {
+      const xml = `<?xml version="1.0" encoding="${encoding}"?>${text}`;
+      if (encoding === "windows-1252") return Uint8Array.from(xml, (char) => char.charCodeAt(0));
+      const bytes = new Uint8Array(2 + xml.length * 2);
+      const view = new DataView(bytes.buffer);
+      const little = encoding === "utf-16le";
+      view.setUint16(0, 0xfeff, little);
+      for (let i = 0; i < xml.length; i++) view.setUint16(2 + i * 2, xml.charCodeAt(i), little);
+      return bytes;
+    };
+    archive.file(
+      "word/document.xml",
+      encode(
+        '<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body><w:p><w:r><w:t>café</w:t></w:r></w:p></w:body></w:document>',
+      ),
+    );
+    archive.file(
+      "word/_rels/document.xml.rels",
+      encode(
+        `<Relationships>${["https://example.com/page", "http://example.com", "mailto:maria@example.com", "javascript:alert(1)", "file:///tmp/private"].map((target, i) => `<Relationship Id="r${i}" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/hyperlink" TargetMode="External" Target="${target}"/>`).join("")}</Relationships>`,
+      ),
+    );
+    const prepared = await prepareOffice(
+      await archive.generateAsync({ type: "arraybuffer" }),
+      "docx",
+    );
+    const result = await JSZip.loadAsync(prepared.bytes);
+    expect(await result.file("word/document.xml")!.async("string")).toContain("café");
+    const links = await result.file("word/_rels/document.xml.rels")!.async("string");
+    expect(links).toContain('encoding="UTF-8"');
+    expect(links).toContain("https://example.com/page");
+    expect(links).toContain("http://example.com");
+    expect(links).toContain("mailto:maria@example.com");
+    expect(links).not.toContain("javascript:");
+    expect(links).not.toContain("file:");
+  },
+);
+
+it.each([
+  ["", "worksheets/./sheet1.xml", false, false],
+  ["x:", "../xl/worksheets/sheet1.xml", false, false],
+  ["", "/xl/worksheets/sheet1.xml", true, false],
+  ["", "worksheets/sheet1.xml", false, true],
+  ["", "worksheets/sheet1.xml", true, true],
+])(
+  "preserves %sworksheet metadata with relationship target %s",
+  async (prefix, target, empty, localPrefix) => {
+    const { default: JSZip } = await import("jszip");
+    const archive = new JSZip();
+    const ns = "http://schemas.openxmlformats.org/spreadsheetml/2006/main";
+    archive.file(
+      "xl/workbook.xml",
+      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Chart" sheetId="2" r:id="c"/><sheet name="Sheet" sheetId="1" r:id="s"/></sheets></workbook>',
+    );
+    archive.file(
+      "xl/_rels/workbook.xml.rels",
+      `<Relationships><Relationship Id="s" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="${target}"/><Relationship Id="c" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/chartsheet" Target="chartsheets/sheet1.xml"/></Relationships>`,
+    );
+    archive.file(
+      "xl/worksheets/sheet1.xml",
+      `<${prefix}worksheet xmlns${prefix ? ":x" : ""}="${ns}"><${prefix}dimension ref="XFD1048576"/><${prefix}sheetViews><${prefix}sheetView showGridLines="0"/></${prefix}sheetViews><${prefix}sheetFormatPr defaultColWidth="30"/><${prefix}cols><${prefix}col min="${OFFICE_PREVIEW_MAX_COLUMNS - 1}" max="${OFFICE_PREVIEW_MAX_COLUMNS + 10}" width="20"/><${prefix}col min="${OFFICE_PREVIEW_MAX_COLUMNS + 1}" max="${OFFICE_PREVIEW_MAX_COLUMNS + 30}" hidden="1"/></${prefix}cols><${prefix}sheetData><${prefix}row ht="42" customHeight="1" hidden="1"><${prefix}c r="A50" t="inlineStr"><${prefix}is><${prefix}t>${"value".repeat(1000)}</${prefix}t></${prefix}is></${prefix}c></${prefix}row></${prefix}sheetData><${prefix}mergeCells><${prefix}mergeCell ref="XFD1048576"/></${prefix}mergeCells></${prefix}worksheet>`
+        .replace(
+          /<((?:x:)?(?:col|dimension|mergeCell))\b([^>]*)\/>/g,
+          prefix ? "<$1$2></$1>" : "$&",
+        )
+        .replace(/<sheetData>[\s\S]*?<\/sheetData>/, (data) => (empty ? "<sheetData/>" : data))
+        .replace(/<(\/?)sheetData\b/g, (tag, closing: string) =>
+          localPrefix ? `<${closing}x:sheetData${closing ? "" : ` xmlns:x="${ns}"`}` : tag,
+        )
+        .replace(/="([^"]*)"/g, (attribute, value: string) =>
+          prefix || empty
+            ? ` = '${value.replace(/\d/g, (digit) => `&#${digit.charCodeAt(0)};`)}'`
+            : attribute,
+        ),
+    );
+    const bytes = await archive.generateAsync({ type: "arraybuffer" });
+    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
+      type: "module",
+    });
+    try {
+      const result = await new Promise<OfficeWorkerResult>((resolve) => {
+        worker.addEventListener(
+          "message",
+          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
+          { once: true },
+        );
+        worker.postMessage({ type: "open", kind: "xlsx", bytes }, [bytes]);
+      });
+      expect(result.type).toBe("xlsx");
+      if (result.type !== "xlsx") throw new Error("Expected bounded workbook");
+      // The engine counts the chart sheet before it.
+      expect(result.view?.hiddenGridlines).toEqual([1]);
+      const bounded = await JSZip.loadAsync(result.bytes);
+      const sheet = new DOMParser().parseFromString(
+        await bounded.file("xl/worksheets/sheet1.xml")!.async("string"),
+        "application/xml",
+      );
+      expect(sheet.querySelector("parsererror")).toBeNull();
+      const row = sheet.getElementsByTagNameNS(ns, "row")[0];
+      if (empty) expect(row).toBeUndefined();
+      else {
+        expect(row!.getAttribute("ht")).toBe("42");
+        expect(row!.getAttribute("hidden")).toBe("1");
+        expect(row!.getElementsByTagNameNS(ns, "c")[0]!.getAttribute("r")).toBe("A50");
+        expect(row!.getElementsByTagNameNS(ns, "t")[0]!.textContent).toHaveLength(4096);
+      }
+      expect(sheet.getElementsByTagNameNS(ns, "dimension")).toHaveLength(0);
+      expect(sheet.getElementsByTagNameNS(ns, "mergeCell")).toHaveLength(0);
+      const columns = [...sheet.getElementsByTagNameNS(ns, "col")].map((column) =>
+        ["min", "max", "width"].map((name) => column.getAttribute(name)),
+      );
+      // The engine ignores `defaultColWidth`, so the columns it sizes are spelled out.
+      expect(columns).toEqual([
+        [String(OFFICE_PREVIEW_MAX_COLUMNS - 1), String(OFFICE_PREVIEW_MAX_COLUMNS), "20"],
+        // Hidden columns keep their span past the limit, so they stay hidden.
+        [String(OFFICE_PREVIEW_MAX_COLUMNS + 1), String(OFFICE_PREVIEW_MAX_COLUMNS + 30), null],
+        ["1", String(OFFICE_PREVIEW_MAX_COLUMNS - 2), "30"],
+      ]);
+    } finally {
+      worker.terminate();
+    }
+  },
+);
+
+it("reports the final slide at maximum scroll after page visibility changes", async () => {
+  const { OfficePages } = await import("./office/OfficePages");
+  const changed = vi.fn();
+  const container = document.createElement("div");
+  container.style.cssText = "display:flex;flex-direction:column;width:400px;height:400px";
+  await using screen = await render(
+    <OfficePages
+      pages={Array.from({ length: 6 }, () => ({ width: 400, height: 240 }))}
+      label="Slide"
+      paint={async () => undefined}
+      onPageChange={changed}
+      onError={(error) => {
+        throw error;
+      }}
+    />,
+    { container },
+  );
+  const scroller = screen.container.querySelector<HTMLElement>("[data-office-pages]")!;
+  await vi.waitFor(() => expect(scroller.scrollHeight).toBeGreaterThan(scroller.clientHeight));
+  await act(() => {
+    scroller.scrollTop = scroller.scrollHeight;
+  });
+  await vi.waitFor(() => expect(changed).toHaveBeenLastCalledWith(5));
+  await act(() => {
+    scroller.scrollTop = 10;
+  });
+  await vi.waitFor(() => expect(changed).toHaveBeenLastCalledWith(0));
+});
+
+it("preserves merged text across tile clears", async () => {
+  const { paintFrame } = await import("./office/sheet-frame");
+  const canvas = new OffscreenCanvas(400, 80);
+  const context = canvas.getContext("2d")!;
+  paintFrame(
+    context,
+    {
+      viewport: { x: 0, y: 0, width: 400, height: 80 },
+      list: { width: 400, height: 80, commands: [] },
+      tiles: [
+        {
+          x: 0,
+          y: 0,
+          clipX: 0,
+          clipY: 0,
+          list: {
+            width: 208,
+            height: 80,
+            commands: [
+              {
+                op: "text",
+                x: 2,
+                y: 40,
+                text: "MMMMMMMMMMMMMMMMMMMMMMMM",
+                fontSize: 20,
+                color: "#000",
+                clip: { x: 0, y: 0, w: 400, h: 80 },
+              },
+            ],
+          },
+        },
+        { x: 192, y: 0, clipX: 200, clipY: 0, list: { width: 208, height: 80, commands: [] } },
+      ],
+    },
+    { ratio: 1, origin: { x: 0, y: 0 } },
+  );
+  const pixels = context.getImageData(240, 15, 100, 35).data;
+  expect(pixels.some((value, index) => index % 4 === 3 && value > 0)).toBe(true);
+});
+
+it.each([
+  "paragraphs",
+  "runs",
+  "tables",
+  "auxiliary XML",
+  "XML bytes",
+  "renamed XML",
+  "section after prefix",
+  "oversized section",
+])("bounds excessive Word %s before rendering DOM", async (scenario) => {
+  const { default: JSZip } = await import("jszip");
+  const archive = new JSZip();
+  const body = ["paragraphs", "section after prefix", "oversized section"].includes(scenario)
+    ? "<w:p><w:r><w:t>x</w:t></w:r></w:p>".repeat(200_000)
+    : scenario === "runs"
+      ? `<w:p>${"<w:r><w:t>x</w:t></w:r>".repeat(50_001)}</w:p>`
+      : scenario === "tables"
+        ? "<w:tbl/>".repeat(2 * WORD_LIMITS.bodyElements)
+        : scenario === "XML bytes"
+          ? `<w:p><w:r><w:t>${"x".repeat(2 * 1024 * 1024)}</w:t></w:r></w:p>`
+          : "<w:p/>";
+  const section =
+    '<w:sectPr><w:pgSz w:w="16838" w:h="11906" w:orient="landscape"/><w:pgMar w:top="1440" w:left="1440" w:bottom="1440" w:right="1440"/></w:sectPr>';
+  archive.file(
+    "word/document.xml",
+    `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body>${body}${scenario === "section after prefix" ? '<w:p xmlns:s="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:pPr><s:sectPr><s:pgSz s:w="11906" s:h="16838"/></s:sectPr></w:pPr></w:p>' : ""}${scenario === "oversized section" ? `<w:sectPr>${"<w:cols/>".repeat(2_001)}</w:sectPr>` : section}</w:body></w:document>`,
+  );
+  if (scenario === "auxiliary XML" || scenario === "renamed XML")
+    archive.file(
+      scenario === "renamed XML" ? "word/footnotes.dat" : "word/footnotes.xml",
+      `<w:footnotes>${"<w:p/>".repeat(WORD_LIMITS.auxiliaryMarkup + 1)}</w:footnotes>`,
+    );
+  const file = await archive.generateAsync({ type: "blob", compression: "DEFLATE" });
+  const src = URL.createObjectURL(file);
+  try {
+    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
+      type: "module",
+    });
+    try {
+      const result = await new Promise<OfficeWorkerResult>((resolve) => {
+        worker.addEventListener(
+          "message",
+          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
+          { once: true },
+        );
+        void file
+          .arrayBuffer()
+          .then((bytes) => worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]));
+      });
+      if (
+        scenario === "auxiliary XML" ||
+        scenario === "renamed XML" ||
+        scenario === "oversized section"
+      ) {
+        expect(result).toMatchObject({
+          type: "error",
+          message: expect.stringContaining("Preview limited"),
+        });
+      } else {
+        expect(result.type).toBe("docx");
+        if (result.type !== "docx") throw new Error("Expected a Word prefix");
+        expect(result.truncated).toBe(true);
+        const bounded = await JSZip.loadAsync(result.bytes);
+        const markup = await bounded.file("word/document.xml")!.async("string");
+        {
+          const xml = markup;
+          const document = new DOMParser().parseFromString(xml, "application/xml");
+          expect(document.querySelector("parsererror")).toBeNull();
+          const bodies = document.getElementsByTagNameNS("*", "body");
+          expect(bodies).toHaveLength(1);
+          const section = bodies[0]!.lastElementChild!;
+          expect(section.localName).toBe("sectPr");
+          const size = section.getElementsByTagNameNS("*", "pgSz")[0]!;
+          expect(size.getAttributeNS(section.namespaceURI, "w")).toBe(
+            scenario === "section after prefix" ? "11906" : "16838",
+          );
+          expect(size.getAttributeNS(section.namespaceURI, "orient")).toBe(
+            scenario === "section after prefix" ? null : "landscape",
+          );
+        }
+        expect(markup.length).toBeLessThan(body.length);
+        expect(markup.length).toBeLessThanOrEqual(WORD_LIMITS.bodyBytes);
+        expect(markup.match(/<(?![!?/])/g)!.length).toBeLessThanOrEqual(WORD_LIMITS.bodyTags);
+      }
+    } finally {
+      worker.terminate();
+    }
+  } finally {
+    URL.revokeObjectURL(src);
+  }
+});
+
+it.each([
+  "relationship markup",
+  "relationship bytes",
+  "content type",
+  "metadata type",
+  "deep XML",
+  "query path",
+])("bounds XML hidden in media by %s", async (scenario) => {
+  const { default: JSZip } = await import("jszip");
+  const archive = new JSZip();
+  const path = `word/media/payload.png${scenario === "query path" ? "?xml" : ""}`;
+  archive.file(
+    "word/document.xml",
+    '<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body><w:p/></w:body></w:document>',
+  );
+  archive.file(
+    "[Content_Types].xml",
+    `<Types><Override PartName="/${path}" ContentType="${scenario === "content type" ? "application/vnd.openxmlformats-officedocument.wordprocessingml.styles+xml" : "image/png"}"/>${scenario === "metadata type" ? '<Default Extension="rels" ContentType="image/png"/>' : ""}</Types>`,
+  );
+  archive.file(
+    "word/_rels/document.xml.rels",
+    `<Relationships>${scenario === "content type" ? "" : `<Relationship Id="style" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/styles" Target="${path.slice(5)}"/>`}${scenario === "metadata type" ? "<unused/>".repeat(WORD_LIMITS.auxiliaryMarkup + 1) : ""}</Relationships>`,
+  );
+  archive.file(
+    path,
+    scenario === "relationship bytes"
+      ? `<styles>${"x".repeat(WORD_LIMITS.auxiliaryPartBytes)}</styles>`
+      : scenario === "deep XML"
+        ? `${"<styles>".repeat(65)}${"</styles>".repeat(65)}`
+        : `<styles>${"<style/>".repeat(WORD_LIMITS.auxiliaryMarkup + 1)}</styles>`,
+  );
+  const bytes = await archive.generateAsync({ type: "arraybuffer", compression: "DEFLATE" });
+  const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
+    type: "module",
+  });
+  try {
+    const result = await new Promise<OfficeWorkerResult>((resolve) => {
+      worker.addEventListener(
+        "message",
+        (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
+        { once: true },
+      );
+      worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]);
+    });
+    expect(result).toMatchObject({
+      type: "error",
+      message: expect.stringContaining("Preview limited"),
+    });
+  } finally {
+    worker.terminate();
+  }
+});
+
+const EXPANDED_WORD_ROLES = [
+  "footnotes",
+  "note roots",
+  "endnotes",
+  "header",
+  "footer",
+  "comments",
+  "styles",
+  "style chain",
+  "style count",
+  "style visits",
+  "numbering",
+  "picture numbering",
+] as const;
+
+async function expandedWordFixture(role: (typeof EXPANDED_WORD_ROLES)[number]) {
+  const archive = new JSZip();
+  const ns = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
+  const type = role.startsWith("style")
+    ? "styles"
+    : role === "picture numbering"
+      ? "numbering"
+      : role === "note roots"
+        ? "footnotes"
+        : role;
+  archive.file(
+    "_rels/.rels",
+    '<Relationships><Relationship Id="doc" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/></Relationships>',
+  );
+  const text = (value: string) => `<w:p><w:r><w:t>${value}</w:t></w:r></w:p>`;
+  // Each copy of the 2,000-paragraph payload costs 6,000 markup units, so enough
+  // references (or pages) exceed the expansion budget.
+  const copies = Math.ceil(WORD_LIMITS.expandedMarkup / 6_000) + 1;
+  archive.file(
+    "word/document.xml",
+    `<w:document xmlns:w="${ns}" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><w:body>${text("body retained")}${Array.from({ length: copies }, () => `<w:p><w:r><w:footnoteReference w:id="1"/><w:endnoteReference w:id="1"/><w:commentReference w:id="1"/><w:br w:type="page"/></w:r></w:p>`).join("")}<w:sectPr><w:headerReference w:type="default" r:id="aux"/><w:footerReference w:type="default" r:id="aux"/></w:sectPr></w:body></w:document>`,
+  );
+  archive.file(
+    "word/_rels/document.xml.rels",
+    `<Relationships><Relationship Id="aux" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/${type}" Target="media/aux.xml"/></Relationships>`,
+  );
+  const xml =
+    role === "style chain" || role === "style count" || role === "style visits"
+      ? `<w:styles xmlns:w="${ns}">${Array.from({ length: role === "style count" ? WORD_LIMITS.styles + 1 : role === "style visits" ? Math.ceil(WORD_LIMITS.styleVisits / 30) + 1 : 1_000 }, (_, i) => `<w:style w:styleId="s${i}" w:type="paragraph">${i ? `<w:basedOn w:val="s${role === "style visits" && i >= 30 ? 29 : i - 1}"/>` : ""}<w:pPr><w:spacing w:after="120"/></w:pPr></w:style>`).join("")}</w:styles>`
+      : role === "styles"
+        ? `<w:styles xmlns:w="${ns}">${Array.from({ length: 100 }, (_, i) => `<w:style w:styleId="${"s".repeat(2_000)}${i}" w:type="paragraph"><w:basedOn w:val="s0"/><w:pPr><w:spacing w:after="120"/></w:pPr></w:style>`).join("")}</w:styles>`
+        : role.includes("numbering")
+          ? `<w:numbering xmlns:w="${ns}">${role === "picture numbering" ? '<w:numPicBullet w:numPicBulletId="1"/>' : ""}<w:abstractNum w:abstractNumId="1">${Array.from({ length: 9 }, (_, i) => `<w:lvl w:ilvl="${i}"><w:lvlText w:val="%1."/></w:lvl>`).join("")}</w:abstractNum>${Array.from({ length: WORD_LIMITS.numberingReferences + 1 }, (_, i) => `<w:num w:numId="${i}"><w:abstractNumId w:val="1"/></w:num>`).join("")}</w:numbering>`
+          : role === "header" || role === "footer"
+            ? `<w:${role === "header" ? "hdr" : "ftr"} xmlns:w="${ns}">${text("omitted payload").repeat(2_000)}</w:${role === "header" ? "hdr" : "ftr"}>`
+            : `<w:${role} xmlns:w="${ns}"><w:${role.slice(0, -1)} w:id="1">${text("omitted payload").repeat(2_000)}</w:${role.slice(0, -1)}></w:${role}>`;
+  archive.file("word/media/aux.xml", xml);
+  if (role === "note roots") {
+    // Each note's XML repeats the 32 KB root, which the expansion budget charges twice.
+    const notes = Math.ceil(WORD_LIMITS.expandedBytes / 64_000) + 1;
+    archive.file(
+      "word/document.xml",
+      `<w:document xmlns:w="${ns}"><w:body>${text("body retained")}${Array.from({ length: notes }, (_, id) => `<w:p><w:r><w:footnoteReference w:id="${id}"/></w:r></w:p>`).join("")}</w:body></w:document>`,
+    );
+    archive.file(
+      "word/media/aux.xml",
+      `<w:footnotes xmlns:w="${ns}" padding="${"x".repeat(32_000)}">${Array.from({ length: notes }, (_, id) => `<w:footnote w:id="${id}">${text("omitted payload")}</w:footnote>`).join("")}</w:footnotes>`,
+    );
+  }
+  return archive.generateAsync({ type: "blob", compression: "DEFLATE" });
+}
+
+// Rendering starts a Word engine worker per case, which compiles about 30 MB of WebAssembly and
+// took 10-17 s per test on loaded CI runners. Omission and retention are prepareOffice decisions,
+// so they are checked there.
+it.each(EXPANDED_WORD_ROLES)(
+  "keeps the body and omits expanded %s from the prepared document",
+  async (role) => {
+    const file = await expandedWordFixture(role);
+    const { SaxesParser } = await import("saxes");
+    const { prepareOffice } = await import("./officeArchive");
+    const parse = vi.spyOn(SaxesParser.prototype, "write");
+    try {
+      const prepared = await prepareOffice(await file.arrayBuffer(), "docx");
+      expect(prepared.truncated).toBe(true);
+      if (role === "note roots")
+        expect(
+          parse.mock.calls.reduce(
+            (sum, [chunk]) => sum + (typeof chunk === "string" ? chunk.length : 0),
+            0,
+          ),
+        ).toBeLessThan(WORD_LIMITS.expandedBytes + 4 * 1024 * 1024);
+      const bounded = await JSZip.loadAsync(prepared.bytes);
+      const markup = await bounded.file("word/document.xml")!.async("string");
+      expect(markup).toContain("body retained");
+      expect(bounded.file("word/media/aux.xml")).toBeNull();
+      // A dangling header or footer reference makes the engine reject the whole body.
+      expect(markup).not.toMatch(/<w:(header|footer)Reference/);
+      for (const entry of Object.values(bounded.files))
+        if (!entry.dir) expect(await entry.async("string")).not.toContain("omitted payload");
+    } finally {
+      parse.mockRestore();
+    }
+  },
+);
+
+it.each([
+  "ordinary parts",
+  "unused parts",
+  "independent styles",
+  "inherited styles",
+  "python-docx package",
+  "default template styles",
+  "binary package properties",
+])("retains Word %s without a limit warning", async (scenario) => {
+  const { default: JSZip } = await import("jszip");
+  const archive = new JSZip();
+  const ns = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
+  const r = "http://schemas.openxmlformats.org/officeDocument/2006/relationships";
+  const text = (value: string) => `<w:p><w:r><w:t>${value}</w:t></w:r></w:p>`;
+  archive.file(
+    "_rels/.rels",
+    `<Relationships><Relationship Id="doc" Type="${r}/officeDocument" Target="word/document.xml"/></Relationships>`,
+  );
+  if (scenario === "python-docx package" || scenario === "binary package properties") {
+    const packageRelationships = "http://schemas.openxmlformats.org/package/2006/relationships";
+    archive.file(
+      "_rels/.rels",
+      `<Relationships xmlns="${packageRelationships}"><Relationship Id="doc" Type="${r}/officeDocument" Target="word/document.xml"/><Relationship Id="thumbnail" Type="${packageRelationships}/metadata/thumbnail" Target="docProps/thumbnail.jpeg"/><Relationship Id="core" Type="${packageRelationships}/metadata/core-properties" Target="docProps/core.xml"/><Relationship Id="app" Type="${r}/extended-properties" Target="docProps/app.xml"/><Relationship Id="custom" Type="${r}/custom-properties" Target="docProps/custom.xml"/><Relationship Id="signature" Type="${packageRelationships}/digital-signature/origin" Target="_xmlsignatures/origin.sigs"/></Relationships>`,
+    );
+    archive.file(
+      "[Content_Types].xml",
+      '<Types xmlns="http://schemas.openxmlformats.org/package/2006/content-types"><Default Extension="jpeg" ContentType="image/jpeg"/><Default Extension="xml" ContentType="application/xml"/><Default Extension="sigs" ContentType="application/vnd.openxmlformats-package.digital-signature-origin"/></Types>',
+    );
+    archive.file(
+      "docProps/thumbnail.jpeg",
+      new Uint8Array([255, 216, 255, 224, 0, 16, 74, 70, 73, 70]),
+    );
+    archive.file("_xmlsignatures/origin.sigs", new Uint8Array());
+    for (const part of ["core", "app", "custom"])
+      archive.file(`docProps/${part}.xml`, '<properties xmlns="urn:properties"/>');
+    if (scenario === "binary package properties") {
+      const roles = [
+        `${packageRelationships}/metadata/core-properties`,
+        `${r}/extended-properties`,
+        `${packageRelationships}/metadata/custom-properties`,
+        `${packageRelationships}/digital-signature/signature`,
+      ];
+      archive.file(
+        "_rels/.rels",
+        `<Relationships><Relationship Id="doc" Type="${r}/officeDocument" Target="word/document.xml"/>${roles.map((role, i) => `<Relationship Id="metadata${i}" Type="${role}" Target="docProps/metadata${i}.dat"/>`).join("")}</Relationships>`,
+      );
+      for (const i of roles.keys())
+        archive.file(`docProps/metadata${i}.dat`, new Uint8Array([255, 216, 255, 0]));
+    }
+  }
+  const ordinary = scenario === "ordinary parts";
+  archive.file(
+    "word/document.xml",
+    `<w:document xmlns:w="${ns}" xmlns:r="${r}"><w:body>${text("ordinary body")}<w:p><w:pPr><w:pStyle w:val="s19"/></w:pPr><w:r><w:t>styled body</w:t>${ordinary ? '<w:footnoteReference w:id="1"/><w:footnoteReference w:id="1"/><w:endnoteReference w:id="1"/><w:commentReference w:id="1"/>' : ""}</w:r></w:p><w:sectPr>${ordinary ? '<w:headerReference w:type="default" r:id="header"/><w:footerReference w:type="default" r:id="footer"/>' : ""}</w:sectPr></w:body></w:document>`,
+  );
+  archive.file(
+    "word/_rels/document.xml.rels",
+    `<Relationships>${["header", "footer", "footnotes", "endnotes", "comments", "fontTable", "styles"].map((role) => `<Relationship Id="${role}" Type="${r}/${role}" Target="${role}.xml"/>`).join("")}</Relationships>`,
+  );
+  for (const [role, root] of [
+    ["header", "hdr"],
+    ["footer", "ftr"],
+  ])
+    archive.file(
+      `word/${role}.xml`,
+      `<w:${root} xmlns:w="${ns}">${text(`${role} retained`)}</w:${root}>`,
+    );
+  for (const role of ["footnotes", "endnotes", "comments"])
+    archive.file(
+      `word/${role}.xml`,
+      `<w:${role} xmlns:w="${ns}"><w:${role.slice(0, -1)} w:id="1" w:author="reviewer" w:date="2026-10-01T00:00:00Z">${text(`${role} retained`)}</w:${role.slice(0, -1)}></w:${role}>`,
+    );
+  archive.file(
+    "word/fontTable.xml",
+    `<w:fonts xmlns:w="${ns}"><w:font w:name="unused"/></w:fonts>`,
+  );
+  archive.file(
+    "word/styles.xml",
+    `<w:styles xmlns:w="${ns}"><w:docDefaults/><w:style w:type="paragraph" w:styleId="base"><w:rPr><w:b/></w:rPr></w:style>${Array.from({ length: 20 }, (_, i) => `<w:style w:styleId="s${i}" w:type="paragraph">${scenario === "inherited styles" ? '<w:basedOn w:val="base"/>' : ""}<w:rPr><w:color w:val="123456"/></w:rPr></w:style>`).join("")}</w:styles>`,
+  );
+  if (scenario === "default template styles") {
+    const heading =
+      '<w:style w:type="paragraph" w:styleId="s19"><w:basedOn w:val="Normal"/><w:link w:val="HeadingChar"/><w:pPr><w:spacing w:after="120"/></w:pPr><w:rPr><w:b/><w:sz w:val="32"/><w:color w:val="123456"/></w:rPr></w:style>';
+    const conditions = [
+      "wholeTable",
+      "firstRow",
+      "lastRow",
+      "firstCol",
+      "lastCol",
+      "band1Horz",
+      "band2Horz",
+      "band1Vert",
+      "band2Vert",
+    ];
+    archive.file(
+      "word/styles.xml",
+      `<w:styles xmlns:w="${ns}"><w:docDefaults><w:rPrDefault><w:rPr><w:sz w:val="22"/></w:rPr></w:rPrDefault></w:docDefaults><w:latentStyles>${Array.from({ length: 276 }, (_, i) => `<w:lsdException w:name="latent ${i}" w:semiHidden="0" w:uiPriority="99"/>`).join("")}</w:latentStyles><w:style w:type="paragraph" w:styleId="Normal"/><w:style w:type="character" w:styleId="HeadingChar"><w:rPr><w:b/></w:rPr></w:style>${heading}${Array.from({ length: 61 }, (_, i) => `<w:style w:type="paragraph" w:styleId="p${i}"><w:basedOn w:val="Normal"/><w:pPr><w:spacing w:after="120"/></w:pPr><w:rPr><w:color w:val="123456"/></w:rPr></w:style>`).join("")}${Array.from({ length: 100 }, (_, i) => `<w:style w:type="table" w:styleId="Table${i}">${i ? '<w:basedOn w:val="Table0"/>' : ""}<w:tblPr><w:tblCellMar><w:top w:w="0"/><w:left w:w="108"/><w:bottom w:w="0"/><w:right w:w="108"/></w:tblCellMar></w:tblPr>${conditions.map((type) => `<w:tblStylePr w:type="${type}"><w:pPr><w:spacing w:after="0"/></w:pPr><w:rPr><w:b/><w:color w:val="123456"/></w:rPr><w:tcPr><w:shd w:fill="D9E2F3"/></w:tcPr></w:tblStylePr>`).join("")}</w:style>`).join("")}</w:styles>`,
+    );
+    archive.file(
+      "word/_rels/document.xml.rels",
+      (await archive.file("word/_rels/document.xml.rels")!.async("string")).replace(
+        "</Relationships>",
+        `<Relationship Id="numbering" Type="${r}/numbering" Target="numbering.xml"/></Relationships>`,
+      ),
+    );
+    archive.file(
+      "word/numbering.xml",
+      `<w:numbering xmlns:w="${ns}">${Array.from({ length: 9 }, (_, i) => `<w:abstractNum w:abstractNumId="${i}"><w:multiLevelType w:val="singleLevel"/><w:lvl w:ilvl="0"><w:start w:val="1"/><w:numFmt w:val="decimal"/><w:lvlText w:val="%1."/><w:lvlJc w:val="left"/><w:pPr><w:tabs><w:tab w:val="num" w:pos="720"/></w:tabs><w:ind w:left="720" w:hanging="360"/></w:pPr></w:lvl></w:abstractNum><w:num w:numId="${i + 1}"><w:abstractNumId w:val="${i}"/></w:num>`).join("")}</w:numbering>`,
+    );
+    const document = await archive.file("word/document.xml")!.async("string");
+    archive.file(
+      "word/document.xml",
+      document.replace(
+        "<w:sectPr>",
+        '<w:tbl><w:tblPr><w:tblStyle w:val="Table99"/></w:tblPr><w:tblGrid><w:gridCol w:w="2000"/></w:tblGrid><w:tr><w:tc><w:p><w:r><w:t>styled cell</w:t></w:r></w:p></w:tc></w:tr></w:tbl><w:sectPr>',
+      ),
+    );
+  }
+  const { prepareOffice } = await import("./officeArchive");
+  const prepared = await prepareOffice(
+    await archive.generateAsync({ type: "arraybuffer", compression: "DEFLATE" }),
+    "docx",
+  );
+  expect(prepared.truncated).toBe(false);
+  const bounded = await JSZip.loadAsync(prepared.bytes);
+  const markup = await bounded.file("word/document.xml")!.async("string");
+  expect(markup).toContain("ordinary body");
+  expect(markup).toContain("styled body");
+  expect(bounded.file("word/styles.xml")).not.toBeNull();
+  if (scenario === "default template styles") {
+    expect(markup).toContain("styled cell");
+    expect(await bounded.file("word/styles.xml")!.async("string")).toContain('w:styleId="Table99"');
+  }
+  if (ordinary) {
+    expect(markup).toMatch(/<w:headerReference/);
+    expect(markup).toMatch(/<w:footerReference/);
+    for (const role of ["header", "footer", "footnotes", "endnotes", "comments"])
+      expect(await bounded.file(`word/${role}.xml`)!.async("string")).toContain(`${role} retained`);
+  }
+});
+
+it.each([false, true])(
+  "bounds shared-string text including CDATA %s per cell and across sheets in the worker",
+  async (cdata) => {
+    const { default: JSZip } = await import("jszip");
+    const archive = new JSZip();
+    archive.file(
+      "xl/workbook.xml",
+      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="one" sheetId="1" r:id="s"/><sheet name="two" sheetId="2" r:id="s"/></sheets></workbook>',
+    );
+    archive.file(
+      "xl/_rels/workbook.xml.rels",
+      '<Relationships><Relationship Id="s" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/></Relationships>',
+    );
+    const sharedPath = cdata ? "customStrings.xml" : "sharedStrings.xml";
+    archive.file(
+      "xl/_rels/workbook.xml.rels",
+      (await archive.file("xl/_rels/workbook.xml.rels")!.async("string")).replace(
+        "</Relationships>",
+        `<Relationship Id="strings" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/sharedStrings" Target="${sharedPath}"/></Relationships>`,
+      ),
+    );
+    const content = "x".repeat(32_767);
+    archive.file(
+      `xl/${sharedPath}`,
+      `<sst><si><t>${cdata ? `<![CDATA[${content}]]>` : content}</t></si></sst>`,
+    );
+    archive.file(
+      "xl/worksheets/sheet1.xml",
+      `<worksheet><sheetData>${Array.from({ length: 500 }, (_, i) => `<row r="${i + 1}">${Array.from({ length: 50 }, (_, j) => `<c r="${j < 26 ? String.fromCharCode(65 + j) : "A" + String.fromCharCode(65 + j - 26)}${i + 1}" t="s"><v>${cdata ? "<![CDATA[0]]>" : "0"}</v></c>`).join("")}</row>`).join("")}</sheetData></worksheet>`.replace(
+        '<c r="A1" t="s"><v><![CDATA[0]]></v></c>',
+        `<c r="A1" t="inlineStr"><is><t><![CDATA[${content}]]></t></is></c>`,
+      ),
+    );
+    const file = await archive.generateAsync({ type: "blob", compression: "DEFLATE" });
+    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
+      type: "module",
+    });
+    try {
+      const result = await new Promise<OfficeWorkerResult>((resolve) => {
+        worker.addEventListener(
+          "message",
+          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
+          { once: true },
+        );
+        void file
+          .arrayBuffer()
+          .then((bytes) => worker.postMessage({ type: "open", kind: "xlsx", bytes }, [bytes]));
+      });
+      expect(result.type).toBe("xlsx");
+      if (result.type !== "xlsx") throw new Error("Expected bounded workbook");
+      const bounded = await JSZip.loadAsync(result.bytes);
+      const sheet = new DOMParser().parseFromString(
+        await bounded.file("xl/worksheets/sheet1.xml")!.async("string"),
+        "application/xml",
+      );
+      const cells = [...sheet.getElementsByTagName("t")].map((cell) => cell.textContent ?? "");
+      expect(cells.reduce((total, cell) => total + cell.length, 0)).toBe(1024 * 1024);
+      expect(Math.max(...cells.map((cell) => cell.length))).toBe(4096);
+      expect(result.truncated).toBe(true);
+    } finally {
+      worker.terminate();
+    }
+  },
+);
+
+// A body just over the read limit once each paragraph repeats its text this often.
+it.each([1, Math.ceil(WORD_LIMITS.bodyBytes / 5_000 / 4)])(
+  "counts shared Word settings once with %s text repetitions",
+  async (repetitions) => {
+    const { default: JSZip } = await import("jszip");
+    const archive = new JSZip();
+    const ns = "http://schemas.openxmlformats.org/wordprocessingml/2006/main";
+    archive.file(
+      "word/document.xml",
+      `<w:document xmlns:w="${ns}"><w:body>${`<w:p><w:r><w:t>${"body".repeat(repetitions)}</w:t></w:r></w:p>`.repeat(5_000)}</w:body></w:document>`,
+    );
+    archive.file(
+      "word/_rels/document.xml.rels",
+      '<Relationships><Relationship Id="settings" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/settings" Target="settings.xml"/></Relationships>',
+    );
+    const settings = `<w:settings xmlns:w="${ns}"><w:unused>${"s".repeat(120_000)}</w:unused></w:settings>`;
+    archive.file("word/settings.xml", settings);
+    const bytes = await archive.generateAsync({ type: "arraybuffer" });
+    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
+      type: "module",
+    });
+    try {
+      const result = await new Promise<OfficeWorkerResult>((resolve) => {
+        worker.addEventListener(
+          "message",
+          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
+          { once: true },
+        );
+        worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]);
+      });
+      expect(result.type).toBe("docx");
+      if (result.type !== "docx") throw new Error("Expected a Word prefix");
+      expect(result.truncated).toBe(repetitions > 1);
+      const bounded = await JSZip.loadAsync(result.bytes);
+      const document = await bounded.file("word/document.xml")!.async("string");
+      const retainedSettings = await bounded.file("word/settings.xml")!.async("string");
+      expect(document.match(/<w:p>/g)!.length).toBeGreaterThan(100);
+      expect(document.length).toBeLessThanOrEqual(WORD_LIMITS.bodyBytes);
+      expect(retainedSettings).toBe(settings);
+    } finally {
+      worker.terminate();
+    }
+  },
+);
+
+it.each(["repeated binary", "XML relationship alias", "duplicate relationship ID"])(
+  "bounds Word image expansion for %s",
+  async (scenario) => {
+    const { default: JSZip } = await import("jszip");
+    const archive = new JSZip();
+    archive.file(
+      "[Content_Types].xml",
+      '<Types><Default Extension="png" ContentType="image/png"/></Types>',
+    );
+    archive.file(
+      "word/_rels/document.xml.rels",
+      `<Relationships><Relationship Id="image" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/${scenario === "XML relationship alias" ? "styles" : "image"}" Target="media/payload.png"/>${scenario === "duplicate relationship ID" ? '<Relationship Id="image" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/image" Target="media/tiny.png"/>' : ""}</Relationships>`,
+    );
+    archive.file(
+      "word/media/payload.png",
+      scenario === "XML relationship alias" ? "<styles/>" : new Uint8Array(8 * 1024 * 1024),
+    );
+    if (scenario === "duplicate relationship ID")
+      archive.file("word/media/tiny.png", new Uint8Array(1));
+    archive.file(
+      "word/document.xml",
+      `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main" xmlns:a="http://schemas.openxmlformats.org/drawingml/2006/main" xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><w:body><w:p>${'<w:r><a:blip r:embed="image"/></w:r>'.repeat(7)}</w:p></w:body></w:document>`,
+    );
+    const bytes = await archive.generateAsync({ type: "arraybuffer", compression: "DEFLATE" });
+    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
+      type: "module",
+    });
+    try {
+      const result = await new Promise<OfficeWorkerResult>((resolve) => {
+        worker.addEventListener(
+          "message",
+          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
+          { once: true },
+        );
+        worker.postMessage({ type: "open", kind: "docx", bytes }, [bytes]);
+      });
+      expect(result).toMatchObject({
+        type: "error",
+        message: expect.stringContaining("expanded markup"),
+      });
+    } finally {
+      worker.terminate();
+    }
+  },
+);
+
+it.each(["XFD200", "XFD300", "XFD1048576", "AX500", "AZ9999999"])(
+  "bounds spreadsheet cells at %s before padding",
+  async (ref) => {
+    const { default: JSZip } = await import("jszip");
+    const archive = new JSZip();
+    archive.file(
+      "xl/workbook.xml",
+      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Sheet" sheetId="1" r:id="rId1"/></sheets></workbook>',
+    );
+    // A nonstandard relationship target must get the same bounds.
+    archive.file(
+      "xl/_rels/workbook.xml.rels",
+      '<Relationships><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="custom.xml"/></Relationships>',
+    );
+    archive.file(
+      "xl/custom.xml",
+      `<worksheet><dimension ref="A1:${ref}"/><sheetData><row r="1"><c r="A1"><v>7</v></c></row><row r="${ref.replace(/\D/g, "")}">${ref === "XFD300" ? `<c r="${ref}" s="1"/>` : `<c r="${ref}"><v>9</v></c>`}</row></sheetData></worksheet>`,
+    );
+    const bytes = await archive.generateAsync({ type: "arraybuffer" });
+    const worker = new Worker(new URL("./officePreview.worker.ts", import.meta.url), {
+      type: "module",
+    });
+    try {
+      const result = await new Promise<OfficeWorkerResult>((resolve) => {
+        worker.addEventListener(
+          "message",
+          (event: MessageEvent<OfficeWorkerResult>) => resolve(event.data),
+          { once: true },
+        );
+        worker.postMessage({ type: "open", kind: "xlsx", bytes }, [bytes]);
+      });
+      if (ref === "AZ9999999" || ref === "XFD1048576") {
+        expect(result).toMatchObject({
+          type: "error",
+          message: expect.stringContaining(ref === "AZ9999999" ? "invalid" : "preview limit"),
+        });
+      } else {
+        expect(result.type).toBe("xlsx");
+        if (result.type !== "xlsx") throw new Error("Expected workbook values");
+        const bounded = await JSZip.loadAsync(result.bytes);
+        const sheet = new DOMParser().parseFromString(
+          await bounded.file("xl/custom.xml")!.async("string"),
+          "application/xml",
+        );
+        expect(sheet.querySelector('c[r="A1"] v')?.textContent).toBe("7");
+        expect(sheet.querySelectorAll("row").length).toBeLessThanOrEqual(500);
+        expect(result.truncated).toBe(ref === "XFD200" || ref === "XFD300");
+        if (ref === "AX500") expect(sheet.querySelector('c[r="AX500"] v')?.textContent).toBe("9");
+        else expect(sheet.querySelector('c[r="' + ref + '"]')).toBeNull();
+      }
+    } finally {
+      worker.terminate();
+    }
+  },
+);
+
+it.each(['<u val="double"/>', '<u val="double"></u>'])(
+  "shows workbook formats and underline %s",
+  async (underline) => {
+    const { default: JSZip } = await import("jszip");
+    const archive = new JSZip();
+    archive.file(
+      "xl/workbook.xml",
+      '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Styles" sheetId="1" r:id="rId1"/></sheets></workbook>',
+    );
+    archive.file(
+      "xl/_rels/workbook.xml.rels",
+      '<Relationships><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/></Relationships>',
+    );
+    archive.file(
+      "xl/styles.xml",
+      `<styleSheet><numFmts count="4"><numFmt numFmtId="164" formatCode="0.000"/><numFmt numFmtId="65535" formatCode="0.0000"/><numFmt numFmtId="007" formatCode="&quot;￥&quot;#,##0.00"/><numFmt numFmtId="82" formatCode="[$-010409]dd-mmm-yyyy"/></numFmts><fonts count="2"><font><sz val="11"/></font><font>${underline}<sz val="11"/></font></fonts><cellXfs count="4"><xf numFmtId="0" fontId="0"/><xf numFmtId="7" fontId="0"/><xf numFmtId="82" fontId="0"/><xf numFmtId="0" fontId="1"/></cellXfs></styleSheet>`,
+    );
+    archive.file(
+      "xl/worksheets/sheet1.xml",
+      '<worksheet><sheetData><row r="1"><c r="A1" s="1"><v>100</v></c><c r="B1" s="2"><v>44986</v></c><c r="C1" s="3" t="inlineStr"><is><t>Total</t></is></c></row></sheetData></worksheet>',
+    );
+    const { prepareOffice } = await import("./officeArchive");
+    const prepared = await prepareOffice(
+      await archive.generateAsync({ type: "arraybuffer" }),
+      "xlsx",
+    );
+    const styles = await (
+      await JSZip.loadAsync(prepared.bytes)
+    )
+      .file("xl/styles.xml")!
+      .async("string");
+    expect(styles).toContain("<font><u/>");
+    const worker = new Worker(new URL("./office/spreadsheet.worker.ts", import.meta.url), {
+      type: "module",
+    });
+    try {
+      const { createWorkerClient } = await import("./office/worker-rpc");
+      const client = createWorkerClient<import("./office/sheet-protocol").SheetMethods>(worker);
+      const bytes = prepared.bytes;
+      await client.call("open", { bytes, view: prepared.view! }, { transfer: [bytes] });
+      const cells = await client.call("cells", {
+        sheet: 0,
+        range: { top: 0, bottom: 0, left: 0, right: 1 },
+      });
+      // Ids under 164 that a workbook defines keep its formats, not Excel's built-in ones.
+      expect(cells[0]).toEqual(["￥100.00", "01-Mar-2023"]);
+    } finally {
+      worker.terminate();
+    }
+    archive.file("xl/styles.xml", "<styleSheet><numFmts/><numFmts/></styleSheet>");
+    await expect(
+      prepareOffice(await archive.generateAsync({ type: "arraybuffer" }), "xlsx"),
+    ).rejects.toThrow("duplicate stylesheet blocks");
+  },
+);
+
+it("keeps spreadsheet dates on their calendar day west of UTC", async () => {
+  const { default: JSZip } = await import("jszip");
+  const archive = new JSZip();
+  archive.file(
+    "xl/workbook.xml",
+    '<workbook xmlns:r="http://schemas.openxmlformats.org/officeDocument/2006/relationships"><sheets><sheet name="Dates" sheetId="1" r:id="rId1"/></sheets></workbook>',
+  );
+  archive.file(
+    "xl/_rels/workbook.xml.rels",
+    '<Relationships><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/worksheet" Target="worksheets/sheet1.xml"/></Relationships>',
+  );
+  archive.file(
+    "xl/styles.xml",
+    '<styleSheet><cellXfs><xf numFmtId="0"/><xf numFmtId="14"/></cellXfs></styleSheet>',
+  );
+  archive.file(
+    "xl/worksheets/sheet1.xml",
+    '<worksheet><sheetData><row r="1"><c r="A1" s="1"><v>46023</v></c></row></sheetData></worksheet>',
+  );
+  const bytes = await archive.generateAsync({ type: "arraybuffer" });
+  const workerModule = new URL(
+    "./office/spreadsheet.worker.ts?worker_file&type=module",
+    import.meta.url,
+  ).href;
+  // Give the worker a west-of-UTC default while preserving explicit format options.
+  const bootstrap = URL.createObjectURL(
+    new Blob(
+      [
+        `
+    const NativeURL = URL;
+    globalThis.URL = class extends NativeURL {
+      constructor(input, base) { super(input, base?.startsWith("blob:") ? ${JSON.stringify(location.href)} : base); }
+    };
+    const format = Date.prototype.toLocaleDateString;
+    Date.prototype.toLocaleDateString = function(locale, options) {
+      return format.call(this, "en-US", { timeZone: "America/Los_Angeles", ...options });
+    };
+    await import(${JSON.stringify(workerModule)});
+    postMessage({ type: "ready" });
+  `,
+      ],
+      { type: "text/javascript" },
+    ),
+  );
+  const worker = new Worker(bootstrap, { type: "module" });
+  try {
+    await new Promise<void>((resolve, reject) => {
+      worker.addEventListener(
+        "message",
+        (event) => {
+          if (event.data.type === "ready") resolve();
+        },
+        { once: true },
+      );
+      worker.addEventListener("error", (event) => reject(new Error(event.message)), { once: true });
+    });
+    const { createWorkerClient } = await import("./office/worker-rpc");
+    const client = createWorkerClient<import("./office/sheet-protocol").SheetMethods>(worker);
+    await client.call(
+      "open",
+      {
+        bytes,
+        view: { hiddenGridlines: [], themeFonts: { major: "Calibri Light", minor: "Calibri" } },
+      },
+      { transfer: [bytes] },
+    );
+    const cells = await client.call("cells", {
+      sheet: 0,
+      range: { top: 0, bottom: 0, left: 0, right: 0 },
+    });
+    expect(cells[0]![0]).toMatch(/^1\/1\/(26|2026)$/);
+  } finally {
+    worker.terminate();
+    URL.revokeObjectURL(bootstrap);
+  }
+});
+
+it.each([60, 100])("prepares all %i pages of a table-heavy Word report", async (pages) => {
+  const { default: JSZip } = await import("jszip");
+  const archive = new JSZip();
+  const paragraph = (text: string) =>
+    `<w:p><w:pPr><w:spacing w:after="120"/><w:jc w:val="left"/></w:pPr><w:r><w:rPr><w:rFonts w:ascii="Calibri"/><w:sz w:val="22"/></w:rPr><w:t>${text}</w:t></w:r></w:p>`;
+  archive.file(
+    "word/document.xml",
+    `<w:document xmlns:w="http://schemas.openxmlformats.org/wordprocessingml/2006/main"><w:body>${Array.from({ length: pages }, (_, page) => paragraph(`page ${page + 1}`) + `<w:tbl>${Array.from({ length: 10 }, () => `<w:tr>${Array.from({ length: 5 }, () => `<w:tc><w:tcPr><w:tcW w:w="1800"/></w:tcPr>${paragraph("report entry")}</w:tc>`).join("")}</w:tr>`).join("")}</w:tbl>`).join("")}</w:body></w:document>`,
+  );
+  archive.file(
+    "_rels/.rels",
+    '<Relationships xmlns="http://schemas.openxmlformats.org/package/2006/relationships"><Relationship Id="rId1" Type="http://schemas.openxmlformats.org/officeDocument/2006/relationships/officeDocument" Target="word/document.xml"/></Relationships>',
+  );
+  archive.file(
+    "[Content_Types].xml",
+    '<Types><Default Extension="png" ContentType="image/png"/></Types>',
+  );
+  // Binary media must not consume the document's markup budget.
+  archive.file("word/media/image.png", new Uint8Array(2_500_000));
+  const file = await archive.generateAsync({ type: "blob", compression: "DEFLATE" });
+  await using screen = await render(
+    <AttachmentFilePreview
+      name="report.docx"
+      mimeType="application/octet-stream"
+      file={file}
+      sizeBytes={file.size}
+    />,
+  );
+  // The first Office preview in the file loads the lazy viewer chain and the preparation worker.
+  await vi.waitFor(() => expect(screen.container.textContent).toContain("page " + pages), {
+    timeout: 10_000,
+  });
+  expect(screen.container.textContent).not.toContain("Preview limited");
+  expect(screen.container.querySelector('[role="alert"]')).toBeNull();
+});