diff --git a/CLAUDE.md b/CLAUDE.md
index 4b41d8d..40250a6 100644
--- a/CLAUDE.md
+++ b/CLAUDE.md
@@ -30,7 +30,7 @@ Tests live in `tests/` (outside `src/`, so `svelte-check` ignores them), jsdom v
 `lo-roundtrip.test.ts` re-saves through LibreOffice and **self-skips** without `soffice`, so
 `npm test`/CI stay green; `corpus.test.ts` round-trips the committed `tests/corpus/`
 documents (by `make-fixtures.mjs` + Word re-saves in `corpus/word/`, never our exporter);
-`fuzz-roundtrip.test.ts` round-trips seeded random documents (`fuzzDoc.ts` generator);
+`fuzz-roundtrip.test.ts` round-trips seeded random documents under random export options (`fuzzDoc.ts`, `fuzzOptions.ts`) through both formats and validates every export against the schemas (`schemaValidate.ts`; `FUZZ_SEEDS=500` widens it);
 `schema-validation.test.ts` validates the `kitchenSink.ts` exports against the vendored
 schemas in `tests/schemas/` (self-skips without `xmllint`); `package-lint.test.ts` checks the semantic invariants schemas can't express (unique ids, dangling references); `tests/unit/` holds fast helper tests; the two browser runs (`tests/smoke/`, `tests/dom/`) share `tests/browser.mjs`. All test tooling stays a
 `devDependency`. No linter/formatter. CI (`.github/workflows/ci.yml`) runs `check` + `test`.
diff --git a/tests/fuzz-roundtrip.test.ts b/tests/fuzz-roundtrip.test.ts
index 9588318..14c20f7 100644
--- a/tests/fuzz-roundtrip.test.ts
+++ b/tests/fuzz-roundtrip.test.ts
@@ -1,24 +1,38 @@
-// Property leg: seeded random documents (fuzzDoc.ts) -> buildOdt -> importOdt must
-// come back unchanged (normalized). A failure names the seed, so it reproduces.
+// Property leg: seeded random documents under random export options (fuzzDoc.ts,
+// fuzzOptions.ts) -> buildOdt/buildDocx -> import come back unchanged (normalized), and every
+// export validates against the schemas. A failure names the seed: genCase(mulberry32(seed)).
 import { describe, it, expect } from 'vitest';
+import { unzipSync } from 'fflate';
 import { buildOdt } from '../src/lib/export/odt';
 import { importOdt } from '../src/lib/import/odt';
 import { buildDocx } from '../src/lib/export/docx';
 import { importDocx } from '../src/lib/import/docx';
 import { normalize, firstDiff, stripFontHoist } from './normalize';
-import { genDoc, mulberry32 } from './fuzzDoc';
+import { mulberry32 } from './fuzzDoc';
+import { genCase, exportArgs, expectedOptions, importedOptions, diffLoose, omit } from './fuzzOptions';
+import { hasXmllint, validateOdt, validateDocx } from './schemaValidate';
 
-const margins = { top: 2, bottom: 2, left: 2, right: 2 };
 const SEEDS = Number(process.env.FUZZ_SEEDS ?? 50); // FUZZ_SEEDS=500 for a wide sweep
+// The schema leg pays ~0.7s of xmllint per seed, so it takes fewer by default.
+const SCHEMA_SEEDS = Number(process.env.SCHEMA_SEEDS ?? Math.min(SEEDS, 20));
+
+// What each format has no place for (see the importers' CLAUDE.md); dropped from both
+// sides of its comparison. Word spaces paragraphs by the larger of the two values and
+// draws its note separator its own way; it has no note prefix/suffix and counts every line.
+const ODT_LOSSY: string[] = [];
+const DOCX_LOSSY: string[] = ['spacingModel', 'notes.separator', 'notes.footnote.prefix', 'notes.footnote.suffix',
+  'notes.endnote.prefix', 'notes.endnote.suffix', 'lineNumbering.countEmpty'];
 
 describe('fuzz round-trip: editor → buildOdt → importOdt', () => {
   it(`${SEEDS} seeded random documents come back identical`, async () => {
     for (let seed = 1; seed <= SEEDS; seed++) {
-      const doc = genDoc(mulberry32(seed));
-      const res = importOdt(await buildOdt(doc, margins, 'portrait'));
+      const { doc, opts } = genCase(mulberry32(seed));
+      const res = importOdt(await buildOdt(doc, ...exportArgs(opts)));
       expect.soft(res.warnings, `seed ${seed}: warnings`).toEqual([]);
       const diff = firstDiff(stripFontHoist(normalize(doc)), stripFontHoist(normalize(res.content)));
-      expect.soft(diff, `seed ${seed} (re-run genDoc(mulberry32(${seed})) to reproduce)`).toBeNull();
+      expect.soft(diff, `seed ${seed}: content`).toBeNull();
+      const optDiff = diffLoose(omit(expectedOptions(opts), ODT_LOSSY), omit(importedOptions(res, opts), ODT_LOSSY));
+      expect.soft(optDiff, `seed ${seed}: options`).toBeNull();
     }
   }, 600_000);
 
@@ -33,16 +47,43 @@ describe('fuzz round-trip: editor → buildOdt → importOdt', () => {
     return node;
   }
 
-  // Cross-format: the same document through both pipelines must import identically —
-  // catches one exporter silently losing what the other keeps.
-  it(`${SEEDS} seeded documents agree between the ODT and DOCX round-trips`, async () => {
+  // Odd/even pages are a document setting in Word (w:evenAndOddHeaders): once any
+  // section asks for it, every section has it, repeating its running zones.
+  function docWideOddEven(canon: any): any {
+    if (!canon.sections.some((s: any) => s.differentOddEven)) return canon;
+    for (const s of canon.sections) {
+      if (s.differentOddEven) continue;
+      Object.assign(s, { differentOddEven: true, headerEven: s.header, footerEven: s.footer });
+    }
+    return canon;
+  }
+
+  // The DOCX leg: its options against what went out, and its content against the ODT
+  // reading — catches one exporter silently losing what the other keeps.
+  it(`${SEEDS} seeded documents survive DOCX and agree with the ODT round-trip`, async () => {
     for (let seed = 1; seed <= SEEDS; seed++) {
-      const doc = genDoc(mulberry32(seed));
-      const viaOdt = importOdt(await buildOdt(doc, margins, 'portrait')).content;
-      const viaDocx = importDocx(await buildDocx(doc, margins, 'portrait')).content;
+      const { doc, opts } = genCase(mulberry32(seed));
+      const viaOdt = importOdt(await buildOdt(doc, ...exportArgs(opts))).content;
+      const res = importDocx(await buildDocx(doc, ...exportArgs(opts)));
       const diff = firstDiff(stripColwidth(stripFontHoist(normalize(viaOdt))),
-        stripColwidth(stripFontHoist(normalize(viaDocx))));
-      expect.soft(diff, `seed ${seed}: ODT vs DOCX import (genDoc(mulberry32(${seed})))`).toBeNull();
+        stripColwidth(stripFontHoist(normalize(res.content))));
+      expect.soft(diff, `seed ${seed}: ODT vs DOCX import`).toBeNull();
+      const optDiff = diffLoose(docWideOddEven(omit(expectedOptions(opts), DOCX_LOSSY)),
+        omit(importedOptions(res, opts), DOCX_LOSSY));
+      expect.soft(optDiff, `seed ${seed}: DOCX options`).toBeNull();
     }
   }, 600_000);
 });
+
+describe.skipIf(!hasXmllint)('fuzz: every export validates against the format schemas', () => {
+  it(`${SCHEMA_SEEDS} seeded documents are schema-valid as ODT and as DOCX`, async () => {
+    for (let seed = 1; seed <= SCHEMA_SEEDS; seed++) {
+      const { doc, opts } = genCase(mulberry32(seed));
+      const failures = [
+        ...validateOdt(unzipSync(await buildOdt(doc, ...exportArgs(opts)))),
+        ...validateDocx(unzipSync(await buildDocx(doc, ...exportArgs(opts)))),
+      ];
+      expect.soft(failures.join('\n\n'), `seed ${seed}`).toBe('');
+    }
+  }, 1_800_000);
+});
diff --git a/tests/fuzzDoc.ts b/tests/fuzzDoc.ts
index bd2f308..16d4905 100644
--- a/tests/fuzzDoc.ts
+++ b/tests/fuzzDoc.ts
@@ -4,7 +4,7 @@ import {
 } from '../src/lib/styles/tableStyles';
 
 type N = any;
-type Rng = () => number;
+export type Rng = () => number;
 
 export function mulberry32(seed: number): Rng {
   let a = seed >>> 0;
@@ -16,9 +16,9 @@ export function mulberry32(seed: number): Rng {
   };
 }
 
-const pick = <T,>(r: Rng, arr: readonly T[]): T => arr[Math.floor(r() * arr.length)];
-const int = (r: Rng, min: number, max: number) => min + Math.floor(r() * (max - min + 1));
-const maybe = (r: Rng, p: number) => r() < p;
+export const pick = <T,>(r: Rng, arr: readonly T[]): T => arr[Math.floor(r() * arr.length)];
+export const int = (r: Rng, min: number, max: number) => min + Math.floor(r() * (max - min + 1));
+export const maybe = (r: Rng, p: number) => r() < p;
 
 // XML-hostile characters, umlauts, an astral-plane glyph and a tab on purpose.
 const WORDS = ['Lorem', 'ipsum', 'Größe', 'fünf', 'a&b', '<tag>', '"quote"', "it's",
@@ -99,6 +99,9 @@ function paraAttrs(r: Rng, indents: boolean, top: boolean): N | null {
   if (indents && maybe(r, 0.1)) attrs.indentFirst = pick(r, [0.75, -0.75]);
   if (indents && maybe(r, 0.1)) attrs.indentRight = 1.5;
   if (top && maybe(r, 0.05)) attrs.breakBefore = 'page';
+  // A section break is a page break as well: naming a master page breaks the page in
+  // ODF, and the DOCX sectPr is a nextPage one.
+  if (top && maybe(r, 0.06)) { attrs.sectionBreak = true; attrs.breakBefore = 'page'; }
   // Paragraph box: shading and/or rule lines (ParaStyle carries them into cells/lists).
   if (maybe(r, 0.08)) {
     if (maybe(r, 0.6)) attrs.backgroundColor = pick(r, ['#CCFFFF', '#FFE0E0']);
@@ -418,7 +421,8 @@ function table(r: Rng): N {
 // Roman labels for endnotes match the importer's default numbering.
 const ROMAN = ['i', 'ii', 'iii', 'iv', 'v'] as const;
 
-export function genDoc(r: Rng): N {
+// `styleNames` are the sheet's user styles; a styled block may name one of them.
+export function genDoc(r: Rng, styleNames: string[] = []): N {
   bmNames = [];
   commentSeq = 0;
   revSeq = 0;
@@ -443,8 +447,8 @@ export function genDoc(r: Rng): N {
       // Title/Subtitle centre + size and Quotations' indent live in the style, and a
       // direct value equal to the style's own is suppressed on import — a styled
       // block carries heading-safe runs and no paragraph attrs of its own.
-      block = maybe(r, 0.07)
-        ? { type: 'paragraph', attrs: { styleName: pick(r, ['Title', 'Subtitle', 'Quotations', 'Caption']) },
+      block = maybe(r, styleNames.length ? 0.15 : 0.07)
+        ? { type: 'paragraph', attrs: { styleName: pick(r, ['Title', 'Subtitle', 'Quotations', 'Caption', ...styleNames]) },
             content: runs(r, true) }
         : paragraph(r, true, true);
       // not beside a lone display formula: company would cost it its own line (= display)
@@ -473,6 +477,8 @@ export function genDoc(r: Rng): N {
     blocks.push(block);
     prev = block.type;
   }
+  // The first block opens section 1 as it is; only a later one can start another.
+  if (blocks[0]?.attrs?.sectionBreak) delete blocks[0].attrs.sectionBreak;
   if (notes.length) blocks.push({ type: 'noteSection', content: notes });
   return { type: 'doc', content: blocks };
 }
diff --git a/tests/fuzzOptions.ts b/tests/fuzzOptions.ts
new file mode 100644
index 0000000..55c7f5a
--- /dev/null
+++ b/tests/fuzzOptions.ts
@@ -0,0 +1,328 @@
+// The export arguments beside the document — page setup, zones and sections, styles,
+// notes, decor — drawn per seed, and both importers' readings of them reduced to one
+// shape (`expectedOptions`/`importedOptions`) so a round trip compares field by field.
+import { builtinStyleSheet, type StyleSheet, type Style, type ParaProps, type TextProps } from '../src/lib/styles/styleSheet';
+import { DEFAULT_OUTLINE_LEVEL, MAX_OUTLINE_LEVELS, type OutlineNumbering } from '../src/lib/styles/outlineNumbering';
+import { EMPTY_HF_SET, HF_DISTANCE_CM, type HfSet, type HfDoc } from '../src/lib/storage/headerFooter';
+import { DEFAULT_NOTE_SETTINGS, type NoteSettings } from '../src/lib/storage/noteSettings';
+import { EMPTY_PAGE_DECOR, type PageDecor } from '../src/lib/storage/pageDecor';
+import { DEFAULT_LINE_NUMBERING, type LineNumbering } from '../src/lib/storage/lineNumbering';
+import { DEFAULT_PAGE_NUMBERING, type PageNumbering } from '../src/lib/storage/pageNumbering';
+import { EMPTY_DOC_PROPERTIES, type DocProperties } from '../src/lib/storage/docProperties';
+import { LANGUAGES } from '../src/lib/storage/documentLanguage';
+import type { PageMargins } from '../src/lib/storage/pageMargins';
+import type { PageFormat } from '../src/lib/storage/pageFormat';
+import type { Orientation } from '../src/lib/storage/pageOrientation';
+import type { SpacingModel } from '../src/lib/storage/spacingModel';
+import type { HfExport } from '../src/lib/export/odt';
+import type { OdtImportResult } from '../src/lib/import/odt';
+import { genDoc, pick, int, maybe, type Rng } from './fuzzDoc';
+import { normalize } from './normalize';
+
+type N = any;
+
+export type FuzzOptions = {
+  margins: PageMargins; orientation: Orientation; hf: HfExport | undefined;
+  language: { language: string; country: string } | null; pageFormat: PageFormat;
+  styles: StyleSheet; tabIntervalCm: number; spacingModel: SpacingModel;
+  notes: NoteSettings; props: DocProperties; hyphenate: boolean; pageNumbering: PageNumbering;
+  decor: PageDecor; lineNumbering: LineNumbering; recordChanges: boolean; foldMarks: boolean;
+  spacingAtPageStart: boolean;
+  // The user styles the document references (plus their parents): the only ones the
+  // export writes, so the only ones that can come back.
+  userStyles: string[];
+};
+
+// The positional arguments after the document, for buildOdt and buildDocx alike.
+export function exportArgs(o: FuzzOptions) {
+  return [o.margins, o.orientation, o.hf, o.language, o.pageFormat, o.styles, o.tabIntervalCm,
+    o.spacingModel, false, o.notes, o.props, o.hyphenate, o.pageNumbering, o.decor,
+    o.lineNumbering, o.recordChanges, o.foldMarks, o.spacingAtPageStart] as const;
+}
+
+const STYLE_NAMES = ['Merksatz', 'Fuzz Body', 'Größe & <Stil>'] as const;
+
+// User styles chain parent → child; each style draws its values from its own pool, so
+// none equals what its chain resolves to (an equal value reads as inherited and is dropped).
+function genStyles(r: Rng): { sheet: StyleSheet; names: string[] } {
+  const sheet = builtinStyleSheet();
+  const names = STYLE_NAMES.slice(0, int(r, 0, 3));
+  names.forEach((name, i) => {
+    const own = <T,>(pool: readonly [T, T, T]): T => pool[i];
+    const para: ParaProps = {};
+    const text: TextProps = {};
+    if (maybe(r, 0.4)) para.textAlign = own(['justify', 'right', 'center']);
+    if (maybe(r, 0.4)) para.lineHeight = own(['1.15', '1.5', '2']);
+    if (maybe(r, 0.4)) para.spaceBefore = own([6, 12, 3]);
+    if (maybe(r, 0.4)) para.spaceAfter = own([8, 4, 2]);
+    if (maybe(r, 0.4)) para.indent = own([1.5, 0.75, 2.25]);
+    if (maybe(r, 0.2)) para.backgroundColor = own(['#EEF3F8', '#FFF2CC', '#E2F0D9']);
+    if (maybe(r, 0.2)) {
+      para.borderBottom = own(['1pt solid #FF0000', '0.5pt solid #00B050', '2pt solid #0070C0']);
+      if (maybe(r, 0.5)) para.borderPadding = own([2, 4, 6]);
+    }
+    if (maybe(r, 0.4)) text.fontFamily = own(['Liberation Sans', 'Courier New', 'Liberation Mono']);
+    if (maybe(r, 0.4)) text.fontSizePt = own([10, 14, 11]);
+    if (maybe(r, 0.4)) text[own(['bold', 'italic', 'underline'] as const)] = true;
+    if (maybe(r, 0.4)) text.color = own(['#004080', '#7030A0', '#385723']);
+    if (maybe(r, 0.2)) text.letterSpacingPt = own([0.5, 1.2, 2]);
+    const style: Style = { name, parent: i > 0 && maybe(r, 0.4) ? names[i - 1] : 'Standard',
+      next: maybe(r, 0.3) ? name : 'Standard', para, text };
+    sheet.paragraph[name] = style;
+  });
+  if (maybe(r, 0.25)) {
+    const depth = int(r, 1, 3);
+    sheet.outline = Array.from({ length: MAX_OUTLINE_LEVELS }, (_, i) => i < depth
+      ? { format: pick(r, ['1', 'a', 'I'] as const), prefix: maybe(r, 0.3) ? '§' : '',
+          suffix: pick(r, ['.', ')', '']), displayLevels: int(r, 1, i + 1), start: pick(r, [1, 1, 3]) }
+      : { ...DEFAULT_OUTLINE_LEVEL });
+  }
+  return { sheet, names };
+}
+
+const MARGIN_SETS: PageMargins[] = [
+  { top: 2, bottom: 2, left: 2, right: 2 },
+  { top: 2.5, bottom: 2, left: 3, right: 1.5 },
+  { top: 1.5, bottom: 1.5, left: 1.9, right: 1.9 },
+];
+
+function zone(r: Rng): HfDoc {
+  const attrs: N = {};
+  if (maybe(r, 0.4)) attrs.textAlign = pick(r, ['center', 'right']);
+  const marks = maybe(r, 0.3) ? [{ type: 'bold' }] : undefined;
+  const content: N[] = [{ type: 'text', text: pick(r, ['Bericht', 'a & <b>', 'Größe']), ...(marks ? { marks } : {}) }];
+  if (maybe(r, 0.3)) content.unshift({ type: 'chapterField', attrs: { level: 1, text: 'Kapitel' } }, { type: 'text', text: ' ' });
+  if (maybe(r, 0.5)) content.push({ type: 'text', text: '\t' }, { type: 'pageNumber' });
+  if (maybe(r, 0.3)) content.push({ type: 'text', text: ' of ' }, { type: 'pageCount' });
+  if (maybe(r, 0.2)) content.push({ type: 'hardBreak' }, { type: 'text', text: 'zweite Zeile' });
+  return { type: 'doc', content: [{ type: 'paragraph', ...(Object.keys(attrs).length ? { attrs } : {}), content }] };
+}
+
+// The zones of one set. The first-page and even-page flags need a running zone to
+// ride on: the file carries them as elements beside it, nowhere else.
+function zones(r: Rng): HfSet {
+  const s: HfSet = { ...EMPTY_HF_SET };
+  if (maybe(r, 0.6)) s.header = zone(r);
+  if (maybe(r, 0.6)) s.footer = zone(r);
+  const running = !!(s.header || s.footer);
+  if (running && maybe(r, 0.3)) {
+    s.differentFirstPage = true;
+    if (maybe(r, 0.6)) s.headerFirst = zone(r);
+    if (maybe(r, 0.5)) s.footerFirst = zone(r);
+  }
+  if (running && maybe(r, 0.25)) {
+    s.differentOddEven = true;
+    if (maybe(r, 0.6)) s.headerEven = zone(r);
+    if (maybe(r, 0.5)) s.footerEven = zone(r);
+  }
+  return s;
+}
+
+// A section past the first: its zones plus whatever page setup of its own it takes.
+function section(r: Rng): HfSet {
+  const s = zones(r);
+  if (maybe(r, 0.2)) s.margins = pick(r, MARGIN_SETS);
+  if (maybe(r, 0.15)) { s.format = pick(r, ['A5', 'letter']); s.orientation = pick(r, ['portrait', 'landscape']); }
+  if (maybe(r, 0.2)) s.pageNumberStart = int(r, 1, 9);
+  if (maybe(r, 0.15)) s.pageNumberFormat = pick(r, ['i', 'I', 'a', 'A']);
+  if (maybe(r, 0.15)) s.distances = { header: pick(r, [0.6, 1]), footer: pick(r, [0.6, 1]) };
+  if (maybe(r, 0.15)) s.startsOn = pick(r, ['odd', 'even']);
+  return s;
+}
+
+function genHf(r: Rng, nSections: number): HfExport | undefined {
+  const top = zones(r);
+  if (!top.header && !top.footer && nSections === 1) return undefined;
+  const hf: HfExport = {
+    header: top.header, footer: top.footer,
+    headerFirst: top.headerFirst, footerFirst: top.footerFirst, differentFirstPage: top.differentFirstPage,
+    headerEven: top.headerEven, footerEven: top.footerEven, differentOddEven: top.differentOddEven,
+    pageCount: nSections + 2,
+  };
+  // Distances stay under the smallest margin (the export clamps them there).
+  if (top.header && maybe(r, 0.4)) hf.headerDistanceCm = pick(r, [0.8, 1]);
+  if (top.footer && maybe(r, 0.4)) hf.footerDistanceCm = pick(r, [0.8, 1]);
+  if (nSections > 1) hf.sections = [top, ...Array.from({ length: nSections - 1 }, () => section(r))];
+  return hf;
+}
+
+const HOSTILE = ['Jahresbericht & <Q1>', 'Größe "quoted"', "it's"] as const;
+
+// `carrier`: whether the document holds a paragraph or heading — ODF keeps the first
+// page number on the first paragraph, so a document of one empty index has no place for it.
+function genOptions(r: Rng, sheet: StyleSheet, nSections: number, carrier: boolean): Omit<FuzzOptions, 'userStyles'> {
+  const margins = { ...pick(r, MARGIN_SETS), ...(maybe(r, 0.2) ? { mirrored: true } : {}) };
+  const notes = structuredClone(DEFAULT_NOTE_SETTINGS);
+  if (maybe(r, 0.3)) {
+    notes.footnote.numFormat = pick(r, ['1', 'i', 'I', 'a', 'A']);
+    notes.footnote.startAt = int(r, 1, 5);
+    notes.footnote.restart = pick(r, ['document', 'page']);
+  }
+  if (maybe(r, 0.2)) { notes.endnote.numFormat = pick(r, ['1', 'I', 'a', 'A']); notes.endnote.startAt = int(r, 1, 5); }
+  if (maybe(r, 0.2)) { notes.footnote.prefix = '('; notes.footnote.suffix = ')'; }
+  if (maybe(r, 0.2)) notes.separator = { ...notes.separator, relWidthPercent: 60, weightPt: 1.5, align: 'center' };
+  const decor: PageDecor = { ...EMPTY_PAGE_DECOR };
+  if (maybe(r, 0.15)) decor.background = pick(r, ['#fffdf5', '#eef3f8']);
+  if (maybe(r, 0.15)) decor.border = { widthPt: pick(r, [0.5, 1, 2.25]), color: '#0046a0', paddingCm: pick(r, [0.05, 0.2, 0.5]) };
+  if (maybe(r, 0.15)) {
+    decor.watermark = { text: pick(r, ['ENTWURF', 'DRAFT & <x>']), font: 'Liberation Sans',
+      color: '#c0c0c0', angle: pick(r, [0, 45, -30, 135]), transparency: pick(r, [0, 50, 80]) };
+  }
+  const lineNumbering: LineNumbering = maybe(r, 0.15)
+    ? { on: true, interval: pick(r, [1, 5, 10]), distanceCm: pick(r, [0.5, 1]),
+        restart: pick(r, ['continuous', 'page']), countEmpty: maybe(r, 0.5) }
+    : { ...DEFAULT_LINE_NUMBERING };
+  return {
+    margins,
+    orientation: maybe(r, 0.15) ? 'landscape' : 'portrait',
+    hf: genHf(r, nSections),
+    language: pick(r, [LANGUAGES[0].odf, LANGUAGES[1].odf, null]),
+    pageFormat: maybe(r, 0.3) ? pick(r, ['A5', 'letter', 'legal', 'A3', 'executive', 'isoB5']) : 'A4',
+    styles: sheet,
+    tabIntervalCm: pick(r, [1.25, 1.25, 2, 0.5]),
+    spacingModel: maybe(r, 0.15) ? 'max' : 'add',
+    notes,
+    props: maybe(r, 0.3)
+      ? { title: pick(r, HOSTILE), subject: 'Finanzen', author: pick(r, HOSTILE), keywords: 'Bilanz, Prüfung', description: pick(r, HOSTILE) }
+      : { ...EMPTY_DOC_PROPERTIES },
+    hyphenate: maybe(r, 0.2),
+    pageNumbering: maybe(r, 0.2) ? { format: pick(r, ['i', 'I', 'a', 'A']), start: carrier ? int(r, 1, 7) : 1 } : { ...DEFAULT_PAGE_NUMBERING },
+    decor,
+    lineNumbering,
+    recordChanges: maybe(r, 0.1),
+    foldMarks: maybe(r, 0.1),
+    spacingAtPageStart: !maybe(r, 0.2),
+  };
+}
+
+function usedStyles(doc: N, sheet: StyleSheet, names: string[]): string[] {
+  const used = new Set<string>();
+  for (const block of doc.content ?? []) {
+    let name: string | undefined = block.attrs?.styleName;
+    while (name && names.includes(name) && !used.has(name)) {
+      used.add(name);
+      name = sheet.paragraph[name]?.parent ?? undefined;
+    }
+  }
+  return names.filter((n) => used.has(n));
+}
+
+export function genCase(r: Rng): { doc: N; opts: FuzzOptions } {
+  const { sheet, names } = genStyles(r);
+  const doc = genDoc(r, names);
+  const nSections = 1 + doc.content.filter((b: N) => b.attrs?.sectionBreak).length;
+  const carrier = doc.content.some((b: N) => b.type === 'paragraph' || b.type === 'heading');
+  const opts = genOptions(r, sheet, nSections, carrier);
+  return { doc, opts: { ...opts, userStyles: usedStyles(doc, sheet, names) } };
+}
+
+// --- the imported reading and the authored options, in one shape ---
+
+const compact = (o: N): N => Object.fromEntries(Object.entries(o ?? {}).filter(([, v]) => v != null));
+const zoneDoc = (d: HfDoc | undefined): N => (d ? normalize(structuredClone(d)) : null);
+const marginsOf = (m: PageMargins | null | undefined): N =>
+  m ? { top: m.top, bottom: m.bottom, left: m.left, right: m.right, ...(m.mirrored ? { mirrored: true } : {}) } : null;
+
+// The document's page setup, which fills whatever a section has none of its own.
+type DocSetup = {
+  margins: PageMargins | null; format: PageFormat | null; orientation: Orientation | null;
+  numFormat: string; headerDist: number | null; footerDist: number | null;
+};
+
+// One section's effective page setup: its zones, and the document's values wherever it
+// has none of its own. An importer may elect a later section's master page as the
+// document's, so only what a section ends up with is comparable, not where it is kept.
+function hfSet(s: Partial<HfSet> | undefined, index: number, doc: DocSetup): N {
+  const z: HfSet = { ...EMPTY_HF_SET, ...(s ?? {}) };
+  const out: N = { header: zoneDoc(z.header), footer: zoneDoc(z.footer),
+    differentFirstPage: !!z.differentFirstPage, differentOddEven: !!z.differentOddEven };
+  if (out.differentFirstPage) { out.headerFirst = zoneDoc(z.headerFirst); out.footerFirst = zoneDoc(z.footerFirst); }
+  if (out.differentOddEven) { out.headerEven = zoneDoc(z.headerEven); out.footerEven = zoneDoc(z.footerEven); }
+  const has = { header: !!(z.header || z.headerFirst || z.headerEven), footer: !!(z.footer || z.footerFirst || z.footerEven) };
+  // Mirroring is the document's, whichever margins a section has of its own.
+  const margins = z.margins ?? doc.margins;
+  Object.assign(out, {
+    margins: margins && marginsOf({ ...margins, mirrored: !!doc.margins?.mirrored }),
+    format: z.format ?? doc.format, orientation: z.orientation ?? doc.orientation,
+    pageNumberFormat: z.pageNumberFormat ?? doc.numFormat,
+    headerDist: has.header ? z.distances?.header ?? doc.headerDist : null,
+    footerDist: has.footer ? z.distances?.footer ?? doc.footerDist : null,
+    pageNumberStart: index > 0 ? z.pageNumberStart ?? null : null,
+    startsOn: index > 0 ? z.startsOn ?? null : null,
+  });
+  return out;
+}
+
+const styleOf = (s: Style | undefined): N => (s ? { parent: s.parent, next: s.next, para: compact(s.para), text: compact(s.text) } : null);
+
+// null where nothing is numbered; the resolved label look is import-only.
+function outlineOf(o: OutlineNumbering | null | undefined): N {
+  if (!o || o.every((l) => l.format === 'none')) return null;
+  return Array.from({ length: MAX_OUTLINE_LEVELS }, (_, i) => {
+    const { labelText, ...rest } = o[i] ?? DEFAULT_OUTLINE_LEVEL;
+    return compact(rest);
+  });
+}
+
+export function expectedOptions(o: FuzzOptions): N {
+  const hf = o.hf;
+  const doc: DocSetup = { margins: o.margins, format: o.pageFormat, orientation: o.orientation,
+    numFormat: o.pageNumbering.format,
+    headerDist: hf?.headerDistanceCm ?? HF_DISTANCE_CM, footerDist: hf?.footerDistanceCm ?? HF_DISTANCE_CM };
+  const sets: Partial<HfSet>[] = hf?.sections ?? [hf ?? {}];
+  return {
+    language: o.language ? LANGUAGES.find((l) => l.odf.language === o.language!.language)!.code : null,
+    tabIntervalCm: o.tabIntervalCm, spacingModel: o.spacingModel, hyphenate: o.hyphenate,
+    recordChanges: o.recordChanges, foldMarks: o.foldMarks, spacingAtPageStart: o.spacingAtPageStart,
+    pageNumberStart: o.pageNumbering.start, decor: o.decor, lineNumbering: o.lineNumbering, props: o.props,
+    notes: o.notes,
+    sections: sets.map((s, i) => hfSet(s, i, doc)),
+    styles: Object.fromEntries(o.userStyles.map((n) => [n, styleOf(o.styles.paragraph[n])])),
+    outline: outlineOf(o.styles.outline),
+  };
+}
+
+export function importedOptions(res: OdtImportResult, o: FuzzOptions): N {
+  const doc: DocSetup = { margins: res.margins, format: res.format, orientation: res.orientation,
+    numFormat: res.pageNumbering.format, headerDist: res.headerDistanceCm, footerDist: res.footerDistanceCm };
+  return {
+    language: res.language,
+    tabIntervalCm: res.tabIntervalCm, spacingModel: res.spacingModel, hyphenate: res.hyphenate,
+    recordChanges: res.recordChanges, foldMarks: res.foldMarks, spacingAtPageStart: res.spacingAtPageStart,
+    pageNumberStart: res.pageNumbering.start, decor: res.decor, lineNumbering: res.lineNumbering, props: res.props,
+    notes: res.notes,
+    sections: (res.hfSections ?? []).map((s, i) => hfSet(s, i, doc)),
+    styles: Object.fromEntries(o.userStyles.map((n) => [n, styleOf(res.styles.paragraph[n])])),
+    outline: outlineOf(res.styles.outline),
+  };
+}
+
+// firstDiff with the slack a unit conversion needs: numbers within 0.02 agree, and a
+// missing value equals a null one.
+export function diffLoose(a: N, b: N, path = '$'): string | null {
+  if (a == null && b == null) return null;
+  if (typeof a === 'number' && typeof b === 'number') return Math.abs(a - b) <= 0.02 ? null : `${path}: ${a} vs ${b}`;
+  if (typeof a !== typeof b || a == null || b == null) return `${path}: ${JSON.stringify(a)} vs ${JSON.stringify(b)}`;
+  if (typeof a !== 'object') return Object.is(a, b) ? null : `${path}: ${JSON.stringify(a)} vs ${JSON.stringify(b)}`;
+  for (const k of new Set([...Object.keys(a), ...Object.keys(b)])) {
+    const d = diffLoose(a[k], b[k], `${path}.${k}`);
+    if (d) return d;
+  }
+  return null;
+}
+
+// Drops the paths a format cannot carry (`a.b`, `sections.*.c`) from a canonical reading.
+export function omit(canon: N, paths: readonly string[]): N {
+  const out = structuredClone(canon);
+  const drop = (node: N, parts: string[]): void => {
+    if (!node || typeof node !== 'object') return;
+    const [head, ...rest] = parts;
+    const keys = head === '*' ? Object.keys(node) : [head];
+    for (const k of keys) {
+      if (rest.length) drop(node[k], rest);
+      else delete node[k];
+    }
+  };
+  for (const p of paths) drop(out, p.split('.'));
+  return out;
+}
diff --git a/tests/kitchenSink.ts b/tests/kitchenSink.ts
index db46fa5..b1efbbb 100644
--- a/tests/kitchenSink.ts
+++ b/tests/kitchenSink.ts
@@ -214,8 +214,8 @@ export function kitchenSinkDoc(): N {
 export function kitchenSinkSheet(): StyleSheet {
   const sheet = builtinStyleSheet();
   sheet.paragraph['Merksatz'] = { name: 'Merksatz', parent: 'Standard',
-    para: { spaceBeforePt: 6, spaceAfterPt: 6, indentCm: 1 },
-    text: { bold: true, color: '#004080' } } as N;
+    para: { spaceBefore: 6, spaceAfter: 6, indent: 1 },
+    text: { bold: true, color: '#004080' } };
   sheet.list['Prüfliste'] = { name: 'Prüfliste', levels: [
     { kind: 'number', numType: 'upper-roman-paren', markerAlign: 'right', indentCm: 0.5 },
     { kind: 'bullet', bulletChar: '✓' },
diff --git a/tests/schema-validation.test.ts b/tests/schema-validation.test.ts
index 043e141..c8d786d 100644
--- a/tests/schema-validation.test.ts
+++ b/tests/schema-validation.test.ts
@@ -1,107 +1,11 @@
-// Validates the kitchen-sink exports against the vendored OOXML XSDs and the ODF 1.2
-// RelaxNG (tests/schemas/) — the structural half of what Word's strict reader enforces
-// and LibreOffice silently forgives. Self-skips without xmllint on PATH.
+// The kitchen-sink exports (every feature at once) against the format schemas —
+// tests/schemaValidate.ts does the work; the fuzz leg runs the same check over seeds.
 import { describe, it, expect, beforeAll } from 'vitest';
-import { spawnSync } from 'node:child_process';
-import { mkdtempSync, writeFileSync } from 'node:fs';
-import { tmpdir } from 'node:os';
-import { join, resolve } from 'node:path';
-import { unzipSync, strFromU8 } from 'fflate';
+import { unzipSync } from 'fflate';
 import { buildOdt } from '../src/lib/export/odt';
 import { buildDocx } from '../src/lib/export/docx';
 import { kitchenSinkDoc, kitchenSinkSheet, kitchenSinkOptions } from './kitchenSink';
-
-const hasXmllint = spawnSync('xmllint', ['--version']).status === 0;
-const SCHEMAS = resolve(__dirname, 'schemas');
-const MC_NS = 'http://schemas.openxmlformats.org/markup-compatibility/2006';
-// A DrawingML text box (wps:wsp inside a:graphicData) is post-ECMA-376 Microsoft
-// markup Word accepts natively; no ECMA schema covers it, so it is stripped like an
-// ignorable — its inner w:p content is exercised by the body paragraphs instead.
-const WPS_NS = 'http://schemas.microsoft.com/office/word/2010/wordprocessingShape';
-
-// The namespaces the ODF 1.2 schema defines. Anything else (loext, …) is a foreign
-// element/attribute an "extended conforming" consumer removes before validating.
-const ODF_NS = new Set([
-  'urn:oasis:names:tc:opendocument:xmlns:office:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:style:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:text:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:table:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:drawing:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:meta:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:datastyle:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:svg-compatible:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:chart:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:dr3d:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:form:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:script:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:config:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:database:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:presentation:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:animation:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:smil-compatible:1.0',
-  'urn:oasis:names:tc:opendocument:xmlns:manifest:1.0',
-  'http://purl.org/dc/elements/1.1/',
-  'http://www.w3.org/1998/Math/MathML',
-  'http://www.w3.org/1999/xlink',
-  'http://www.w3.org/1999/xhtml',
-  'http://www.w3.org/2002/xforms',
-  'http://www.w3.org/2003/g/data-view#',
-  'http://www.w3.org/XML/1998/namespace',
-  'http://www.w3.org/2000/xmlns/',
-]);
-
-// Removes foreign elements and attributes: keep what `keep(ns)` allows, drop the rest.
-// For OOXML `keep` is "not declared mc:Ignorable"; for ODF it is the ODF_NS whitelist.
-function stripForeign(xml: string, keep: (ns: string | null) => boolean): string {
-  const doc = new DOMParser().parseFromString(xml, 'application/xml');
-  const prune = (el: Element): void => {
-    for (const child of [...el.children]) {
-      if (child.namespaceURI === MC_NS && child.localName === 'AlternateContent') {
-        // An ECMA-376-only consumer takes the Fallback branch.
-        const fb = [...child.children].find(
-          (c) => c.namespaceURI === MC_NS && c.localName === 'Fallback');
-        for (const inner of fb ? [...fb.children] : []) el.insertBefore(inner, child);
-        el.removeChild(child);
-        continue;
-      }
-      if (!keep(child.namespaceURI)) { el.removeChild(child); continue; }
-      prune(child);
-    }
-    for (const attr of [...el.attributes]) {
-      if (attr.namespaceURI === MC_NS
-        || (attr.namespaceURI && !keep(attr.namespaceURI))) el.removeAttributeNode(attr);
-    }
-  };
-  prune(doc.documentElement);
-  return new XMLSerializer().serializeToString(doc);
-}
-
-// The namespace URIs a part's root declares mc:Ignorable — an MCE consumer removes
-// their elements and attributes before schema validation, exactly as Word reads them.
-function mceIgnorable(xml: string): Set<string> {
-  const doc = new DOMParser().parseFromString(xml, 'application/xml');
-  const root = doc.documentElement;
-  const out = new Set<string>([MC_NS]);
-  const ig = root.getAttributeNS(MC_NS, 'Ignorable') ?? '';
-  for (const prefix of ig.trim().split(/\s+/).filter(Boolean)) {
-    const uri = root.getAttribute(`xmlns:${prefix}`);
-    if (uri) out.add(uri);
-  }
-  out.add(WPS_NS);
-  return out;
-}
-
-let tmp: string;
-function validate(schema: string, kind: 'xsd' | 'rng', xml: string, label: string): string | null {
-  const file = join(tmp, `${label.replace(/[^\w.-]+/g, '_')}.xml`);
-  writeFileSync(file, xml);
-  const flag = kind === 'xsd' ? '--schema' : '--relaxng';
-  const r = spawnSync('xmllint', ['--noout', '--nonet', flag, join(SCHEMAS, schema), file],
-    { encoding: 'utf8', maxBuffer: 64 * 1024 * 1024 });
-  if (r.status === 0) return null;
-  return `${label} (${schema}):\n${(r.stderr || r.stdout || `exit ${r.status}`).slice(0, 4000)}`;
-}
+import { hasXmllint, validateOdt, validateDocx } from './schemaValidate';
 
 describe.skipIf(!hasXmllint)('exported XML validates against the format schemas', () => {
   const opts = kitchenSinkOptions();
@@ -109,7 +13,6 @@ describe.skipIf(!hasXmllint)('exported XML validates against the format schemas'
   let docx: Record<string, Uint8Array>;
 
   beforeAll(async () => {
-    tmp = mkdtempSync(join(tmpdir(), 'edentext-schema-'));
     const doc = kitchenSinkDoc();
     const sheet = kitchenSinkSheet();
     odt = unzipSync(await buildOdt(doc, undefined, 'portrait', opts.hf, opts.language, 'A4',
@@ -121,50 +24,12 @@ describe.skipIf(!hasXmllint)('exported XML validates against the format schemas'
   });
 
   it('every ODF part is schema-valid (foreign namespaces stripped, as extended conformance allows)', () => {
-    const failures: string[] = [];
-    const keepOdf = (ns: string | null) => ns == null || ODF_NS.has(ns);
-    for (const [name, bytes] of Object.entries(odt)) {
-      const isDoc = /^(content|styles|meta|settings)\.xml$/.test(name);
-      const isManifest = name === 'META-INF/manifest.xml';
-      // Formula sub-documents root math:math, which the schema's start pattern
-      // excludes; mimetype and Pictures/ are not XML.
-      if (!isDoc && !isManifest) continue;
-      const schema = isManifest
-        ? 'odf/OpenDocument-v1.3-manifest-schema.rng' : 'odf/OpenDocument-v1.3-schema.rng';
-      const fail = validate(schema, 'rng', stripForeign(strFromU8(bytes), keepOdf), `odt ${name}`);
-      if (fail) failures.push(fail);
-    }
     expect(Object.keys(odt)).toContain('content.xml');
-    expect(failures.join('\n\n')).toBe('');
+    expect(validateOdt(odt).join('\n\n')).toBe('');
   });
 
   it('every DOCX part is schema-valid after MCE resolution, as Word reads it', () => {
-    const partSchema = (name: string): string | null => {
-      if (/^word\/(document|styles|numbering|settings|fontTable|footnotes|endnotes|comments|header\d+|footer\d+)\.xml$/.test(name)) return 'ooxml/wml.xsd';
-      if (name === 'docProps/core.xml') return 'opc/opc-coreProperties.xsd';
-      if (name === 'docProps/app.xml') return 'ooxml/shared-documentPropertiesExtended.xsd';
-      if (name === 'docProps/custom.xml') return 'ooxml/shared-documentPropertiesCustom.xsd';
-      // commentsExtended is a Microsoft w15 part with no ECMA-376 schema.
-      if (name === 'word/commentsExtended.xml') return null;
-      if (name === '[Content_Types].xml') return 'opc/opc-contentTypes.xsd';
-      if (/(^|\/)_rels\/[^/]+$/.test(name)) return 'opc/opc-relationships.xsd';
-      if (/^customXml\/itemProps\d+\.xml$/.test(name)) return 'ooxml/shared-customXmlDataProperties.xsd';
-      if (/^customXml\/item\d+\.xml$/.test(name)) return 'ooxml/shared-bibliography.xsd';
-      if (/^word\/(media|fonts)\//.test(name)) return null; // binary
-      return `UNMAPPED:${name}`; // a new part must be mapped or listed here
-    };
-    const failures: string[] = [];
-    for (const [name, bytes] of Object.entries(docx)) {
-      if (name.endsWith('/')) continue; // zip directory entry
-      const schema = partSchema(name);
-      if (schema == null) continue;
-      if (schema.startsWith('UNMAPPED:')) { failures.push(schema); continue; }
-      const xml = strFromU8(bytes);
-      const ignorable = mceIgnorable(xml);
-      const fail = validate(schema, 'xsd', stripForeign(xml, (ns) => !ns || !ignorable.has(ns)), `docx ${name}`);
-      if (fail) failures.push(fail);
-    }
     expect(Object.keys(docx)).toContain('word/document.xml');
-    expect(failures.join('\n\n')).toBe('');
+    expect(validateDocx(docx).join('\n\n')).toBe('');
   });
 });
diff --git a/tests/schemaValidate.ts b/tests/schemaValidate.ts
new file mode 100644
index 0000000..f7ee9bc
--- /dev/null
+++ b/tests/schemaValidate.ts
@@ -0,0 +1,163 @@
+// Validates an exported package against the vendored schemas (tests/schemas/) through
+// xmllint — the ODF 1.3 RelaxNG and the ECMA-376 XSDs, the structural half of what Word's
+// strict reader enforces and LibreOffice forgives. Callers self-skip without `hasXmllint`.
+import { spawnSync } from 'node:child_process';
+import { mkdtempSync, writeFileSync } from 'node:fs';
+import { tmpdir } from 'node:os';
+import { join, resolve } from 'node:path';
+import { strFromU8 } from 'fflate';
+
+export const hasXmllint = spawnSync('xmllint', ['--version']).status === 0;
+const SCHEMAS = resolve(__dirname, 'schemas');
+const MC_NS = 'http://schemas.openxmlformats.org/markup-compatibility/2006';
+// A DrawingML text box (wps:wsp inside a:graphicData) is post-ECMA-376 Microsoft
+// markup Word accepts natively; no ECMA schema covers it, so it is stripped like an
+// ignorable — its inner w:p content is exercised by the body paragraphs instead.
+const WPS_NS = 'http://schemas.microsoft.com/office/word/2010/wordprocessingShape';
+
+// The namespaces the ODF 1.2 schema defines. Anything else (loext, …) is a foreign
+// element/attribute an "extended conforming" consumer removes before validating.
+const ODF_NS = new Set([
+  'urn:oasis:names:tc:opendocument:xmlns:office:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:style:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:text:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:table:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:drawing:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:xsl-fo-compatible:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:meta:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:datastyle:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:svg-compatible:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:chart:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:dr3d:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:form:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:script:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:config:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:database:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:presentation:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:animation:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:smil-compatible:1.0',
+  'urn:oasis:names:tc:opendocument:xmlns:manifest:1.0',
+  'http://purl.org/dc/elements/1.1/',
+  'http://www.w3.org/1998/Math/MathML',
+  'http://www.w3.org/1999/xlink',
+  'http://www.w3.org/1999/xhtml',
+  'http://www.w3.org/2002/xforms',
+  'http://www.w3.org/2003/g/data-view#',
+  'http://www.w3.org/XML/1998/namespace',
+  'http://www.w3.org/2000/xmlns/',
+]);
+
+// Removes foreign elements and attributes: keep what `keep(ns)` allows, drop the rest.
+// For OOXML `keep` is "not declared mc:Ignorable"; for ODF it is the ODF_NS whitelist.
+function stripForeign(xml: string, keep: (ns: string | null) => boolean): string {
+  const doc = new DOMParser().parseFromString(xml, 'application/xml');
+  const prune = (el: Element): void => {
+    for (const child of [...el.children]) {
+      if (child.namespaceURI === MC_NS && child.localName === 'AlternateContent') {
+        // An ECMA-376-only consumer takes the Fallback branch.
+        const fb = [...child.children].find(
+          (c) => c.namespaceURI === MC_NS && c.localName === 'Fallback');
+        for (const inner of fb ? [...fb.children] : []) el.insertBefore(inner, child);
+        el.removeChild(child);
+        continue;
+      }
+      if (!keep(child.namespaceURI)) { el.removeChild(child); continue; }
+      prune(child);
+    }
+    for (const attr of [...el.attributes]) {
+      if (attr.namespaceURI === MC_NS
+        || (attr.namespaceURI && !keep(attr.namespaceURI))) el.removeAttributeNode(attr);
+    }
+  };
+  prune(doc.documentElement);
+  return new XMLSerializer().serializeToString(doc);
+}
+
+// The namespace URIs a part's root declares mc:Ignorable — an MCE consumer removes
+// their elements and attributes before schema validation, exactly as Word reads them.
+function mceIgnorable(xml: string): Set<string> {
+  const doc = new DOMParser().parseFromString(xml, 'application/xml');
+  const root = doc.documentElement;
+  const out = new Set<string>([MC_NS]);
+  const ig = root.getAttributeNS(MC_NS, 'Ignorable') ?? '';
+  for (const prefix of ig.trim().split(/\s+/).filter(Boolean)) {
+    const uri = root.getAttribute(`xmlns:${prefix}`);
+    if (uri) out.add(uri);
+  }
+  out.add(WPS_NS);
+  return out;
+}
+
+type Part = { label: string; xml: string };
+let tmp: string | null = null;
+
+// One xmllint run per schema: parsing the schema is what costs, so every part it
+// covers rides the same call. Returns the failures, one entry per schema.
+function validate(schema: string, kind: 'xsd' | 'rng', parts: Part[]): string[] {
+  if (!parts.length) return [];
+  tmp ??= mkdtempSync(join(tmpdir(), 'edentext-schema-'));
+  const files = parts.map((p) => {
+    const file = join(tmp!, `${p.label.replace(/[^\w.-]+/g, '_')}.xml`);
+    writeFileSync(file, p.xml);
+    return file;
+  });
+  const flag = kind === 'xsd' ? '--schema' : '--relaxng';
+  const r = spawnSync('xmllint', ['--noout', '--nonet', flag, join(SCHEMAS, schema), ...files],
+    { encoding: 'utf8', maxBuffer: 64 * 1024 * 1024 });
+  if (r.status === 0) return [];
+  const out = (r.stderr || r.stdout || `exit ${r.status}`).split('\n')
+    .filter((line) => !/ validates$/.test(line)).join('\n');
+  return [`${schema}:\n${out.slice(0, 4000)}`];
+}
+
+// Every XML part of an unzipped .odt against the ODF schema (foreign namespaces
+// stripped, as extended conformance allows). Formula sub-documents root math:math,
+// which the schema's start pattern excludes; mimetype and Pictures/ are not XML.
+export function validateOdt(files: Record<string, Uint8Array>): string[] {
+  const keepOdf = (ns: string | null) => ns == null || ODF_NS.has(ns);
+  const docs: Part[] = [];
+  const manifests: Part[] = [];
+  for (const [name, bytes] of Object.entries(files)) {
+    const part = { label: `odt ${name}`, xml: stripForeign(strFromU8(bytes), keepOdf) };
+    if (/^(content|styles|meta|settings)\.xml$/.test(name)) docs.push(part);
+    else if (name === 'META-INF/manifest.xml') manifests.push(part);
+  }
+  return [
+    ...validate('odf/OpenDocument-v1.3-schema.rng', 'rng', docs),
+    ...validate('odf/OpenDocument-v1.3-manifest-schema.rng', 'rng', manifests),
+  ];
+}
+
+function docxPartSchema(name: string): string | null {
+  if (/^word\/(document|styles|numbering|settings|fontTable|footnotes|endnotes|comments|header\d+|footer\d+)\.xml$/.test(name)) return 'ooxml/wml.xsd';
+  if (name === 'docProps/core.xml') return 'opc/opc-coreProperties.xsd';
+  if (name === 'docProps/app.xml') return 'ooxml/shared-documentPropertiesExtended.xsd';
+  if (name === 'docProps/custom.xml') return 'ooxml/shared-documentPropertiesCustom.xsd';
+  // commentsExtended is a Microsoft w15 part with no ECMA-376 schema.
+  if (name === 'word/commentsExtended.xml') return null;
+  if (name === '[Content_Types].xml') return 'opc/opc-contentTypes.xsd';
+  if (/(^|\/)_rels\/[^/]+$/.test(name)) return 'opc/opc-relationships.xsd';
+  if (/^customXml\/itemProps\d+\.xml$/.test(name)) return 'ooxml/shared-customXmlDataProperties.xsd';
+  if (/^customXml\/item\d+\.xml$/.test(name)) return 'ooxml/shared-bibliography.xsd';
+  if (/^word\/(media|fonts)\//.test(name)) return null; // binary
+  return `UNMAPPED:${name}`; // a new part must be mapped or listed here
+}
+
+// Every part of an unzipped .docx against its schema after MCE resolution, as Word
+// reads it.
+export function validateDocx(files: Record<string, Uint8Array>): string[] {
+  const failures: string[] = [];
+  const bySchema = new Map<string, Part[]>();
+  for (const [name, bytes] of Object.entries(files)) {
+    if (name.endsWith('/')) continue; // zip directory entry
+    const schema = docxPartSchema(name);
+    if (schema == null) continue;
+    if (schema.startsWith('UNMAPPED:')) { failures.push(schema); continue; }
+    const xml = strFromU8(bytes);
+    const ignorable = mceIgnorable(xml);
+    const part = { label: `docx ${name}`, xml: stripForeign(xml, (ns) => !ns || !ignorable.has(ns)) };
+    bySchema.set(schema, [...(bySchema.get(schema) ?? []), part]);
+  }
+  for (const [schema, parts] of bySchema) failures.push(...validate(schema, 'xsd', parts));
+  return failures;
+}