test(#351 ): close the mark-attr coverage hole + reclassify table spans (review round 1)

F1 [WARNING] The 'no invisible coverage hole' guard enumerated only schema.nodes, so MARK attributes silently escaped the value-fuzz completeness check — link.internal/target/rel/class are never fuzzed and nothing flagged it, and a new attributed mark would slip through. Added allSchemaMarkAttrKeys() plus a MARK_ATTR_FUZZED / MARK_ATTR_ALLOWLIST registry and two tests: every schema mark attr must be in exactly one set (a new one turns it red), and neither set may hold a stale row. F2 [WARNING] The ACCEPTED annotation misclassified table colspan/rowspan as having 'no md representation'. They DO round-trip — a spanned cell makes the converter emit the whole table as a raw <table> with colspan/rowspan, which the tiptap parser reads back. They are frozen only because generating a geometrically-valid spanned table is deferred PR-2 structural work (the flat generator hardcodes span = 1), not a markdown limit. Reclassified them as DEFERRED-BUG (distinct from ACCEPTED) so a maintainer does not read them as an inherent limitation; colwidth / backgroundColor(Name) stay ACCEPTED (the raw-<table> fallback drops them). Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
test(prosemirror-markdown): generative round-trip testing — attribute level, flat docs (#351 PR 1)
2026-07-05 06:40:13 +03:00 · 2026-07-05 04:38:40 +03:00
21 changed files with 1432 additions and 904 deletions
@@ -201,7 +201,7 @@ pnpm workspace (`pnpm@10.4.0`) orchestrated by **Nx**. Four workspace packages:
 | `apps/client` | `client` | React 18 + Vite + Mantine 8 + TanStack Query + Jotai | SPA frontend |
 | `packages/editor-ext` | `@docmost/editor-ext` | Tiptap/ProseMirror | Shared Tiptap node/mark extensions, imported by both the client and the server |
 | `packages/mcp` | `@docmost/mcp` | MCP SDK, Tiptap, Yjs | Standalone MCP server, also bundled into the server at `/mcp`. Consumes the shared converter/schema from `@docmost/prosemirror-markdown` (#293) — it no longer carries its own vendored converter/schema copy |
-| `packages/prosemirror-markdown` | `@docmost/prosemirror-markdown` | Tiptap, marked, jsdom | The single, canonical ProseMirror↔Markdown converter + Docmost schema mirror (#293). Consumed by `mcp`, `git-sync`, AND `apps/server` (server-side markdown import/export, #345); there is exactly ONE copy of the converter now |
+| `packages/prosemirror-markdown` | `@docmost/prosemirror-markdown` | Tiptap, marked, jsdom | The single, canonical ProseMirror↔Markdown converter + Docmost schema mirror (#293). Consumed by `mcp` and `git-sync`; there is exactly ONE copy of the converter now |

 `build` targets are Nx-cached and dependency-ordered (`dependsOn: ["^build"]`), so `editor-ext` builds before the apps. `nx.json` sets `affected.defaultBase: main`.

@@ -284,7 +284,7 @@ The API server is a Fastify app with a global `/api` prefix (`main.ts` excludes
 ### Client structure
 Vite SPA. Code is organized by feature under `apps/client/src/features/*` (mirrors the server domains: `page`, `space`, `comment`, `ai-chat`, `editor`, …). Conventions:
 - **TanStack Query** for server state (one `queries/` file per feature), **Jotai** atoms for local/shared UI state, **Mantine 8** + CSS modules (`*.module.css`) + `postcss-preset-mantine` for UI.
- The editor is Tiptap; shared node/mark extensions live in `packages/editor-ext` and are imported by **both the client and the server** (collaboration, schema, `canonicalizeFootnotes`) — editor schema changes often need to be made in `editor-ext`, not just the client. Server-side markdown import/export no longer lives in `editor-ext`: it goes through the canonical converter (#345, see below). The ProseMirror↔Markdown converter and its Docmost schema mirror now live in a SINGLE package, `@docmost/prosemirror-markdown` (#293), consumed by `mcp`, `git-sync`, and `apps/server` (#345) — do NOT reintroduce a per-package copy. `editor-ext` is the upstream source of the Tiptap schema; the package's `docmost-schema.ts` mirrors it and a serializer-contract test (`packages/prosemirror-markdown/test/serializer-contract.test.ts`) guards the boundary (every schema node must have a converter case), so a drift surfaces as a failing test rather than silent divergence.
+- The editor is Tiptap; shared node/mark extensions live in `packages/editor-ext` and are imported by **both the client and the server** (collaboration, import/export) — editor schema changes often need to be made in `editor-ext`, not just the client. The ProseMirror↔Markdown converter and its Docmost schema mirror now live in a SINGLE package, `@docmost/prosemirror-markdown` (#293), consumed by both `mcp` and `git-sync` — do NOT reintroduce a per-package copy. `editor-ext` is the upstream source of the Tiptap schema; the package's `docmost-schema.ts` mirrors it and a serializer-contract test (`packages/prosemirror-markdown/test/serializer-contract.test.ts`) guards the boundary (every schema node must have a converter case), so a drift surfaces as a failing test rather than silent divergence.
 - API access goes through `apps/client/src/lib/api-client.ts` (axios). The `@` alias maps to `apps/client/src`.
 - Runtime config is injected at build time by `vite.config.ts` via `define` (`APP_URL`, `COLLAB_URL`, `APP_VERSION`, …) — these come from the root `.env`, not from `import.meta.env`.

@@ -23,7 +23,7 @@
    "migration:reset": "tsx src/database/migrate.ts down-to NO_MIGRATIONS",
    "migration:codegen": "kysely-codegen --dialect=postgres --camel-case --env-file=../../.env --out-file=./src/database/types/db.d.ts",
    "lint": "eslint \"{src,apps,libs,test}/**/*.ts\" --fix",
-    "pretest": "pnpm --filter @docmost/editor-ext build && pnpm --filter @docmost/prosemirror-markdown build",
+    "pretest": "pnpm --filter @docmost/editor-ext build",
    "test": "jest",
    "test:int": "jest --config test/jest-integration.json",
    "test:watch": "jest --watch",
@@ -43,7 +43,6 @@
    "@clickhouse/client": "^1.18.2",
    "@docmost/mcp": "workspace:*",
    "@docmost/pdf-inspector": "1.9.6",
-    "@docmost/prosemirror-markdown": "workspace:*",
    "@fastify/cookie": "^11.0.2",
    "@fastify/multipart": "^10.0.0",
    "@fastify/static": "^9.1.3",
@@ -176,7 +175,7 @@
      "/node_modules/"
    ],
    "transform": {
-      "(happy-dom.+|prosemirror-markdown/build/.+)\\.js$": [
+      "happy-dom.+\\.js$": [
        "babel-jest",
        {
          "presets": [
@@ -194,7 +193,7 @@
      "^.+\\.(t|j)sx?$": "ts-jest"
    },
    "transformIgnorePatterns": [
-      "/node_modules/(?!(\\.pnpm/)?(nanoid|uuid|image-dimensions|marked|happy-dom|lib0|@docmost/prosemirror-markdown)(@|/))"
+      "/node_modules/(?!(\\.pnpm/)?(nanoid|uuid|image-dimensions|marked|happy-dom|lib0)(@|/))"
    ],
    "collectCoverageFrom": [
      "**/*.(t|j)s"
@@ -205,8 +204,7 @@
      "^@docmost/db/(.*)$": "<rootDir>/database/$1",
      "^@docmost/transactional/(.*)$": "<rootDir>/integrations/transactional/$1",
      "^@docmost/ee/(.*)$": "<rootDir>/ee/$1",
-      "^src/(.*)$": "<rootDir>/$1",
-      "^@tiptap/react$": "<rootDir>/../test/stubs/tiptap-react.js"
+      "^src/(.*)$": "<rootDir>/$1"
    }
  }
 }
@@ -43,6 +43,7 @@ import {
  Column,
  Status,
  addUniqueIdsToDoc,
+  htmlToMarkdown,
  TransclusionSource,
  TransclusionReference,
  FootnoteReference,
@@ -50,7 +51,6 @@ import {
  FootnoteDefinition,
  PageEmbed,
 } from '@docmost/editor-ext';
-import { convertProseMirrorToMarkdown } from '@docmost/prosemirror-markdown';
 import { generateText, getSchema, JSONContent } from '@tiptap/core';
 import { generateHTML, generateJSON } from '../common/helpers/prosemirror/html';
 // @tiptap/html library works best for generating prosemirror json state but not HTML
@@ -239,10 +239,6 @@ export function prosemirrorNodeToYElement(node: any): Y.XmlElement | Y.XmlText {
 }

 export function jsonToMarkdown(tiptapJson: any): string {
-  // Direct ProseMirror JSON -> Markdown via the canonical converter
-  // (`@docmost/prosemirror-markdown`) — no HTML intermediate, no second
-  // editor-ext markdown layer. Same serializer as the page/space export and the
-  // git-sync vault writer, so every server PM->MD path emits identical canonical
-  // markdown (issue #345).
-  return convertProseMirrorToMarkdown(tiptapJson);
+  const html = jsonToHtml(tiptapJson);
+  return htmlToMarkdown(html);
 }
@@ -52,9 +52,7 @@ import {
  INTERNAL_LINK_REGEX,
  extractPageSlugId,
 } from '../../../integrations/export/utils';
-import { canonicalizeFootnotes } from '@docmost/editor-ext';
-import { markdownToProseMirror } from '@docmost/prosemirror-markdown';
-import { normalizeForeignMarkdown } from '../../../integrations/import/utils/foreign-markdown';
+import { markdownToHtml, canonicalizeFootnotes } from '@docmost/editor-ext';
 import { WatcherService } from '../../watcher/watcher.service';
 import { sql } from 'kysely';
 import { TransclusionService } from '../transclusion/transclusion.service';
@@ -1303,14 +1301,8 @@ export class PageService {

    switch (format) {
      case 'markdown': {
-        // Canonical markdown -> ProseMirror JSON directly via
-        // `@docmost/prosemirror-markdown` (issue #345) — no HTML intermediate,
-        // no editor-ext markdown layer. Foreign markdown surfaces the strict
-        // parser rejects (GFM `[^id]` reference footnotes) are normalized to the
-        // canonical inline form first.
-        prosemirrorJson = await markdownToProseMirror(
-          normalizeForeignMarkdown(content as string),
-        );
+        const html = await markdownToHtml(content as string);
+        prosemirrorJson = htmlToJson(html as string);
        break;
      }
      case 'html': {
@@ -1,145 +0,0 @@
-// export.service.ts imports the ESM-only @sindresorhus/slugify (not in jest's
-// transform allowlist). It is irrelevant to the markdown-serialization path under
-// test (only used for page-mention link slugs on the DB path), so it is mocked
-// out to keep the module graph loadable under ts-jest (mirrors the import specs).
-jest.mock('@sindresorhus/slugify', () => ({
-  __esModule: true,
-  default: (input: string) => String(input),
-}));
-
-import { convertProseMirrorToMarkdown } from '@docmost/prosemirror-markdown';
-import { ExportService } from './export.service';
-import { ExportFormat } from './dto/export-dto';
-
-/**
- * STEP 1 golden test for issue #345: server MARKDOWN export runs DIRECTLY through
- * the canonical converter (`convertProseMirrorToMarkdown`) — no HTML intermediate
- * and no `@docmost/editor-ext` markdown layer — so the emitted markdown is in the
- * canonical package forms and is byte-identical to the git-sync vault body.
- *
- * These are the goldens the swap has to satisfy: they assert the CANONICAL
- * surface (callout `> [!type]`, inline footnote `^[…]`, lossless image
- * `<!--img …-->`) rather than the old editor-ext forms (`:::type`, `[^id]`,
- * lossy `![alt](src)`).
- *
- * `exportPage(..., singlePage=false)` takes no DB path (no mention rewriting), so
- * the service is constructed with null collaborators and only the pure
- * PM -> Markdown path is exercised.
- */
-
-function makeService(): ExportService {
-  return new ExportService(
-    null as any, // pageRepo
-    null as any, // pagePermissionRepo
-    null as any, // db
-    null as any, // storageService
-    null as any, // environmentService
-    null as any, // domainService
-  );
-}
-
-// A representative page exercising the node types whose canonical markdown form
-// changed with the move off the editor-ext layer: callout, inline footnote, and a
-// lossless image carrying width/align attrs that the old layer dropped.
-const REPRESENTATIVE_DOC = {
-  type: 'doc',
-  content: [
-    {
-      type: 'paragraph',
-      content: [
-        { type: 'text', text: 'Body ' },
-        { type: 'footnoteReference', attrs: { id: 'fn-1' } },
-        { type: 'text', text: ' end.' },
-      ],
-    },
-    {
-      type: 'callout',
-      attrs: { type: 'info', icon: null },
-      content: [
-        {
-          type: 'paragraph',
-          content: [{ type: 'text', text: 'Heads up' }],
-        },
-      ],
-    },
-    {
-      type: 'image',
-      attrs: {
-        src: '/files/pic.png',
-        alt: 'Pic',
-        width: 320,
-        align: 'left',
-      },
-    },
-    {
-      type: 'footnotesList',
-      content: [
-        {
-          type: 'footnoteDefinition',
-          attrs: { id: 'fn-1' },
-          content: [
-            {
-              type: 'paragraph',
-              content: [{ type: 'text', text: 'the note' }],
-            },
-          ],
-        },
-      ],
-    },
-  ],
-};
-
-describe('ExportService — markdown export via the canonical converter (#345)', () => {
-  it('emits canonical callout, inline footnote and lossless image forms', async () => {
-    const service = makeService();
-    const md = (await service.exportPage(ExportFormat.Markdown, {
-      title: '',
-      content: REPRESENTATIVE_DOC,
-    } as any)) as string;
-
-    // Callout: Obsidian `> [!type]`, NOT the legacy `:::type`.
-    expect(md).toContain('> [!info]');
-    expect(md).not.toContain(':::');
-
-    // Inline footnote: `^[…]`, NOT the reference `[^id]` form.
-    expect(md).toContain('^[the note]');
-    expect(md).not.toMatch(/\[\^/);
-
-    // Lossless image: trailing `<!--img …-->` carrying the dropped attrs.
-    expect(md).toContain('![Pic](/files/pic.png)');
-    expect(md).toContain('<!--img');
-    expect(md).toContain('"width":"320"');
-    expect(md).toContain('"align":"left"');
-  });
-
-  it('export body is byte-identical to the git-sync vault serializer (export == vault)', async () => {
-    const service = makeService();
-    // A title-less page: exportPage prepends NO heading, so the whole output is
-    // the page BODY — exactly what git-sync serializes (git-sync stores the title
-    // in frontmatter / the filename, never as an in-body H1).
-    const exported = (await service.exportPage(ExportFormat.Markdown, {
-      title: '',
-      content: REPRESENTATIVE_DOC,
-    } as any)) as string;
-
-    // The git-sync vault writer feeds this SAME converter (git-sync
-    // `stabilizePageBody` = convertProseMirrorToMarkdown(content) at the
-    // fixpoint). For an already-stable doc the single pass IS the fixpoint, so
-    // the two are byte-identical by construction — assert it.
-    const vaultBody = convertProseMirrorToMarkdown(REPRESENTATIVE_DOC);
-    expect(exported).toBe(vaultBody);
-  });
-
-  it('prepends the page title as an H1 heading (the one documented export/vault delta)', async () => {
-    const service = makeService();
-    const md = (await service.exportPage(ExportFormat.Markdown, {
-      title: 'My Page',
-      content: { type: 'doc', content: [] },
-    } as any)) as string;
-
-    // Export makes standalone files, so it prepends the title as an H1. This is
-    // the ONE deliberate difference from the vault body (which carries the title
-    // in frontmatter). The body below the heading still serializes canonically.
-    expect(md.startsWith('# My Page')).toBe(true);
-  });
-});
@@ -37,7 +37,7 @@ import {
  getAttachmentIds,
  getProsemirrorContent,
 } from '../../common/helpers/prosemirror/utils';
-import { convertProseMirrorToMarkdown } from '@docmost/prosemirror-markdown';
+import { htmlToMarkdown } from '@docmost/editor-ext';

 type AllowedAttachment = { id: string; fileName: string; filePath: string };

@@ -79,8 +79,9 @@ export class ExportService {
      prosemirrorJson.content.unshift(titleNode);
    }

+    const pageHtml = jsonToHtml(prosemirrorJson);
+
    if (format === ExportFormat.HTML) {
-      const pageHtml = jsonToHtml(prosemirrorJson);
      return `<!DOCTYPE html>
      <html>
        <head>
@@ -91,14 +92,11 @@ export class ExportService {
    }

    if (format === ExportFormat.Markdown) {
-      // Direct ProseMirror JSON -> Markdown via the canonical converter
-      // (`@docmost/prosemirror-markdown`). This is the SAME serializer the
-      // git-sync vault writer feeds (see git-sync `stabilizePageBody`), so an
-      // exported page body is byte-identical to its vault representation — no
-      // HTML intermediate, no second markdown layer, no format drift (issue
-      // #345). The old `<colgroup>` scrub is gone with the HTML step: the
-      // converter emits GFM tables directly and never produces `<colgroup>`.
-      return convertProseMirrorToMarkdown(prosemirrorJson);
+      const newPageHtml = pageHtml.replace(
+        /<colgroup[^>]*>[\s\S]*?<\/colgroup>/gim,
+        '',
+      );
+      return htmlToMarkdown(newPageHtml);
    }

    return;
@@ -17,22 +17,6 @@ jest.mock('image-dimensions', () => ({
  __esModule: true,
  imageDimensionsFromData: () => undefined,
 }));
-// FileImportTaskService -> PageService -> collaboration.gateway ->
-// metrics.registry imports `prom-client`, which is not resolvable in this
-// workspace's node_modules (types-only stub, no runtime entry). Metrics are
-// disabled on this path, so a virtual no-op mock keeps the module graph loadable.
-jest.mock(
-  'prom-client',
-  () => ({
-    collectDefaultMetrics: () => undefined,
-    Registry: class {},
-    Histogram: class {},
-    Gauge: class {},
-    Counter: class {},
-    Summary: class {},
-  }),
-  { virtual: true },
-);

 import { promises as fs } from 'fs';
 import * as os from 'os';
@@ -42,17 +26,14 @@ import { ImportService } from './import.service';

 /**
 * Binding test for issue #228 / review #5: FileImportTaskService.processGenericImport
- * is a NON-editor write path, so a zip-imported `.md` page ends up with canonical
- * footnotes before persisting: ordered by first reference, reused refs deduped,
- * orphan definitions dropped.
+ * is a NON-editor write path (markdownToHtml -> processHTML -> JSON, never runs
+ * footnoteSyncPlugin), so it canonicalizes footnotes before persisting. This pins
+ * that binding — the same one import.service has a spec for — which previously had
+ * NO spec at all.
 *
- * Since #345 the `.md` parse runs `normalizeForeignMarkdown` ->
- * `markdownToProseMirror` -> `jsonToHtml` (feeding the shared HTML attachment /
- * link pipeline) -> `processHTML` -> `canonicalizeFootnotes`. The parser assigns
- * fresh `fn-*` ids, so we assert by definition BODY order rather than the source
- * labels. The conversion is REAL (a real ImportService, its createYdoc stubbed);
- * the filesystem is a real temp dir with one .md file; the DB transaction is
- * stubbed to capture the persisted page content.
+ * The markdown -> HTML -> ProseMirror conversion is REAL (a real ImportService,
+ * its createYdoc stubbed); the filesystem is a real temp dir with one .md file;
+ * the DB transaction is stubbed to capture the persisted page content.
 */

 // Out-of-order references (c, a, b), a REUSED reference ([^a] twice), and an
@@ -68,14 +49,13 @@ const MARKDOWN = [
  '[^z]: orphan note',
 ].join('\n');

-/** Definition body texts of the (single) footnotesList, in list order. */
-function footnoteListBodies(content: any): string[] {
+function footnoteListIds(content: any): string[] {
  const list = (content?.content ?? []).find(
    (n: any) => n.type === 'footnotesList',
  );
  return (list?.content ?? [])
    .filter((n: any) => n.type === 'footnoteDefinition')
-    .map((n: any) => n.content?.[0]?.content?.[0]?.text);
+    .map((n: any) => n.attrs?.id);
 }

 // A permissive chainable stub for the spaces lookup (selectFrom(...).select(...)
@@ -91,127 +71,80 @@ function chainable(result: any): any {
  return proxy;
 }

-/**
- * Run one markdown file through the REAL zip-import pipeline
- * (`processGenericImport` -> `markdownToProseMirror` -> `jsonToHtml` ->
- * `processHTML`/`htmlToJson`) and return the persisted page `content`. This is
- * the server-specific PM->HTML->PM hop that the package's own PM<->MD tests do
- * NOT cover.
- */
-async function runZipImport(markdown: string): Promise<any> {
-  const extractDir = await fs.mkdtemp(path.join(os.tmpdir(), 'fit-canon-'));
-  await fs.writeFile(path.join(extractDir, 'note.md'), markdown, 'utf-8');
-
-  const importService = new ImportService(
-    {} as any,
-    {} as any,
-    {} as any,
-    {} as any,
-  );
-  jest
-    .spyOn(importService as any, 'createYdoc')
-    .mockResolvedValue(Buffer.from([]) as any);
-
-  let captured: any = null;
-  const trx = {
-    insertInto: (table: string) => ({
-      values: (v: any) => {
-        if (table === 'pages') captured = v;
-        return { execute: async () => {} };
-      },
-    }),
-  };
-  const db: any = {
-    selectFrom: () => chainable({ slug: 'space-slug' }),
-    transaction: () => ({ execute: (fn: any) => fn(trx) }),
-  };
-
-  const importAttachmentService = {
-    processAttachments: async ({ html }: any) => html,
-  };
-  const service = new FileImportTaskService(
-    {} as any, // storageService
-    importService as any,
-    { nextPagePosition: async () => 'a0' } as any,
-    { insertBacklink: jest.fn() } as any,
-    db,
-    importAttachmentService as any,
-    { emit: jest.fn() } as any,
-    { logBatchWithContext: jest.fn() } as any,
-  );
-
-  const fileTask: any = {
-    id: 'task-1',
-    source: 'generic',
-    spaceId: 'space-1',
-    workspaceId: 'ws-1',
-    creatorId: 'user-1',
-  };
-
-  try {
-    await service.processGenericImport({ extractDir, fileTask });
-    expect(captured).toBeTruthy();
-    return captured.content;
-  } finally {
-    await fs.rm(extractDir, { recursive: true, force: true });
-  }
-}
-
-/** Find the first node of a given type anywhere in a PM content tree. */
-function findFirst(node: any, type: string): any {
-  if (!node || typeof node !== 'object') return null;
-  if (node.type === type) return node;
-  for (const child of node.content ?? []) {
-    const hit = findFirst(child, type);
-    if (hit) return hit;
-  }
-  return null;
-}
-
 describe('FileImportTaskService.processGenericImport — footnote canonicalization (#228)', () => {
  it('orders footnotes by first reference, dedupes reuse, and drops orphans on zip import', async () => {
-    const content = await runZipImport(MARKDOWN);
-    // Definitions ordered by FIRST REFERENCE (C, A, B), NOT the markdown
-    // definition order (A, B, C). Ids are the parser's fresh `fn-*`, so pin
-    // the BODIES.
-    expect(footnoteListBodies(content)).toEqual(['note C', 'note A', 'note B']);
-    // Orphan [^z] dropped; reused [^a] collapses to one definition; one list.
-    expect(footnoteListBodies(content)).not.toContain('orphan note');
-    const lists = (content.content ?? []).filter(
-      (n: any) => n.type === 'footnotesList',
+    const extractDir = await fs.mkdtemp(path.join(os.tmpdir(), 'fit-canon-'));
+    await fs.writeFile(path.join(extractDir, 'note.md'), MARKDOWN, 'utf-8');
+
+    // Real ImportService for the html -> JSON conversion; stub the yjs encode.
+    const importService = new ImportService(
+      {} as any,
+      {} as any,
+      {} as any,
+      {} as any,
    );
-    expect(lists).toHaveLength(1);
-    expect(
-      footnoteListBodies(content).filter((b) => b === 'note A'),
-    ).toHaveLength(1);
-  });
+    jest
+      .spyOn(importService as any, 'createYdoc')
+      .mockResolvedValue(Buffer.from([]) as any);

-  // #345 F4: the zip path routes markdown through jsonToHtml -> processHTML ->
-  // htmlToJson (the shared HTML attachment pipeline). #345's headline is LOSSLESS
-  // image width/align via the `<!--img {...}-->` comment; a callout carries its
-  // `type`. This asserts those survive the PM->HTML->PM hop — the one hop the
-  // package's PM<->MD suite does not exercise.
-  it('preserves image width/align and callout type through the PM->HTML->PM hop', async () => {
-    const md = [
-      '# Doc',
-      '',
-      '![a picture](https://example.com/i.png) <!--img {"width":"320","align":"left"}-->',
-      '',
-      ':::warning',
-      'Careful now.',
-      ':::',
-    ].join('\n');
+    let captured: any = null;
+    const trx = {
+      insertInto: (table: string) => ({
+        values: (v: any) => {
+          if (table === 'pages') captured = v;
+          return { execute: async () => {} };
+        },
+      }),
+    };
+    const db: any = {
+      selectFrom: () => chainable({ slug: 'space-slug' }),
+      transaction: () => ({ execute: (fn: any) => fn(trx) }),
+    };

-    const content = await runZipImport(md);
+    const importAttachmentService = {
+      processAttachments: async ({ html }: any) => html,
+    };
+    const backlinkRepo = { insertBacklink: jest.fn() };
+    const eventEmitter = { emit: jest.fn() };
+    const auditService = { logBatchWithContext: jest.fn() };

-    const image = findFirst(content, 'image');
-    expect(image).toBeTruthy();
-    // The lossless sizing/alignment must survive the HTML hop.
-    expect(String(image.attrs?.width)).toBe('320');
-    expect(image.attrs?.align).toBe('left');
+    const pageService = { nextPagePosition: async () => 'a0' };

-    const callout = findFirst(content, 'callout');
-    expect(callout).toBeTruthy();
-    expect(callout.attrs?.type).toBe('warning');
+    const service = new FileImportTaskService(
+      {} as any, // storageService
+      importService as any,
+      pageService as any,
+      backlinkRepo as any,
+      db,
+      importAttachmentService as any,
+      eventEmitter as any,
+      auditService as any,
+    );
+
+    const fileTask: any = {
+      id: 'task-1',
+      source: 'generic',
+      spaceId: 'space-1',
+      workspaceId: 'ws-1',
+      creatorId: 'user-1',
+    };
+
+    try {
+      await service.processGenericImport({ extractDir, fileTask });
+
+      expect(captured).toBeTruthy();
+      const content = captured.content;
+      // Reference order is c, a, b (NOT the markdown definition order a, b, c).
+      expect(footnoteListIds(content)).toEqual(['c', 'a', 'b']);
+      // Orphan [^z] dropped; reused [^a] collapses to one definition; one list.
+      expect(footnoteListIds(content)).not.toContain('z');
+      const lists = (content.content ?? []).filter(
+        (n: any) => n.type === 'footnotesList',
+      );
+      expect(lists).toHaveLength(1);
+      expect(footnoteListIds(content).filter((id) => id === 'a')).toHaveLength(1);
+    } finally {
+      await fs.rm(extractDir, { recursive: true, force: true });
+    }
  });
 });
@@ -1,9 +1,6 @@
 import { Inject, Injectable, Logger } from '@nestjs/common';
 import * as path from 'path';
-import {
-  jsonToHtml,
-  jsonToText,
-} from '../../../collaboration/collaboration.util';
+import { jsonToText } from '../../../collaboration/collaboration.util';
 import { InjectKysely } from 'nestjs-kysely';
 import { KyselyDB } from '@docmost/db/types/kysely.types';
 import {
@@ -21,11 +18,9 @@ import { generateSlugId } from '../../../common/helpers';
 import { v7 } from 'uuid';
 import { generateJitteredKeyBetween } from 'fractional-indexing-jittered';
 import { FileTask, InsertablePage } from '@docmost/db/types/entity.types';
-import { canonicalizeFootnotes } from '@docmost/editor-ext';
-import { markdownToProseMirror } from '@docmost/prosemirror-markdown';
+import { markdownToHtml, canonicalizeFootnotes } from '@docmost/editor-ext';
 import { getProsemirrorContent } from '../../../common/helpers/prosemirror/utils';
 import { formatImportHtml } from '../utils/import-formatter';
-import { normalizeForeignMarkdown } from '../utils/foreign-markdown';
 import {
  buildAttachmentCandidates,
  collectMarkdownAndHtmlFiles,
@@ -466,18 +461,7 @@ export class FileImportTaskService {
              content = await fs.readFile(absPath, 'utf-8');

              if (page.fileExtension.toLowerCase() === '.md') {
-                // Parse markdown with the single canonical converter
-                // (`@docmost/prosemirror-markdown`), after normalizing foreign
-                // reference footnotes, then serialize to HTML so the shared HTML
-                // pipeline below (processAttachments + formatImportHtml +
-                // processHTML) keeps handling `.md` and `.html` imports
-                // uniformly. The markdown PARSE no longer goes through the
-                // editor-ext markdown layer (issue #345) — the drift source is
-                // gone. The PM -> HTML -> PM hop that follows is lossless
-                // plumbing for attachment/link resolution, NOT a second parse.
-                content = jsonToHtml(
-                  await markdownToProseMirror(normalizeForeignMarkdown(content)),
-                );
+                content = await markdownToHtml(content);
              }
            } catch (err: any) {
              if (err?.code === 'ENOENT') {
@@ -516,12 +500,10 @@ export class FileImportTaskService {
              this.importService.extractTitleAndRemoveHeading(pmState);

            // Canonicalize footnote topology on this non-editor write path
-            // (the HTML pipeline's processHTML never runs footnoteSyncPlugin), so
-            // a zip-imported page's footnotes are reference-ordered, deduped, and
+            // (markdownToHtml/processHTML never runs footnoteSyncPlugin), so a
+            // zip-imported page's footnotes are reference-ordered, deduped, and
            // orphan-free like the editor's invariant (issue #228). Pure +
-            // idempotent + shape-safe; a footnote-free doc is unchanged. (For a
-            // `.md` file the package parser already yields canonical footnotes,
-            // so this is a no-op there.)
+            // idempotent + shape-safe; a footnote-free doc is unchanged.
            // (Future consolidation, architecture B: like import.service, this
            // path persists directly rather than via PageService — a shared
            // "prepare JSON for persist" helper would centralize this call.)
@@ -12,19 +12,13 @@ import { canonicalizeFootnotes } from '@docmost/editor-ext';

 /**
 * Integration-ish test for the USER-FACING markdown import path
- * (`ImportService.importPage`). It exercises the REAL markdown -> ProseMirror
- * conversion and asserts the stored page's footnotes are canonical: ordered by
- * FIRST REFERENCE (not markdown definition order), reused references deduped to a
- * single definition, and orphan definitions dropped.
- *
- * Since #345 the markdown parse runs through the canonical package
- * (`normalizeForeignMarkdown` -> `markdownToProseMirror`), which owns this
- * canonicalization: the input's GFM `[^id]` reference footnotes are normalized to
- * inline `^[…]`, and the parser assigns fresh sequential ids (`fn-*`) in
- * reference order while merging identical bodies — so we assert by definition
- * BODY order, not by the source labels. `canonicalizeFootnotes` remains wired as
- * an idempotent safety net (issue #228) and is a no-op on this already-canonical
- * output.
+ * (`ImportService.importPage`). It exercises the REAL markdown -> HTML -> JSON
+ * conversion and asserts that the stored page content has its footnotes
+ * canonicalized — the gap that issue #228 fixes: the import path builds
+ * ProseMirror JSON directly (never running the editor's footnoteSyncPlugin), so
+ * before this wiring the stored footnotes kept the markdown's physical
+ * definition order (out of order vs. references), retained orphan definitions,
+ * and did not collapse reused references.
 *
 * The DB/ydoc side-effects are stubbed: `getNewPagePosition` (DB query) and
 * `createYdoc` (Yjs encode) are spied, and `pageRepo.insertPage` captures the
@@ -73,14 +67,24 @@ function makeService() {
 }

 /** List the footnote-definition ids of the (single) footnotesList, in order. */
-/** Definition body texts of the (single) footnotesList, in list order. */
-function footnoteListBodies(content: any): string[] {
+function footnoteListIds(content: any): string[] {
  const list = (content.content ?? []).find(
    (n: any) => n.type === 'footnotesList',
  );
-  return (list?.content ?? [])
+  if (!list) return [];
+  return (list.content ?? [])
    .filter((n: any) => n.type === 'footnoteDefinition')
-    .map((n: any) => n.content?.[0]?.content?.[0]?.text);
+    .map((n: any) => n.attrs?.id);
+}
+
+function definitionText(content: any, id: string): string | undefined {
+  const list = (content.content ?? []).find(
+    (n: any) => n.type === 'footnotesList',
+  );
+  const def = (list?.content ?? []).find(
+    (n: any) => n.type === 'footnoteDefinition' && n.attrs?.id === id,
+  );
+  return def?.content?.[0]?.content?.[0]?.text;
 }

 describe('ImportService.importPage — footnote canonicalization (#228)', () => {
@@ -97,23 +101,23 @@ describe('ImportService.importPage — footnote canonicalization (#228)', () =>
    const content = getCaptured().content;
    expect(content).toBeTruthy();

-    // Definitions ordered by FIRST REFERENCE (C, A, B) — NOT the markdown
-    // definition order (A, B, C) — with the orphan [^z] dropped and the reused
-    // [^a] collapsed to a single definition. (Ids are the parser's fresh `fn-*`,
-    // so we pin the BODIES.)
-    expect(footnoteListBodies(content)).toEqual(['note C', 'note A', 'note B']);
+    // Reference order is c, a, b (NOT the markdown definition order a, b, c).
+    expect(footnoteListIds(content)).toEqual(['c', 'a', 'b']);
+
+    // Definitions preserved and attached to the right ids.
+    expect(definitionText(content, 'c')).toBe('note C');
+    expect(definitionText(content, 'a')).toBe('note A');
+    expect(definitionText(content, 'b')).toBe('note B');

    // Orphan definition [^z] is dropped.
-    expect(footnoteListBodies(content)).not.toContain('orphan note');
+    expect(footnoteListIds(content)).not.toContain('z');

    // Reused [^a] yields exactly ONE definition, and exactly one list.
    const lists = (content.content ?? []).filter(
      (n: any) => n.type === 'footnotesList',
    );
    expect(lists).toHaveLength(1);
-    expect(
-      footnoteListBodies(content).filter((b) => b === 'note A'),
-    ).toHaveLength(1);
+    expect(footnoteListIds(content).filter((id) => id === 'a')).toHaveLength(1);
  });

  it('is idempotent: canonicalizing the stored output again is a no-op', async () => {
@@ -130,6 +134,6 @@ describe('ImportService.importPage — footnote canonicalization (#228)', () =>
    // time must not change it (safe to wire into every write path).
    const second = canonicalizeFootnotes(stored);
    expect(second).toEqual(stored);
-    expect(footnoteListBodies(second)).toEqual(['note C', 'note A', 'note B']);
+    expect(footnoteListIds(second)).toEqual(['c', 'a', 'b']);
  });
 });
@@ -17,9 +17,7 @@ import {
 import { generateJitteredKeyBetween } from 'fractional-indexing-jittered';
 import { TiptapTransformer } from '@hocuspocus/transformer';
 import * as Y from 'yjs';
-import { canonicalizeFootnotes } from '@docmost/editor-ext';
-import { markdownToProseMirror } from '@docmost/prosemirror-markdown';
-import { normalizeForeignMarkdown } from '../utils/foreign-markdown';
+import { markdownToHtml, canonicalizeFootnotes } from '@docmost/editor-ext';
 import {
  FileTaskStatus,
  FileTaskType,
@@ -87,13 +85,11 @@ export class ImportService {

    const extracted = this.extractTitleAndRemoveHeading(prosemirrorState);
    const title = extracted.title;
-    // The markdown path now canonicalizes footnotes itself (the package parser),
-    // but the HTML path (processHTML -> htmlToJson) does NOT run the editor's
-    // footnoteSyncPlugin, so an imported HTML doc can keep its source's PHYSICAL
-    // definition order (out of order vs. references), retain orphan definitions,
-    // and not be deduped. Canonicalize before persisting so the stored page
-    // matches the editor's invariant (issue #228); it is an idempotent no-op on
-    // the already-canonical markdown output.
+    // Imported markdown/HTML is built via markdownToHtml -> htmlToJson, which
+    // never runs the editor's footnoteSyncPlugin, so the footnote topology keeps
+    // the source's PHYSICAL definition order (out of order vs. references),
+    // retains orphan definitions, and is not deduped. Canonicalize before
+    // persisting so the stored page matches the editor's invariant (issue #228).
    // Pure + idempotent + shape-safe: a doc with no footnotes is unchanged.
    // (Future consolidation, architecture B: this import path persists directly
    // via pageRepo.insertPage rather than through PageService.createPage, so the
@@ -137,15 +133,12 @@ export class ImportService {
  }

  async processMarkdown(markdownInput: string): Promise<any> {
-    // Canonical markdown -> ProseMirror JSON directly via
-    // `@docmost/prosemirror-markdown` (issue #345) — no HTML intermediate and no
-    // second editor-ext markdown layer. Foreign markdown surfaces the strict
-    // canonical parser does not accept (GFM `[^id]` reference footnotes) are
-    // rewritten to the canonical inline form by `normalizeForeignMarkdown` first.
-    // The HTML-cleanup pass (`normalizeImportHtml`) is intentionally skipped here:
-    // it targets foreign *HTML* (Notion/XWiki), which only ever arrives on the
-    // `.html` path (`processHTML`), never as canonical markdown.
-    return markdownToProseMirror(normalizeForeignMarkdown(markdownInput));
+    try {
+      const html = await markdownToHtml(markdownInput);
+      return this.processHTML(html);
+    } catch (err) {
+      throw err;
+    }
  }

  async processHTML(htmlInput: string): Promise<any> {
@@ -1,218 +0,0 @@
-import {
-  convertProseMirrorToMarkdown,
-  markdownToProseMirror,
-} from '@docmost/prosemirror-markdown';
-import { normalizeForeignMarkdown } from './foreign-markdown';
-
-/**
- * STEP 2 goldens for issue #345: the foreign-markdown normalizer that runs at the
- * import boundary BEFORE the strict canonical parser (`markdownToProseMirror`).
- *
- * Two layers:
- *  1. PURE string→string cases pinning the normalizer's own behavior (GFM
- *     reference footnotes → inline `^[…]`).
- *  2. END-TO-END acceptance: for a foreign corpus, `normalizeForeignMarkdown`
- *     then `markdownToProseMirror` then `convertProseMirrorToMarkdown` must leave
- *     NO literal `[^id]` / `:::` garbage in the document and must re-export in the
- *     canonical forms.
- */
-
-describe('normalizeForeignMarkdown — GFM reference footnotes', () => {
-  it('inlines a single-line reference footnote and drops its definition', () => {
-    const out = normalizeForeignMarkdown(
-      'A note[^1] here.\n\n[^1]: The definition.',
-    );
-    expect(out).toBe('A note^[The definition.] here.\n');
-  });
-
-  it('inlines every reference to a reused id (downstream dedups)', () => {
-    const out = normalizeForeignMarkdown(
-      'X[^a] and Y[^a].\n\n[^a]: shared.',
-    );
-    expect(out).toBe('X^[shared.] and Y^[shared.].\n');
-  });
-
-  it('joins indented continuation lines of a definition with a space', () => {
-    const out = normalizeForeignMarkdown(
-      'See[^n].\n\n[^n]: line one\n    line two',
-    );
-    expect(out).toBe('See^[line one line two].\n');
-  });
-
-  it('never rewrites a reference inside a fenced code block', () => {
-    const out = normalizeForeignMarkdown(
-      '```\ncode[^1] here\n```\n\n[^1]: def.',
-    );
-    expect(out).toContain('code[^1] here');
-    // The (now orphaned) definition line is still removed.
-    expect(out).not.toContain('[^1]: def.');
-  });
-
-  it('never rewrites a reference inside an INLINE-code span (backticks)', () => {
-    // The `[^1]` inside backticks is literal code and must survive verbatim;
-    // the one outside is rewritten. (Bug #1: only fenced blocks were protected.)
-    const out = normalizeForeignMarkdown(
-      'Use `arr[^1]` in code but note[^1] in prose.\n\n[^1]: def.',
-    );
-    expect(out).toBe('Use `arr[^1]` in code but note^[def.] in prose.\n');
-  });
-
-  it('escapes brackets in a body so an unbalanced ] cannot truncate the footnote', () => {
-    // A foreign definition body with a stray `]` would, unescaped, close the
-    // canonical `^[...]` early and leak the tail as text (bug #2). The body's
-    // brackets are backslash-escaped so the footnote stays whole.
-    const out = normalizeForeignMarkdown(
-      'Ref[^1] here.\n\n[^1]: see item ] and [more] later',
-    );
-    expect(out).toBe('Ref^[see item \\] and \\[more\\] later] here.\n');
-    // The tokenizer must see exactly one unescaped closing bracket (our own).
-    expect(out.match(/(?<!\\)\]/g)).toHaveLength(1);
-  });
-
-  it('leaves a reference with no matching definition literal (no body to inline)', () => {
-    const out = normalizeForeignMarkdown('Dangling[^x] ref.');
-    expect(out).toBe('Dangling[^x] ref.');
-  });
-
-  it('returns the input unchanged when there are no reference footnotes', () => {
-    const md = '# Title\n\nJust text with `inline code` and a [link](/x).';
-    expect(normalizeForeignMarkdown(md)).toBe(md);
-  });
-
-  it('does NOT touch callout surfaces — the canonical parser handles them', () => {
-    const callouts = ':::info\nHi\n:::\n\n> [!warning]\n> Careful';
-    expect(normalizeForeignMarkdown(callouts)).toBe(callouts);
-  });
-
-  it('strips a leading YAML front-matter block (Obsidian/Hugo/git-sync files)', () => {
-    const out = normalizeForeignMarkdown(
-      '---\ntitle: My Page\ntags: [a, b]\n---\n\n# Heading\n\nBody.',
-    );
-    expect(out).toBe('# Heading\n\nBody.');
-    // The front-matter must not leak into the body as a setext heading.
-    expect(out).not.toContain('title: My Page');
-    expect(out).not.toContain('---');
-  });
-
-  it('does not strip a horizontal rule that is not leading front-matter', () => {
-    const md = 'Intro paragraph.\n\n---\n\nAfter the rule.';
-    expect(normalizeForeignMarkdown(md)).toBe(md);
-  });
-
-  it('is linear on a document with thousands of definitions (no quadratic blowup)', () => {
-    // F2(a): the pass-2 rewrite must be O(text), not O(text × defs). Build a
-    // pathological doc (many defs + many plain text lines) and assert it
-    // completes well under a second — a quadratic implementation took ~14s.
-    const N = 4000;
-    const refs = Array.from({ length: N }, (_, i) => `line ${i} plain text`).join('\n');
-    const defs = Array.from({ length: N }, (_, i) => `[^n${i}]: def ${i}`).join('\n');
-    const doc = `start[^n0] and[^n${N - 1}] end\n\n${refs}\n\n${defs}`;
-    const t0 = Date.now();
-    const out = normalizeForeignMarkdown(doc);
-    const elapsed = Date.now() - t0;
-    expect(elapsed).toBeLessThan(2000);
-    // Sanity: the two real references were still inlined.
-    expect(out).toContain('^[def 0]');
-    expect(out).toContain(`^[def ${N - 1}]`);
-  });
-
-  it('is bounded on a long unclosed backtick run (no inline-split ReDoS)', () => {
-    // F2(b): a huge unterminated backtick run must not cause quadratic
-    // backtracking in the inline-code split. Oversized lines skip the split
-    // entirely (left untouched), so this returns promptly.
-    const line = 'x' + '`'.repeat(200000);
-    const doc = `${line}\n\n[^1]: def`;
-    const t0 = Date.now();
-    normalizeForeignMarkdown(doc);
-    expect(Date.now() - t0).toBeLessThan(2000);
-  });
-
-  it('does not crash or slow down on thousands of prefix-chain definition ids', () => {
-    // F7: the rewrite must use a FIXED generic scanner, not an alternation built
-    // from the ids. A `(a|aa|aaa|…)` alternation over prefix-chain ids blows the
-    // V8 regex compiler (FATAL RegExpCompiler Allocation failed — uncatchable,
-    // kills the process). A fixed scanner has no id-dependent compilation cost.
-    const N = 4000;
-    const ids = Array.from({ length: N }, (_, i) => 'a'.repeat(i + 1));
-    const defs = ids.map((id) => `[^${id}]: body ${id.length}`).join('\n');
-    const doc = `ref[^${ids[0]}] and[^${ids[N - 1]}] end\n\n${defs}`;
-    const t0 = Date.now();
-    const out = normalizeForeignMarkdown(doc);
-    expect(Date.now() - t0).toBeLessThan(2000);
-    // Prefix disambiguation is correct: [^a] and [^aaaa...] inline their OWN body.
-    expect(out).toContain('^[body 1]');
-    expect(out).toContain(`^[body ${N}]`);
-  });
-
-  it('strips a CRLF (Windows) front-matter block, not just LF', () => {
-    // F9: the line-anchored regex needs LF after the opening `---`, so a Windows
-    // file (`---\r\n…`) would slip past the strip and leak the front-matter into
-    // the body. normalizeForeignMarkdown normalizes CRLF -> LF first.
-    const out = normalizeForeignMarkdown(
-      '---\r\ntitle: Foo\r\ntags: [a]\r\n---\r\n\r\n# Heading\r\n\r\nBody.',
-    );
-    expect(out).toBe('# Heading\n\nBody.');
-    expect(out).not.toContain('title: Foo');
-    expect(out).not.toContain('---');
-  });
-
-  it('strips front-matter whose value contains a triple-dash (line-anchored)', () => {
-    // F8: the block must close only on a `\n---` LINE, not the first inline
-    // `---`. A value like `title: Q1 --- Q2` must not truncate the front-matter
-    // and leak the rest (author/closing ---) into the body.
-    const out = normalizeForeignMarkdown(
-      '---\ntitle: Q1 --- Q2 results\nauthor: bob\n---\n\nReal body.',
-    );
-    expect(out).toBe('Real body.');
-    expect(out).not.toContain('author: bob');
-    expect(out).not.toContain('Q2 results');
-  });
-});
-
-describe('foreign markdown import acceptance (normalizer + canonical parser)', () => {
-  const FOREIGN = [
-    '# Doc',
-    '',
-    'Body refs [^c] and [^a] and [^b] and again [^a].',
-    '',
-    ':::info',
-    'A legacy callout.',
-    ':::',
-    '',
-    '| h1 | h2 |',
-    '| --- | --- |',
-    '| 1 | 2 |',
-    '',
-    '[^a]: note A',
-    '[^b]: note B',
-    '[^c]: note C',
-    '[^z]: orphan note',
-  ].join('\n');
-
-  it('leaves no literal [^id] or ::: in the imported doc and re-exports canonically', async () => {
-    const normalized = normalizeForeignMarkdown(FOREIGN);
-    const doc = await markdownToProseMirror(normalized);
-    const reexport = convertProseMirrorToMarkdown(doc);
-
-    // No foreign garbage leaks into the document.
-    expect(reexport).not.toMatch(/\[\^/); // no reference footnote refs/defs
-    expect(reexport).not.toContain(':::'); // no legacy callout fences
-
-    // Canonical forms are present.
-    expect(reexport).toContain('^[note C]');
-    expect(reexport).toContain('> [!info]');
-    expect(reexport).toContain('| h1 | h2 |');
-
-    // Footnotes: ordered by first reference (C, A, B), reused [^a] deduped to one,
-    // orphan [^z] dropped (it had no reference after normalization).
-    const list = doc.content.find((n: any) => n.type === 'footnotesList');
-    const bodies = list.content.map(
-      (d: any) => d.content[0].content[0].text,
-    );
-    expect(bodies).toEqual(['note C', 'note A', 'note B']);
-    expect(bodies).not.toContain('orphan note');
-    expect(
-      doc.content.filter((n: any) => n.type === 'footnotesList'),
-    ).toHaveLength(1);
-  });
-});
@@ -1,265 +0,0 @@
-/**
- * Foreign-markdown normalizer — an input-liberal / output-canonical adapter that
- * runs at the IMPORT boundary, BEFORE the canonical parser
- * (`markdownToProseMirror` from `@docmost/prosemirror-markdown`).
- *
- * The canonical parser is deliberately STRICT: it only understands Docmost's
- * canonical markdown surface (Obsidian-style `> [!type]` callouts, Pandoc/Obsidian
- * inline footnotes `^[body]`, lossless `![alt](src) <!--img {...}-->` images, …).
- * Import, however, ingests FOREIGN files (GitHub/GFM, Notion, old Docmost
- * exports). Those use surfaces the canonical parser does not accept, most notably
- * GitHub-flavoured *reference* footnotes:
- *
- *     Text with a note[^1] and another[^long].
- *
- *     [^1]: The first definition.
- *     [^long]: A second one.
- *
- * Left untouched, the parser does NOT recognise `[^id]` (it only parses `^[body]`),
- * so the reference leaks as literal text — and worse, the trailing `[^id]: def`
- * line is a valid CommonMark *link-reference definition*, so `[^id]` is silently
- * rendered as a bogus link. This normalizer rewrites reference footnotes into the
- * canonical inline form so the parser materialises real footnote nodes.
- *
- * This is a TEXT pre-pass, NOT a second parser fork: it does not re-implement any
- * converter logic. Callout surfaces (`:::type` and `> [!type]`) are intentionally
- * NOT touched here — the canonical parser already accepts BOTH natively (its
- * `preprocessCallouts` pass), so normalizing them would be redundant and would
- * only risk degrading the parser's nesting/code-fence-aware handling.
- */
-
-/** Matches a fenced code block delimiter (``` or ~~~), capturing the marker run. */
-const CODE_FENCE_RE = /^(\s*)(`{3,}|~{3,})/;
-
-/**
- * Matches a GFM footnote DEFINITION line: `[^id]: body`. The id is any run of
- * non-`]` characters; the body is the remainder of the line (possibly empty).
- */
-const FOOTNOTE_DEF_RE = /^\[\^([^\]]+)\]:[ \t]?(.*)$/;
-
-/** True when a line is a code-fence delimiter that toggles fenced-code state. */
-function fenceMarker(line: string): string | null {
-  const m = line.match(CODE_FENCE_RE);
-  return m ? m[2] : null;
-}
-
-/** True when a line is indented (leading space/tab) and not blank — a continuation. */
-function isIndentedContinuation(line: string): boolean {
-  return /^[ \t]+\S/.test(line);
-}
-
-function escapeRegExp(value: string): string {
-  return value.replace(/[.*+?^${}()|[\]\\]/g, '\\$&');
-}
-
-/**
- * Backslash-escape any square bracket in a footnote body before it is wrapped in
- * `^[...]`. The canonical inline-footnote tokenizer scans the body with bracket
- * balancing and closes on the first UNMATCHED `]`, so an unbalanced bracket in a
- * foreign definition (e.g. `[^1]: see item ] later`) would otherwise truncate the
- * footnote and leak the tail as literal text. Escaping every `[`/`]` makes the
- * body an inert run of characters — the tokenizer then closes only on our own
- * closing `]`. (A balanced `[link](url)` inside a body still round-trips because
- * the escaped form renders the literal brackets, which is the safe reading for a
- * footnote body; the alternative — brittle balance tracking — risks worse.)
- */
-function escapeFootnoteBody(body: string): string {
-  return body.replace(/[[\]]/g, '\\$&');
-}
-
-/**
- * Rewrite every `[^id]` reference on a line to its `^[body]` form, but ONLY in the
- * text OUTSIDE inline-code spans. A `[^id]` inside backticks is literal code
- * content and must be preserved verbatim (a footnote ref never lives inside code).
- * We split the line on inline-code spans (paired backtick runs) and rewrite only
- * the non-code segments.
- */
-// Above this length a single line is not split into inline-code spans (see
-// below). A genuine markdown line carrying a footnote reference is never tens of
-// KB; the cap only bypasses the inline-code protection for pathological lines.
-const INLINE_SPLIT_MAX_LINE = 8192;
-
-function rewriteRefsOutsideInlineCode(
-  line: string,
-  replace: (text: string) => string,
-): string {
-  // The inline-code split alternation `(`+)(?:(?!\1)[\s\S])*\1` backtracks
-  // quadratically on a long UNCLOSED backtick run (its middle can consume the
-  // rest of the line, then fail to find a closing run and retry from each
-  // position). On an untrusted import this is a request-thread ReDoS. A real
-  // footnote line is short, so for an oversized line we skip the inline-code
-  // protection entirely and leave the line UNTOUCHED (rewriting it wholesale
-  // could corrupt a `[^id]` that legitimately lives inside inline code). This is
-  // a conservative bypass: an over-8KB line simply does not get its reference
-  // footnotes inlined — acceptable for a pathological input.
-  if (line.length > INLINE_SPLIT_MAX_LINE) return line;
-
-  // Alternation: an inline-code span (one or more backticks, then anything up to
-  // the SAME run of backticks) OR a run of non-backtick text. Unterminated
-  // backticks fall through as ordinary text (matched by the second branch on the
-  // leftover), so a stray backtick never swallows the rest of the line.
-  const parts = line.match(/(`+)(?:(?!\1)[\s\S])*\1|[^`]+|`+/g);
-  if (!parts) return line;
-  return parts
-    .map((seg) => (seg.startsWith('`') ? seg : replace(seg)))
-    .join('');
-}
-
-/**
- * Convert GFM reference footnotes (`[^id]` + `[^id]: def`) into canonical inline
- * footnotes (`^[def]`).
- *
- * - Definitions are collected first (a leading `[^id]: text` line plus any
- *   immediately-following indented continuation lines, joined with a space) and
- *   removed from the output.
- * - Each in-text reference `[^id]` for which a definition was found is replaced by
- *   `^[def]`. References with no matching definition are left literal (there is no
- *   body to inline; the parser fails them open the same way).
- * - Code is respected on both passes: `[^id]` inside a fenced ``` / ~~~ block is
- *   never rewritten and a `[^id]:` line inside a fence is never a definition; and
- *   on the rewrite pass a `[^id]` inside an INLINE-code span (backticks) is left
- *   literal too.
- * - The inlined body is bracket-escaped so an unbalanced `[`/`]` in a foreign
- *   definition cannot truncate the resulting `^[...]` footnote.
- *
- * Deduplication / reference-ordering / orphan-dropping of the resulting footnotes
- * is handled downstream by the canonical parser (`assembleFootnotes`); this pass
- * only changes the surface syntax.
- */
-function convertReferenceFootnotes(markdown: string): string {
-  const lines = markdown.split('\n');
-
-  // Pass 1: collect definitions and mark their lines for removal.
-  const defs = new Map<string, string>();
-  const dropped = new Array<boolean>(lines.length).fill(false);
-  let inFence = false;
-  let fence = '';
-
-  for (let i = 0; i < lines.length; i++) {
-    const line = lines[i];
-    const marker = fenceMarker(line);
-    if (inFence) {
-      if (marker && marker[0] === fence[0] && marker.length >= fence.length) {
-        inFence = false;
-        fence = '';
-      }
-      continue;
-    }
-    if (marker) {
-      inFence = true;
-      fence = marker;
-      continue;
-    }
-
-    const def = line.match(FOOTNOTE_DEF_RE);
-    if (!def) continue;
-
-    const id = def[1];
-    const body: string[] = [def[2].trim()];
-    dropped[i] = true;
-
-    // Consume immediately-following indented continuation lines (GFM lazy
-    // continuation is not supported by design — keep it simple and predictable).
-    let j = i + 1;
-    while (j < lines.length && isIndentedContinuation(lines[j])) {
-      body.push(lines[j].trim());
-      dropped[j] = true;
-      j++;
-    }
-    i = j - 1;
-
-    // Last definition wins for a duplicated id (matches CommonMark link-ref
-    // semantics closely enough for a foreign-input adapter).
-    defs.set(id, body.filter((s) => s.length > 0).join(' '));
-  }
-
-  if (defs.size === 0) {
-    return markdown;
-  }
-
-  // ONE fixed, generic scanner regex — NOT one built from the definition ids.
-  // It matches ANY `[^id]` shape, and the replacer decides per match via a map
-  // lookup whether that id is a real definition (replace) or not (leave as-is).
-  // This is genuinely O(total text) with no per-document regex compilation.
-  //
-  // Do NOT rebuild this as an alternation over `[...defs.keys()]`: a giant
-  // `(id1|id2|...)` alternation over thousands of ids can blow the V8 regex
-  // compiler's stack — a fatal, UNCATCHABLE "RegExpCompiler Allocation failed"
-  // on prefix-chain ids (`a`, `aa`, `aaa`, ...) that kills the whole process
-  // (worse than the earlier per-def thread-hang). A fixed scanner has no
-  // id-dependent compilation cost and cannot blow up.
-  const refRe = /\[\^([^\]]+)\]/g;
-  const rewriteSegment = (segment: string): string =>
-    segment.replace(refRe, (whole, id: string) => {
-      const body = defs.get(id);
-      // Only real definitions are inlined; an unknown id is left literal (same as
-      // the old per-def loop, which simply never matched it).
-      return body === undefined ? whole : `^[${escapeFootnoteBody(body)}]`;
-    });
-
-  // Pass 2: rewrite in-text references, skipping fenced code and dropped lines.
-  const out: string[] = [];
-  inFence = false;
-  fence = '';
-  for (let i = 0; i < lines.length; i++) {
-    if (dropped[i]) continue;
-    let line = lines[i];
-
-    const marker = fenceMarker(line);
-    if (inFence) {
-      out.push(line);
-      if (marker && marker[0] === fence[0] && marker.length >= fence.length) {
-        inFence = false;
-        fence = '';
-      }
-      continue;
-    }
-    if (marker) {
-      inFence = true;
-      fence = marker;
-      out.push(line);
-      continue;
-    }
-
-    line = rewriteRefsOutsideInlineCode(line, rewriteSegment);
-    out.push(line);
-  }
-
-  return out.join('\n');
-}
-
-/**
- * Strip a single leading YAML front-matter block (`---\n…\n---`). Foreign files
- * from Obsidian / Hugo / Jekyll / Notion — and Docmost's OWN git-sync page files
- * — open with front-matter that the canonical parser does not consume, so
- * without this it leaks into the body (and `title: Foo` above the closing `---`
- * renders as a setext `<h2>` that `extractTitleAndRemoveHeading` can hijack as
- * the page title). It is a no-op for front-matter-free input.
- *
- * LINE-ANCHORED (the same shape the canonical parser uses in
- * prosemirror-markdown/page-file.ts): the block opens only on `---\n` at the
- * very start and closes only on a `\n---` line. The retired `markdownToHtml`
- * strip closed on the FIRST `---` ANYWHERE (an unanchored close), so a value
- * containing a triple-dash (e.g. `title: Q1 --- Q2`) truncated the front-matter
- * and leaked the rest into the body. An optional leading BOM is tolerated.
- */
-const YAML_FRONT_MATTER_RE = /^\uFEFF?---\n[\s\S]*?\n---\n?/;
-
-/**
- * Normalize a foreign markdown string into Docmost's canonical markdown surface
- * so the strict canonical parser accepts it losslessly: normalize line endings,
- * strip a leading YAML front-matter block, then rewrite GFM reference footnotes
- * into inline footnotes. Add further fixture-driven foreign-surface cases here as
- * they are found.
- */
-export function normalizeForeignMarkdown(markdown: string): string {
-  if (!markdown) return markdown;
-  // Normalize CRLF -> LF FIRST. The line-anchored front-matter regex requires a
-  // bare `\n` after the opening `---`, and convertReferenceFootnotes splits on
-  // `\n`; a Windows/CRLF foreign file (`---\r\n…`) would otherwise slip past the
-  // front-matter strip and leak into the body. The canonical parser
-  // (page-file.ts parsePageFile) normalizes the same way before its FRONTMATTER_RE.
-  const src = markdown.replace(/\r\n/g, '\n');
-  const withoutFrontMatter = src.replace(YAML_FRONT_MATTER_RE, '').trimStart();
-  return convertReferenceFootnotes(withoutFrontMatter);
-}
@@ -1,23 +0,0 @@
-// Jest stub for @tiptap/react.
-//
-// The server export/import code paths transitively import editor-ext, whose node
-// extensions import from `@tiptap/react`. The real module re-exports all of
-// `@tiptap/core` (headless, safe under node) AND adds React view helpers
-// (`ReactNodeViewRenderer`, …) that eagerly pull in react-dom — which throws
-// `navigator is not defined` under jest's node environment.
-//
-// So this stub DELEGATES to the real `@tiptap/core` (keeping `mergeAttributes`,
-// `Node`, `Mark`, `nodeInputRule`, … working — they are used by
-// `jsonToHtml`/`htmlToJson` on the server) and overrides ONLY the React view
-// helpers with no-ops. Those helpers are referenced solely inside `addNodeView()`
-// — code that runs only in a live browser editor, never on the server; if any
-// were actually invoked here it would (correctly) surface as a test failure.
-const core = require('@tiptap/core');
-
-module.exports = {
-  ...core,
-  ReactNodeViewRenderer: () => () => ({}),
-  NodeViewWrapper: () => null,
-  NodeViewContent: () => null,
-  ReactRenderer: class {},
-};
@@ -0,0 +1,16 @@
+{
+  "_bug": "BUG #351: a `column` whose `width` is a percentage string (e.g. \"50%\") is NOT byte-stable across export->import->export (violates P2). The `column` schema's parseHTML does `parseFloat(getAttribute('data-width'))`, which silently drops the '%' unit and returns the NUMBER 50. So the first export emits data-width=\"50%\" but the re-import stores width=50, and the second export emits data-width=\"50\": md2 !== md1, a permanent GS-EDIT-REVERT churn (every git-sync pull rewrites the column width). The editor authors column widths as percentages, so this is a real data/round-trip defect. Fix belongs in src/lib/docmost-schema.ts column.width parseHTML (preserve the unit / keep the string), which is OUT OF SCOPE for this test-only PR and must be a separate, maintainer-approved change. This flat generator therefore keeps `column.width` frozen (never generates a non-default width).",
+  "doc": {
+    "type": "doc",
+    "content": [
+      {
+        "type": "columns",
+        "attrs": { "layout": "two_equal", "widthMode": "normal" },
+        "content": [
+          { "type": "column", "attrs": { "width": "50%" }, "content": [{ "type": "paragraph", "content": [{ "type": "text", "text": "L" }] }] },
+          { "type": "column", "attrs": { "width": "50%" }, "content": [{ "type": "paragraph", "content": [{ "type": "text", "text": "R" }] }] }
+        ]
+      }
+    ]
+  }
+}
@@ -0,0 +1,19 @@
+{
+  "doc": {
+    "type": "doc",
+    "content": [
+      {
+        "type": "orderedList",
+        "attrs": { "type": null, "start": 5 },
+        "content": [
+          {
+            "type": "listItem",
+            "content": [
+              { "type": "paragraph", "content": [{ "type": "text", "text": "alpha" }] }
+            ]
+          }
+        ]
+      }
+    ]
+  }
+}
@@ -0,0 +1,325 @@
+/**
+ * Schema-DERIVED attribute-state fast-check arbitraries (#351, PR 1).
+ *
+ * This GENERALIZES the #350 stability-matrix helper (roundtrip-stability.helper.ts)
+ * to fast-check. Where that helper sweeps a HAND-WRITTEN 2-state matrix for one
+ * node spec, this module reads the attribute list straight from
+ * `schema.nodes[type].spec.attrs` (never a hand list) and, per attribute,
+ * generates over the FOUR states the issue calls for:
+ *
+ *   - `absent`      : the attribute is OMITTED entirely (the empty-string-vs-
+ *                     absent churn class the #350 fix targets).
+ *   - `default`     : the schema default value, authored explicitly.
+ *   - `nonDefault`  : a representative legal non-default value.
+ *   - `degenerate`  : `""` for strings, `0`/negative for numbers, the flipped
+ *                     value for booleans.
+ *
+ * ── Why a per-attribute override table ──────────────────────────────────────
+ * Everything that CAN be derived generically from the default's runtime type is
+ * (booleans flip; the degenerate value follows the runtime type). But two facts
+ * force a small, DOCUMENTED override table:
+ *
+ *  1. CONSTRAINED domains the schema does not encode. `image.align ∈
+ *     {left,center,right}`, `heading.level ∈ 1..6`, `callout.type ∈
+ *     {info,success,warning,danger}`, `columns.layout`, table-cell `align`,
+ *     `status.color`, `orderedList.start ≥ 1`, etc. A generic "default + 1"
+ *     would emit an ILLEGAL value, so these get an explicit legal domain.
+ *  2. ROUND-TRIP-safety, established EMPIRICALLY by probing the live converter
+ *     (the classification captured in flat-roundtrip.property.test.ts). A frozen
+ *     attribute falls into ONE of TWO explicitly-distinguished classes — never a
+ *     silent "it just doesn't round-trip":
+ *
+ *       (a) ACCEPTED LIMITATION — the attribute has NO markdown representation,
+ *           so the loss is inherent to targeting markdown, not a converter
+ *           defect. These: `paragraph`/`heading` `indent`, `callout.icon`,
+ *           `orderedList.type` (a/A/i markers), table `colwidth` /
+ *           `backgroundColor(Name)` (dropped by the raw-<table> fallback). Each is
+ *           tagged `// ACCEPTED:` inline. Freezing them is correct — there is
+ *           nothing to preserve in the target format.
+ *
+ *       (b) PINNED BUG — the attribute IS representable in markdown but the
+ *           converter drops it anyway (a real defect). These are NOT silently
+ *           frozen: each is captured as a LOUD `it.fails` counterexample in
+ *           test/fixtures/counterexamples/ + counterexamples.test.ts, and the
+ *           freeze here only keeps the P1/P2 union green until a MAINTAINER rules
+ *           on accept-vs-fix (the epic guardrail reserves that call). These:
+ *           `column.width` (parseFloat drops `%`), `orderedList.start` (non-1
+ *           start renders as `1.`). Tagged `// PINNED-BUG:` inline.
+ *
+ *       (c) DEFERRED-BUG — representable AND round-trips, frozen only because the
+ *           flat generator can't yet build a valid instance. Table
+ *           `colspan`/`rowspan` round-trip via the raw-<table> fallback, but a
+ *           geometrically-valid spanned table is PR-2 structural work; the flat
+ *           generator hardcodes span = 1. Tagged `// DEFERRED-BUG:` inline so a
+ *           maintainer does not read them as an inherent limitation.
+ *       - Several non-null-default attrs are MATERIALIZED on import but are not
+ *         in canonicalize's KNOWN_DEFAULTS (`callout.type`, `status.color`,
+ *         table `colspan`/`rowspan`, `columns.layout`/`widthMode`,
+ *         `embed.width`/`height`, `heading.level`, `taskItem.checked`,
+ *         `details.open`, `subpages.recursive`, `orderedList.start`). If left
+ *         `absent` they re-materialize as a non-canonical default and diverge
+ *         under P1. We mark them `always` so they are authored explicitly.
+ *       - The documented numeric→string coercion set (`width height size
+ *         aspectRatio`) is generated as STRINGS for the media family (a stored
+ *         number re-parses as a string), EXCEPT `embed.width/height` which the
+ *         embed schema keeps numeric — handled per-attr.
+ *
+ * Both PINNED-BUG attrs (`column.width` P2 churn, `orderedList.start` P1 loss)
+ * are captured as committed `it.fails` counterexamples — NOT hidden here.
+ */
+import fc from 'fast-check';
+import { getSchema } from '@tiptap/core';
+import { docmostExtensions } from '../../src/lib/index.js';
+import { phraseArb, letterPhraseArb, urlArb } from './text-arbitraries.js';
+
+/** The exact ProseMirror schema the converter targets. */
+export const schema = getSchema(docmostExtensions as any);
+
+/** Sentinel: this attribute is OMITTED (the `absent` state). */
+export const ABSENT = Symbol('ABSENT');
+
+/** The documented numeric→string coercion set (issue + roundtrip-stability.helper). */
+export const NUMERIC_STRING_ATTRS = ['width', 'height', 'size', 'aspectRatio'];
+
+/** Read the schema default for every attribute of a node type. */
+export function schemaAttrDefaults(type: string): Record<string, unknown> {
+  const specAttrs = (schema.nodes[type]?.spec?.attrs ?? {}) as Record<
+    string,
+    { default: unknown }
+  >;
+  const out: Record<string, unknown> = {};
+  for (const [k, v] of Object.entries(specAttrs)) out[k] = v.default;
+  return out;
+}
+
+/** Attribute names for a node type, straight from the schema (never hand-listed). */
+export function schemaAttrNames(type: string): string[] {
+  return Object.keys((schema.nodes[type]?.spec?.attrs ?? {}) as object);
+}
+
+/**
+ * Per-attribute policy. Everything unlisted falls back to a generic policy:
+ *   - a BOOLEAN default is fuzzable (its non-default is the flipped value);
+ *   - any other default is `frozen` (only `absent`/`default` are generated) so
+ *     we never invent an unverified non-default that might not round-trip.
+ * Listed attrs override this with a legal `arb` domain and/or flags.
+ */
+interface AttrPolicy {
+  /** Arbitrary for the `nonDefault` state's value. */
+  arb?: fc.Arbitrary<unknown>;
+  /** Value for the `degenerate` state (fuzz mode only). Omit to skip degenerate. */
+  degen?: unknown;
+  /** Never emit `absent` — the attr must be authored (materialized default class). */
+  always?: boolean;
+  /** Never emit the schema default value (required-ish attrs like `src`). Implies always. */
+  noDefault?: boolean;
+  /** Never emit non-default/degenerate — attr has no md representation or churns. */
+  frozen?: boolean;
+}
+
+const num = (...xs: number[]) => fc.constantFrom(...xs);
+const str = (...xs: string[]) => fc.constantFrom(...xs);
+const widthStr = str('120', '320', '640');
+
+// The documented override table, keyed `type.attr`. Every entry is grounded in
+// the empirical converter probe (see flat-roundtrip.property.test.ts header).
+const OVERRIDES: Record<string, AttrPolicy> = {
+  // ── block text containers ────────────────────────────────────────────────
+  // 'left' is the IMPLICIT default alignment: the converter drops it on export
+  // (empirically confirmed), so it never round-trips. Only center/right/justify
+  // carry through the `<!--attrs {textAlign}-->` comment.
+  'paragraph.textAlign': { arb: str('center', 'right', 'justify') },
+  'paragraph.indent': { frozen: true }, // ACCEPTED: no md representation
+  'heading.level': { always: true, arb: num(2, 3, 4, 5, 6) },
+  'heading.textAlign': { arb: str('center', 'right', 'justify') },
+  'heading.indent': { frozen: true }, // ACCEPTED: no md representation
+  // ── lists ────────────────────────────────────────────────────────────────
+  // PINNED-BUG: markdown CAN express a non-1 start ("5."), but the converter
+  // renders "1." and drops it -> P1 loss. See counterexamples.test.ts
+  // (ordered-list-start.json). Frozen only until the maintainer rules accept-vs-fix.
+  'orderedList.start': { always: true, frozen: true },
+  'orderedList.type': { frozen: true }, // ACCEPTED: a/A/i markers not expressible in GFM
+  'taskItem.checked': { always: true, arb: fc.constant(true) }, // boolean, default false
+  // ── codeBlock ────────────────────────────────────────────────────────────
+  'codeBlock.language': { arb: str('js', 'ts', 'python', 'go', 'rust', 'bash') },
+  // ── image / media (numeric→string width family) ──────────────────────────
+  'image.src': { noDefault: true, arb: urlArb, degen: '' },
+  'image.align': { arb: str('left', 'right') },
+  'image.alt': { arb: letterPhraseArb, degen: '' },
+  'image.title': { arb: letterPhraseArb },
+  'image.width': { arb: widthStr, degen: '' },
+  'image.height': { arb: widthStr, degen: '' },
+  'video.src': { noDefault: true, arb: urlArb, degen: '' },
+  'video.alt': { arb: letterPhraseArb },
+  'video.width': { arb: widthStr },
+  'video.height': { arb: widthStr },
+  'audio.src': { noDefault: true, arb: urlArb, degen: '' },
+  'youtube.src': { noDefault: true, arb: urlArb },
+  'pdf.src': { noDefault: true, arb: urlArb },
+  'pdf.name': { arb: phraseArb },
+  'drawio.src': { noDefault: true, arb: urlArb },
+  'excalidraw.src': { noDefault: true, arb: urlArb },
+  'attachment.url': { noDefault: true, arb: urlArb },
+  'attachment.name': { arb: phraseArb },
+  // ── callout / status ─────────────────────────────────────────────────────
+  'callout.type': { always: true, arb: str('success', 'warning', 'danger') },
+  'callout.icon': { frozen: true }, // ACCEPTED: no md representation (dropped on export)
+  'status.text': { noDefault: true, arb: phraseArb, degen: '' },
+  'status.color': { always: true, arb: str('green', 'orange', 'red', 'blue', 'yellow', 'purple') },
+  // ── table cells ────────────────────────────────────────────────────────────
+  // DEFERRED-BUG (not ACCEPTED): colspan/rowspan ARE representable and round-trip
+  // — a spanned cell makes the converter emit the whole table as a raw <table>
+  // with colspan/rowspan attrs (markdown-converter.ts tableToHtml), which the
+  // tiptap parser reads back. They are frozen only because generating a
+  // geometrically-valid spanned table is deferred STRUCTURAL work (the flat
+  // generator hardcodes colspan/rowspan = 1), NOT a markdown limitation.
+  'tableCell.colspan': { always: true, frozen: true },
+  'tableCell.rowspan': { always: true, frozen: true },
+  // ACCEPTED: colwidth / backgroundColor(Name) have no representation — the
+  // raw-<table> fallback (tableToHtml) drops them, so there is nothing to preserve.
+  'tableCell.colwidth': { frozen: true },
+  'tableCell.backgroundColor': { frozen: true },
+  'tableCell.backgroundColorName': { frozen: true },
+  'tableCell.align': { arb: str('left', 'center', 'right') },
+  'tableHeader.colspan': { always: true, frozen: true }, // DEFERRED-BUG (see tableCell.colspan)
+  'tableHeader.rowspan': { always: true, frozen: true }, // DEFERRED-BUG (see tableCell.rowspan)
+  'tableHeader.colwidth': { frozen: true }, // ACCEPTED: no representation
+  'tableHeader.backgroundColor': { frozen: true }, // ACCEPTED: no representation
+  'tableHeader.backgroundColorName': { frozen: true }, // ACCEPTED: no representation
+  'tableHeader.align': { arb: str('left', 'center', 'right') },
+  // ── details ──────────────────────────────────────────────────────────────
+  'details.open': { always: true, arb: fc.constant(true) }, // boolean, default false
+  // ── columns ──────────────────────────────────────────────────────────────
+  'columns.layout': { always: true, arb: str('three_equal', 'left_sidebar', 'right_sidebar') },
+  // widthMode round-trips via the `data-width-mode` attribute (verified P1+P2),
+  // so it is fuzzed, not frozen.
+  'columns.widthMode': { always: true, arb: str('custom') },
+  // PINNED-BUG: parseFloat import drops the `%` unit -> P2 churn. See
+  // counterexamples.test.ts (columns-column-width-percent.json).
+  'column.width': { frozen: true },
+  // ── embed (schema keeps width/height NUMERIC, not string-coerced) ─────────
+  'embed.src': { noDefault: true, arb: urlArb, degen: '' },
+  'embed.provider': { noDefault: true, arb: str('iframe', 'youtube', 'vimeo') },
+  'embed.width': { always: true, frozen: true },
+  'embed.height': { always: true, frozen: true },
+  // ── subpages / math / htmlEmbed ──────────────────────────────────────────
+  'subpages.recursive': { always: true, arb: fc.constant(true) }, // boolean, default false
+  'mathBlock.text': { noDefault: true, arb: str('x^2', 'a < b', '\\frac{1}{2}'), degen: '' },
+  'mathInline.text': { noDefault: true, arb: str('x^2', 'a < b', '\\frac{1}{2}'), degen: '' },
+  'htmlEmbed.source': { noDefault: true, arb: str('<b>hi</b>', '<i>x</i>', '<span>y</span>'), degen: '' },
+  'htmlEmbed.height': { arb: num(200, 300, 400) },
+  // ── footnotes / transclusion / pageEmbed / mention ───────────────────────
+  'footnoteDefinition.id': { noDefault: true, arb: str('fn1', 'fn2', 'note') },
+  'footnoteReference.id': { noDefault: true, arb: str('fn1', 'fn2', 'note') },
+  'pageEmbed.sourcePageId': { noDefault: true, arb: fc.uuid() },
+  'transclusionSource.id': { noDefault: true, arb: str('src1', 'src2') },
+  'transclusionReference.sourcePageId': { noDefault: true, arb: fc.uuid() },
+  'transclusionReference.transclusionId': { noDefault: true, arb: str('tr1', 'tr2') },
+  'mention.id': { noDefault: true, arb: fc.uuid() },
+  'mention.label': { noDefault: true, arb: phraseArb },
+  'mention.entityType': { noDefault: true, arb: str('user') },
+  'mention.entityId': { noDefault: true, arb: fc.uuid() },
+};
+
+/** Resolve the effective policy for one attribute (override merged over generic). */
+function policyFor(type: string, attr: string, def: unknown): AttrPolicy {
+  const override = OVERRIDES[`${type}.${attr}`];
+  if (override) return override;
+  // Generic: booleans are fuzzable via their flipped value; everything else is
+  // frozen (only absent/default) so no unverified non-default is invented.
+  if (typeof def === 'boolean') return { arb: fc.constant(!def) };
+  return { frozen: true };
+}
+
+/**
+ * Whether an attribute is actually exercised at a NON-DEFAULT value (i.e. its
+ * policy has an `arb`, which the generic fallback does not). Used by the
+ * attribute-coverage snapshot test to make the generic-frozen space VISIBLE: any
+ * string/number attr not in OVERRIDES is silently only tested at absent/default,
+ * so the snapshot pins exactly which attrs are NOT value-fuzzed and forces a
+ * reviewer to look when a new attr lands in that invisible bucket.
+ */
+export function attrIsValueFuzzed(type: string, attr: string): boolean {
+  const def = schemaAttrDefaults(type)[attr];
+  return !!policyFor(type, attr, def).arb;
+}
+
+/** Every node `type.attr` in the schema (excluding the auto `id`), sorted. */
+export function allSchemaAttrKeys(): string[] {
+  const keys: string[] = [];
+  for (const type of Object.keys(schema.nodes)) {
+    for (const attr of schemaAttrNames(type)) {
+      if (attr === 'id') continue;
+      keys.push(`${type}.${attr}`);
+    }
+  }
+  return keys.sort();
+}
+
+/**
+ * Every MARK attribute in the schema, keyed `mark:<name>.<attr>`, sorted. Marks
+ * are not driven by the node OVERRIDES table (they are fuzzed by the text
+ * generator, text-arbitraries.ts), so their value-fuzz coverage is tracked with a
+ * separate snapshot (see flat-roundtrip.property.test.ts) — without this the
+ * "no invisible coverage hole" guarantee would hold for node attrs only, letting a
+ * new mark attr slip through unfuzzed and unallowlisted.
+ */
+export function allSchemaMarkAttrKeys(): string[] {
+  const keys: string[] = [];
+  for (const [name, mark] of Object.entries(schema.marks)) {
+    const attrs = (mark.spec?.attrs ?? {}) as Record<string, unknown>;
+    for (const attr of Object.keys(attrs)) keys.push(`mark:${name}.${attr}`);
+  }
+  return keys.sort();
+}
+
+export type AttrMode = 'p1' | 'fuzz';
+
+/**
+ * Build an arbitrary for ONE attribute's value (or the ABSENT sentinel) across
+ * the states legal for `mode`:
+ *   - p1   : absent / default / nonDefault (the round-trip-safe space).
+ *   - fuzz : the above PLUS degenerate (P2 tolerates the one-time
+ *            normalization; P3 only needs totality).
+ */
+export function attrValueArb(
+  type: string,
+  attr: string,
+  mode: AttrMode,
+): fc.Arbitrary<unknown | typeof ABSENT> {
+  const def = schemaAttrDefaults(type)[attr];
+  const p = policyFor(type, attr, def);
+
+  const states: fc.Arbitrary<unknown | typeof ABSENT>[] = [];
+  if (!p.always && !p.noDefault) states.push(fc.constant(ABSENT));
+  if (!p.noDefault) states.push(fc.constant(def));
+  if (!p.frozen && p.arb) states.push(p.arb);
+  if (mode === 'fuzz' && !p.frozen && p.degen !== undefined) {
+    states.push(fc.constant(p.degen));
+  }
+  if (states.length === 0) states.push(fc.constant(def));
+  return fc.oneof(...states);
+}
+
+/**
+ * Build an arbitrary for a node's full `attrs` object over all schema attrs.
+ * `base` pins caller-required attrs (e.g. a concrete `src`) verbatim; any attr
+ * present in `base` is NOT re-generated. Omitted (ABSENT) attrs are dropped.
+ */
+export function nodeAttrsArb(
+  type: string,
+  mode: AttrMode,
+  base: Record<string, unknown> = {},
+): fc.Arbitrary<Record<string, unknown>> {
+  const names = schemaAttrNames(type).filter((n) => !(n in base) && n !== 'id');
+  if (names.length === 0) return fc.constant({ ...base });
+  return fc
+    .tuple(...names.map((n) => attrValueArb(type, n, mode)))
+    .map((vals) => {
+      const attrs: Record<string, unknown> = { ...base };
+      names.forEach((n, i) => {
+        if (vals[i] !== ABSENT) attrs[n] = vals[i];
+      });
+      return attrs;
+    });
+}
@@ -0,0 +1,74 @@
+import { describe, expect, it } from 'vitest';
+import { readFileSync } from 'node:fs';
+import { fileURLToPath } from 'node:url';
+import path from 'node:path';
+import { convertProseMirrorToMarkdown } from '../../src/lib/markdown-converter.js';
+import { markdownToProseMirror } from '../../src/lib/markdown-to-prosemirror.js';
+import { docsCanonicallyEqual } from '../../src/lib/canonicalize.js';
+
+// ---------------------------------------------------------------------------
+// #351 committed counterexamples — REAL round-trip bugs surfaced by the flat
+// generative probing (attribute level). Each is pinned here as an `it.fails`
+// (vitest passes ONLY WHILE the assertion still fails), so that the day the
+// underlying src/ bug is fixed, the `it.fails` starts PASSING and vitest turns
+// this test RED — forcing us to delete the counterexample and (per the epic
+// guardrail) tighten the generator. A bare `it.fails` would ship silent
+// corruption, so every case below carries a loud `// BUG #351:` explanation.
+//
+// These bugs are NOT worked around by weakening any property: the offending
+// attribute is kept OUT of the P1/P2 generators (documented in
+// attr-arbitraries.ts), and the exact failing document lives here as the
+// regression pin. FIXING the bug is a separate, maintainer-approved src/ change.
+// ---------------------------------------------------------------------------
+
+const here = path.dirname(fileURLToPath(import.meta.url));
+const fixtureDir = path.resolve(here, '../fixtures/counterexamples');
+
+function loadDoc(file: string): any {
+  return JSON.parse(readFileSync(path.join(fixtureDir, file), 'utf8')).doc;
+}
+
+describe('#351 counterexamples (known round-trip bugs, pinned as it.fails)', () => {
+  // BUG #351: a `column` with a PERCENTAGE width ("50%") is not byte-stable.
+  // The column schema parses `data-width` with parseFloat, dropping the '%':
+  //   md1 = '...data-width="50%"...'   (first export)
+  //   re-import stores width = 50 (number)
+  //   md2 = '...data-width="50"...'    (second export)  => md2 !== md1
+  // A permanent GS-EDIT-REVERT churn on every git-sync pull. The editor stores
+  // column widths as percentages, so this is a genuine defect. The fix is in
+  // src/lib/docmost-schema.ts (column.width parseHTML must preserve the unit)
+  // and is out of scope for this test-only PR.
+  it.fails('column percentage width is byte-stable (P2)', async () => {
+    const doc = loadDoc('columns-column-width-percent.json');
+    const md1 = convertProseMirrorToMarkdown(doc);
+    const doc2 = await markdownToProseMirror(md1);
+    const md2 = convertProseMirrorToMarkdown(doc2);
+    // This assertion currently FAILS (md2 drops the '%'), which is exactly what
+    // `it.fails` expects. When the schema is fixed, it will PASS and flip this
+    // test red — our cue to remove the pin.
+    expect(md2).toBe(md1);
+  });
+
+  // BUG #351: an `orderedList` with a non-1 `start` loses its start number.
+  // CommonMark CAN express this ("5." starts the list at 5), but the converter
+  // always emits "1." and ignores `attrs.start` (markdown-converter.ts renders
+  // `${index + 1}.`; the <ol> HTML path also omits `start`):
+  //   doc.start = 5   ->   md1 = "1. alpha"   (start dropped on export)
+  //   re-import stores start = 1   =>   docsCanonicallyEqual(rt, doc) === false
+  // This is a P1 (semantic round-trip) loss of the SAME class as column.width:
+  // representable in markdown, silently dropped by the converter. It is pinned
+  // here as the LOUD counterexample rather than being masked as an "accepted
+  // normalization" in the generator — per the epic guardrail, deciding
+  // accept-vs-fix for a markdown-representable loss is a MAINTAINER call, so this
+  // stays a visible known-bug until the maintainer rules on it. The fix would be
+  // in src/lib/markdown-converter.ts (emit the start number on the first item)
+  // and is out of scope for this test-only PR.
+  it.fails('ordered list start number is preserved (P1)', async () => {
+    const doc = loadDoc('ordered-list-start.json');
+    const md1 = convertProseMirrorToMarkdown(doc);
+    const doc2 = await markdownToProseMirror(md1);
+    // Currently FAILS: doc2.start === 1 while doc.start === 5. When the converter
+    // preserves `start`, this PASSES and flips the test red — remove the pin then.
+    expect(docsCanonicallyEqual(doc2, doc)).toBe(true);
+  });
+});
@@ -0,0 +1,284 @@
+import { describe, expect, it, vi } from 'vitest';
+import fc from 'fast-check';
+// Real converter, imported the same way the sibling property test does.
+import { convertProseMirrorToMarkdown } from '../../src/lib/markdown-converter.js';
+// Importing markdownToProseMirror mutates the global DOM via jsdom at module
+// load (expected, required for @tiptap/html's generateJSON under Node).
+import { markdownToProseMirror } from '../../src/lib/markdown-to-prosemirror.js';
+import { docsCanonicallyEqual, canonicalizeContent } from '../../src/lib/index.js';
+import { firstDivergence } from '../roundtrip-helpers.js';
+import {
+  schema,
+  allSchemaAttrKeys,
+  allSchemaMarkAttrKeys,
+  attrIsValueFuzzed,
+} from './attr-arbitraries.js';
+import {
+  buildGenerators,
+  coveredTypes,
+  KNOWN_UNCOVERED,
+} from './node-generators.js';
+
+// ── Attribute-value coverage allowlist ──────────────────────────────────────
+// The node/mark completeness contract guarantees every TYPE is generated, but
+// NOT that every attribute is exercised at a NON-DEFAULT value. An attribute
+// with no `arb` in attr-arbitraries.ts is only ever tested at absent/default —
+// an INVISIBLE coverage hole (the reviewer's concern). This allowlist makes that
+// hole EXPLICIT: it is the exact set of attrs deliberately not value-fuzzed, so
+// a NEW attribute (or a newly-frozen one) that lands in this bucket flips the
+// snapshot test red and forces a reviewer to classify it. Each belongs to one of:
+//   - internal/opaque ids & placeholders (attachmentId, slugId, placeholder,
+//     creatorId, anchorId) — no meaningful non-default to assert;
+//   - dimensions/among the media family with no standalone md form here
+//     (aspectRatio, size, caption, drawio/excalidraw/pdf/video/youtube w/h/align)
+//     — round-trip candidates deferred to a later PR, not silently dropped;
+//   - ACCEPTED limitations with no md representation (indent, callout.icon,
+//     orderedList.type, table spans/bg/colwidth);
+//   - PINNED bugs (column.width, orderedList.start) tracked in
+//     counterexamples.test.ts.
+const ATTR_VALUE_FUZZ_ALLOWLIST = new Set<string>([
+  'attachment.attachmentId', 'attachment.mime', 'attachment.placeholder', 'attachment.size',
+  'audio.attachmentId', 'audio.placeholder', 'audio.size',
+  'callout.icon', 'column.width',
+  'drawio.align', 'drawio.alt', 'drawio.aspectRatio', 'drawio.attachmentId',
+  'drawio.height', 'drawio.size', 'drawio.title', 'drawio.width',
+  'embed.align', 'embed.height', 'embed.width',
+  'excalidraw.align', 'excalidraw.alt', 'excalidraw.aspectRatio', 'excalidraw.attachmentId',
+  'excalidraw.height', 'excalidraw.size', 'excalidraw.title', 'excalidraw.width',
+  'heading.indent',
+  'image.aspectRatio', 'image.attachmentId', 'image.caption', 'image.placeholder', 'image.size',
+  'mention.anchorId', 'mention.creatorId', 'mention.slugId',
+  'orderedList.start', 'orderedList.type', 'paragraph.indent',
+  'pdf.attachmentId', 'pdf.height', 'pdf.placeholder', 'pdf.size', 'pdf.width',
+  'tableCell.backgroundColor', 'tableCell.backgroundColorName', 'tableCell.colspan',
+  'tableCell.colwidth', 'tableCell.rowspan',
+  'tableHeader.backgroundColor', 'tableHeader.backgroundColorName', 'tableHeader.colspan',
+  'tableHeader.colwidth', 'tableHeader.rowspan',
+  'video.align', 'video.aspectRatio', 'video.attachmentId', 'video.placeholder', 'video.size',
+  'youtube.align', 'youtube.height', 'youtube.width',
+]);
+
+// ── MARK attribute-value coverage ───────────────────────────────────────────
+// Marks are fuzzed by the text generator (text-arbitraries.ts markedTextRunArb),
+// not the node OVERRIDES table, so their value-fuzz coverage is tracked with this
+// separate registry — otherwise the "no invisible coverage hole" guarantee would
+// hold for node attrs only, and a new mark attr (or a new attributed mark) would
+// silently escape the fuzz set. Every schema mark attr must be in exactly one of:
+//   MARK_ATTR_FUZZED    — actually driven at a non-default value by the generator;
+//   MARK_ATTR_ALLOWLIST — deliberately not value-fuzzed, with a reason.
+const MARK_ATTR_FUZZED = new Set<string>([
+  'mark:link.href', // markedTextRunArb sets a random webUrl href
+  'mark:link.title', // ...and an optional letter-bearing title
+  'mark:highlight.color', // highlight mark carries a generated color
+  'mark:textStyle.color', // textStyle mark carries a generated color
+  'mark:comment.commentId', // comment anchor id (alphanumeric token)
+  'mark:comment.resolved', // comment resolved flag (rides only when true)
+]);
+const MARK_ATTR_ALLOWLIST = new Set<string>([
+  // link presentational/routing attrs: not part of the markdown link surface the
+  // converter emits (it round-trips href + title only), so there is no
+  // non-default value to assert here — a deferred concern for a link-specific
+  // fixture, not the flat generative pass.
+  'mark:link.internal',
+  'mark:link.target',
+  'mark:link.rel',
+  'mark:link.class',
+]);
+
+// Each run does a real convert + marked + jsdom parse (~ms). Give ample headroom
+// so the suite is deterministic regardless of parallel worker load (like the
+// sibling property file).
+vi.setConfig({ testTimeout: 30000 });
+
+// ---------------------------------------------------------------------------
+// #351 PR 1 — GENERATIVE (property-based) round-trip over FLAT (single-node)
+// documents at the ATTRIBUTE level.
+//
+// We assert three invariants for ANY generated valid flat document `d`
+// (pmToMd = convertProseMirrorToMarkdown, mdToPm = markdownToProseMirror):
+//
+//   P1 — semantic round-trip (nothing lost):
+//        docsCanonicallyEqual(await mdToPm(pmToMd(d)), d) === true
+//   P2 — byte fixpoint (anti "GS-EDIT-REVERT" churn):
+//        pmToMd(await mdToPm(pmToMd(d))) === pmToMd(d)
+//   P3 — totality: neither converter throws; bounded.
+//
+// The generators are schema-DERIVED (attribute lists come from
+// schema.nodes[type].spec.attrs) and stay inside the round-trip-supported space
+// proven empirically by probing the live converter (see attr-arbitraries.ts and
+// text-arbitraries.ts). P1 runs over the safe attribute space; P2/P3 run over
+// the wider 'fuzz' space that also injects degenerate attribute states, which
+// P2 tolerates via a one-time first-pass normalization and P3 via totality only.
+// ---------------------------------------------------------------------------
+
+// Fixed seed so every failure is reproducible; fast-check also prints the
+// shrunk counterexample. numRuns starts modest to keep CI under budget — the
+// issue's CI target is ~300-500 per property; the nightly / PR 3 will crank
+// this up further. Each property runs over the UNION (fc.oneof) of all flat
+// node generators, so the runs are shared across node types (one test per
+// property keeps the jsdom import cost and memory bounded — a per-generator ×
+// per-property matrix is ~200 heavy tests that OOMs the worker).
+const SEED = 20250705;
+const NUM_RUNS = 300;
+
+const P1_GENERATORS = buildGenerators('p1');
+const FUZZ_GENERATORS = buildGenerators('fuzz');
+
+// Union arbitraries: a single draw picks one node generator, then a document
+// from it. On failure fast-check prints the shrunk counterexample doc, which
+// names the offending node type directly.
+const p1Union = fc.oneof(...P1_GENERATORS.map((g) => g.arb));
+const fuzzUnion = fc.oneof(...FUZZ_GENERATORS.map((g) => g.arb));
+
+async function roundTrip(doc: unknown): Promise<{ md1: string; md2: string; doc2: any }> {
+  const md1 = convertProseMirrorToMarkdown(doc);
+  const doc2 = await markdownToProseMirror(md1);
+  const md2 = convertProseMirrorToMarkdown(doc2);
+  return { md1, md2, doc2 };
+}
+
+describe('#351 flat generative round-trip — completeness contract', () => {
+  it('every schema node and mark is covered by a generator or explicitly allowlisted', () => {
+    const covered = coveredTypes();
+    const uncovered: string[] = [];
+
+    for (const nodeType of Object.keys(schema.nodes)) {
+      if (covered.has(nodeType)) continue;
+      if (nodeType in KNOWN_UNCOVERED) continue;
+      uncovered.push(`node:${nodeType}`);
+    }
+    for (const markType of Object.keys(schema.marks)) {
+      if (covered.has(`mark:${markType}`)) continue;
+      if (markType in KNOWN_UNCOVERED) continue;
+      uncovered.push(`mark:${markType}`);
+    }
+
+    // A new node/mark added to the schema with no generator AND no allowlist
+    // entry MUST turn this test red — that is the whole point (no silent blind
+    // spots).
+    expect(
+      uncovered,
+      `these schema types have no generator and no KNOWN_UNCOVERED reason:\n  ${uncovered.join(
+        '\n  ',
+      )}`,
+    ).toEqual([]);
+  });
+
+  it('every KNOWN_UNCOVERED entry is a real schema type (no stale allowlist rows)', () => {
+    const all = new Set([...Object.keys(schema.nodes), ...Object.keys(schema.marks)]);
+    for (const t of Object.keys(KNOWN_UNCOVERED)) {
+      expect(all.has(t), `stale KNOWN_UNCOVERED entry: ${t}`).toBe(true);
+    }
+  });
+
+  it('every attribute is value-fuzzed OR explicitly allowlisted (no invisible hole)', () => {
+    // Makes the "generic-frozen" coverage hole VISIBLE: any schema attr not
+    // exercised at a non-default value must be a KNOWN entry in the allowlist.
+    // A new attr (or one that loses its `arb`) that falls into the not-fuzzed
+    // bucket without an allowlist row turns this red — no silent blind spots.
+    const unaccounted: string[] = [];
+    for (const key of allSchemaAttrKeys()) {
+      const i = key.indexOf('.');
+      const fuzzed = attrIsValueFuzzed(key.slice(0, i), key.slice(i + 1));
+      if (!fuzzed && !ATTR_VALUE_FUZZ_ALLOWLIST.has(key)) unaccounted.push(key);
+    }
+    expect(
+      unaccounted,
+      `these attrs are not value-fuzzed and not in ATTR_VALUE_FUZZ_ALLOWLIST:\n  ${unaccounted.join(
+        '\n  ',
+      )}`,
+    ).toEqual([]);
+  });
+
+  it('the attribute allowlist has no stale rows (every entry is really not-fuzzed)', () => {
+    const notFuzzed = new Set(
+      allSchemaAttrKeys().filter((key) => {
+        const i = key.indexOf('.');
+        return !attrIsValueFuzzed(key.slice(0, i), key.slice(i + 1));
+      }),
+    );
+    for (const key of ATTR_VALUE_FUZZ_ALLOWLIST) {
+      expect(
+        notFuzzed.has(key),
+        `stale allowlist row (attr is now value-fuzzed, remove it): ${key}`,
+      ).toBe(true);
+    }
+  });
+
+  it('every MARK attribute is value-fuzzed OR allowlisted (no invisible hole)', () => {
+    // The node guard above covers node attrs; marks are fuzzed by the text
+    // generator, so their coverage is tracked separately. A new mark attr (or a
+    // newly-attributed mark) that lands in neither set turns this red.
+    const unaccounted: string[] = [];
+    for (const key of allSchemaMarkAttrKeys()) {
+      if (!MARK_ATTR_FUZZED.has(key) && !MARK_ATTR_ALLOWLIST.has(key)) {
+        unaccounted.push(key);
+      }
+    }
+    expect(
+      unaccounted,
+      `these mark attrs are neither in MARK_ATTR_FUZZED nor MARK_ATTR_ALLOWLIST:\n  ${unaccounted.join(
+        '\n  ',
+      )}`,
+    ).toEqual([]);
+  });
+
+  it('the MARK fuzz/allowlist sets have no stale rows (every entry is a real schema mark attr)', () => {
+    const all = new Set(allSchemaMarkAttrKeys());
+    for (const key of [...MARK_ATTR_FUZZED, ...MARK_ATTR_ALLOWLIST]) {
+      expect(all.has(key), `stale mark-attr registry row: ${key}`).toBe(true);
+    }
+  });
+});
+
+describe('#351 flat generative round-trip — properties', () => {
+  it('generator validity: every generated doc passes schema.check()', () => {
+    // A generator that emits an invalid ProseMirror document is a GENERATOR bug.
+    fc.assert(
+      fc.property(fuzzUnion, (doc) => {
+        schema.nodeFromJSON(doc).check(); // throws on an invalid doc
+        return true;
+      }),
+      { numRuns: NUM_RUNS, seed: SEED },
+    );
+  });
+
+  it('P1 — semantic round-trip: docsCanonicallyEqual(mdToPm(pmToMd(d)), d)', async () => {
+    await fc.assert(
+      fc.asyncProperty(p1Union, async (doc) => {
+        const { doc2 } = await roundTrip(doc);
+        if (!docsCanonicallyEqual(doc2, doc)) {
+          // Surface the precise divergence in the failure message.
+          const div = firstDivergence(
+            JSON.parse(JSON.stringify(canonicalizeContent(doc2))),
+            JSON.parse(JSON.stringify(canonicalizeContent(doc))),
+          );
+          throw new Error(
+            `P1 divergence @ ${div?.path}: got=${JSON.stringify(div?.a)} want=${JSON.stringify(div?.b)}`,
+          );
+        }
+      }),
+      { numRuns: NUM_RUNS, seed: SEED },
+    );
+  });
+
+  it('P2 — byte fixpoint: pmToMd(mdToPm(pmToMd(d))) === pmToMd(d)', async () => {
+    await fc.assert(
+      fc.asyncProperty(fuzzUnion, async (doc) => {
+        const { md1, md2 } = await roundTrip(doc);
+        expect(md2).toBe(md1);
+      }),
+      { numRuns: NUM_RUNS, seed: SEED },
+    );
+  });
+
+  it('P3 — totality: neither converter throws', async () => {
+    await fc.assert(
+      fc.asyncProperty(fuzzUnion, async (doc) => {
+        // Throwing here fails the property; fast-check shrinks to a minimal doc.
+        await roundTrip(doc);
+      }),
+      { numRuns: NUM_RUNS, seed: SEED },
+    );
+  });
+});
@@ -0,0 +1,310 @@
+/**
+ * Flat single-node document generators (#351, PR 1).
+ *
+ * For every schema node type that can stand alone, a fast-check arbitrary
+ * producing `{ type:'doc', content:[ <the target node> ] }` with generated attrs
+ * (via nodeAttrsArb) and the minimal REQUIRED immediate children the schema
+ * demands (a heading's inline text, a listItem's one paragraph, a table's
+ * minimal rows, details' summary+content, a callout's one paragraph). Kept
+ * FLAT: a single target node, no deep nesting — nested structural generation is
+ * PR 2.
+ *
+ * The `mode` threads through to the attribute arbitraries:
+ *   - 'p1'   : the round-trip-safe attribute space (P1 semantic round-trip).
+ *   - 'fuzz' : adds degenerate attribute states (P2 byte-fixpoint tolerates the
+ *              one-time normalization; P3 only needs totality).
+ *
+ * A COMPLETENESS CONTRACT (see flat-roundtrip.property.test.ts) enumerates the
+ * whole schema and asserts every node/mark is EITHER produced by a generator
+ * here OR listed in KNOWN_UNCOVERED with a reason — so a new schema type with no
+ * generator turns the suite RED.
+ */
+import fc from 'fast-check';
+import { type AttrMode, nodeAttrsArb } from './attr-arbitraries.js';
+import {
+  inlineContentArb,
+  headingInlineContentArb,
+  plainInlineContentArb,
+  phraseArb,
+  markedTextRunArb,
+} from './text-arbitraries.js';
+
+const doc = (node: any) => ({ type: 'doc', content: [node] });
+const para = (content: any[]) => ({ type: 'paragraph', content });
+
+/** A named flat-document generator. */
+export interface NamedGen {
+  name: string;
+  arb: fc.Arbitrary<any>;
+}
+
+// ---------------------------------------------------------------------------
+// Per-target generators, each a function of mode.
+// ---------------------------------------------------------------------------
+
+const gen = {
+  paragraph: (m: AttrMode) =>
+    fc.tuple(nodeAttrsArb('paragraph', m), inlineContentArb).map(([attrs, content]) =>
+      doc({ type: 'paragraph', attrs, content }),
+    ),
+
+  heading: (m: AttrMode) =>
+    fc.tuple(nodeAttrsArb('heading', m), headingInlineContentArb).map(([attrs, content]) =>
+      doc({ type: 'heading', attrs, content }),
+    ),
+
+  blockquote: (_m: AttrMode) =>
+    inlineContentArb.map((content) => doc({ type: 'blockquote', content: [para(content)] })),
+
+  bulletList: (_m: AttrMode) =>
+    fc
+      .array(inlineContentArb, { minLength: 1, maxLength: 3 })
+      .map((items) =>
+        doc({
+          type: 'bulletList',
+          content: items.map((c) => ({ type: 'listItem', content: [para(c)] })),
+        }),
+      ),
+
+  orderedList: (m: AttrMode) =>
+    fc
+      .tuple(nodeAttrsArb('orderedList', m), fc.array(inlineContentArb, { minLength: 1, maxLength: 3 }))
+      .map(([attrs, items]) =>
+        doc({
+          type: 'orderedList',
+          attrs,
+          content: items.map((c) => ({ type: 'listItem', content: [para(c)] })),
+        }),
+      ),
+
+  taskList: (m: AttrMode) =>
+    fc
+      .array(fc.tuple(nodeAttrsArb('taskItem', m), inlineContentArb), { minLength: 1, maxLength: 3 })
+      .map((items) =>
+        doc({
+          type: 'taskList',
+          content: items.map(([attrs, c]) => ({ type: 'taskItem', attrs, content: [para(c)] })),
+        }),
+      ),
+
+  codeBlock: (m: AttrMode) =>
+    fc
+      .tuple(
+        nodeAttrsArb('codeBlock', m),
+        // A fenced code block always re-imports with a TRAILING NEWLINE in its
+        // text (empirically confirmed). Author the newline so the doc is already
+        // at the round-trip fixpoint (supported-space shaping, not a masked bug).
+        fc.array(phraseArb, { minLength: 1, maxLength: 3 }).map((lines) => lines.join('\n') + '\n'),
+      )
+      .map(([attrs, code]) =>
+        doc({ type: 'codeBlock', attrs, content: [{ type: 'text', text: code }] }),
+      ),
+
+  horizontalRule: (_m: AttrMode) => fc.constant(doc({ type: 'horizontalRule' })),
+
+  pageBreak: (_m: AttrMode) => fc.constant(doc({ type: 'pageBreak' })),
+
+  image: (m: AttrMode) => nodeAttrsArb('image', m).map((attrs) => doc({ type: 'image', attrs })),
+
+  callout: (m: AttrMode) =>
+    fc.tuple(nodeAttrsArb('callout', m), inlineContentArb).map(([attrs, content]) =>
+      doc({ type: 'callout', attrs, content: [para(content)] }),
+    ),
+
+  mathBlock: (m: AttrMode) =>
+    nodeAttrsArb('mathBlock', m).map((attrs) => doc({ type: 'mathBlock', attrs })),
+
+  details: (m: AttrMode) =>
+    fc
+      .tuple(nodeAttrsArb('details', m), plainInlineContentArb, inlineContentArb)
+      .map(([attrs, summary, body]) =>
+        doc({
+          type: 'details',
+          attrs,
+          content: [
+            { type: 'detailsSummary', content: summary },
+            { type: 'detailsContent', content: [para(body)] },
+          ],
+        }),
+      ),
+
+  table: (_m: AttrMode) =>
+    fc.integer({ min: 1, max: 3 }).chain((cols) => {
+      // GFM alignment is column-wide (encoded in the header separator), so a
+      // column's alignment must be identical on the header and every body cell,
+      // else the second export re-aligns and churns. Pick ONE align per column.
+      const alignsArb = fc.array(fc.constantFrom(undefined, 'left', 'center', 'right'), {
+        minLength: cols,
+        maxLength: cols,
+      });
+      const cell = (header: boolean, align?: string) =>
+        phraseArb.map((t) => ({
+          type: header ? 'tableHeader' : 'tableCell',
+          // colspan/rowspan pinned to 1 (GFM cannot express spans); optional
+          // column-consistent align.
+          attrs: { colspan: 1, rowspan: 1, ...(align ? { align } : {}) },
+          content: [para([{ type: 'text', text: t }])],
+        }));
+      return alignsArb.chain((aligns) => {
+        const headerRow = fc
+          .tuple(...aligns.map((a) => cell(true, a)))
+          .map((cells) => ({ type: 'tableRow', content: cells }));
+        const bodyRow = fc
+          .tuple(...aligns.map((a) => cell(false, a)))
+          .map((cells) => ({ type: 'tableRow', content: cells }));
+        return fc
+          .tuple(headerRow, fc.array(bodyRow, { minLength: 1, maxLength: 2 }))
+          .map(([h, body]) => doc({ type: 'table', content: [h, ...body] }));
+      });
+    }),
+
+  columns: (m: AttrMode) =>
+    // Couple the column count to the layout so the two stay consistent
+    // (two_equal/left_sidebar/right_sidebar -> 2, three_equal -> 3).
+    fc
+      .constantFrom('two_equal', 'three_equal', 'left_sidebar', 'right_sidebar')
+      .chain((layout) => {
+        const count = layout === 'three_equal' ? 3 : 2;
+        return fc
+          .tuple(
+            nodeAttrsArb('columns', m, { layout, widthMode: 'normal' }),
+            fc.array(inlineContentArb, { minLength: count, maxLength: count }),
+          )
+          .map(([attrs, bodies]) =>
+            doc({
+              type: 'columns',
+              attrs,
+              content: bodies.map((c) => ({ type: 'column', content: [para(c)] })),
+            }),
+          );
+      }),
+
+  subpages: (m: AttrMode) =>
+    nodeAttrsArb('subpages', m).map((attrs) => doc({ type: 'subpages', attrs })),
+
+  audio: (m: AttrMode) => nodeAttrsArb('audio', m).map((attrs) => doc({ type: 'audio', attrs })),
+  video: (m: AttrMode) => nodeAttrsArb('video', m).map((attrs) => doc({ type: 'video', attrs })),
+  pdf: (m: AttrMode) => nodeAttrsArb('pdf', m).map((attrs) => doc({ type: 'pdf', attrs })),
+  youtube: (m: AttrMode) => nodeAttrsArb('youtube', m).map((attrs) => doc({ type: 'youtube', attrs })),
+  embed: (m: AttrMode) => nodeAttrsArb('embed', m).map((attrs) => doc({ type: 'embed', attrs })),
+  drawio: (m: AttrMode) => nodeAttrsArb('drawio', m).map((attrs) => doc({ type: 'drawio', attrs })),
+  excalidraw: (m: AttrMode) =>
+    nodeAttrsArb('excalidraw', m).map((attrs) => doc({ type: 'excalidraw', attrs })),
+  attachment: (m: AttrMode) =>
+    nodeAttrsArb('attachment', m).map((attrs) => doc({ type: 'attachment', attrs })),
+  htmlEmbed: (m: AttrMode) =>
+    nodeAttrsArb('htmlEmbed', m).map((attrs) => doc({ type: 'htmlEmbed', attrs })),
+  pageEmbed: (m: AttrMode) =>
+    nodeAttrsArb('pageEmbed', m).map((attrs) => doc({ type: 'pageEmbed', attrs })),
+  transclusionReference: (m: AttrMode) =>
+    nodeAttrsArb('transclusionReference', m).map((attrs) =>
+      doc({ type: 'transclusionReference', attrs }),
+    ),
+
+  transclusionSource: (m: AttrMode) =>
+    fc.tuple(nodeAttrsArb('transclusionSource', m), inlineContentArb).map(([attrs, content]) =>
+      doc({ type: 'transclusionSource', attrs, content: [para(content)] }),
+    ),
+
+  // A footnote reference PLUS its definition (the reference has no standalone
+  // markdown form without its definition — see KNOWN_UNCOVERED note for the
+  // bare reference). Both carry the same id. The definition body uses
+  // headingInlineContentArb (NO hard breaks): a footnote is serialized inline as
+  // `^[...]`, so a hard break inside it collapses to a single space on re-parse
+  // (empirically confirmed) — that is the container's markdown limitation, not
+  // an attribute-level concern. The reference-bearing paragraph is a NORMAL
+  // paragraph and keeps the full inline corpus.
+  footnotes: (m: AttrMode) =>
+    fc.tuple(fc.constantFrom('fn1', 'fn2', 'note'), inlineContentArb, headingInlineContentArb).map(
+      ([id, refText, noteBody]) => ({
+        type: 'doc',
+        content: [
+          para([...refText, { type: 'footnoteReference', attrs: { id } }]),
+          {
+            type: 'footnotesList',
+            content: [{ type: 'footnoteDefinition', attrs: { id }, content: [para(noteBody)] }],
+          },
+        ],
+      }),
+    ),
+
+  // ── inline targets wrapped in a paragraph ────────────────────────────────
+  mention: (m: AttrMode) =>
+    nodeAttrsArb('mention', m).map((attrs) => doc(para([{ type: 'mention', attrs }]))),
+
+  mathInline: (m: AttrMode) =>
+    fc.tuple(phraseArb, nodeAttrsArb('mathInline', m)).map(([t, attrs]) =>
+      doc(para([{ type: 'text', text: t }, { type: 'mathInline', attrs }])),
+    ),
+
+  status: (m: AttrMode) =>
+    nodeAttrsArb('status', m).map((attrs) => doc(para([{ type: 'status', attrs }]))),
+
+  hardBreak: (_m: AttrMode) =>
+    fc.tuple(phraseArb, phraseArb).map(([a, b]) =>
+      doc(para([{ type: 'text', text: a }, { type: 'hardBreak' }, { type: 'text', text: b }])),
+    ),
+
+  // ── marks: a paragraph of marked runs (covers every mark type) ───────────
+  marksOnText: (_m: AttrMode) =>
+    fc.array(markedTextRunArb, { minLength: 1, maxLength: 5 }).map((runs) => {
+      // Merge adjacent same-mark runs (see text-arbitraries.normalizeInline).
+      const out: any[] = [];
+      for (const r of runs) {
+        const prev = out[out.length - 1];
+        if (prev && JSON.stringify(prev.marks ?? []) === JSON.stringify(r.marks ?? [])) {
+          prev.text += r.text;
+        } else out.push({ ...r });
+      }
+      return doc(para(out));
+    }),
+};
+
+/** Build the full list of named generators for a given mode. */
+export function buildGenerators(mode: AttrMode): NamedGen[] {
+  return Object.entries(gen).map(([name, f]) => ({ name, arb: f(mode) }));
+}
+
+// ---------------------------------------------------------------------------
+// Completeness contract support.
+// ---------------------------------------------------------------------------
+
+/**
+ * Schema node/mark types deliberately NOT covered by a P1/P2 generator, each
+ * with a one-line reason. Excluding a type means it is kept OUT of the round-
+ * trip generators — it does NOT weaken any property.
+ *
+ * NOTE (empirical): the candidates the issue flagged for review — pageEmbed,
+ * subpages, transclusionSource/Reference, mention, status — were PROBED against
+ * the live converter and DO round-trip P1/P2 with placeholder ids, so they are
+ * COVERED by real generators rather than allowlisted here. The allowlist below
+ * holds only types with no standalone flat generator by construction.
+ */
+export const KNOWN_UNCOVERED: Record<string, string> = {
+  // The root node; it is the wrapper every generated doc already is, never a
+  // "target" content node, so it has no standalone generator of its own.
+  doc: 'the document root wrapper, not a content node with a standalone generator',
+};
+
+/** Recursively collect every node type and `mark:<type>` under a tree. */
+export function collectTypes(node: any, seen = new Set<string>()): Set<string> {
+  if (!node || typeof node !== 'object') return seen;
+  if (node.type) seen.add(node.type);
+  for (const m of node.marks ?? []) if (m?.type) seen.add(`mark:${m.type}`);
+  for (const c of node.content ?? []) collectTypes(c, seen);
+  return seen;
+}
+
+/**
+ * Sample every generator and return the union of node/mark types they produce.
+ * Deterministic (fixed seed) so the completeness contract is stable.
+ */
+export function coveredTypes(seed = 12345, perGen = 60): Set<string> {
+  const seen = new Set<string>();
+  for (const { arb } of buildGenerators('p1')) {
+    for (const sample of fc.sample(arb, { numRuns: perGen, seed })) {
+      collectTypes(sample, seen);
+    }
+  }
+  return seen;
+}
@@ -0,0 +1,258 @@
+/**
+ * Hostile inline-text corpus for the generative flat-document round-trip suite
+ * (#351, PR 1).
+ *
+ * These arbitraries are a DIRECT PORT of the "supported space" guardrails that
+ * `test/markdown-roundtrip.property.test.ts` proved empirically against the live
+ * converter. That file's long header documents WHY each guardrail exists; rather
+ * than re-derive them, we reuse the exact same shapes here so the attribute-level
+ * generative suite inherits the same byte-stable text space. Each guardrail is
+ * cited back to that file below.
+ *
+ * The corpus deliberately spans the CommonMark / canon hostile alphabet
+ * (`* _ [ ] ( ) { } | < > & # ! ~ = + -`), unicode / emoji / RTL, and the legal
+ * mark combinations on runs (including the `code` mark, which the schema's
+ * `excludes: "_"` makes suppress every co-occurring mark — so it is never
+ * combined with another mark in the byte-stable space).
+ */
+import fc from 'fast-check';
+
+// ---------------------------------------------------------------------------
+// Words and the hostile special-character alphabet.
+// (Ported from markdown-roundtrip.property.test.ts, "Inline text arbitraries".)
+// ---------------------------------------------------------------------------
+
+/** Alphanumeric "word" (no markdown-significant characters). Length 1..6. */
+export const wordArb = fc
+  .stringMatching(/^[A-Za-z0-9]{1,6}$/)
+  .filter((w) => w.length > 0);
+
+/**
+ * A SINGLE markdown-significant character, emitted only as an isolated,
+ * space-flanked token. Every char the task calls out plus a few more; each was
+ * verified byte-stable in this position by the sibling property test.
+ *
+ * NOTE: the backtick (`) is DELIBERATELY excluded from free-floating plain text
+ * (it is a code-span delimiter that re-pairs globally). It is exercised only via
+ * the `code` mark and code blocks — see markdown-roundtrip.property.test.ts.
+ */
+export const specialCharArb = fc.constantFrom(
+  '*', '_', '[', ']', '(', ')', '{', '}', '|', '<', '>', '&', '#', '!', '~', '=', '+', '-',
+);
+
+// A pinch of unicode / emoji / RTL, always word-like (no markdown specials) so
+// it stays inside the space-flanked corpus. Kept letter/emoji-bearing so it is
+// never coerced to a number (see letterPhraseArb rationale).
+export const unicodeWordArb = fc.constantFrom(
+  'café', 'naïve', 'Zürich', 'Москва', 'こんにちは', '你好', '😀', '🚀x', 'مرحبا', 'שלום',
+);
+
+/**
+ * A "safe special" text string: a space-joined sequence of tokens that always
+ * BEGINS and ENDS with an alphanumeric word, with any isolated special chars (or
+ * unicode words) confined to the MIDDLE, each space-flanked by words.
+ *
+ * Both boundary guarantees matter (verbatim from the sibling test):
+ *   * Leading word: the line never opens with a block/inline trigger
+ *     (">", "*", "-", "#", "1." ...).
+ *   * Trailing word: adjacent text runs CONCATENATE with no separator, so a run
+ *     ending in a bare "<" beside a run starting with a letter would form a fake
+ *     HTML tag. Ending every run with a word keeps every special internal and
+ *     space-flanked even after concatenation.
+ */
+export const safeTextArb: fc.Arbitrary<string> = fc
+  .tuple(
+    wordArb,
+    fc.array(fc.oneof(wordArb, specialCharArb, unicodeWordArb), {
+      minLength: 0,
+      maxLength: 3,
+    }),
+    wordArb,
+  )
+  .map(([first, middle, last]) => [first, ...middle, last].join(' '));
+
+/**
+ * A plain alphanumeric phrase (1..3 words) for places where even isolated
+ * specials are not wanted (e.g. code-block language, mention labels, status
+ * text, table cells rendered on the plain-markdown path).
+ */
+export const phraseArb: fc.Arbitrary<string> = fc
+  .array(wordArb, { minLength: 1, maxLength: 3 })
+  .map((ws) => ws.join(' '));
+
+/**
+ * A phrase guaranteed to contain at least one letter. Used for image/media alt
+ * text and link titles: a PURELY numeric alt/title (e.g. "0") is parsed back as
+ * a NUMBER and then dropped by the converter's `value || ""` coercion — not
+ * byte-stable. A letter anywhere keeps it a string. (Ported verbatim.)
+ */
+export const letterPhraseArb: fc.Arbitrary<string> = fc
+  .tuple(
+    fc.stringMatching(/^[A-Za-z]{1,4}$/),
+    fc.array(wordArb, { minLength: 0, maxLength: 2 }),
+  )
+  .map(([head, rest]) => [head, ...rest].join(' '));
+
+/** A paren/space-free URL — safe inside markdown link/image `(...)` syntax. */
+export const urlArb: fc.Arbitrary<string> = fc
+  .webUrl()
+  .filter((u) => !/[()\s]/.test(u));
+
+// ---------------------------------------------------------------------------
+// Marked inline runs.
+// (Ported from markdown-roundtrip.property.test.ts "markedTextRunArb".)
+// ---------------------------------------------------------------------------
+
+/**
+ * A text run with an OPTIONAL single non-code formatting mark (bold/italic/
+ * strike/underline/superscript/subscript/spoiler), or a SOLE `code` mark, or a
+ * link, or an inline comment anchor. `code` is NEVER combined with another mark
+ * in the byte-stable space (that combination is a documented converter
+ * limitation — the schema's `code` mark declares `excludes: "_"`). Marks wrap
+ * `safeTextArb`, which stays stable even when it contains isolated specials.
+ *
+ * The mark set here is broadened past the sibling test's {bold,italic,strike}
+ * to also cover underline / superscript / subscript / spoiler / textStyle /
+ * highlight (all single, non-code marks), so the marks-on-text generator
+ * exercises every mark the schema declares except the deliberately-excluded
+ * `code`+other combination.
+ */
+export const markedTextRunArb: fc.Arbitrary<any> = fc.oneof(
+  // Plain text.
+  safeTextArb.map((t) => ({ type: 'text', text: t })),
+  // Single formatting mark (attribute-free marks).
+  fc
+    .tuple(
+      safeTextArb,
+      fc.constantFrom('bold', 'italic', 'strike', 'underline', 'superscript', 'subscript', 'spoiler'),
+    )
+    .map(([t, m]) => ({ type: 'text', text: t, marks: [{ type: m }] })),
+  // highlight with a color attr.
+  fc
+    .tuple(safeTextArb, fc.constantFrom('#ffcc00', '#a0e0ff', 'yellow'))
+    .map(([t, color]) => ({ type: 'text', text: t, marks: [{ type: 'highlight', attrs: { color } }] })),
+  // textStyle with a color attr.
+  fc
+    .tuple(safeTextArb, fc.constantFrom('#123456', '#ff0000', '#00aa88'))
+    .map(([t, color]) => ({ type: 'text', text: t, marks: [{ type: 'textStyle', attrs: { color } }] })),
+  // Sole code mark (backtick span). safeTextArb is backtick-free, so the span
+  // content cannot contain an inner backtick.
+  safeTextArb.map((t) => ({ type: 'text', text: t, marks: [{ type: 'code' }] })),
+  // Link with safe text, a paren/space-free href, optionally a letter-bearing
+  // title (a purely numeric title is coerced to a number and dropped).
+  fc
+    .tuple(phraseArb, urlArb, fc.option(letterPhraseArb, { nil: undefined }))
+    .map(([t, href, title]) => ({
+      type: 'text',
+      text: t,
+      marks: [{ type: 'link', attrs: title ? { href, title } : { href } }],
+    })),
+  // Inline comment anchor: a span[data-comment-id] that must survive byte-for-
+  // byte. commentId is an alphanumeric token; `resolved` rides only when true.
+  fc
+    .tuple(safeTextArb, fc.stringMatching(/^[A-Za-z0-9]{4,10}$/), fc.boolean())
+    .map(([t, commentId, resolved]) => ({
+      type: 'text',
+      text: t,
+      marks: [
+        { type: 'comment', attrs: resolved ? { commentId, resolved: true } : { commentId } },
+      ],
+    })),
+);
+
+// ---------------------------------------------------------------------------
+// Inline atoms and inline-content assembly.
+// (Ported from markdown-roundtrip.property.test.ts.)
+// ---------------------------------------------------------------------------
+
+/** Inline math node carrying LaTeX that includes the `a < b` the task asks for. */
+export const mathInlineArb: fc.Arbitrary<any> = fc
+  .constantFrom('a < b', 'x^2 + y^2', 'a < b < c', '\\frac{1}{2}', 'E = mc^2')
+  .map((text) => ({ type: 'mathInline', attrs: { text } }));
+
+/** Mention node; label/id/entity are plain phrases / uuids. */
+export const mentionArb: fc.Arbitrary<any> = fc
+  .tuple(phraseArb, fc.uuid(), fc.uuid())
+  .map(([label, id, entityId]) => ({
+    type: 'mention',
+    attrs: { id, label, entityType: 'user', entityId },
+  }));
+
+export const hardBreakArb: fc.Arbitrary<any> = fc.constant({ type: 'hardBreak' });
+
+const sameMarks = (a: any[] | undefined, b: any[] | undefined): boolean =>
+  JSON.stringify(a ?? []) === JSON.stringify(b ?? []);
+
+/**
+ * Canonicalize a generated inline-content array the way ProseMirror stores it,
+ * then trim the markdown-fragile edges. (Ported verbatim from
+ * markdown-roundtrip.property.test.ts "normalizeInline":)
+ *   1) MERGE adjacent text runs with IDENTICAL marks (the editor coalesces
+ *      them; split same-mark runs export to ambiguous "**a****b**").
+ *   2) Collapse CONSECUTIVE hard breaks (two render a blank line marked eats).
+ *   3) Drop a TRAILING hard break (removed by the converter's .trim()).
+ */
+export function normalizeInline(nodes: any[]): any[] {
+  const out: any[] = [];
+  for (const node of nodes) {
+    const prev = out[out.length - 1];
+    if (node.type === 'hardBreak' && prev && prev.type === 'hardBreak') continue;
+    if (
+      node.type === 'text' &&
+      prev &&
+      prev.type === 'text' &&
+      sameMarks(prev.marks, node.marks)
+    ) {
+      prev.text += node.text;
+      continue;
+    }
+    out.push(node.type === 'text' ? { ...node } : node);
+  }
+  while (out.length > 1 && out[out.length - 1].type === 'hardBreak') out.pop();
+  return out;
+}
+
+/**
+ * Inline content for a paragraph: at least one marked text run, optionally with
+ * inline atoms (math/mention) and hard breaks interspersed. Always starts with a
+ * text run so the paragraph never opens with a block trigger. (Ported.)
+ */
+export const inlineContentArb: fc.Arbitrary<any[]> = fc
+  .tuple(
+    markedTextRunArb,
+    fc.array(
+      fc.oneof(
+        { weight: 5, arbitrary: markedTextRunArb },
+        { weight: 1, arbitrary: mathInlineArb },
+        { weight: 1, arbitrary: mentionArb },
+        { weight: 1, arbitrary: hardBreakArb },
+      ),
+      { minLength: 0, maxLength: 4 },
+    ),
+  )
+  .map(([first, rest]) => normalizeInline([first, ...rest]));
+
+/**
+ * Inline content for a HEADING — identical to a paragraph's, but WITHOUT hard
+ * breaks. A hard break inside an ATX heading is not byte-stable (marked splits
+ * the heading). (Ported.)
+ */
+export const headingInlineContentArb: fc.Arbitrary<any[]> = fc
+  .tuple(
+    markedTextRunArb,
+    fc.array(
+      fc.oneof(
+        { weight: 5, arbitrary: markedTextRunArb },
+        { weight: 1, arbitrary: mathInlineArb },
+        { weight: 1, arbitrary: mentionArb },
+      ),
+      { minLength: 0, maxLength: 4 },
+    ),
+  )
+  .map(([first, rest]) => normalizeInline([first, ...rest]));
+
+/** Simple plain-text inline content (single run) for containers rendered on the
+ * raw-HTML path (table cells / column bodies) where fancy inline is undesirable. */
+export const plainInlineContentArb: fc.Arbitrary<any[]> = phraseArb.map((t) => [
+  { type: 'text', text: t },
+]);
@@ -543,9 +543,6 @@ importers:
      '@docmost/pdf-inspector':
        specifier: 1.9.6
        version: 1.9.6
-      '@docmost/prosemirror-markdown':
-        specifier: workspace:*
-        version: link:../../packages/prosemirror-markdown
      '@fastify/cookie':
        specifier: ^11.0.2
        version: 11.0.2