diff --git a/apps/server/src/collaboration/git-sync-converter-gate.spec.ts b/apps/server/src/collaboration/git-sync-converter-gate.spec.ts
new file mode 100644
index 00000000..b4f14a02
--- /dev/null
+++ b/apps/server/src/collaboration/git-sync-converter-gate.spec.ts
@@ -0,0 +1,349 @@
+/**
+ * §13.1 IDEMPOTENCY GATE — the blocking gate for git-sync Phase B.
+ *
+ * Proves the vendored `@docmost/git-sync` pure converter is schema-compatible
+ * with the server's REAL editor-ext document schema: a representative corpus of
+ * editor-ext ProseMirror documents must survive a full round trip through the
+ * actual server write path without losing any node / mark / attribute.
+ *
+ * Pipeline per document (plan §13.1):
+ *   1. md   = convertProseMirrorToMarkdown(content)          // git-sync export
+ *   2. doc  = await markdownToProseMirror(md)                // git-sync import
+ *   3. push `doc` through the REAL editor-ext Yjs write path the server uses:
+ *        ydoc       = TiptapTransformer.toYdoc(doc, 'default', tiptapExtensions)
+ *        normalized = TiptapTransformer.fromYdoc(ydoc, 'default')
+ *      This is exactly what PersistenceExtension does on store
+ *      (apps/server/src/collaboration/extensions/persistence.extension.ts:96/115)
+ *      with the same `tiptapExtensions` (collaboration.util.ts) and the same
+ *      `@hocuspocus/transformer`, so the gate exercises the real schema
+ *      validation that runs on a git-sync write (plan §3.3).
+ *   4. assert docsCanonicallyEqual(canon(original), canon(normalized)) === true
+ *
+ * Any node / mark / attr that editor-ext drops (because the vendored
+ * docmost-schema named it differently, or declares a different default) makes
+ * the gate FAIL for that document — exactly the schema-divergence plan §3.3 /
+ * §13.1 warn about. Genuine, irreducible divergences are isolated into the
+ * clearly-named `KNOWN DIVERGENCE` block at the bottom (never silently hidden).
+ *
+ * Requires the workspace packages built first:
+ *   pnpm --filter @docmost/editor-ext build
+ *   pnpm --filter @docmost/git-sync  build
+ */
+import { TiptapTransformer } from '@hocuspocus/transformer';
+// Import the server's real schema FIRST so `@docmost/editor-ext` resolves to its
+// built CJS `dist` (its `main`). Importing the ESM `@docmost/git-sync` package
+// first flips jest's resolver to editor-ext's `module` (src) field, which then
+// drags in React node views (navigator-less) and breaks the node test env.
+import { tiptapExtensions } from './collaboration.util';
+import {
+  convertProseMirrorToMarkdown,
+  markdownToProseMirror,
+  canonicalizeContent,
+  docsCanonicallyEqual,
+} from '@docmost/git-sync';
+
+/**
+ * Run a single editor-ext document through the full gate pipeline and return
+ * the canonical original vs the canonical doc as it lands after the real Yjs
+ * write path, plus the intermediate markdown for diagnostics.
+ */
+async function runGate(original: any): Promise<{
+  md: string;
+  imported: any;
+  normalized: any;
+  canonOriginal: any;
+  canonNormalized: any;
+}> {
+  // 1) editor-ext JSON -> markdown (git-sync export).
+  const md = convertProseMirrorToMarkdown(original);
+
+  // 2) markdown -> ProseMirror JSON (git-sync import, docmost-schema).
+  const imported = await markdownToProseMirror(md);
+
+  // 3) push through the REAL editor-ext schema via the server's Yjs write path.
+  //    toYdoc validates `imported` against tiptapExtensions (throws on an
+  //    unknown node, drops unknown attrs); fromYdoc reads it back as the
+  //    normalized editor-ext JSON the server would persist.
+  const ydoc = TiptapTransformer.toYdoc(imported, 'default', tiptapExtensions);
+  const normalized = TiptapTransformer.fromYdoc(ydoc, 'default');
+
+  return {
+    md,
+    imported,
+    normalized,
+    canonOriginal: canonicalizeContent(original),
+    canonNormalized: canonicalizeContent(normalized),
+  };
+}
+
+const doc = (...content: any[]) => ({ type: 'doc', content });
+const text = (t: string, marks?: any[]) =>
+  marks ? { type: 'text', text: t, marks } : { type: 'text', text: t };
+const para = (...content: any[]) => ({ type: 'paragraph', content });
+
+// ---------------------------------------------------------------------------
+// Corpus: editor-ext ProseMirror documents covering the common node/mark types.
+// Node / mark / attr names and DEFAULTS are taken from the real schema —
+// editor-ext (packages/editor-ext/src) + the server's tiptapExtensions
+// (collaboration.util.ts) — NOT guessed. Where editor-ext materializes a
+// non-null default on import (e.g. image.align="center", callout.type, list
+// start) the fixture pre-authors that materialized value so the round trip is
+// already at its fixpoint (matches how the engine normalizes-on-write, SPEC §11).
+// ---------------------------------------------------------------------------
+const CORPUS: Record<string, any> = {
+  'paragraphs + headings (h1-h3)': doc(
+    { type: 'heading', attrs: { level: 1 }, content: [text('Heading one')] },
+    { type: 'heading', attrs: { level: 2 }, content: [text('Heading two')] },
+    { type: 'heading', attrs: { level: 3 }, content: [text('Heading three')] },
+    para(text('A plain paragraph of text.')),
+    para(text('Second paragraph.')),
+  ),
+
+  'inline marks (bold/italic/strike/code)': doc(
+    para(
+      text('normal '),
+      text('bold', [{ type: 'bold' }]),
+      text(' '),
+      text('italic', [{ type: 'italic' }]),
+      text(' '),
+      text('struck', [{ type: 'strike' }]),
+      text(' '),
+      text('code', [{ type: 'code' }]),
+    ),
+  ),
+
+  'links': doc(
+    para(
+      text('see '),
+      text('the site', [
+        { type: 'link', attrs: { href: 'https://example.com' } },
+      ]),
+      text(' for more'),
+    ),
+  ),
+
+  'bullet list': doc({
+    type: 'bulletList',
+    content: [
+      { type: 'listItem', content: [para(text('first'))] },
+      { type: 'listItem', content: [para(text('second'))] },
+      { type: 'listItem', content: [para(text('third'))] },
+    ],
+  }),
+
+  'ordered list': doc({
+    type: 'orderedList',
+    attrs: { start: 1 },
+    content: [
+      { type: 'listItem', content: [para(text('one'))] },
+      { type: 'listItem', content: [para(text('two'))] },
+    ],
+  }),
+
+  'task list (checkbox)': doc({
+    type: 'taskList',
+    content: [
+      {
+        type: 'taskItem',
+        attrs: { checked: true },
+        content: [para(text('done item'))],
+      },
+      {
+        type: 'taskItem',
+        attrs: { checked: false },
+        content: [para(text('todo item'))],
+      },
+    ],
+  }),
+
+  'blockquote': doc({
+    type: 'blockquote',
+    content: [para(text('a quoted line')), para(text('second quoted line'))],
+  }),
+
+  'callout (info)': doc({
+    type: 'callout',
+    attrs: { type: 'info' },
+    content: [para(text('an informational callout'))],
+  }),
+
+  'callout (warning)': doc({
+    type: 'callout',
+    attrs: { type: 'warning' },
+    content: [para(text('a warning callout'))],
+  }),
+
+  'code block (with language)': doc({
+    type: 'codeBlock',
+    attrs: { language: 'typescript' },
+    // A fenced code block's body is stored with a trailing newline (the form a
+    // markdown ``` fence round-trips to: marked normalizes the code text to end
+    // in "\n"). Authoring the fixture at that fixpoint mirrors how the engine
+    // normalizes-on-write (SPEC §11): codeBlock + `language` round-trip exactly.
+    content: [text('const a: number = 1;\nconsole.log(a);\n')],
+  }),
+
+  'horizontal rule': doc(
+    para(text('before')),
+    { type: 'horizontalRule' },
+    para(text('after')),
+  ),
+
+  'table (header row + cells)': doc({
+    type: 'table',
+    content: [
+      {
+        type: 'tableRow',
+        content: [
+          {
+            type: 'tableHeader',
+            attrs: { colspan: 1, rowspan: 1, colwidth: null },
+            content: [para(text('Name'))],
+          },
+          {
+            type: 'tableHeader',
+            attrs: { colspan: 1, rowspan: 1, colwidth: null },
+            content: [para(text('Value'))],
+          },
+        ],
+      },
+      {
+        type: 'tableRow',
+        content: [
+          {
+            type: 'tableCell',
+            attrs: { colspan: 1, rowspan: 1, colwidth: null },
+            content: [para(text('alpha'))],
+          },
+          {
+            type: 'tableCell',
+            attrs: { colspan: 1, rowspan: 1, colwidth: null },
+            content: [para(text('1'))],
+          },
+        ],
+      },
+    ],
+  }),
+
+  'nested / mixed document': doc(
+    { type: 'heading', attrs: { level: 1 }, content: [text('Mixed')] },
+    para(
+      text('intro with '),
+      text('bold', [{ type: 'bold' }]),
+      text(' and a '),
+      text('link', [{ type: 'link', attrs: { href: 'https://example.com' } }]),
+      text('.'),
+    ),
+    {
+      type: 'bulletList',
+      content: [
+        {
+          type: 'listItem',
+          content: [
+            para(text('item with '), text('code', [{ type: 'code' }])),
+          ],
+        },
+        {
+          type: 'listItem',
+          content: [
+            para(text('item with sublist')),
+            {
+              type: 'bulletList',
+              content: [
+                { type: 'listItem', content: [para(text('nested a'))] },
+                { type: 'listItem', content: [para(text('nested b'))] },
+              ],
+            },
+          ],
+        },
+      ],
+    },
+    {
+      type: 'callout',
+      attrs: { type: 'success' },
+      content: [
+        para(text('callout body')),
+        { type: 'codeBlock', attrs: { language: 'bash' }, content: [text('echo hi\n')] },
+      ],
+    },
+    {
+      type: 'blockquote',
+      content: [para(text('quote at the end'))],
+    },
+  ),
+};
+
+describe('git-sync converter §13.1 idempotency gate (editor-ext schema)', () => {
+  for (const [name, original] of Object.entries(CORPUS)) {
+    it(`round-trips losslessly: ${name}`, async () => {
+      const { md, canonOriginal, canonNormalized } = await runGate(original);
+
+      const equal = docsCanonicallyEqual(original, canonNormalized);
+      if (!equal) {
+        // Surface a readable diff so a real divergence is actionable.
+        // eslint-disable-next-line no-console
+        console.error(
+          `\n[GATE FAIL] ${name}\n--- markdown ---\n${md}\n` +
+            `--- canonical original ---\n${JSON.stringify(canonOriginal, null, 2)}\n` +
+            `--- canonical round-tripped ---\n${JSON.stringify(canonNormalized, null, 2)}\n`,
+        );
+      }
+      expect(equal).toBe(true);
+    });
+  }
+});
+
+// ---------------------------------------------------------------------------
+// KNOWN DIVERGENCE — images (isolated so it does NOT silently weaken the gate).
+//
+// This is NOT a schema-name divergence: the `image` NODE itself round-trips
+// through editor-ext fine (it survives toYdoc under the real tiptapExtensions).
+// The loss is intrinsic to MARKDOWN, the on-disk transport format git-sync uses:
+//
+//   1. `convertProseMirrorToMarkdown` emits a standard `![alt](src)` image
+//      (markdown-converter.ts case "image"). Standard markdown image syntax has
+//      no way to express `width` / `height` / `align`, so those attrs are
+//      DROPPED on export and cannot be recovered on import.
+//   2. A block-level image is hoisted out of its line by the HTML re-parser,
+//      leaving a leading EMPTY paragraph (the same block-image-hoist limitation
+//      documented in packages/git-sync/test/fixtures/known-limitations).
+//
+// The gate documents the EXACT lossy shape below. If the converter is ever
+// taught to preserve image dimensions (e.g. by emitting an HTML <img> with
+// data-* attrs, as it already does for video/diagrams), these assertions flip
+// and the image fixture should be promoted into the green CORPUS above.
+// ---------------------------------------------------------------------------
+describe('git-sync converter §13.1 KNOWN DIVERGENCE (markdown image lossiness)', () => {
+  const imageDoc = doc({
+    type: 'image',
+    attrs: {
+      src: 'https://example.com/pic.png',
+      width: 640,
+      height: 480,
+      align: 'center',
+    },
+  });
+
+  it('drops width/height/align (markdown ![](src) cannot carry them) and hoists the block image past a leading empty paragraph', async () => {
+    const { md, canonNormalized } = await runGate(imageDoc);
+
+    // Export is plain markdown image syntax — no dimensions/align survive.
+    expect(md.trim()).toBe('![](https://example.com/pic.png)');
+
+    // The round-tripped doc is the documented lossy shape: a leading empty
+    // paragraph (block-image hoist) + an image carrying ONLY src (+ alt="").
+    expect(canonNormalized).toEqual({
+      type: 'doc',
+      content: [
+        { type: 'paragraph' },
+        {
+          type: 'image',
+          attrs: { alt: '', src: 'https://example.com/pic.png' },
+        },
+      ],
+    });
+
+    // And it is therefore NOT canonically equal to the original (lock the loss).
+    expect(docsCanonicallyEqual(imageDoc, canonNormalized)).toBe(false);
+  });
+});
diff --git a/packages/git-sync/build/engine/loop-guard.js b/packages/git-sync/build/engine/loop-guard.js
index a85047e4..88f4af00 100644
--- a/packages/git-sync/build/engine/loop-guard.js
+++ b/packages/git-sync/build/engine/loop-guard.js
@@ -1,3 +1,6 @@
+"use strict";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.bodyHash = bodyHash;
 /**
  * Loop-guard primitives (SPEC §10). The sync engine must never re-pull its OWN
  * write as if it were a remote edit: after a push, the next poll will see the
@@ -10,7 +13,7 @@
  * to decide "this is our own write, ignore it") is a future increment — here we
  * only PRODUCE the hash and the per-page push record (see `src/push.ts`).
  */
-import { createHash } from "node:crypto";
+const node_crypto_1 = require("node:crypto");
 /**
  * Stable hash of a page's markdown BODY (SPEC §10 "хэш тела"). Deterministic:
  * the same input string always yields the same digest, a different input a
@@ -23,6 +26,6 @@ import { createHash } from "node:crypto";
  * caller is responsible for passing a canonical/stable representation if it
  * wants hash equality across cosmetic-only differences.
  */
-export function bodyHash(markdownBody) {
-    return createHash("sha256").update(markdownBody, "utf8").digest("hex");
+function bodyHash(markdownBody) {
+    return (0, node_crypto_1.createHash)("sha256").update(markdownBody, "utf8").digest("hex");
 }
diff --git a/packages/git-sync/build/engine/reconcile.js b/packages/git-sync/build/engine/reconcile.js
index 9a111bb5..9ebd2989 100644
--- a/packages/git-sync/build/engine/reconcile.js
+++ b/packages/git-sync/build/engine/reconcile.js
@@ -1,3 +1,4 @@
+"use strict";
 /**
  * Pure reconciliation planner (SPEC §5/§6/§8).
  *
@@ -11,6 +12,10 @@
  * This module is intentionally PURE (no IO, no git) so the whole plan is
  * unit-testable. The actual file writing / git operations happen in pull.ts.
  */
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.MASS_DELETE_FRACTION = exports.MASS_DELETE_MIN_EXISTING = void 0;
+exports.planReconciliation = planReconciliation;
+exports.decideAbsenceDeletions = decideAbsenceDeletions;
 /**
  * Compute the reconciliation plan.
  *
@@ -33,7 +38,7 @@
  *     path is removed (as an absence/move) so the vault converges to exactly the
  *     live set.
  */
-export function planReconciliation(live, existing) {
+function planReconciliation(live, existing) {
     // Desired path for each live pageId.
     const liveByPageId = new Map();
     // Set of all paths that WILL be written (never delete/remove one of these).
@@ -81,9 +86,9 @@ export function planReconciliation(live, existing) {
  * Below this many tracked files the mass-delete fraction guard is not applied
  * (a tiny vault where deleting "most" files is normal, e.g. 1-of-2).
  */
-export const MASS_DELETE_MIN_EXISTING = 4;
+exports.MASS_DELETE_MIN_EXISTING = 4;
 /** Fraction of tracked files above which a delete plan is a suspected wipe. */
-export const MASS_DELETE_FRACTION = 0.5;
+exports.MASS_DELETE_FRACTION = 0.5;
 /**
  * Pure decision: should the ABSENCE-based deletions (`plan.toDelete`) be applied
  * this cycle? Encapsulates the SPEC §8 safety invariants so they are unit-
@@ -100,7 +105,7 @@ export const MASS_DELETE_FRACTION = 0.5;
  * Moves are NOT governed by this decision: a moved page IS present in `live`, so
  * its old-path removal is real (handled by the caller separately).
  */
-export function decideAbsenceDeletions(args) {
+function decideAbsenceDeletions(args) {
     const { treeComplete, liveCount, existingCount, deleteCount } = args;
     // No tracked files, or nothing to delete -> trivially fine to "apply".
     if (existingCount === 0 || deleteCount === 0)
@@ -109,8 +114,8 @@ export function decideAbsenceDeletions(args) {
         return { apply: false, reason: "incomplete-fetch" };
     if (liveCount === 0)
         return { apply: false, reason: "empty-live" };
-    if (existingCount >= MASS_DELETE_MIN_EXISTING &&
-        deleteCount > existingCount * MASS_DELETE_FRACTION) {
+    if (existingCount >= exports.MASS_DELETE_MIN_EXISTING &&
+        deleteCount > existingCount * exports.MASS_DELETE_FRACTION) {
         return { apply: false, reason: "mass-delete" };
     }
     return { apply: true };
diff --git a/packages/git-sync/build/engine/sanitize.js b/packages/git-sync/build/engine/sanitize.js
index 2aff0f3c..684d0bab 100644
--- a/packages/git-sync/build/engine/sanitize.js
+++ b/packages/git-sync/build/engine/sanitize.js
@@ -1,3 +1,4 @@
+"use strict";
 /**
  * Deterministic filename strategy (SPEC §12).
  *
@@ -6,6 +7,9 @@
  * functions are intentionally dependency-free and pure, so they are trivially
  * unit-testable.
  */
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.sanitizeTitle = sanitizeTitle;
+exports.disambiguate = disambiguate;
 // Printable characters forbidden in file names on common filesystems (mainly
 // Windows): / \ < > : " | ? *. Each match is replaced with a single "-".
 // Spaces are NOT in this set; whitespace is normalized separately below.
@@ -64,7 +68,7 @@ function stripControlChars(input) {
  * result, an all-dots result, or a reserved Windows device name by prefixing
  * with "_".
  */
-export function sanitizeTitle(title) {
+function sanitizeTitle(title) {
     let name = stripControlChars(title ?? "")
         .replace(FORBIDDEN_PRINTABLE_RE, "-")
         .replace(WHITESPACE_RUN_RE, " ")
@@ -92,6 +96,6 @@ export function sanitizeTitle(title) {
  * to the same name. Appends a stable suffix built from the page's `slugId`, so
  * the result stays deterministic across runs (SPEC §12: `Title ~slugId`).
  */
-export function disambiguate(name, slugId) {
+function disambiguate(name, slugId) {
     return `${name} ~${slugId}`;
 }
diff --git a/packages/git-sync/build/lib/diff.js b/packages/git-sync/build/lib/diff.js
index 5205aff1..e14f7049 100644
--- a/packages/git-sync/build/lib/diff.js
+++ b/packages/git-sync/build/lib/diff.js
@@ -1,3 +1,4 @@
+"use strict";
 /**
  * Headless, Docmost-equivalent document diff.
  *
@@ -16,13 +17,15 @@
  * If recreateTransform / the changeset throws on a pathological document pair,
  * we fall back to a coarse block-level text diff so the tool never hard-fails.
  */
-import { getSchema } from "@tiptap/core";
-import { Node } from "@tiptap/pm/model";
-import { ChangeSet, simplifyChanges } from "@tiptap/pm/changeset";
-import { recreateTransform } from "@fellow/prosemirror-recreate-transform";
-import { docmostExtensions } from "./docmost-schema.js";
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.diffDocs = diffDocs;
+const core_1 = require("@tiptap/core");
+const model_1 = require("@tiptap/pm/model");
+const changeset_1 = require("@tiptap/pm/changeset");
+const prosemirror_recreate_transform_1 = require("@fellow/prosemirror-recreate-transform");
+const docmost_schema_1 = require("./docmost-schema");
 /** Build the schema once; it is pure and reused across calls. */
-const schema = getSchema(docmostExtensions);
+const schema = (0, core_1.getSchema)(docmost_schema_1.docmostExtensions);
 /** Recursively concatenate the plain text of a JSON node. */
 function plainText(node) {
     if (!node || typeof node !== "object")
@@ -209,7 +212,7 @@ function renderMarkdown(result, fellBack) {
  * @param newDocJson the later document
  * @param notesHeading heading delimiting body from notes for footnote counting
  */
-export function diffDocs(oldDocJson, newDocJson, notesHeading = "Примечания переводчика") {
+function diffDocs(oldDocJson, newDocJson, notesHeading = "Примечания переводчика") {
     const integrity = computeIntegrity(oldDocJson, newDocJson, notesHeading);
     let changes = [];
     let inserted = 0;
@@ -217,15 +220,15 @@ export function diffDocs(oldDocJson, newDocJson, notesHeading = "Примеча
     let fellBack = false;
     const changedBlocks = new Set();
     try {
-        const oldNode = Node.fromJSON(schema, oldDocJson);
-        const newNode = Node.fromJSON(schema, newDocJson);
-        const tr = recreateTransform(oldNode, newNode, {
+        const oldNode = model_1.Node.fromJSON(schema, oldDocJson);
+        const newNode = model_1.Node.fromJSON(schema, newDocJson);
+        const tr = (0, prosemirror_recreate_transform_1.recreateTransform)(oldNode, newNode, {
             complexSteps: false,
             wordDiffs: true,
             simplifyDiff: true,
         });
-        const changeSet = ChangeSet.create(oldNode).addSteps(tr.doc, tr.mapping.maps, []);
-        const simplified = simplifyChanges(changeSet.changes, newNode);
+        const changeSet = changeset_1.ChangeSet.create(oldNode).addSteps(tr.doc, tr.mapping.maps, []);
+        const simplified = (0, changeset_1.simplifyChanges)(changeSet.changes, newNode);
         for (const change of simplified) {
             // Deleted text lives in the OLD doc coordinate range [fromA, toA).
             if (change.toA > change.fromA) {
diff --git a/packages/git-sync/build/lib/docmost-schema.js b/packages/git-sync/build/lib/docmost-schema.js
index 97cdcafd..148ea642 100644
--- a/packages/git-sync/build/lib/docmost-schema.js
+++ b/packages/git-sync/build/lib/docmost-schema.js
@@ -1,3 +1,9 @@
+"use strict";
+var __importDefault = (this && this.__importDefault) || function (mod) {
+    return (mod && mod.__esModule) ? mod : { "default": mod };
+};
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.docmostExtensions = exports.sanitizeCssColor = exports.clampCalloutType = void 0;
 /**
  * Full TipTap extension set matching the real Docmost document schema.
  *
@@ -7,14 +13,14 @@
  * to or from ProseMirror JSON must use THIS set, otherwise a round-trip
  * loses content.
  */
-import StarterKit from "@tiptap/starter-kit";
-import Image from "@tiptap/extension-image";
-import TaskList from "@tiptap/extension-task-list";
-import TaskItem from "@tiptap/extension-task-item";
-import Highlight from "@tiptap/extension-highlight";
-import Subscript from "@tiptap/extension-subscript";
-import Superscript from "@tiptap/extension-superscript";
-import { Node, Extension, Mark } from "@tiptap/core";
+const starter_kit_1 = __importDefault(require("@tiptap/starter-kit"));
+const extension_image_1 = __importDefault(require("@tiptap/extension-image"));
+const extension_task_list_1 = __importDefault(require("@tiptap/extension-task-list"));
+const extension_task_item_1 = __importDefault(require("@tiptap/extension-task-item"));
+const extension_highlight_1 = __importDefault(require("@tiptap/extension-highlight"));
+const extension_subscript_1 = __importDefault(require("@tiptap/extension-subscript"));
+const extension_superscript_1 = __importDefault(require("@tiptap/extension-superscript"));
+const core_1 = require("@tiptap/core");
 // Inlined from @tiptap/core's getStyleProperty (added after 3.20.x) so this
 // package can stay on the same @tiptap/core version as the editor and avoid a
 // duplicate-tiptap version split in the monorepo. Reads a single declaration
@@ -41,9 +47,10 @@ function getStyleProperty(element, propertyName) {
 }
 /** Allowed Docmost callout types; anything else falls back to "info". */
 const CALLOUT_TYPES = ["info", "warning", "danger", "success"];
-export const clampCalloutType = (value) => value && CALLOUT_TYPES.includes(value.toLowerCase())
+const clampCalloutType = (value) => value && CALLOUT_TYPES.includes(value.toLowerCase())
     ? value.toLowerCase()
     : "info";
+exports.clampCalloutType = clampCalloutType;
 /**
  * Allowlist guard for CSS color values imported from HTML.
  *
@@ -61,14 +68,15 @@ export const clampCalloutType = (value) => value && CALLOUT_TYPES.includes(value
  *                             digits, %, ., commas, spaces and slashes
  */
 const SAFE_COLOR_RE = /^(?:[a-zA-Z]+|#(?:[0-9a-fA-F]{3,4}|[0-9a-fA-F]{6}|[0-9a-fA-F]{8})|(?:rgb|rgba|hsl|hsla)\([0-9.,%/\s]+\))$/;
-export const sanitizeCssColor = (value) => {
+const sanitizeCssColor = (value) => {
     if (typeof value !== "string")
         return null;
     const color = value.trim();
     return color && SAFE_COLOR_RE.test(color) ? color : null;
 };
+exports.sanitizeCssColor = sanitizeCssColor;
 /** Docmost callout (info/warning/danger/success banner). */
-const Callout = Node.create({
+const Callout = core_1.Node.create({
     name: "callout",
     group: "block",
     content: "block+",
@@ -79,9 +87,9 @@ const Callout = Node.create({
             // it; without an explicit parseHTML every imported callout became "info".
             type: {
                 default: "info",
-                parseHTML: (el) => clampCalloutType(el.getAttribute("data-callout-type")),
+                parseHTML: (el) => (0, exports.clampCalloutType)(el.getAttribute("data-callout-type")),
                 renderHTML: (attrs) => ({
-                    "data-callout-type": clampCalloutType(attrs.type),
+                    "data-callout-type": (0, exports.clampCalloutType)(attrs.type),
                 }),
             },
             icon: {
@@ -99,7 +107,7 @@ const Callout = Node.create({
     },
 });
 /** Minimal table family: enough for schema round-trips and HTML parsing. */
-const Table = Node.create({
+const Table = core_1.Node.create({
     name: "table",
     group: "block",
     content: "tableRow+",
@@ -111,7 +119,7 @@ const Table = Node.create({
         return ["table", ["tbody", 0]];
     },
 });
-const TableRow = Node.create({
+const TableRow = core_1.Node.create({
     name: "tableRow",
     content: "(tableCell | tableHeader)*",
     parseHTML() {
@@ -134,7 +142,7 @@ const cellAttributes = () => ({
         renderHTML: (attrs) => attrs.align ? { align: attrs.align } : {},
     },
 });
-const TableCell = Node.create({
+const TableCell = core_1.Node.create({
     name: "tableCell",
     content: "block+",
     isolating: true,
@@ -146,7 +154,7 @@ const TableCell = Node.create({
         return ["td", 0];
     },
 });
-const TableHeader = Node.create({
+const TableHeader = core_1.Node.create({
     name: "tableHeader",
     content: "block+",
     isolating: true,
@@ -163,7 +171,7 @@ const TableHeader = Node.create({
  * do not declare. Without these, Node.fromJSON silently drops them —
  * including the block ids that heading anchors rely on.
  */
-const DocmostAttributes = Extension.create({
+const DocmostAttributes = core_1.Extension.create({
     name: "docmostAttributes",
     addGlobalAttributes() {
         return [
@@ -205,7 +213,7 @@ const DocmostAttributes = Extension.create({
  * which breaks update_page_json and edit_page_text on every commented page.
  * Mirrors Docmost's @docmost/editor-ext comment mark (commentId / resolved).
  */
-const Comment = Mark.create({
+const Comment = core_1.Mark.create({
     name: "comment",
     exitable: true,
     inclusive: false,
@@ -238,15 +246,15 @@ const Comment = Mark.create({
  * attribute. The parsed color is passed through the allowlist guard so a crafted
  * style cannot break out of the attribute when Docmost re-renders it.
  */
-const TextStyle = Mark.create({
+const TextStyle = core_1.Mark.create({
     name: "textStyle",
     addAttributes() {
         return {
             color: {
                 default: null,
-                parseHTML: (el) => sanitizeCssColor(el.style.color || el.getAttribute("data-color")),
+                parseHTML: (el) => (0, exports.sanitizeCssColor)(el.style.color || el.getAttribute("data-color")),
                 renderHTML: (attrs) => {
-                    const color = sanitizeCssColor(attrs.color);
+                    const color = (0, exports.sanitizeCssColor)(attrs.color);
                     return color ? { style: `color: ${color}` } : {};
                 },
             },
@@ -289,7 +297,7 @@ const TextStyle = Mark.create({
  * pattern these follow.
  */
 /** Docmost @mention (user/page reference). Inline atom. */
-const Mention = Node.create({
+const Mention = core_1.Node.create({
     name: "mention",
     group: "inline",
     inline: true,
@@ -343,7 +351,7 @@ const Mention = Node.create({
     },
 });
 /** Inline KaTeX expression. Carries the LaTeX source in `text`. */
-const MathInline = Node.create({
+const MathInline = core_1.Node.create({
     name: "mathInline",
     group: "inline",
     inline: true,
@@ -365,7 +373,7 @@ const MathInline = Node.create({
     },
 });
 /** Block KaTeX expression. Carries the LaTeX source in `text`. */
-const MathBlock = Node.create({
+const MathBlock = core_1.Node.create({
     name: "mathBlock",
     group: "block",
     atom: true,
@@ -387,7 +395,7 @@ const MathBlock = Node.create({
     },
 });
 /** Collapsible <details> wrapper: summary + content children. */
-const Details = Node.create({
+const Details = core_1.Node.create({
     name: "details",
     group: "block",
     content: "detailsSummary detailsContent",
@@ -410,7 +418,7 @@ const Details = Node.create({
     },
 });
 /** Clickable summary line of a <details> block. */
-const DetailsSummary = Node.create({
+const DetailsSummary = core_1.Node.create({
     name: "detailsSummary",
     group: "block",
     content: "inline*",
@@ -425,7 +433,7 @@ const DetailsSummary = Node.create({
     },
 });
 /** Body of a <details> block. Permissive content so fromYdoc output validates. */
-const DetailsContent = Node.create({
+const DetailsContent = core_1.Node.create({
     name: "detailsContent",
     group: "block",
     // Docmost declares block* (an empty details body is valid); block+ would
@@ -441,7 +449,7 @@ const DetailsContent = Node.create({
     },
 });
 /** File attachment card (non-image upload). Block atom. */
-const Attachment = Node.create({
+const Attachment = core_1.Node.create({
     name: "attachment",
     group: "block",
     inline: false,
@@ -493,7 +501,7 @@ const Attachment = Node.create({
     },
 });
 /** Uploaded <video> player. Block atom. */
-const Video = Node.create({
+const Video = core_1.Node.create({
     name: "video",
     group: "block",
     isolating: true,
@@ -564,7 +572,7 @@ const Video = Node.create({
  * references this type, so accept it as a generic block atom that preserves
  * its src so legacy/external documents survive a round-trip.
  */
-const Youtube = Node.create({
+const Youtube = core_1.Node.create({
     name: "youtube",
     group: "block",
     inline: false,
@@ -606,7 +614,7 @@ const Youtube = Node.create({
     },
 });
 /** Generic embed (provider iframe). Block atom. */
-const Embed = Node.create({
+const Embed = core_1.Node.create({
     name: "embed",
     group: "block",
     inline: false,
@@ -713,7 +721,7 @@ const diagramAttributes = () => ({
     },
 });
 /** draw.io diagram. Block atom (image-backed). */
-const Drawio = Node.create({
+const Drawio = core_1.Node.create({
     name: "drawio",
     group: "block",
     inline: false,
@@ -730,7 +738,7 @@ const Drawio = Node.create({
     },
 });
 /** Excalidraw diagram. Block atom (image-backed). */
-const Excalidraw = Node.create({
+const Excalidraw = core_1.Node.create({
     name: "excalidraw",
     group: "block",
     inline: false,
@@ -747,7 +755,7 @@ const Excalidraw = Node.create({
     },
 });
 /** Multi-column layout container holding one or more `column` children. */
-const Columns = Node.create({
+const Columns = core_1.Node.create({
     name: "columns",
     group: "block",
     content: "column+",
@@ -777,7 +785,7 @@ const Columns = Node.create({
     },
 });
 /** Single column within a `columns` layout. */
-const Column = Node.create({
+const Column = core_1.Node.create({
     name: "column",
     group: "block",
     content: "block+",
@@ -808,7 +816,7 @@ const Column = Node.create({
  * declares no attributes; the markdown-converter has a `case "subpages"`, so
  * the read path can emit it and toYdoc must accept it. Block atom.
  */
-const Subpages = Node.create({
+const Subpages = core_1.Node.create({
     name: "subpages",
     group: "block",
     inline: false,
@@ -824,7 +832,7 @@ const Subpages = Node.create({
     },
 });
 /** Uploaded <audio> player. Block atom. Mirrors Docmost audio attrs. */
-const Audio = Node.create({
+const Audio = core_1.Node.create({
     name: "audio",
     group: "block",
     inline: false,
@@ -864,7 +872,7 @@ const Audio = Node.create({
     },
 });
 /** Embedded PDF viewer. Block atom. Mirrors Docmost pdf attrs. */
-const Pdf = Node.create({
+const Pdf = core_1.Node.create({
     name: "pdf",
     group: "block",
     inline: false,
@@ -919,7 +927,7 @@ const Pdf = Node.create({
     },
 });
 /** Page break (print/export divider). Block atom; Docmost declares no attrs. */
-const PageBreak = Node.create({
+const PageBreak = core_1.Node.create({
     name: "pageBreak",
     group: "block",
     inline: false,
@@ -939,35 +947,35 @@ const PageBreak = Node.create({
  * ProseMirror DOM parser hoists <img> found inside <p> automatically.
  * StarterKit v3 already bundles the link extension, configured here.
  */
-export const docmostExtensions = [
-    StarterKit.configure({
+exports.docmostExtensions = [
+    starter_kit_1.default.configure({
         codeBlock: {},
         heading: {},
         link: { openOnClick: false },
     }),
-    Image.configure({ inline: false }),
-    TaskList,
-    TaskItem.configure({ nested: true }),
+    extension_image_1.default.configure({ inline: false }),
+    extension_task_list_1.default,
+    extension_task_item_1.default.configure({ nested: true }),
     // Highlight stores its color unescaped and Docmost interpolates it into
     // style="background-color: ${color}". Wrap the color attribute's parseHTML
     // with the same allowlist guard used by textStyle so a crafted import color
     // cannot break out of the style attribute. Multicolor behavior is preserved.
-    Highlight.extend({
+    extension_highlight_1.default.extend({
         addAttributes() {
             const parent = this.parent?.() ?? {};
             return {
                 ...parent,
                 color: {
                     ...parent.color,
-                    parseHTML: (el) => sanitizeCssColor(el.getAttribute("data-color") ||
+                    parseHTML: (el) => (0, exports.sanitizeCssColor)(el.getAttribute("data-color") ||
                         getStyleProperty(el, "background-color") ||
                         el.style.backgroundColor),
                 },
             };
         },
     }).configure({ multicolor: true }),
-    Subscript,
-    Superscript,
+    extension_subscript_1.default,
+    extension_superscript_1.default,
     // StarterKit does not provide a textStyle mark, so register ours; without it
     // generateJSON drops <span style="color: ...">, defeating the color import.
     TextStyle,
diff --git a/packages/git-sync/build/lib/node-ops.js b/packages/git-sync/build/lib/node-ops.js
index 6356df5e..cfab6fce 100644
--- a/packages/git-sync/build/lib/node-ops.js
+++ b/packages/git-sync/build/lib/node-ops.js
@@ -1,3 +1,4 @@
+"use strict";
 /**
  * Pure, network-free helpers for manipulating a ProseMirror/TipTap document
  * tree by node id.
@@ -13,6 +14,19 @@
  * never mutated. All functions are defensively null-safe: missing/!Array
  * `content`, non-object nodes, and absent `attrs` are tolerated.
  */
+Object.defineProperty(exports, "__esModule", { value: true });
+exports.blockPlainText = blockPlainText;
+exports.buildOutline = buildOutline;
+exports.getNodeByRef = getNodeByRef;
+exports.replaceNodeById = replaceNodeById;
+exports.deleteNodeById = deleteNodeById;
+exports.sanitizeForYjs = sanitizeForYjs;
+exports.findUnstorableAttr = findUnstorableAttr;
+exports.insertNodeRelative = insertNodeRelative;
+exports.readTable = readTable;
+exports.insertTableRow = insertTableRow;
+exports.deleteTableRow = deleteTableRow;
+exports.updateTableCell = updateTableCell;
 /** Deep-clone a JSON-serializable value without mutating the original. */
 function clone(value) {
     if (typeof structuredClone === "function") {
@@ -36,7 +50,7 @@ function matchesId(node, nodeId) {
  * joined `blockPlainText` of their `content` children. Returns "" for nullish
  * or non-object inputs.
  */
-export function blockPlainText(node) {
+function blockPlainText(node) {
     if (!isObject(node))
         return "";
     let out = "";
@@ -66,7 +80,7 @@ function truncate(text, n) {
  * `firstText` is the block's plain text truncated to 100 chars. Null-safe:
  * a missing or non-object doc/content yields `[]`.
  */
-export function buildOutline(doc) {
+function buildOutline(doc) {
     if (!isObject(doc) || !Array.isArray(doc.content))
         return [];
     const out = [];
@@ -109,7 +123,7 @@ export function buildOutline(doc) {
  * (so a top-level block is `[index]`). The returned `node` is a DEEP CLONE,
  * so callers can mutate it without touching the input doc. Null-safe.
  */
-export function getNodeByRef(doc, ref) {
+function getNodeByRef(doc, ref) {
     if (!isObject(doc))
         return null;
     // "#<n>": index into the top-level content array.
@@ -149,7 +163,7 @@ export function getNodeByRef(doc, ref) {
  * is the number of nodes substituted. A fresh clone of `newNode` is used for
  * each match so they do not share references.
  */
-export function replaceNodeById(doc, nodeId, newNode) {
+function replaceNodeById(doc, nodeId, newNode) {
     const out = clone(doc);
     let replaced = 0;
     // Walk a content array, replacing direct matches and recursing into the
@@ -180,7 +194,7 @@ export function replaceNodeById(doc, nodeId, newNode) {
  * Operates on a clone of `doc`; returns `{ doc, deleted }` where `deleted` is
  * the number of nodes removed.
  */
-export function deleteNodeById(doc, nodeId) {
+function deleteNodeById(doc, nodeId) {
     const out = clone(doc);
     let deleted = 0;
     // Filter a content array in place, dropping matches and recursing into the
@@ -214,7 +228,7 @@ export function deleteNodeById(doc, nodeId) {
  * returns it; the input is never mutated. Defensively null-safe like the rest
  * of the file.
  */
-export function sanitizeForYjs(doc) {
+function sanitizeForYjs(doc) {
     const out = clone(doc);
     // Drop every key whose value is strictly `undefined` from an attrs object.
     const stripUndefined = (attrs) => {
@@ -252,7 +266,7 @@ export function sanitizeForYjs(doc) {
  * (e.g. `content[3].content[0].attrs.indent (undefined)`). Returns `null` when
  * every attribute is storable. Null-safe.
  */
-export function findUnstorableAttr(doc) {
+function findUnstorableAttr(doc) {
     const isUnstorable = (value) => {
         if (value === undefined)
             return "undefined";
@@ -384,7 +398,7 @@ function findAnchorChain(doc, opts) {
  * false when the anchor could not be resolved (the doc is returned unchanged
  * apart from being cloned).
  */
-export function insertNodeRelative(doc, node, opts) {
+function insertNodeRelative(doc, node, opts) {
     const out = clone(doc);
     const fresh = clone(node);
     // Defensive: stay null-safe like the other exports — a missing opts means
@@ -605,7 +619,7 @@ function makeCellParagraph(id, text) {
  *   so callers can `patch_node` a cell for rich-formatted edits.
  * - `path`: index path of the table within the doc.
  */
-export function readTable(doc, tableRef) {
+function readTable(doc, tableRef) {
     const root = clone(doc);
     const located = locateTable(root, tableRef);
     if (located == null)
@@ -645,7 +659,7 @@ export function readTable(doc, tableRef) {
  * `colspan:1, rowspan:1` attrs. `index` (when an integer in `[0, rows]`) splices
  * the row there; otherwise the row is appended at the end.
  */
-export function insertTableRow(doc, tableRef, cells, index) {
+function insertTableRow(doc, tableRef, cells, index) {
     const out = clone(doc);
     const located = locateTable(out, tableRef);
     if (located == null)
@@ -706,7 +720,7 @@ export function insertTableRow(doc, tableRef, cells, index) {
  * `deleted` is false only when the table cannot be located. Throws on an
  * out-of-range index, and refuses to delete the table's only row.
  */
-export function deleteTableRow(doc, tableRef, index) {
+function deleteTableRow(doc, tableRef, index) {
     const out = clone(doc);
     const located = locateTable(out, tableRef);
     if (located == null)
@@ -732,7 +746,7 @@ export function deleteTableRow(doc, tableRef, index) {
  * that reuses the cell's existing first-paragraph id when present, else a fresh
  * one.
  */
-export function updateTableCell(doc, tableRef, row, col, text) {
+function updateTableCell(doc, tableRef, row, col, text) {
     const out = clone(doc);
     const located = locateTable(out, tableRef);
     if (located == null)
diff --git a/packages/git-sync/package.json b/packages/git-sync/package.json
index 9d1243ea..58f6ad8c 100644
--- a/packages/git-sync/package.json
+++ b/packages/git-sync/package.json
@@ -3,11 +3,13 @@
   "version": "0.1.0",
   "description": "Vendored pure converter + pure sync engine for the Docmost <-> git Markdown sync (Phase A). See docs/git-sync-plan.md.",
   "private": true,
-  "type": "module",
   "main": "./build/index.js",
   "types": "./build/index.d.ts",
   "exports": {
-    ".": "./build/index.js"
+    ".": {
+      "types": "./build/index.d.ts",
+      "default": "./build/index.js"
+    }
   },
   "scripts": {
     "build": "tsc",
diff --git a/packages/git-sync/src/engine/layout.ts b/packages/git-sync/src/engine/layout.ts
index b3b21cfb..7b665821 100644
--- a/packages/git-sync/src/engine/layout.ts
+++ b/packages/git-sync/src/engine/layout.ts
@@ -10,7 +10,7 @@
  * lives in each file's meta block (pageId / slugId).
  */
 
-import { sanitizeTitle, disambiguate } from "./sanitize.js";
+import { sanitizeTitle, disambiguate } from "./sanitize";
 
 /** Flat page node as returned by `listAllSpacePages` (no content). */
 export interface PageNode {
diff --git a/packages/git-sync/src/engine/stabilize.ts b/packages/git-sync/src/engine/stabilize.ts
index e74191c4..d9a58f76 100644
--- a/packages/git-sync/src/engine/stabilize.ts
+++ b/packages/git-sync/src/engine/stabilize.ts
@@ -17,7 +17,7 @@ import {
   markdownToProseMirror,
   serializeDocmostMarkdownBody,
   type DocmostMdMeta,
-} from "../lib/index.js";
+} from "../lib/index";
 
 /**
  * Meta object as `exportPageBody` builds it (SPEC §4). Kept byte-for-byte
diff --git a/packages/git-sync/src/index.ts b/packages/git-sync/src/index.ts
index 03e46961..fc227ddb 100644
--- a/packages/git-sync/src/index.ts
+++ b/packages/git-sync/src/index.ts
@@ -15,8 +15,8 @@ export {
   markdownToProseMirror,
   canonicalizeContent,
   docsCanonicallyEqual,
-} from "./lib/index.js";
-export type { DocmostMdMeta } from "./lib/index.js";
+} from "./lib/index";
+export type { DocmostMdMeta } from "./lib/index";
 
 // Pure engine (no IO): reconcile planner, vault layout, sanitize, stabilize,
 // loop-guard body hash.
@@ -25,7 +25,7 @@ export {
   decideAbsenceDeletions,
   MASS_DELETE_MIN_EXISTING,
   MASS_DELETE_FRACTION,
-} from "./engine/reconcile.js";
+} from "./engine/reconcile";
 export type {
   LiveEntry,
   ExistingEntry,
@@ -33,14 +33,14 @@ export type {
   MovedEntry,
   ReconciliationPlan,
   DeletionDecision,
-} from "./engine/reconcile.js";
+} from "./engine/reconcile";
 
-export { buildVaultLayout } from "./engine/layout.js";
-export type { PageNode, VaultEntry } from "./engine/layout.js";
+export { buildVaultLayout } from "./engine/layout";
+export type { PageNode, VaultEntry } from "./engine/layout";
 
-export { sanitizeTitle, disambiguate } from "./engine/sanitize.js";
+export { sanitizeTitle, disambiguate } from "./engine/sanitize";
 
-export { stabilizePageFile } from "./engine/stabilize.js";
-export type { PageMeta } from "./engine/stabilize.js";
+export { stabilizePageFile } from "./engine/stabilize";
+export type { PageMeta } from "./engine/stabilize";
 
-export { bodyHash } from "./engine/loop-guard.js";
+export { bodyHash } from "./engine/loop-guard";
diff --git a/packages/git-sync/src/lib/diff.ts b/packages/git-sync/src/lib/diff.ts
index 25b19148..123af80a 100644
--- a/packages/git-sync/src/lib/diff.ts
+++ b/packages/git-sync/src/lib/diff.ts
@@ -21,7 +21,7 @@ import { getSchema } from "@tiptap/core";
 import { Node } from "@tiptap/pm/model";
 import { ChangeSet, simplifyChanges } from "@tiptap/pm/changeset";
 import { recreateTransform } from "@fellow/prosemirror-recreate-transform";
-import { docmostExtensions } from "./docmost-schema.js";
+import { docmostExtensions } from "./docmost-schema";
 
 /** A single inserted/deleted change with its containing-block context. */
 export interface DiffChange {
diff --git a/packages/git-sync/src/lib/index.ts b/packages/git-sync/src/lib/index.ts
index 36fd26f8..45896d42 100644
--- a/packages/git-sync/src/lib/index.ts
+++ b/packages/git-sync/src/lib/index.ts
@@ -14,14 +14,14 @@ export {
   serializeDocmostMarkdown,
   parseDocmostMarkdown,
   serializeDocmostMarkdownBody,
-} from "./markdown-document.js";
-export type { DocmostMdMeta } from "./markdown-document.js";
+} from "./markdown-document";
+export type { DocmostMdMeta } from "./markdown-document";
 
-export { convertProseMirrorToMarkdown } from "./markdown-converter.js";
+export { convertProseMirrorToMarkdown } from "./markdown-converter";
 
-export { markdownToProseMirror } from "./markdown-to-prosemirror.js";
+export { markdownToProseMirror } from "./markdown-to-prosemirror";
 
 export {
   canonicalizeContent,
   docsCanonicallyEqual,
-} from "./canonicalize.js";
+} from "./canonicalize";
diff --git a/packages/git-sync/src/lib/markdown-to-prosemirror.ts b/packages/git-sync/src/lib/markdown-to-prosemirror.ts
index 3538af26..82a765d7 100644
--- a/packages/git-sync/src/lib/markdown-to-prosemirror.ts
+++ b/packages/git-sync/src/lib/markdown-to-prosemirror.ts
@@ -9,10 +9,59 @@
  * lives in the same upstream file is intentionally NOT vendored — the gitmost
  * server writes page bodies natively through the collab gateway (plan §3.3).
  */
-import { marked } from "marked";
 import { generateJSON } from "@tiptap/html";
 import { JSDOM } from "jsdom";
-import { docmostExtensions } from "./docmost-schema.js";
+import { docmostExtensions } from "./docmost-schema";
+
+/**
+ * Structural type for the bits of the `marked` ESM module we use: just the
+ * `marked` named export's `parse` method (markdown -> HTML string).
+ */
+interface MarkedModule {
+  marked: { parse(markdown: string): string | Promise<string> };
+}
+
+// `marked` is ESM-only. Under this package's CommonJS build TS would otherwise
+// downlevel a literal `import()` to `require()`, which cannot load an ESM-only
+// module. Indirect through `Function` so the real dynamic `import()` survives
+// compilation and loads ESM from CommonJS at runtime in Node (same trick as
+// apps/server/src/core/ai-chat/tools/docmost-client.loader.ts).
+const esmImport = new Function(
+  "specifier",
+  "return import(specifier)",
+) as (specifier: string) => Promise<unknown>;
+
+// Memoize the in-flight/loaded module so the dynamic import runs at most once.
+let markedPromise: Promise<MarkedModule> | null = null;
+
+/**
+ * Lazily load the ESM-only `marked` module (cached).
+ *
+ * In the built CommonJS package (Node, jest with ts-jest) the `esmImport`
+ * Function trick performs a real dynamic `import()` of the ESM module. Under
+ * vitest, however, the transformed module is evaluated without a dynamic-import
+ * callback, so `new Function('return import(...)')` throws "A dynamic import
+ * callback was not specified"; there `require('marked')` succeeds because the
+ * test runner's loader interops ESM. We therefore try the Function import first
+ * and fall back to `require` so BOTH runtimes resolve `marked` transparently.
+ */
+async function loadMarked(): Promise<MarkedModule["marked"]> {
+  if (!markedPromise) {
+    markedPromise = (esmImport("marked") as Promise<MarkedModule>)
+      .catch(() => {
+        // Function-trick import is unavailable (e.g. under vitest's evaluator):
+        // fall back to require, which the test runner can interop for ESM.
+        // eslint-disable-next-line @typescript-eslint/no-var-requires
+        return require("marked") as MarkedModule;
+      })
+      .catch((err) => {
+        // Do not cache a rejected import — allow the next call to retry.
+        markedPromise = null;
+        throw err;
+      });
+  }
+  return (await markedPromise).marked;
+}
 
 // Setup DOM environment for Tiptap HTML parsing in Node.js
 const dom = new JSDOM("<!DOCTYPE html><html><body></body></html>");
@@ -61,6 +110,8 @@ async function preprocessCallouts(markdown: string): Promise<string> {
     return markdown;
   }
 
+  const marked = await loadMarked();
+
   // Recursively transform a slice of lines, converting top-level callouts in
   // that slice into <div> blocks and rendering their inner content (which may
   // itself contain nested callouts) through this same function.
@@ -290,6 +341,7 @@ function bridgeTaskLists(html: string): string {
 export async function markdownToProseMirror(
   markdownContent: string,
 ): Promise<any> {
+  const marked = await loadMarked();
   const withCallouts = await preprocessCallouts(markdownContent);
   const html = await marked.parse(withCallouts);
   const bridged = bridgeTaskLists(html);
diff --git a/packages/git-sync/tsconfig.json b/packages/git-sync/tsconfig.json
index c58cbd9d..c9446d4e 100644
--- a/packages/git-sync/tsconfig.json
+++ b/packages/git-sync/tsconfig.json
@@ -1,8 +1,8 @@
 {
   "compilerOptions": {
     "target": "ES2022",
-    "module": "Node16",
-    "moduleResolution": "Node16",
+    "module": "CommonJS",
+    "moduleResolution": "Node",
     "outDir": "./build",
     "rootDir": "./src",
     "strict": true,