diff --git a/packages/prosemirror-markdown/test/schema-editor-ext-contract.test.ts b/packages/prosemirror-markdown/test/schema-editor-ext-contract.test.ts
index 4778ea5c..7570ff11 100644
--- a/packages/prosemirror-markdown/test/schema-editor-ext-contract.test.ts
+++ b/packages/prosemirror-markdown/test/schema-editor-ext-contract.test.ts
@@ -16,14 +16,16 @@ import * as editorExt from "@docmost/editor-ext";
 // or mark added upstream that the mirror forgets to vendor fails CI loudly
 // (otherwise it is silently dropped on the markdown <-> ProseMirror round-trip).
 //
-// LIMITATION (intentional, see schema-surface-snapshot.test.ts): this is a
-// NAME-LEVEL contract only, not a full attribute-level structural compare.
-// editor-ext's Tiptap representation (node views, commands, suggestion plugins,
-// addGlobalAttributes spread across separate extensions) differs from this
-// minimal mirror, so a mechanical attribute-by-attribute equality would be
-// fragile and produce false drift. Attribute parity is guarded by the inline
-// surface snapshot (reviewed in every diff); this test guards that no canonical
-// node/mark TYPE goes unmirrored. StarterKit-provided types (paragraph, bold,
+// This file now holds TWO contracts (see the two describe blocks): the original
+// NAME-LEVEL type contract (no canonical node/mark TYPE goes unmirrored) AND, as
+// of #493, an ATTRIBUTE-LEVEL contract that compares each editor-ext node/mark's
+// OWN declared attributes (names + defaults) against the mirror's built schema.
+// A full mechanical attribute-by-attribute EQUALITY would be fragile (the mirror
+// is a deliberate superset: it injects the global id/textAlign/indent attrs and
+// normalizes some editor-ext defaults to null), so the attribute contract is
+// asymmetric — editor-ext -> mirror — with a small, reasoned, stale-guarded
+// allowlist for the two blessed divergence kinds (non-round-trippable omissions
+// and null-normalized defaults). StarterKit-provided types (paragraph, bold,
 // heading, …) are contributed by @tiptap/starter-kit in the mirror rather than
 // by editor-ext, so they are naturally covered by the mirror's superset.
 //
@@ -85,3 +87,191 @@ describe("docmost schema vs @docmost/editor-ext (name-level contract)", () => {
     expect(missing).toEqual([]);
   });
 });
+
+// ── ATTRIBUTE-LEVEL CONTRACT (#493 commit 2) ────────────────────────────────
+//
+// The name-level contract above catches a WHOLE node/mark type going unmirrored,
+// but not ATTRIBUTE drift within a vendored type — the exact class that silently
+// dropped `subpages.recursive`: editor-ext grew an attribute the hand-synced
+// mirror forgot, so documents using it lost that attribute on a git-sync
+// round-trip while CI stayed green. This closes that gap by comparing each
+// editor-ext node/mark's OWN declared attributes (names + defaults) against the
+// mirror's built ProseMirror schema `spec.attrs`.
+//
+// DIRECTION: editor-ext -> mirror. The mirror is deliberately a SUPERSET (it
+// injects the global `id`/`textAlign`/`indent` attributes and normalizes some
+// editor-ext "required" attrs to a `null` default), so a reverse compare would
+// be pure false drift; the meaningful failure is an editor-ext attribute the
+// mirror DROPS (name) or whose DEFAULT it silently changes. Both directions of
+// staleness are guarded so the allowlists cannot rot.
+
+/**
+ * The attributes an editor-ext Tiptap Node/Mark DECLARES itself, read from its
+ * `config.addAttributes()`. Global attributes injected by separate extensions
+ * (unique-id, indent, textAlign) are NOT included here — they are the mirror's
+ * superset and are not part of a per-type declaration — so this isolates each
+ * type's own contribution. A declared attribute with no explicit `default` is a
+ * required attr (Tiptap default `undefined`); we surface that as-is so the
+ * default compare can skip it (the mirror makes such attrs optional/`null`).
+ */
+function editorExtOwnAttrs(): Map<
+  string,
+  { kind: "node" | "mark"; attrs: Record<string, unknown> }
+> {
+  const out = new Map<
+    string,
+    { kind: "node" | "mark"; attrs: Record<string, unknown> }
+  >();
+  for (const value of Object.values(editorExt)) {
+    if (!isTiptapNodeOrMark(value)) continue;
+    const ext = value as unknown as {
+      name: string;
+      type: "node" | "mark";
+      options?: unknown;
+      storage?: unknown;
+      config?: { addAttributes?: () => Record<string, { default?: unknown }> };
+    };
+    const fn = ext.config?.addAttributes;
+    // addAttributes reads `this.options`/`this.name`; bind a minimal context
+    // (verified sufficient for every editor-ext extension — none reach for
+    // `this.editor` here). A type with no addAttributes contributes no attrs.
+    const declared =
+      typeof fn === "function"
+        ? fn.call({
+            options: ext.options ?? {},
+            name: ext.name,
+            parent: undefined,
+            storage: ext.storage ?? {},
+          } as never)
+        : {};
+    const attrs: Record<string, unknown> = {};
+    for (const [attr, spec] of Object.entries(declared || {})) {
+      // `undefined` marks a required (no-default) attr; keep it so the default
+      // compare can distinguish "no default declared" from "default is null".
+      attrs[attr] = (spec as { default?: unknown })?.default;
+    }
+    out.set(ext.name, { kind: ext.type, attrs });
+  }
+  return out;
+}
+
+/** The mirror's built-schema `spec.attrs` for a type: attr name -> default. */
+function mirrorAttrs(
+  name: string,
+  kind: "node" | "mark",
+): Record<string, unknown> | null {
+  const schema = getSchema(docmostExtensions as never);
+  const spec = kind === "node" ? schema.nodes[name]?.spec : schema.marks[name]?.spec;
+  if (!spec) return null;
+  const out: Record<string, unknown> = {};
+  for (const [attr, def] of Object.entries(spec.attrs || {})) {
+    out[attr] = (def as { default?: unknown }).default;
+  }
+  return out;
+}
+
+// An editor-ext attribute the mirror deliberately does NOT vendor because it has
+// NO markdown round-trip representation — dropping it loses nothing on the
+// git-sync cycle (the same rationale the flat-roundtrip property suite uses to
+// allowlist e.g. `tableCell.backgroundColorName`). Blessed by the hand-curated
+// surface snapshot (schema-surface-snapshot.test.ts), reviewed in every diff.
+const ACCEPTED_ATTR_OMISSIONS = new Set<string>([
+  "highlight.colorName", // only `highlight.color` round-trips (==text==); the
+  // secondary palette-name is presentational and has no markdown form.
+]);
+
+// An editor-ext attribute the mirror vendors but with a DIFFERENT default: the
+// mirror normalizes an "absent" value to `null` (its uniform optional-attr
+// convention) rather than editor-ext's UI-oriented default. None of these attrs
+// is emitted on the markdown surface (the converter round-trips only the
+// serializable ones), so the default never round-trips and the divergence is
+// inert — but pinned here so a NEW default change on either side forces review.
+const ACCEPTED_DEFAULT_DIVERGENCE = new Set<string>([
+  "image.src", // mirror null vs editor "" (an image is never emitted src-less)
+  "link.internal", // mirror null vs editor false (routing attr, not in md link)
+  "pdf.width", // mirror null vs editor 800 (presentational sizing, not in md)
+  "pdf.height", // mirror null vs editor 600 (presentational sizing, not in md)
+]);
+
+describe("docmost schema vs @docmost/editor-ext (attribute-level contract)", () => {
+  it("vendors every editor-ext attribute (name) of every shared type — no silently-dropped attrs", () => {
+    const dropped: string[] = [];
+    for (const [name, { kind, attrs }] of editorExtOwnAttrs()) {
+      const mirror = mirrorAttrs(name, kind);
+      if (!mirror) continue; // whole-type omission is the name-level test's job
+      for (const attr of Object.keys(attrs)) {
+        const key = `${name}.${attr}`;
+        if (!(attr in mirror) && !ACCEPTED_ATTR_OMISSIONS.has(key)) {
+          dropped.push(key);
+        }
+      }
+    }
+    // Any entry here exists on the editor-ext node/mark but NOT in the mirror
+    // (and is not a blessed non-round-trippable omission): documents using it
+    // lose that attribute on a git-sync round-trip — the subpages.recursive
+    // class. Re-sync src/lib/docmost-schema.ts (and the surface snapshot) or add
+    // a reasoned ACCEPTED_ATTR_OMISSIONS entry before clearing.
+    expect(dropped.sort()).toEqual([]);
+  });
+
+  it("keeps every editor-ext attribute DEFAULT in sync — no silent default drift", () => {
+    const drift: string[] = [];
+    for (const [name, { kind, attrs }] of editorExtOwnAttrs()) {
+      const mirror = mirrorAttrs(name, kind);
+      if (!mirror) continue;
+      for (const [attr, extDefault] of Object.entries(attrs)) {
+        const key = `${name}.${attr}`;
+        // Skip attrs editor-ext declares WITHOUT a default (required attrs):
+        // the mirror deliberately makes them optional (`null`), a safe superset.
+        if (extDefault === undefined) continue;
+        if (!(attr in mirror)) continue; // a drop, reported by the name test
+        if (
+          JSON.stringify(mirror[attr]) !== JSON.stringify(extDefault) &&
+          !ACCEPTED_DEFAULT_DIVERGENCE.has(key)
+        ) {
+          drift.push(
+            `${key}: mirror=${JSON.stringify(mirror[attr])} editor-ext=${JSON.stringify(extDefault)}`,
+          );
+        }
+      }
+    }
+    expect(drift.sort()).toEqual([]);
+  });
+
+  it("the attribute allowlists have no stale rows (each is really omitted / divergent)", () => {
+    const ext = editorExtOwnAttrs();
+    const staleOmission: string[] = [];
+    for (const key of ACCEPTED_ATTR_OMISSIONS) {
+      const [name, attr] = key.split(".");
+      const entry = ext.get(name);
+      const mirror = entry ? mirrorAttrs(name, entry.kind) : null;
+      // Stale if editor-ext no longer declares it, or the mirror now DOES vendor
+      // it (so it should be removed from the omission allowlist).
+      if (!entry || !(attr in entry.attrs) || (mirror && attr in mirror)) {
+        staleOmission.push(key);
+      }
+    }
+    expect(staleOmission, "stale ACCEPTED_ATTR_OMISSIONS rows").toEqual([]);
+
+    const staleDivergence: string[] = [];
+    for (const key of ACCEPTED_DEFAULT_DIVERGENCE) {
+      const [name, attr] = key.split(".");
+      const entry = ext.get(name);
+      const mirror = entry ? mirrorAttrs(name, entry.kind) : null;
+      const extDefault = entry?.attrs[attr];
+      // Stale if the divergence no longer exists (attr gone, or defaults now
+      // agree) — the row should be dropped so the allowlist stays honest.
+      if (
+        !entry ||
+        !mirror ||
+        !(attr in entry.attrs) ||
+        !(attr in mirror) ||
+        extDefault === undefined ||
+        JSON.stringify(mirror[attr]) === JSON.stringify(extDefault)
+      ) {
+        staleDivergence.push(key);
+      }
+    }
+    expect(staleDivergence, "stale ACCEPTED_DEFAULT_DIVERGENCE rows").toEqual([]);
+  });
+});