diff --git a/.changeset/doc-order-group-frontmatter.md b/.changeset/doc-order-group-frontmatter.md
new file mode 100644
index 0000000000..4755297efb
--- /dev/null
+++ b/.changeset/doc-order-group-frontmatter.md
@@ -0,0 +1,19 @@
+---
+"@objectstack/cli": patch
+---
+
+fix(build): collect per-doc `order:` and `group:` frontmatter so book sorting/placement works
+
+The doc collector (`collectDocsFromSrc`) parsed only `title:`/`description:` from
+each `src/docs/*.md` frontmatter, so the `order` and `group` fields defined on the
+`Doc` schema (ADR-0046 §6) were never populated on the compiled `doc` item. The
+book resolver (`resolveBookTree`) already sorts group members by `doc.order` then
+label and honors explicit `doc.group` placement — but with the collection half
+silently dropping both fields, frontmatter-driven sorting/placement never reached
+the artifact.
+
+`parseFrontmatter` now also reads `order:` (parsed to a number; ignored when
+non-numeric) and `group:` (string), threading them onto the collected doc when
+present. Absent leaves both undefined so the schema/resolver defaults apply. Also
+corrects the `order` JSDoc in `doc.zod.ts` to match the resolver, which treats an
+absent `order` as `0` (not "after ordered siblings").
diff --git a/packages/cli/src/utils/collect-docs.test.ts b/packages/cli/src/utils/collect-docs.test.ts
index 86603d4991..a8dabc1ad4 100644
--- a/packages/cli/src/utils/collect-docs.test.ts
+++ b/packages/cli/src/utils/collect-docs.test.ts
@@ -50,6 +50,28 @@ describe('collectDocsFromSrc (ADR-0046 §3.2)', () => {
     expect(plain.description).toBeUndefined(); // absent → omitted, not ''
   });
 
+  it('reads frontmatter `order:` as a number and ignores non-numeric values', () => {
+    write('crm_a.md', '---\norder: 3\n---\n\n# A');
+    write('crm_b.md', '---\norder: not-a-number\n---\n\n# B');
+    write('crm_c.md', '---\norder: 0\n---\n\n# C');
+    const { docs, issues } = collectDocsFromSrc(configPath);
+    expect(issues).toHaveLength(0);
+    expect(docs.find((d) => d.name === 'crm_a')!.order).toBe(3); // parsed to number
+    expect(docs.find((d) => d.name === 'crm_b')!.order).toBeUndefined(); // NaN → dropped
+    expect(docs.find((d) => d.name === 'crm_c')!.order).toBe(0); // zero is a valid order
+  });
+
+  it('reads frontmatter `group:` as a string; absent leaves order/group undefined', () => {
+    write('crm_grouped.md', '---\ngroup: crm_admin\n---\n\n# Grouped');
+    write('crm_bare.md', '# Bare\n\nNo frontmatter.');
+    const { docs, issues } = collectDocsFromSrc(configPath);
+    expect(issues).toHaveLength(0);
+    expect(docs.find((d) => d.name === 'crm_grouped')!.group).toBe('crm_admin');
+    const bare = docs.find((d) => d.name === 'crm_bare')!;
+    expect(bare.order).toBeUndefined();
+    expect(bare.group).toBeUndefined();
+  });
+
   it('errors on subdirectories — flatness is the contract', () => {
     fs.mkdirSync(path.join(docsDir, 'user'));
     write('crm_index.md', '# x');
diff --git a/packages/cli/src/utils/collect-docs.ts b/packages/cli/src/utils/collect-docs.ts
index b80a29a572..15df357800 100644
--- a/packages/cli/src/utils/collect-docs.ts
+++ b/packages/cli/src/utils/collect-docs.ts
@@ -37,6 +37,13 @@ export interface DocItem {
   label?: string;
   description?: string;
   content: string;
+  /**
+   * Sort key + explicit book-group placement (ADR-0046 §6), read from
+   * frontmatter `order:`/`group:`. The book resolver honors both; absent
+   * leaves them out so the schema defaults apply.
+   */
+  order?: number;
+  group?: string;
   /**
    * Per-locale variants (ADR-0046 i18n), compiled from sibling
    * `<name>.<locale>.md` files. The base file is the default + fallback.
@@ -68,19 +75,30 @@ function frontmatterScalar(block: string, key: string): string | undefined {
 }
 
 /**
- * Strip a leading `---` frontmatter block; extract `title:` and
- * `description:` if present (both optional, single-line scalars).
+ * Strip a leading `---` frontmatter block; extract `title:`, `description:`,
+ * `order:`, and `group:` if present (all optional, single-line scalars).
+ * `order:` is parsed to a number and dropped when non-numeric.
  */
-function parseFrontmatter(raw: string): { title?: string; description?: string; body: string } {
+function parseFrontmatter(raw: string): {
+  title?: string;
+  description?: string;
+  order?: number;
+  group?: string;
+  body: string;
+} {
   if (!raw.startsWith('---\n') && !raw.startsWith('---\r\n')) return { body: raw };
   const end = raw.indexOf('\n---', 3);
   if (end === -1) return { body: raw };
   const block = raw.slice(raw.indexOf('\n') + 1, end);
   const bodyStart = raw.indexOf('\n', end + 1);
   const body = bodyStart === -1 ? '' : raw.slice(bodyStart + 1);
+  const orderRaw = frontmatterScalar(block, 'order');
+  const order = orderRaw !== undefined ? Number(orderRaw) : undefined;
   return {
     title: frontmatterScalar(block, 'title'),
     description: frontmatterScalar(block, 'description'),
+    ...(order !== undefined && !Number.isNaN(order) ? { order } : {}),
+    group: frontmatterScalar(block, 'group'),
     body,
   };
 }
@@ -126,7 +144,7 @@ export function collectDocsFromSrc(configPath: string): { docs: DocItem[]; issue
 
     const stem = entry.name.slice(0, -3);
     const raw = fs.readFileSync(path.join(docsDir, entry.name), 'utf-8');
-    const { title, description, body } = parseFrontmatter(raw);
+    const { title, description, order, group, body } = parseFrontmatter(raw);
 
     // Locale variant `<base>.<locale>.md` (ADR-0046 i18n) — checked before the
     // bare-name rule, since a variant stem legitimately contains a dot.
@@ -156,6 +174,8 @@ export function collectDocsFromSrc(configPath: string): { docs: DocItem[]; issue
       label: title ?? firstHeading(body),
       ...(description ? { description } : {}),
       content: body,
+      ...(order !== undefined ? { order } : {}),
+      ...(group ? { group } : {}),
     });
   }
 
diff --git a/packages/spec/src/system/doc.zod.ts b/packages/spec/src/system/doc.zod.ts
index 6181cf9c96..bd48a566e6 100644
--- a/packages/spec/src/system/doc.zod.ts
+++ b/packages/spec/src/system/doc.zod.ts
@@ -64,7 +64,8 @@ export const DocSchema = lazySchema(() => z.object({
   /**
    * Optional sort key within a book group (ADR-0046 §6.2.1). A scalar, so it
    * three-way-merges cleanly under overlay — unlike a central nav array. Absent
-   * ⇒ sorts after ordered siblings, then alphabetically by label.
+   * ⇒ treated as 0 by the resolver (sorts among 0-keyed siblings), then
+   * alphabetically by label.
    */
   order: z.number().optional().describe('Sort key within a book group (ADR-0046 §6)'),