diff --git a/LIBRARY.md b/LIBRARY.md
index 4a4b3c91..a94d6c3d 100644
--- a/LIBRARY.md
+++ b/LIBRARY.md
@@ -57,17 +57,25 @@ owner's address. Phones and tablets stay read-only, so a signed-in owner
 without a library reads "Use a desktop to create your library" there. A
 visitor at an address no library answers to reads "No such library".
 
-The AI shelf and the magic books are behind the `library-ai` account flag,
-read from `GET /api/users/me` as `featureNames` (LIBRARY_AI_FLAG). The page
-draws neither surface without it, and `/api/library/ai-shelf` and
-`/api/library/magic-book` answer 403 without it through `ownerOfLibrary`, so
-the hidden shelf is not the gate. Both surfaces are the owner's alone on
-every account: a visitor never sees them. An operator hands the flag out in
+The AI shelf and the magic books open to an owner who holds the `library-ai`
+account flag, read from `GET /api/users/me` as `featureNames`
+(LIBRARY_AI_FLAG), or whose library holds more than 15 books
+(LIBRARY_AI_BOOKS_OVER, Wolf, 2026-09-25). Only objects of type book count,
+on every shelf, private ones included; the count is read from the library on
+every check, so the AI arrives with the sixteenth book and leaves if the
+library drops back to fifteen, while the flag holds regardless. One check,
+`opensLibraryAi` in `src/lib/library/flags.ts`, decides for the page and the
+routes: the page draws neither surface without it, and
+`/api/library/ai-shelf` and `/api/library/magic-book` answer 403 without it
+through `ownerOfLibrary`, so the hidden shelf is not the gate. The AI shelf
+itself stays locked until 30 books (AI_SHELF_MIN_BOOKS). Both surfaces are
+the owner's alone on every account: a visitor never sees them. An operator hands the flag out in
 the CMS admin panel (the user's Feature Flags relation) or ahead of signup
 through the Mail Permission List; it takes effect on the account's next page
 load, no new sign-in. Wolf names the accounts, one at a time, to the agent;
-on 2026-09-12 they are Alina, Mary, Lemongrass and Wolf. Cover, video and
-audio autofill stay open to everyone: they cost no model call.
+on 2026-09-12 they are Alina, Mary, Lemongrass and Wolf. On 2026-09-25
+Lilith and Maksim got it for holding more than 15 books, before the rule
+above shipped. Cover, video and audio autofill stay open to everyone: they cost no model call.
 
 A library carries `hidden`, set only in the CMS admin panel (the content API
 refuses it on update). Hidden, it leaves the home list and
diff --git a/scripts/release/library-batch-check.cjs b/scripts/release/library-batch-check.cjs
index 478a697b..01f27456 100644
--- a/scripts/release/library-batch-check.cjs
+++ b/scripts/release/library-batch-check.cjs
@@ -3,6 +3,7 @@ const path = require('node:path');
 const vm = require('node:vm');
 const assert = require('node:assert/strict');
 const ts = require('typescript');
+
 process.chdir(path.resolve(__dirname, '../..'));
 function load(file, mocks = {}) {
   const exports = {};
@@ -279,27 +280,61 @@ function check() {
   // LIBRARY ACCESS. Creation needs no flag; the AI does, and the routes
   // behind it check the same flag the page draws by, so a direct call is
   // stopped where the shelf is not drawn.
-  const { holdsFlag } = load('src/lib/library/flags.ts');
+  const flags = load('src/lib/library/flags.ts', {
+    '@constants/library/common': {
+      LIBRARY_AI_FLAG: 'library-ai',
+      LIBRARY_AI_BOOKS_OVER: 15,
+    },
+  });
+  const { holdsFlag, countBooks, opensLibraryAi } = flags;
   assert(holdsFlag({ featureNames: ['library-ai'] }, 'library-ai'));
   assert(!holdsFlag({ featureNames: ['can-create-library'] }, 'library-ai'));
   assert(!holdsFlag({ featureNames: 'library-ai' }, 'library-ai'));
   assert(!holdsFlag({}, 'library-ai'));
   assert(!holdsFlag(null, 'library-ai'));
+  // More than 15 books opens the AI without the flag (Wolf, 2026-09-25);
+  // only books count, on every shelf.
+  const shelf = (...types) => ({
+    attributes: {
+      objects: { data: types.map(type => ({ attributes: { type } })) },
+    },
+  });
+  const libraryOf = (...shelves) => ({
+    attributes: { singleShelves: { data: shelves } },
+  });
+  const fifteen = libraryOf(
+    shelf(...Array(10).fill('book'), 'audio', 'video'),
+    shelf(...Array(5).fill('book'), 'audio'),
+  );
+  const sixteen = libraryOf(
+    shelf(...Array(10).fill('book')),
+    shelf(...Array(6).fill('book')),
+  );
+  assert.equal(countBooks(fifteen), 15);
+  assert.equal(countBooks(sixteen), 16);
+  assert.equal(countBooks(null), 0);
+  assert(!opensLibraryAi({}, fifteen));
+  assert(opensLibraryAi({}, sixteen));
+  assert(opensLibraryAi({ featureNames: ['library-ai'] }, fifteen));
+  assert(!opensLibraryAi(null, null));
   // The constants file carries icon components for its sample cards; the
   // icons are not what is checked here.
   const common = load('src/constants/library/common.ts', {
     '@icons/library/svg': new Proxy({}, { get: () => () => null }),
   });
   assert.equal(common.LIBRARY_AI_FLAG, 'library-ai');
+  assert.equal(common.LIBRARY_AI_BOOKS_OVER, 15);
   assert.equal(common.MAX_OBJECTS_PER_LIBRARY, 300);
   for (const route of [
     'src/pages/api/library/ai-shelf.ts',
     'src/pages/api/library/magic-book.ts',
   ])
-    assert(
-      fs.readFileSync(route, 'utf8').includes('flag: LIBRARY_AI_FLAG'),
-      route,
-    );
+    assert(fs.readFileSync(route, 'utf8').includes('libraryAi: true'), route);
+  assert(
+    fs
+      .readFileSync('src/layouts/library/Library/Library.tsx', 'utf8')
+      .includes('opensLibraryAi(accountData, library)'),
+  );
   for (const file of [
     'src/layouts/library/Library/Library.tsx',
     'src/layouts/library/Home/Home.tsx',
diff --git a/src/constants/library/common.ts b/src/constants/library/common.ts
index 086ad0f8..2aeae658 100644
--- a/src/constants/library/common.ts
+++ b/src/constants/library/common.ts
@@ -97,6 +97,10 @@ export const LIBRARY_OBJECTS_FULL_MESSAGE =
 // library needs no flag since 2026-09-12.
 export const LIBRARY_AI_FLAG = 'library-ai';
 
+// A library holding more books than this opens the AI to its owner without the
+// flag (Wolf, 2026-09-25). Only objects of type book count.
+export const LIBRARY_AI_BOOKS_OVER = 15;
+
 export const SHELF_FULL_MESSAGE = 'This shelf is full.';
 
 // The library-level twin, worded the same way so the two limits read as one
diff --git a/src/layouts/library/Library/Library.tsx b/src/layouts/library/Library/Library.tsx
index 53feb891..4ad26d04 100644
--- a/src/layouts/library/Library/Library.tsx
+++ b/src/layouts/library/Library/Library.tsx
@@ -27,7 +27,6 @@ import React, {
 } from 'react';
 
 import {
-  LIBRARY_AI_FLAG,
   LIBRARY_FULL_MESSAGE,
   LIBRARY_SHELVES_REFETCH_EVENT,
   MAX_OBJECTS_PER_LIBRARY,
@@ -61,7 +60,7 @@ import {
   keepFavoriteFields,
   sortFavorites,
 } from '@lib/library/favorites';
-import { holdsFlag } from '@lib/library/flags';
+import { opensLibraryAi } from '@lib/library/flags';
 import { libraryPath } from '@lib/library/libraryPath';
 import { objectIdFromSlug } from '@lib/library/objectSlug';
 import {
@@ -268,12 +267,13 @@ export function LibraryTemplate({
   // and on first paint, so the markup hydrates identically everywhere.
   const canEditHere = viewAsOwner && supportsEditing;
 
-  // The AI shelf and the magic books are behind the `library-ai` account
-  // flag from GET /api/users/me; the routes behind them check the same flag,
-  // so this decides what is drawn, not what is allowed. Creating a library
+  // The AI shelf and the magic books open with the `library-ai` account flag
+  // or with more than LIBRARY_AI_BOOKS_OVER books in this library; the routes
+  // behind them run the same check, so this decides what is drawn, not what
+  // is allowed. Creating a library
   // needs no flag: any signed-in owner of this address bootstraps one from
   // their first shelf.
-  const hasLibraryAi = holdsFlag(accountData, LIBRARY_AI_FLAG);
+  const hasLibraryAi = opensLibraryAi(accountData, library);
 
   // The magic books are read once the owner is known to be editing here:
   // desktop, own library, not previewing as a guest, and flagged. The
diff --git a/src/lib/library/flags.ts b/src/lib/library/flags.ts
index 9dcd8d42..466ffeca 100644
--- a/src/lib/library/flags.ts
+++ b/src/lib/library/flags.ts
@@ -1,3 +1,10 @@
+import {
+  LIBRARY_AI_BOOKS_OVER,
+  LIBRARY_AI_FLAG,
+} from '@constants/library/common';
+
+import type { StrapiLibraryEntry } from '@local-types/library/library';
+
 /**
  * Account feature flags, as `GET /api/users/me` reports them in
  * `featureNames`. One pure check, shared by the page (what is drawn) and the
@@ -7,3 +14,29 @@ export const holdsFlag = (
   me: { featureNames?: unknown } | null | undefined,
   flag: string,
 ): boolean => Array.isArray(me?.featureNames) && me.featureNames.includes(flag);
+
+/** Books in the library across every shelf, private ones included. Audio and
+ * video do not count. */
+export const countBooks = (
+  library: StrapiLibraryEntry | null | undefined,
+): number =>
+  (library?.attributes.singleShelves?.data ?? []).reduce(
+    (sum, shelf) =>
+      sum +
+      (shelf.attributes.objects?.data ?? []).filter(
+        object => object.attributes.type === 'book',
+      ).length,
+    0,
+  );
+
+/**
+ * The AI shelf and the magic books open to an owner who holds the
+ * `library-ai` flag, or whose library holds more than LIBRARY_AI_BOOKS_OVER
+ * books (Wolf, 2026-09-25). The count is read from the library each time, so
+ * the AI arrives with the book that crosses the line and nothing is stored.
+ */
+export const opensLibraryAi = (
+  me: { featureNames?: unknown } | null | undefined,
+  library: StrapiLibraryEntry | null | undefined,
+): boolean =>
+  holdsFlag(me, LIBRARY_AI_FLAG) || countBooks(library) > LIBRARY_AI_BOOKS_OVER;
diff --git a/src/lib/library/owner.ts b/src/lib/library/owner.ts
index 6bed5496..ddfe7a14 100644
--- a/src/lib/library/owner.ts
+++ b/src/lib/library/owner.ts
@@ -2,7 +2,7 @@ import type { NextApiRequest } from 'next';
 
 import type { StrapiLibraryEntry } from '@local-types/library/library';
 
-import { holdsFlag } from '@lib/library/flags';
+import { opensLibraryAi } from '@lib/library/flags';
 
 /**
  * Who is asking, and do they own the library they are asking about. Every
@@ -45,14 +45,15 @@ export interface OwnerWording {
   signIn?: string;
   /** A session, but not the owner of this library. */
   forbidden?: string;
-  /** The owner, but without the account flag this surface needs. */
+  /** The owner, but the surface is not open to their account. */
   locked?: string;
 }
 
 /** What the surface needs of the account beyond owning the library. */
 export interface OwnerRequires {
-  /** A `featureNames` entry from /api/users/me, e.g. LIBRARY_AI_FLAG. */
-  flag?: string;
+  /** The AI shelf and the magic books: the `library-ai` flag, or more than
+   * LIBRARY_AI_BOOKS_OVER books in this library (opensLibraryAi). */
+  libraryAi?: boolean;
 }
 
 export interface OwnerCheck {
@@ -99,9 +100,9 @@ export async function ownerOfLibrary(
       userId: me.id,
     };
 
-  // The owner, but the surface is behind an account flag they do not hold:
-  // the page does not draw it, and this is what stops a direct call.
-  if (requires.flag && !holdsFlag(me, requires.flag))
+  // The owner, but the surface is not open to their account: the page does
+  // not draw it, and this is what stops a direct call.
+  if (requires.libraryAi && !opensLibraryAi(me, library))
     return {
       status: 403,
       error: wording.locked ?? 'This surface is not open to your account.',
diff --git a/src/pages/api/library/ai-shelf.ts b/src/pages/api/library/ai-shelf.ts
index 741b817d..5aa0afa7 100644
--- a/src/pages/api/library/ai-shelf.ts
+++ b/src/pages/api/library/ai-shelf.ts
@@ -1,8 +1,6 @@
 // motion-passport: exempt — a server route; nothing here is drawn.
 import type { NextApiRequest, NextApiResponse } from 'next';
 
-import { LIBRARY_AI_FLAG } from '@constants/library/common';
-
 import type {
   BannedBook,
   RecommendedPick,
@@ -178,7 +176,7 @@ export default async function handler(
     req,
     libraryId,
     { locked: 'The AI shelf is not open to your account.' },
-    { flag: LIBRARY_AI_FLAG },
+    { libraryAi: true },
   );
   if (owner.status !== 200 || !owner.library) {
     if (owner.status === 403)
diff --git a/src/pages/api/library/magic-book.ts b/src/pages/api/library/magic-book.ts
index 05556d81..7aac31e5 100644
--- a/src/pages/api/library/magic-book.ts
+++ b/src/pages/api/library/magic-book.ts
@@ -1,8 +1,6 @@
 // motion-passport: exempt — a server route; nothing here is drawn.
 import type { NextApiRequest, NextApiResponse } from 'next';
 
-import { LIBRARY_AI_FLAG } from '@constants/library/common';
-
 import type {
   MagicBooksResponse,
   MagicShelfResult,
@@ -112,7 +110,7 @@ export default async function handler(
       forbidden: 'Only the owner sees the magic books.',
       locked: 'The magic books are not open to your account.',
     },
-    { flag: LIBRARY_AI_FLAG },
+    { libraryAi: true },
   );
   if (owner.status !== 200 || !owner.library) {
     if (owner.status === 403)