Add Google Books support

Match books.google.com and google.com/books/edition pages, extract the ISBN
from page text with a title/author fallback, and bump version to 1.2 so
userscript auto-update picks it up.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01X4uRGZZ4EpYHA4PNK3x5JY

README.md

@@ -11,7 +11,7 @@ The script auto-updates itself from this repo (via `@updateURL`), so you don't n
 
 ## What it does
 
-On a book page on Bookshop.org, Amazon (`.fr`/`.com`), or Waterstones, it:
+On a book page on Bookshop.org, Amazon (`.fr`/`.com`), Waterstones, or Google Books, it:
 
 1. Extracts the book's ISBN (from the URL or page content) and, as a fallback, title/author.
 2. Checks whether the book is available on:
@@ -24,6 +24,7 @@ On a book page on Bookshop.org, Amazon (`.fr`/`.com`), or Waterstones, it:
 - `bookshop.org/p/books/*`
 - `waterstones.com/book/*`
 - `amazon.fr` and `amazon.com` product pages (`/dp/*`)
+- Google Books (`books.google.com/books?id=…`, `google.com/books/edition/…`)
 
 ## Notes
 

book-links.user.js

@@ -1,7 +1,7 @@
 // ==UserScript==
 // @name         Book Links
 // @namespace    http://tampermonkey.net/
-// @version      1.1
+// @version      1.2
 // @description  Show Anna's Archive and Waterstones links when browsing books
 // @license      MIT
 // @match        https://bookshop.org/p/books/*
@@ -10,6 +10,8 @@
 // @match        https://www.amazon.fr/*/dp/*
 // @match        https://www.amazon.com/dp/*
 // @match        https://www.amazon.com/*/dp/*
+// @match        https://books.google.com/books?*
+// @match        https://www.google.com/books/edition/*
 // @connect      annas-archive.gl
 // @connect      www.waterstones.com
 // @connect      www.chez-mon-libraire.fr
@@ -62,6 +64,17 @@
       return null;
     }
 
+    if (host.includes('google.com')) {
+      const text = document.body?.innerText || '';
+      const m13 = text.match(/\b(97[89][-\d ]{9,14}\d)\b/);
+      if (m13) {
+        const cleaned = m13[1].replace(/[-\s]/g, '');
+        if (/^97[89]\d{10}$/.test(cleaned)) return cleaned;
+      }
+      const m10 = text.match(/ISBN[\s:]+(?:[\d-]+,\s*)?(\d{9}[\dX])\b/);
+      return m10 ? isbn10to13(m10[1]) : null;
+    }
+
     if (host.includes('bookshop.org')) {
       const el = document.querySelector('[itemprop="isbn"]');
       if (el && /^97[89]\d{10}$/.test(el.textContent.trim())) return el.textContent.trim();
@@ -106,6 +119,12 @@
       return { title, author };
     }
 
+    if (host.includes('google.com')) {
+      const title = document.querySelector('h1')?.textContent?.trim();
+      const author = document.querySelector('a[href*="inauthor"]')?.textContent?.trim();
+      return { title, author };
+    }
+
     if (host.includes('waterstones.com')) {
       const title = (
         document.querySelector('[itemprop="name"]') ||