Check internal links during the docs build

README.md

@@ -30,7 +30,7 @@ The home page is `src/pages/index.astro`, the templates it lists are in `src/dat
 
 The template docs are built with [Starlight](https://starlight.astro.build). Each template has a folder in `src/content/docs` named after its key, and its `index.mdx` is the template's home page, the one its repository links to. Each template also gets its own sidebar, set in `astro.config.mjs`, and its own colour, which `src/components/docs/Head.astro` picks from the first part of the page's path. Same site, five outfits.
 
-To add a page, drop a Markdown or MDX file in the template's folder and add it to that template's sidebar.
+To add a page, drop a Markdown or MDX file in the template's folder and add it to that template's sidebar. `npm run build` checks every internal link and heading anchor across the docs and fails if one is broken.
 
 ## The brand pages
 

astro.config.mjs

@@ -1,6 +1,7 @@
 // @ts-check
 import { defineConfig } from 'astro/config';
 import starlight from '@astrojs/starlight';
+import starlightLinksValidator from 'starlight-links-validator';
 import starlightLlmsTxt from 'starlight-llms-txt';
 import starlightSidebarTopics from 'starlight-sidebar-topics';
 import { brand, templates } from './src/data/templates.ts';
@@ -125,6 +126,10 @@ export default defineConfig({
             items: sidebars[t.id],
           })),
         ),
+        starlightLinksValidator({
+          errorOnLocalLinks: false,
+          exclude: ['/', '/#*'],
+        }),
         starlightLlmsTxt({
           projectName: 'Lean Mean Clean Apps',
           description: