feat: add persistent book navigation and public-only pages

site/plugins/document-links.mjs

@@ -10,7 +10,7 @@ export function normalizeBase(value = '/') {
   return value === '/' ? '/' : `/${value.split('/').filter(Boolean).join('/')}/`;
 }
 
-/** Rewrite Markdown document links, not code, fragments, or external URLs. */
+/** Rewrite published Markdown links; null means a source-only draft target. */
 export function documentHref(href, sourceFile, base = '/') {
   if (/^(?:[a-z][a-z\d+.-]*:|\/\/|#)/i.test(href)) return href;
   const match = href.match(/^([^?#]+\.md)([?#].*)?$/i);
@@ -20,18 +20,30 @@ export function documentHref(href, sourceFile, base = '/') {
   if (relative.startsWith('..') || path.isAbsolute(relative)) {
     throw new Error(`Markdown link outside contents/: ${href} in ${sourceFile}`);
   }
+  if (relative.split(path.sep)[0] === 'draft') return null;
   const slug = relative.replace(/\.md$/i, '').split(path.sep).map(encodeURIComponent).join('/');
   return `${normalizeBase(base)}book/${slug}/${match[2] ?? ''}`;
 }
 
 export default function documentLinks({ base = '/' } = {}) {
   return (tree, file) => {
-    function walk(node) {
-      if ((node.type === 'link' || node.type === 'definition') && typeof node.url === 'string') {
-        node.url = documentHref(node.url, file.path, base);
-      }
-      for (const child of node.children ?? []) walk(child);
+    const draftReferences = new Set();
+    function collect(node) {
+      if (node.type === 'definition' && documentHref(node.url, file.path, base) === null) draftReferences.add(node.identifier);
+      for (const child of node.children ?? []) collect(child);
     }
-    walk(tree);
+    collect(tree);
+    function rewrite(node) {
+      if (node.children) node.children = node.children.flatMap(rewrite);
+      if (node.type === 'linkReference' && draftReferences.has(node.identifier)) return node.children;
+      if ((node.type === 'link' || node.type === 'definition') && typeof node.url === 'string') {
+        const url = documentHref(node.url, file.path, base);
+        // Retain authored link text/formatting, but expose no unpublished URL.
+        if (url === null) return node.type === 'link' ? node.children : [];
+        node.url = url;
+      }
+      return [node];
+    }
+    rewrite(tree);
   };
 }