Add support for root destination markdown routing in toMarkdownDestination

packages/gitbook/src/routes/markdownPage.test.ts

@@ -81,6 +81,11 @@ describe('toMarkdownDestination', () => {
         expect(toMarkdownDestination('/docs/new-page/?a=1#b')).toBe('/docs/new-page.md?a=1#b');
     });
 
+    it('points the site root to its markdown route', () => {
+        expect(toMarkdownDestination('/')).toBe('/.md');
+        expect(toMarkdownDestination('/?a=1#b')).toBe('/.md?a=1#b');
+    });
+
     it('leaves markdown paths and external URLs untouched', () => {
         expect(toMarkdownDestination('/docs/new-page.md')).toBe('/docs/new-page.md');
         expect(toMarkdownDestination('https://example.com/page')).toBe('https://example.com/page');

packages/gitbook/src/routes/markdownPage.ts

@@ -99,11 +99,12 @@ export function toMarkdownDestination(destination: string): string {
 
     const url = new URL(destination, 'https://gitbook.invalid');
     const pathname = url.pathname.replace(/\/+$/, '');
-    if (!pathname || pathname.endsWith('.md')) {
+    if (pathname.endsWith('.md')) {
         return destination;
     }
 
-    return `${pathname}.md${url.search}${url.hash}`;
+    // A root destination trims to an empty pathname; its markdown route is `/.md`.
+    return `${pathname || '/'}.md${url.search}${url.hash}`;
 }
 
 function markdownRedirect(location: string, permanent: boolean) {