Static prerendering: Duplicate crawled/sitemap entries for nested index pages

Which project does this relate to?

Start

Describe the bug

Example route structure:

├── blog
│   ├── $slug.tsx
│   └── index.tsx
├── contact
│   └── index.tsx
├── index.tsx
└── __root.tsx

For /blog/index.tsx and /contact/index.tsx page routes, when building with static prerendering and sitemaps enabled, they are crawled twice and result in duplicate sitemap entries.

[prerender] Prerendering pages...
[prerender] Concurrency: 12
...
[prerender] Crawling: /blog/
[prerender] Crawling: /contact/
[prerender] Crawling: /blog
[prerender] Crawling: /contact
...
[prerender] Prerendered 8 pages:
...
[prerender] - /blog/
[prerender] - /contact/
[prerender] - /blog
[prerender] - /contact
...
[sitemap] Building Sitemap...

These routes do not have any layout routes, so only the page routes with no trailing slashes must be crawled and added to the sitemap. This trailing-slash consistency is important for SEO.

Router is configured for no trailing slashes (which is also the default afaik) so this should be followed for the output:
https://github.com/dotnize/start-static-test/blob/main/src/router.tsx#L19

Same behavior with

blog.index.tsx
contact.index.tsx

---

but this route structure works fine. These will only be crawled once, but only works well for routes that don't have child routes:

blog.tsx // breaks /blog/$slug
contact.tsx // OK for /contact, since this has no child routes

With that structure, I assume blog.tsx is treated as a layout route, so blog/$slug.tsx contents are never rendered since blog.tsx doesn't have an Outlet.

Your Example Website or App

https://github.com/dotnize/start-static-test

Steps to Reproduce the Bug or Issue

1. pnpm install
2. pnpm build
3. See build logs, and dist/client/sitemap.xml. Duplicate entries for /blog and /contact are generated, one with a trailing slash, and one without

Expected behavior

Only one entry should be generated for each page, for structures like blog.index.tsx or blog/index.tsx

Screenshots or Videos

No response

Platform

• Router / Start Version: 1.167.5 / 1.166.17
• OS: Fedora Linux 43
• Bundler: Vite
• Bundler Version: 8.0.1

Additional context

Workarounds:

• As mentioned above, a flat route structure like contact.tsx works fine if it doesn't have child routes, otherwise it will get treated like a layout route.
• For routes that have child routes like /blog, These pages can be manually excluded in the Start Vite plugin

  {
    // Workaround to exclude "/blog/" from sitemap, so we only get "/blog"
    path: "/blog/",
    prerender: { enabled: false },
    sitemap: { exclude: true },
  },
  

  ref: https://github.com/dotnize/start-static-test/blob/main/vite.config.ts#L35-L40

Reproduce the issue with pnpm install and pnpm build in the linked start-static-test example, then inspect src/router.tsx, vite.config.ts, and dist/client/sitemap.xml. Compare the /blog and /contact entries for both trailing-slash forms; done means each page is crawled once and the sitemap contains only the configured no-trailing-slash URL.