Infinite loop caused by default rules in _redirects

[husayt]

I have described the issue in nuxthub repo, but this is caused by recent change in cloudflare pages and will affect all nitro deploys to cloudflare pages:

nuxt-hub/core#902

Maybe it should be addressed here

[MILLERMARRU]

This is exactly what's happening, and yes it belongs here since it affects the cloudflare_pages preset itself, not just Nuxt.

With ssr: false, Nitro's Cloudflare Pages preset writes the standard SPA fallback rule into _redirects:

/* /index.html 200

Cloudflare Pages recently added infinite loop detection to their redirect processing. Since Cloudflare strips .html extensions from URLs automatically, a request that lands on /index.html normalizes to / or /index, which matches /* again, which redirects to /index.html again, and so on. Cloudflare now refuses to apply that rule at all rather than loop, which means direct navigation to any sub route 404s since there's no fallback active anymore.

The cleaner fix doesn't need a redirect rule at all, Cloudflare Pages natively supports a 200.html file as the SPA catch all with no loop risk, since it's served directly rather than through a redirect. You can do this from nitro.config.ts using the compiled hook, so it runs after Nitro has already written its own output:

export default defineConfig({
  hooks: {
    async compiled(nitro) {
      const { readFile, writeFile, copyFile } = await import("node:fs/promises");
      const { join } = await import("node:path");
      const outDir = nitro.options.output.publicDir;

      const indexPath = join(outDir, "index.html");
      await copyFile(indexPath, join(outDir, "200.html"));

      const redirectsPath = join(outDir, "_redirects");
      const contents = await readFile(redirectsPath, "utf-8");
      const cleaned = contents
        .split("\n")
        .filter((line) => !line.startsWith("/* /index.html"))
        .join("\n");
      await writeFile(redirectsPath, cleaned);
    },
  },
});

Since this is a preset level problem rather than something specific to any one project's config, it'd be worth having the cloudflare_pages preset itself skip writing the /* /index.html 200 rule when 200.html is present in the output, and write 200.html directly instead of relying on the redirect for the SPA fallback case. That would fix it for everyone on this preset without each project needing the hook above.