I have a Node.js webapp with high ranking SEO that has about ten pages (example.com/blog) that contain static content. I want to move the app part to a subdomain (app.example.com), and replace the existing parent domain with a CMS where my client can easily write content.
For the static pages, I can keep the exact same URL structure (example.com/blog). Apart from this what steps do I need to take in order to maintain SEO rankings?