The drop is predictable
Sites that lose visibility after a redesign rarely lose it because the design changed. They lose it because URLs moved without redirects, content was cut, the new build renders differently to crawlers, or the whole thing shipped with staging’s no-index still attached.
1. Map every URL before you start
Export the full list of current URLs with their traffic, and decide for each whether it survives, moves, or goes. Every move needs a permanent redirect to the closest equivalent — not to the homepage, which search engines treat as a soft removal.
2. Don’t quietly delete content
Redesigns shorten pages, and the removed paragraphs are often the specific, factual ones that were being cited. Losing them costs exactly the passages that made the page quotable.
Most post-redesign traffic loss is content that got tidied away, not design that got worse.
3. Check what crawlers actually receive
A rebuild that moves rendering to the client can serve an empty document to anything that doesn’t execute scripts. Fetch your own pages without JavaScript and confirm the words are present — which is the same property that makes server-rendered HTML fast.
4. Ship the boring files
Sitemap regenerated, robots not blocking, canonicals pointing at the new URLs, no-index removed from production. Each is a one-line mistake capable of removing a site from search entirely, and all four are worth a written pre-launch check.
Then watch the right things
For a fortnight, monitor crawl errors, indexed page count, and how assistants describe you against a fixed prompt set — the appearance-rate measurement is the one that catches an AI-visibility loss a rankings dashboard would miss.