The site stays up.

The site was going down every few days. Not catastrophically, but enough that people would hit a blank page or an error. We fixed it.

The problem was how we updated the site. When we pushed new code, the system would write changes while people were using it. If something went wrong halfway through, the site would break. If two updates happened at the same time, they could corrupt each other.

Now we write all changes to a backup folder first. Once everything is ready, we flip the switch to the new version. If something breaks, the old version keeps running. If two updates happen at once, a lock makes sure they don't interfere. The site stays up while we work.