Two files hold the same listings, and only one of them survives you editing a search

Notifio watches rental search pages from your own machine and tells you when a listing appears that was not there last time. For a long while a find existed in exactly one place: an email. That is a strange thing for a desktop app to do. The app knew about the room first, and then had nothing to show for it. If you missed the email, or the send failed, or you just wanted to see what turned up overnight, the app's answer was a line in the activity log saying 3 new listing(s) on Kamernet - Leiden and the links were somewhere in a mailbox. Fixing that looked like a small feature. It turned into a question about lifetimes, because the app already stored every listing it had ever seen. Why the existing store could not be reused Diffing needs a record of what a page held last time. Notifio keeps one snapshot per search, keyed by the search URL, and compares against it. It is the mechanism the entire product rests on, and the rules around it are stricter than you would guess: th