@technomancy Yeah, but it's coming from a URL that could get changed out from under me unless I control the domain. As a user I have no idea what stability properties it will have on my side. Will my browser load it once and save the contents permanently? Will it re-query it periodically? What happens if it's down? Will the owner of the site gain information that I'm using the search they published? Etc.

All of these are artificial headaches made by using a URL rather than a text entry box where you type/paste a pattern.