Would be nice to be able to filter the data before it is sent to the API about freebase-suggest HOT 2 OPEN

That sounds useful, but note there is at least one case where URLs are 
valid/useful 
input - when they represent Freebase topics.  Then it's basically an alternate 
form of 
the ID which is easier to cut & paste in some circumstances.

tfmorris is right, freebase suggest service recognizes freebase topic URLs and 
it's possible it will support other 
URLs as well. If I am understanding you correctly, you basically want a hook 
for you to examine the input value 
before letting suggest submit the query?  Or if you want free form text and NOT 
require the user to select 
something from the suggest list, there is an option you can pass to suggest 
{"soft": true}. This allows the input to 
behave normally within a form field. For example in a search box, with 
soft=true, you can intercept the select 
event or have the user submit the free form text to your own search service.