Graham:Yes, Synapse deletes the csv file ASAP so there's no chance of it being imported again. Very Safe!
Not really.
Please rethink this.
Acceptable would be .. rename .csv to .csx
Prompt user for deletion.
Name it: IMPORTED_originalfilename.csv (and code in Synapse to never import files starting with IMPORTED_ )
etc.
Deleting a .csv file I spent hours and hours making is dangerous.
There is no way for a user to know that Synapse is going to destroy the .csv file.
Seriously I was just lucky to have a backup of the .csv file.