I'd like to suggest two things that might enhance the new download history feature:
1. Similar to the OP's request, an ability to log automatically the names of all downloaded NZB root nodes in a text file, with date & time, and/or unrared filenames, and maybe directory info. Something simpler than the full log file is what I'm thinking. I like to get a quick view of what I've been leeching over the last few days and weeks, at the moment I do this manually with a batch routine (using a bit of a roundabout method, tbh). I also add comments like the OP - mainly to record which files I've replaced with propers or internals, etc. This log is purely for information purposes, the dl history takes care of dupes nicely.
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2. An option to keep all entries in the Download Queue with status updates instead of automatic removal of completed files. The new cleanup button and/or timer option can do that work now, and it's nice sometimes to see what's happened to each file in the set without digging through the full log.
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-Hecks