Puzzle #173 - Thirty Nine (Kakuro)

For how common of a genre Kakuro is I've never had a real desire to try making one until very recently, while thinking about highly constrained sums. 39 is highly constrained in 6, 7 and 8 cell groups, so... I had to try utilizing that. It was a bit of a headache to try to keep some of the logic I discovered intact, and hopefully it survived into the final puzzle.

puzz.link interface

update to fix uniqueness in the lower left (thanks rob!)