Good judgement, I guess

I discovered the following end of game position while browsing games in Game Center.

Black is to move. At first, I thought black resigned in a winning position, but upon closer examination I believe white was winning after all, because white can play O13 which starts a new threat on the top right and simultaneously improves the connection to O18. Am I wrong? Is black actually winning here?

Here's another good one, from Gamerz game 1842. Any attempt by red to prolong the suffering with R4 is doomed to fail.

What about the classical U6 instead of the tactical R4?

I did not analyze so maybe it is directly losing but at least we should consider it first.

I don't find anything for red (white) after 25.U6 26.T8. I added that line to the commentator (link above.) The R4 variation seems to last longer, although hypercube likely would not have been fooled.

The underlying theme here is about games where resignation may have been correct, but there were still resources the resigning player might have used. So in the first diagram Black could have tried K14 threatening black M18 or black G13, and under a fast time control maybe white would have missed O13 covering both threats.

I am not sure about that.

25.U6 26.T8 27.Q6

Thanks! I updated the analysis. So red resigned in a winning position.

Remember my words: resigning is the worst move, it is directly losing.