Filters:after appears to be ignored

Yeah... exit() kills everything right there... like a flu excuse on a global financial system.

How one terminates is like a box of chocolates... sometimes it works out ok, sometimes is sux.  The best place to have exit() is evidently where one knows nothing further will or can ever happen afterwards (saves a hiccup line mine when one comes to insert more code further down the execution chain, a long time after one's forgotten about the code in the preceding flow).  I suspect (without having looked into the fine details) the very last return will also end up destroying everything anyway (?).

Yes. The last return gets to the post event and sessions get destroyed. Without the exit() it gets destroyed before a redirect happens and the message is not seen, I tested this after reading your post. I've had tons of session files plague my CI3 projects, to the point where a client had to buy more space on hosting, and, though my coding improved since then, I'm just trying to keep sessions down to flash messages and short term data.

You can see things I made with codeigniter here: itart.pro its not overly impressive as I have very little time to learn.