not (completely) open source but signal has a “note to self” function i use for that

for me it says “Version 25.08.1” in the “about” section of kate, what does it say for you? maybe this is something i could fix with downgrading the installed version of kate?

“trotz” is the one word i’d want it to auto-complete. the rest also show up in an >empty< document when it type “tro”. see: https://imgur.com/Jx27urr

this is what the “spellcheck” section looks like: https://imgur.com/g0agLyX none of the languages under “preferred languages” are ticked. i tried disabling “enabling autodetection of language” but it did not change this behavior.

here is what it says under “components” in the “about” section (i’d think a dictionary would show up here):
Kate: 25.08.1
KDE Frameworks: 6.17.0
Qt: Using 6.9.2 and built against 6.9.2
Ubuntu 25.10 (Wayland)
Build ABI: x86_64-little_endian-lp64
Kernel: linux 6.17.0-14-generic