With 2026.2 in a split-mode plugin, I got a warning about an annotator:
The annotator is in a frontend module because it only updates syntax highlighting (based on PSI) and PSI is supposed to be shared with frontend and backend.
Is the warning correct and what’s the reason that annotator is backend-only?
intellij-community has at least one frontend annotator 
: com.intellij.editorconfig.frontend.highlighting.EditorConfigAnnotator.
Thanks!
Good catch!
The assumption about annotator was that it more frequently does some heavy lifting and effectively needs backend.
However I agree, that in case it is lightweight, it can be in frontend. We’ll consider adjusting the inspection. Should you see any reports that sound irrelevant, please share. It is very valuable for us and for all external plugin developers 
Do not forget though that .resolve() in frontend annotator is usually pointless if relies on indexes
