There is inconsistency here because digikam-plugin-gmic krita-plugin-gmic are made optdeps to digikam and krita so I request to open the bug and discuss why you think this inconsistency is justified.

There is no reason to list external plugins as optional dependencies. gmic is an independent project from gimp.

@Balló György
This is not the current policy in Arch. Just take a look at the current optional dependencies of gimp which are
gutenprint poppler-glib alsa-lib curl ghostscript gvfs
They are all independent and external projects! The only common denominator is they "are not needed for the software to function, but provide additional features" as per https://wiki.archlinux.org/title/PKGBUILD

External and internal plugins are two different things. alsa-lib and ghostscript are needed for internal plugins packaged in gimp.

We usually don't list external plugins. E.g. firefox has no dependency on firefox-ublock-orig, firefox-extension-mailvelope and firefox-extension-passff even they provide additional features for firefox.

It's a good point but there are lots of cases where this is not the case currently. Is firewalld optdeps on bash-completion conforms to this?

what about languages and documentation packages? The are not needed for internal working, but if we keep adding these as explicit, it would be a cumbersome task to track them and remove them manually if the original package is removed. How do you prefer to handle this dilemma?

I don't think that bash-completion should be added as dependency for firewalld, but it's up to the maintainer, there are no strict rules.

You can always search related packages with 'pacman -Ss gimp-' or using the web interface.

Thanks for your patience and clear explanation