On English Wiktionary, we would like a way to automatically display a message at the top of pages in the Reconstruction namespace. At the moment, we have to manually add the template {{reconstruction}} at the top of every page. See for example Reconstruction:Proto-Indo-European/dn̥ǵʰwéh₂s. It looks like the PageNotice extension will be able to do this if it is deployed.
This has been discussed at Wiktionary:Grease pit/2018/September#{{reconstruction}}, Wiktionary:Beer parlour/2017/September#Proposal: install mw:Extension:PageNotice, and at Wiktionary:Grease pit/2017/June#Citations at citations where several people expressed support or interest in looking into it.
This task was revised from a comment on T61245 by suggestion of @Victar.