Is there a way to determine which messages are used?

@Pcoombe and the Fundraising banner team would know best. As we're getting close to peak banner season, I'm now doubtful that we will attempt this before Q3.

There is the list I made at T166346: List of DonationInterface messages used in banners/donatewiki, but it's outdated. Note that we also use some messages on donate.wikimedia.org, so would need to either keep DonationInterface there or copy those messages too.

As Elliott says we're getting into peak season now, so I would definitely not touch this before Q3. I can provide a more up-to-date list then.

@Pcoombe I'd be inclined to copy all the donatewiki messages to the WikimediaMessages too so we can get DonationInterface off the main cluster entirely. Looks like WikimediaMessages is already installed there.

@Pcoombe would we be able to find all the message keys in use by grepping for them in a dump of the banner namespace and a dump of donatewiki, or are they sometimes concatenated from shorter strings in JS?

Change #1017370 had a related patch set uploaded (by Jforrester; author: Jforrester):

[mediawiki/extensions/WikimediaMessages@master] [WIP] Mass-import all DonationInterface i18n messages

https://gerrit.wikimedia.org/r/1017370

The easiest thing to do would be to lift+shift all of them to WikimediaMessages and then prune them later? This would allow us to undeploy DI from the main cluster swiftly, and clean things up without pressure.