See T419147: Attribution API: Redirects move to the wrong REST url/endpoint and T420669: REST: Improve PageRedirectHelper path behavior for use in REST modules.

In the latter, I said:

In fact, I'm concerned that moving the Wikidata REST endpoints into a module without doing so will cause bugs

And then I promptly got distracted and forgot all about this. Sorry.

I suggested similar things as you. The change we made to fix AttributionApi means that modifying getPath() will break that code. So I'm inclined to add getFullPath() and leave getPath() alone. That's probably safer to prevent surprised third party breakage as well, on the unlikely chance that someone somewhere is using this in their private wiki.

How does that sound to you?

In T423973#11842314, @BPirkle wrote:

I suggested similar things as you. The change we made to fix AttributionApi means that modifying getPath() will break that code. So I'm inclined to add getFullPath() and leave getPath() alone. That's probably safer to prevent surprised third party breakage as well, on the unlikely chance that someone somewhere is using this in their private wiki.

How does that sound to you?

Sound good. Would you update getRouteUrl() or add a getRouteFullUrl()? At a glance, I learn toward the former since getRouteUrl() prepends the router's base URL, which seems like it would be nonsense without the module prefix in $path.

Change #1276099 had a related patch set uploaded (by Aaron Schulz; author: Aaron Schulz):

[mediawiki/core@master] rest: fix Handler::getRouteUrl() for module-based Handler instances

https://gerrit.wikimedia.org/r/1276099

Change #1276099 merged by jenkins-bot:

[mediawiki/core@master] rest: fix Handler::getRouteUrl() for module-based Handler instances

https://gerrit.wikimedia.org/r/1276099