Thanks for letting us know! I'm not entirely sure it's a good idea to add optdepends, validation layers is a huge and heavy dependency meant only for debugging purposes, it is not correct for wlroots to require it... I get it that it's a temporary dependency while the feature is very unstable, and indeed we enabled the feature on purpose, to make it easier for users to tinker around if they want and know what they are doing, but at the same time adding debugging dependencies to the package seems a bit wrong, if you see what I mean... Brett, any opinions? Feel free to add if you think it should be done, in that case lets just remember to remove it.

I definitely don't think we should add a full dependency, especially since it won't be a dep in the long term. Considering the unstable nature of the Vulkan renderer I think it would be best for us to not parade the renderer as an optdep like it's a beta feature. That it's for debugging purposes also disqualifies it as a candidate IMO (by that logic we'd optdepends e.g. gdb everywhere). But then again, we typically don't ship software that requires gdb to run. :D

As a middleground, we could update the sway wiki page, but I'm not so sure it would belong there: It feels like it should be mentioned upstream in their Vulkan documentation for contributing (à la "If you're on Ubuntu, install `foo`. If on Arch Linux, install vulkan-validation-layers).