Three things:

1 - If VE is OK to edit a namespace (and, in general, it's probably fine for any

that aren't signed, Template: or MediaWiki:) then we should just make that
config change and not vary it per wiki. Make a distinct bug for that?

2 - Project: is frequently signed, especially on enwiki, so I think giving a VE

editor in this context would be confusing and actively wrong. There is no VE
tool for signing comments, nor for creating the definition lists which are
(ab)used so very widely for MediaWiki discussions right now. The intent has
always been that signed content would be covered by Flow, and I think trying
to build tools now for a few months' usage would be a diversion from the main
task of improving VisualEditor.

3 - I think that this would end up being a rather broken user experience when a

wiki switched from opt-in to opt-out, and all the pages that you used to be
able to edit with VE suddenly vanish in a cloud of WT-only smoke, without any
explanation or obvious cause.

Consequently, minded to WONTFIX, but am open to suggestions

Let's take a step back here. Here's my use-case: I don't edit articles very much, but I still want to be able to test VisualEditor when I do occasionally edit non-articles. Today I came across [[Wikipedia:Meetup/DC]] and wanted to use VisualEditor to edit it. I wasn't able to. :-(

You bring up a good point about user signatures, but many project-space pages are informational in nature, not discussion-oriented.

Perhaps there's some way to programmatically detect whether a page is a discussion page?

Or perhaps we can remove the hard restriction on VisualEditor editing? For example, if I try to navigate to https://en.wikipedia.org/w/index.php?title=Wikipedia:Meetup/DC&veaction=edit directly, VisualEditor won't load. We could remove the hard restriction and leave in place the soft restriction (not exposing the user interface tab). This would allow people like me to just hack in an extra tab. Dirty, but probably fine for now.

(In reply to comment #1)

If VE is OK to edit a namespace (and, in general, it's probably fine for
any that aren't signed, Template: or MediaWiki:) then we should just make
that config change and not vary it per wiki. Make a distinct bug for that?

I vaguely understand what you're saying here, but I think it would be best if you filed the bug.

This is not a site request but a VisualEditor enhancement.

The check in [1] needs to be moved somewhere else (one of the hooks in VisualEditor.hooks.php?).

[1] https://git.wikimedia.org/blob/mediawiki%2Fextensions%2FVisualEditor.git/a531b396981042da09280df2ea5dceb6be3fa106/ApiVisualEditor.php#L218

(In reply to comment #3)

(In reply to comment #1)

If VE is OK to edit a namespace (and, in general, it's probably fine for
any that aren't signed, Template: or MediaWiki:) then we should just make
that config change and not vary it per wiki. Make a distinct bug for that?

I vaguely understand what you're saying here, but I think it would be best if
you filed the bug.

Sure - bug 55968 filed.