After a looong discussion, in Wikimedia we came up with a policy that avoids the use of spaces in project names. We use dashes instead. The reasons include the potential risk of breaking things by using spaces. Meanwhile, enough users would prefer to user the natural spaces instead of the techy dashes. If you have a recommendation about the use of spaces in project names, please share it.

We expect projects with spaces to work properly, and have a number of projects which use spaces (Blessed Committers, Blessed Reviewers, Cowboy Commits, Custom Fields, Support Impact, High Support Impact, etc.). This glitch is the first issue I'm aware of that we've run into.

One small cost is that figuring out the hashtag is less obvious (e.g., Cowboy Commits becomes #cowboy_commits), but T3725 should remedy that sooner or later by popping up a typeahead after you type a # symbol.

We don't specifically recommend things one way or the other, but spaces in projects names are definitely allowed/supported/expected and considered a normal use case.

I'm not exactly sure what the factors are that lead to the dash policy and all the related tasks look like they have a minimum of 2,000 comments on them, but if there are specific concerns around fragility/breaking things we may be able to remedy them technically.

In T7284#96783, @epriestley wrote:

I'm not exactly sure what the factors are that lead to the dash policy and all the related tasks look like they have a minimum of 2,000 comments on them, but if there are specific concerns around fragility/breaking things we may be able to remedy them technically.

As this was kind of asked for, let me try to explain: Looking at the previous comment via "View Raw", project names were entered by using underscores (e.g. #blessed_committers) it seems. Literally entering #Cowboy Commits triggers no autolinking magic (for obvious reasons). We don't expect our users to learn/remember the mental model replacing spaces by underscores, hence using dashes allows users to enter project names etc. simply 'as is'.

Furthermore, https://secure.phabricator.com/tag/custom_fields/ works while https://secure.phabricator.com/tag/custom%20fields/ is a 404.

Longer version in https://phabricator.wikimedia.org/T283#3526, sections "Case of tags" and "referencing" (some parts might be outdated nowadays though).

Literally entering #Cowboy Commits triggers no autolinking magic (for obvious reasons).

Yeah, understandable. T3725 might be good enough to fix that, but I don't have a patch about to land or anything.

Furthermore, https://secure.phabricator.com/tag/custom_fields/ works while https://secure.phabricator.com/tag/custom%20fields/ is a 404.

Ah! We can probably fix this.

A note here that didn't get carried over from T7297, it looks like this might happen because the project gets created with an empty name and then undergoes a rename.