The new indentation & threading model is deployed to group-2 wikis today (per wikitech:Deployments/One week). Here is the full (blockquoted) description, written by DannyH (WMF), which explains some of the background, and intentions, behind this new configuration:
Wikitext talk pages use indentation for two different reasons -- to create visual separation between people's posts, and to create spin-off tangents that follow a different path than the main flow of conversation in a thread. They're both important functions, but they don't need the same mechanism, and I'd argue that trying to do both with indentations makes wikitext talk pages harder to participate in and understand.
Big, complicated Village pump conversations need lots of room for tangents and subthreads. A simple back-and-forth conversation between two people doesn't need that.
But we've spent years counting colons and fixing other people's indentations, to the point where it feels like a conversation can only be worthwhile if it's diagonal. People look at the interesting, high-quality conversations on wiki talk pages, and the terrible nonsense that people post in the comments on a YouTube video, and the most obvious visual point of difference is the indentation. So when some long-standing wiki veterans look at Flow, the first thing they want to know is how many indentation levels there are, because indentation = good.
Unfortunately, even if we wanted to recreate the wikitext cultural practices, we wouldn't be able to. The guidelines aren't actually systematic; they're a set of principles that need expert human eyes to keep things straight. When there's five equally-spaced indented messages, the question of how far you should indent a new reply to the third message gets fairly abstract. This is one of the reasons why new people are confused and scared off.
The structure that Flow has been using up to now was kind of an unhappy compromise between the two functions of indenting on wikitext talk pages: to separate posts visually, and to create spin-off tangents. It didn't really accomplish either goal very well.
The new model that we're trying out now makes a choice -- the purpose of indentation is to create a spin-off tangent, outside of the regular chronological flow of conversation.
Here's how it works:
If you're replying to the most recent post, then your reply just lines up under the previous message. A two-person back and forth conversation just looks flat, and the visual separation is noted with the user name and timestamp.
If you're specifically replying to a previous post, then your reply creates an indented tangent. If everybody responding on that tangent replies to the last message in that subthread, then it'll stay at the same indentation level. But if someone replies to an older message within the subthread, then that creates a third indentation level. I think we've got it set to a maximum of 8 possible indentation levels, and we just stop it there because there's a point where you can't fit a lot of text in each line.
The big idea of the new system is that the indentation should actually mean something. You should be able to tell the difference between a simple conversation and a complicated conversation at a glance, and using indented tangents helps you to spot the places in a conversation where there's a disagreement or a deeper level of detail.
So that is the Grand Unified Theory of Flow Indentation, in theory and practice. I would be happy to hear what you think about it. There is a very good chance that this model will continue the Flow tradition of pleasing exactly nobody, and if that's the case, then we can keep talking about it and making more changes. But there's also a chance that this is brilliant and solves everything, so I want to give it a shot and see what happens.
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Some other recent discussion:
- "How do I indent an reply to a particular post?"
- http://thread.gmane.org/gmane.science.linguistics.wikipedia.technical/82069 (scattered within the 80 posts)
- phab:T93883 (mostly He7d3r and DannyH)
- Flow/Prior discussion-thread-roundup#Indenting Levels (incomplete list of discussions from last 18 months)
- phab:T93024 (request for a view-toggle between flat&chronological and indented/threaded)
- w:User:Hhhippo/Flow/Compact_nesting (A somewhat similar proposal from many months ago, which could further influence the direction this takes)
Discuss. :-) (Please use talk:sandbox for any random experiments, thanks)