Neat! Two questions:
Is it possible to create a link that always lead to the newest version of an article, or will all links lead to the version that existed when the link was created?
Will all edits be visible in the history, or can the author make minor edits without triggering a new version?
By default, edits will not be visible in the history – it's a special option you can check when you've made significant changes to the post.
To be precise, the versioning system is based off of "semantic versioning", which has three types of changes:
1. Major update: This constitutes a breaking change, in our case this means old comments are marked as outdated
2. Minor update: This constitutes a significant change, that you want people to be notified by, that adds new info, but doesn't break old comments or old links to it
3. Patch: This is a minor change, like fixing a typo. Nobody needs to get notified, but old links that specifically link to a specific version will still display the original.
A few weeks ago MIRI released new editions of the "Map and Territory" and "How To Actually Change Your Mind" books, and those changes are now finally also reflected in the posts on LessWrong.
To make that happen smoothly, I've also implemented a revision and versioning system, allowing you to view the past revisions of all the posts in those books, and marking comments made against older versions of the post. I did this because a significant fraction of the discussion in the comments was referencing problems in the posts that are addressed in the latest versions, as well as wording that has been changed.
A post having past revisions is indicated by a small history-icon next to its date, which when clicked will allow you to select from all past versions of the post after it has been published. This is currently only available on desktop, the mobile version will follow soon.
We are planning to make the revision system available to everyone soon, which will allow you to uniquely link to any article in its current version, without having to worry that it will ever change. I hope to also make it so that you can get notifications to new major versions of posts that you are subscribed to. This is part of a broader effort to make posts on LessWrong longer-lived and have more of a wiki-feeling to them, and also to make it harder to accidentally delete your whole post with a wrong submission.