Moderator Tools/Content moderation on mobile web/Diff

In the mobile web interface, editors cannot - by default - easily access mechanisms for undoing edits. With Advanced Mobile Contributions (AMC) turned on, editors can access an Undo button on page histories only, which opens the desktop undo interface.

The Moderator Tools team would like to enable undoing edits from diffs in mobile web, and improve the diff UI in the process.

'''We have some open questions about how to approach this work. Please share your thoughts on the talk page.'''

Background
Mobile editors who do not have Advanced Mobile Contributions (AMC) turned on cannot access buttons for undoing edits from page histories or diffs. Enabling AMC adds Undo and Rollback buttons to page histories, along with revision deletion functionality, but does not add these to diffs.

When using Undo from mobile web, the desktop edit window is shown, enabling a partial revert, where edits are made to the page while the edit is undone. This interface is clearly not designed for mobile screen widths and results in users needing to scroll far down the page to confirm undoing the edit.

Diffs in MobileFrontend are currently displayed via Special:MobileDiff, an interface designed to be optimised for mobile devices. MobileDiff presents diffs with an in-line comparison colored red and green, in contrast to the two-column blue and yellow design used in the desktop Vector skin. Special:MobileDiff should be deprecated in favour of styling Special:Diff (T117279).

Open questions

 * What do we need to know about diffs and undoing edits which isn't captured above?
 * What do you like or dislike about the in-line and two-column diff views? Do you just want to use one of these, or should users be able to toggle between them?
 * When undoing edits do you usually undo the entire edit, or do you often use the edit window to make adjustments (a "partial revert")?
 * Do you use any gadgets or user scripts which extend the functionality of the diff page or the process of undoing edits (on desktop or mobile)?

Related links

 * T191706 - It's not possible to undo/rollback edits from diff on Mobile
 * Community Wishlist Survey 2019/Mobile and apps/Add an undo/revert button to diff view
 * Community Wishlist Survey 2021/Mobile and apps/Undo on mobile
 * User:FR30799386/undo