Once a user has edited on desktop they are assumed to have a preferred editor. The first time they edit on mobile, this preference should be respected.
TBD: How to determine if a user has edited on desktop, as this may not result in any user options changing.
=== Behavior
**TWO EDIT TAB WIKIS**
|Published an edit on *mobile* before|Published an edit on *desktop* before|Interface shown when tapping `Edit` on mobile
|---|---|---
|Yes|No|The editing interface they opened last on mobile
|Yes|Yes| The editing interface they opened last on mobile
|No|Yes|The editing interface they opened last on desktop
|No|No|The `source` editing interface [ii]
**SINGLE-EDIT-TAB-WIKIS** [i]
|Published an edit on *mobile* before|Published an edit on *desktop* before|Value set in `Special:Preferences#mw-prefsection-editing` > `Editing mode`|Interface shown when tapping `Edit` on mobile|
|---|---|---|---
|Yes|No|`Remember my last editor`|The editing interface they opened last on mobile
|Yes|No|`Always give me the visual editor if possible`|The editing interface they opened last on mobile [iii]
|Yes|No|`Always give me the source editor`|The editing interface they opened last on mobile [iii]
|Yes|No|`Show me both editor tabs`|The editing interface they opened last on mobile
|Yes|Yes|`Remember my last editor`|The editing interface they opened last on mobile
|Yes|Yes|`Always give me the visual editor if possible`|The editing interface they opened last on mobile [iii]
|Yes|Yes|`Always give me the source editor`|The editing interface they opened last on mobile [iii]
|Yes|Yes|`Show me both editor tabs`|The editing interface they opened last on mobile
|No|Yes|`Remember my last editor`|The editing interface they opened last on desktop
|No|Yes|`Always give me the visual editor if possible`| The editing interface they opened last on desktop [iii]
|No|Yes|`Always give me the source editor`| The editing interface they opened last on desktop [iii]
|No|Yes|`Show me both editor tabs`|The editing interface they opened last on desktop
|No|No|`Remember my last editor`|The `source` editing interface [ii]
|No|No|`Always give me the visual editor if possible`|The `source` editing interface [ii]
|No|No|`Always give me the source editor`|The `source` editing interface [ii]
|No|No|`Show me both editor tabs`|The `source` editing interface [ii]
//Note: people who are participating in the mobile editing interface default A/B test should not be subject to any of the logic above.//
=== Done
- [ ] The "Behavior" described above is implemented
---
i. Defined as wikis listed at https://noc.wikimedia.org/conf/InitialiseSettings.php.txt as having the following value set: `wmgVisualEditorUseSingleEditTab`
ii. This behavior could change pending the results of the mobile editing interface default A/B test
iii. Currently, the values people set in `Special:Preferences#mw-prefsection-editing` > `Editing mode` (e.g. `Always give me the visual editor if possible`) only apply to desktop. //See: T261423#6500559 //