The deployment of T239676 will introduce an option for all contributors, including those included in our ongoing A/B test , to opt into the mobile wikitext editor, even in instances when the mobile visualeditor would have otherwise loaded by default. 
To ensure these contributors are appropriately accounted for in our analysis, we will need to add new tracking events that enable us to see which users assigned to the default-visual bucket have opted into the mobile wikitext editor by way of the new "fallback workflow" T239676 will introduce.
What we would like to know
We would like to know...
- When/whether a contributor is shown the fallback prompt
- Whether they elect to use the fallback editor
- How long after being shown the fallback editor do they elect to use the fallback editor
- When a contributor elects to use the fallback editor whether they switch to visual mode
- Which contributors in the A/B test group were shown the fallback prompt
- All "Open questions" above have been resolved
- The instrumentation required to satisfy the "What we would like to know" requirements have been defined
- The instrumentation required to satisfy the "What we would like to know" requirements have been implemented
- T227338: Test visual editor as the default mobile editor on select wikis
- E.g. a contributor in the A/B test could be assigned to the default-visual bucket, but elect to use the mobile wikitext editor if they felt the mobile visual editor was taking too long to load.