This task is about preventing the username suggestion list (T232601) from opening if the {key @} is preceded by a non-whitespace character.
This way, people can type things like email addresses and article names (e.g. [3D@Home](https://en.wikipedia.org/wiki/3D@Home_Consortium)) without having to interact with the username suggestion list.
=== Behavior
1. Open the Reply or New Discussion Tool's `Visual` mode
2. Type: `hello@`
**Current behavior**
3. Notice that upon typing {key @}, the username suggestion list appears
**Desired behavior**
3. ✅ Notice that upon typing {key @}, the username suggestion list does NOT appear
//Note: the behavior above should also apply to the two tools' `Source` modes once T257391 is implemented.//
=== Done
- [ ] The 'Desired behavior" is implemented
- [ ] @Thryduulf is notified