From T345678:
> Before testwiki deployment we will only migrate usernames beginning with **"~2"** (there are only two such accounts based on the analysis in T346465. After testwiki deployment we will consider migrating all other usernames so that the identifier can be simple **"~"**.
The default patterns for naming temporary users are:
```lang=php
'genPattern' => [ 'type' => 'string', 'default' => '*Unregistered $1' ],
'matchPattern' => [ 'type' => 'string|array', 'default' => '*$1' ],
'reservedPattern' => [ 'type' => 'string|null', 'default' => null ],
```
...with accompanying documentation:
```
- genPattern: (string) The pattern used when generating new usernames.
This should have "$1" indicating the place where the serial string will
be substituted.
- matchPattern: (string|string[]) The pattern used when determining whether a
username is a temporary user. This affects the rights of the user
and also prevents explicit creation of users with matching names.
This is ignored if "enabled" is false.
- reservedPattern: (string) A pattern used to determine whether a
username should be denied for explicit creation, in addition to
matchPattern. This is used even if "enabled" is false.
```
Ahead of testwiki deployment, we should update these on beta to:
```lang=php
$wgAutoCreateTempUser['genPattern'] = '~$1';
$wgAutoCreateTempUser['matchPattern'] = ['*$1', '~2$1'];
$wgAutoCreateTempUser['reservedPattern'] = '~$1';
$wgAutoCreateTempUser['serialProvider']['useYear'] = true;
```