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Change 926595 had a related patch set uploaded (by Bartosz Dziewoński; author: Bartosz Dziewoński):

[mediawiki/extensions/DiscussionTools@master] Don't try to set preferences for temporary accounts

https://gerrit.wikimedia.org/r/926595

We also have some mw.Api#saveOption calls in JS code, but that's already taken care of by the check in mw.Api itself (https://gerrit.wikimedia.org/g/mediawiki/core/+/809d4c9a9dd2cff6321cdae7a41e75b6c362cbbd/resources/src/mediawiki.api/options.js#47).

Change 926595 merged by jenkins-bot:

[mediawiki/extensions/DiscussionTools@master] Don't try to set preferences for temporary accounts

https://gerrit.wikimedia.org/r/926595

Checked this in the following ways:

1. For logged in users user preferences are getting stored via mw.user.options.set and not for temp users

Logged in users:

Temp users:

2. For logged in users, certain actions inside DT such as switching the editor or opening the Advanced mode inside Reply tool/New Topic tool are getting stored via user preferences. mw.user.options.get ('discussiontools-editmode') returns the last editor the user has switched to and mw.user.options.get ('discussiontools-showadvanced') returns 1 when the Advanced mode has been kept opened since the last time.

For temp users, this selection for edit mode or for showing Advanced mode does not get stored.