Mark threads that were settled automatically in the Settled list

[mimen]

Auto-settle is the correct default. Most threads that sit idle for a few days are probably not very valuable, and clearing them keeps the active list usable. The cost shows up if & when an important thread disappears. Since the settled list is sorted by the time of the last interaction, they immediately disappear deep into the list, and you can't immediately tell which threads you consciously settled, or auto-settled.

Proposal: record why a thread was settled (user, inactive, or merged) and show a subtle marker on auto-settled rows in the Settled list, such as a small icon with a tooltip like "Settled automatically after 3 days inactive".

Today thread.auto-settle goes through thread.settle and stores only settledOverride/settledAt, so the reason isn't kept. The change would be one optional field on the thread, written by the settle handler and cleared on unsettle, plus the marker on web and mobile. Existing settled threads would show no marker.

The goal is to increase trust in this default. If people can find what auto-settle put away, they will be more willing to leave it on. I have increased the auto-settle time to 7 days in order to protect myself against this issue, and would be more comfortable bringing it back down to 3 days if this was implemented.

Happy to implement this if the direction works for the team!