This data is retained for 30 days. After not visiting a particular topic for 30 days, the data about your last visit to it will be deleted.
We've had discussions before about long-lived topics, resurrecting old topics, etc. and the general consensus is that they were good and encouraged. Unfortunately, with the limited 30-day memory for topic read-vs-new comments, resurrected posts become a real pain. The current activity-sorted all-time front page has three topics from 2018, each with over a hundred comments. It'd be nice to read the new activity, but that takes either some tedious Ctrl+F with various terms ("minutes", "days", etc.) to find newish comments or re-reading everything.
I'd like to avoid relying on a third-party extension to handle this (browser and device support, issues with syncing multiple devices, etc.), and I understand the privacy goals. What are people's thoughts on making read-comment memory user-configurable, even if it's just "default 30-days" and "all-time"?