> time-series sentiment analysis [...] much negativity on HN these days, I hope I'm wrong

Depending on the members, there certainly is. Put aside the "dismissers", those who have a habit or a hormonal reliance to cast a "meh". Those who objectively assess according to the input that the development of facts provide may bend their "apparent mood" accordingly. This may be more evident here because in brighter times we may be more inclined to post and submit about more idle intellectual beauty ("complications in ancient clocks"), and in darker times it makes sense that we are more focused on the problems.