Product-market fit, in depth
Fit is felt before it is measured: usage retains without bribery, word of mouth appears, and support load shifts from “what is this?” to “I need more of it.” Proxies exist — the Sellers question (how disappointed if this disappeared?), retention curves flattening — but all triangulate the same underlying pull.
Feedback texture is one of the clearest informal signals. Pre-fit feedback is polite and fundamental (“have you considered doing something else?”); post-fit feedback is demanding and specific (“your export breaks my Tuesday workflow”). Angry specificity means people depend on you — an odd but genuine milestone.
Putting it into practice
Instrument the search: collect feedback continuously, watch which complaints recur (recurrence = dependence), and use roadmap votes to see which promises generate pull. The week your inbox turns demanding and specific, keep shipping — you are closer than the revenue chart shows.