Direct calque of English 'seed users' from product/growth literature. The metaphor: a small group of early adopters that, like seeds, grow the user base organically through word of mouth. Standard part of Chinese startup playbooks — Xiaomi's famous 100
米粉 ('100 Mi fans') in 2010 is the textbook
种子用户 case. Recruited via internal beta, niche communities (Zhihu, Douban groups), or invitation-only launches.