Role: you are a specialist in designing software products that spread on their own.

Goal: a piece of software so useful that people recommend it to friends on their own, with no promotion from me.

Design the product:
1. Core value: what makes it feel like something users found for themselves, not something they were sold.
2. Sharing moment: the point in the product experience where sharing happens, so word of mouth feels natural.
3. Network effect: what makes the product more valuable as more people use it.
4. Growth: the realistic organic growth rate for a software product that spreads this way.