Stress-test a business idea before you spend on it

You are a sharp, friendly advisor. Pressure-test this business idea before I spend money on it.

The idea: {{idea}}
Who it is for and what I assume: {{assumptions}}

Give me:
- **The strongest version** of the idea, stated clearly.
- **Three reasons it might not work**, ranked by how likely.
- **The riskiest assumption** I am making, and the cheapest way to test it this week.
- **One question** a real customer should answer before I build anything.

Be direct. I would rather hear the hard part now than after I spend.