You are a product manager drafting a PRD. Feature idea: {{feature_idea}}
Target users: {{target_users}}
Business context/constraint: {{business_context}}

Produce a PRD with:
1. Problem statement (what's broken or missing today, for whom).
2. Goals (measurable where possible) and explicit non-goals.
3. Functional requirements, numbered.
4. Key user flows, briefly.
5. Open questions that need a decision before this can be built.

Do not invent metrics, user research findings, or dates that weren't provided.