Design a Mobile App From Scratch: A Lost-Pet Alert and Neighborhood Search App

Interview prompt, live, 30-40 minutes: "Design a mobile app that helps someone who has just lost a pet alert nearby neighbors and coordinate a search, and lets neighbors report sightings. Walk me through your approach from scratch."

1. Ask your clarifying questions and state your assumptions.
2. Frame the core job-to-be-done, being explicit that there are two different user roles here.
3. Define MVP scope — one primary flow, and what's explicitly out.
4. Sketch the information architecture, addressing both user roles.
5. Wireframe the core flow for the pet owner, naming at least one interaction-design principle.
6. Write the alert-creation confirmation microcopy and a sighting-report confirmation microcopy.
7. Name one accessibility consideration specific to this app.
8. Propose HEART metrics for at least three categories, adapted to this app's two-sided nature.
9. Close with a one-sentence summary and the single highest-priority open risk.