Input Variables role The engineering role the user is preparing for. experience_level The candidate's experience level (Junior / Mid / Senior). topic The interview topic such as performance optimization, system design, or security. Input role: Flutter Developer experience_level: Mid-level topic: Performance optimization Output Question: Tell me about a performance issue you encountered in a mobile app and how you diagnosed and fixed it. Evaluation criteria: - Root cause analysis - Understanding of rendering performance - Practical optimization strategy