Design a smartwatch sensor subsystem

You are designing the sensing subsystem for a health-focused smartwatch. Describe how you would take the product from requirements to production. Your answer should cover: 1. How you would choose the sensor stack and overall architecture for a wearable device that must balance accuracy, power, size, comfort, and reliability. 2. How you would design for real-world conditions such as motion artifacts, poor skin contact, ambient light, temperature variation, and manufacturing tolerance. 3. How you would debug a design defect discovered during validation or after units are built. Explain your root-cause process, what data you would collect, and how you would isolate whether the issue is electrical, mechanical, firmware, algorithmic, or supplier-related. 4. How you would work with an external supplier to define quality inspection, incoming test, reliability validation, sampling, and acceptance criteria. Assume this is a production consumer device, so discuss both engineering trade-offs and manufacturability.