As a Senior AR/UX Designer, your task is to create a detailed product design brief for 'StreetScan AR', a smart-glass Head-Up Display (HUD) system designed for real-time street food nutritional analysis. Your design must address the following pillars: 1. Visual Interface Architecture: Describe a minimalist HUD that uses spatial anchoring to attach nutritional data cards to identified food items in the wearer's field of view. Specify color schemes for legibility in outdoor environments and font choices for glanceable data. 2. Data Visualization: Detail how calories, macronutrients (Protein, Carbs, Fats), and allergens are presented. Include a 'Smart-Warning' system for high-sodium or high-sugar items based on user health profiles. 3. Interaction Design: Define the user flow for identifying a dish, estimating portion size via depth sensors, and 'logging' the meal using gaze-tracking or voice commands. 4. Technical AI Framework: Outline the computer vision logic required to decompose complex street food dishes (like Tacos or Pad Thai) into their likely ingredients to provide accurate estimates. Provide the final response as a structured design specification document.