Same shopper. Two jeans that look identical. One fits at Size 29, the other at Size 28. A size chart reads her waist and hands back one size for both jeans. Only one of them is right. We built Contour to answer the question a size chart never can: does this fabric have room for this body when she sits down? Meet Riley, one of the synthetic shoppers in the demo. On the Ironside raw selvedge, her correct size is 29 (95% confidence). The waist-only chart most stores run says 28, and at 28 her thigh blows past this zero-stretch denim's limit. Put the same Riley in the Driftwood stretch slim and the right size drops to 28, because stretch denim forgives the thigh. Same body, different fabric, different correct size. 👖 The reason a chart misses this: four waist-and-hip numbers cannot feel the fabric. Contour computes the actual strain at each zone (waist, hip, thigh, inseam) against that fabric's stretch limit, and the size is decided in plain, unit-tested code, never guessed by a language model. Agents advise, code decides. On a labeled 105-pair synthetic golden set, the engine beats the waist-only size chart by 40 percentage points. And when no single size clears every zone, it abstains and says "bracket, or speak to a stylist" instead of bluffing a confident wrong number. If your team is fighting fit-driven returns, we would genuinely like to hear which category drives yours: denim, tailoring, or stretch knits? Fit is a physics problem, and the answers will be shared ones. 📐 #FashionTech #RetailAI #Ecommerce #ReturnsReduction #FitTech