PHASE 1: VISUAL DECONSTRUCTION - **Fabric Physics:** The source garment appears to be a lightweight cotton or linen blend. It has a matte finish with low specularity (no shine). The physics engine must simulate a "crisp but breathable" behavior, allowing for sharp creases where folded (arms) but a softer drape around the torso compared to heavy denim or starch-stiffened formal wear. - **Key Features:** The standard spread collar with the inner white band detail must be preserved. The visible button placket, the specific "lemon yellow" hue, and the cuff construction are critical. The dark retail tag hanging from the button is a foreign object and should ideally be removed for a realistic "worn" look, but the buttonhole it hangs from must remain intact. PHASE 2: FIT & DRAPE SIMULATION - **Body Mapping:** Due to the user's "arms crossed" pose, high-stress tension maps must be applied across the upper back and shoulders. The fabric must bunch significantly at the inner elbows (anticubital fossa) and billow slightly above the crossed forearms. The hemline should interact naturally with the hips, likely bunching slightly on the user's backside where he leans against the stone wall. - **Occlusion Handling:** This is a high-complexity occlusion scenario. The user's forearms, hands, and the wristwatch on his left wrist (image right) must be segmented and layered *over* the new yellow shirt. The shirt fabric must appear to pass underneath the crossed arms, compressing accordingly. The neck and jawline must properly occlude the back of the collar. PHASE 3: ENVIRONMENT & LIGHTING - **Light Match:** The target environment features harsh, high-contrast outdoor sunlight coming from the upper-left (relative to the viewer). The flat, soft indoor lighting of the source shirt must be replaced. The yellow fabric requires bright, blown-out highlights on the left shoulder and chest, with deep, sharp cast shadows underneath the crossed arms and on the right side of the torso. - **Color Calibration:** The source shirt reflects warm pink tones from the bedspread; this color bleed must be neutralized. The yellow must be color-graded to react to the bright blue sky (ambient light) and the warm direct sunlight, ensuring it doesn't appear "neon" or "flat" against the natural stone background. PHASE 4: IDENTITY PROTECTION - **Facial Lock:** The user's facial structure, skin tone, beard texture, hairstyle, and gaze direction (looking to his right) must be strictly frozen and masked out of the generation area. - **Body Integrity:** The user's shoulder width and arm muscularity must remain unchanged. The simulation must fit the shirt to his existing volumetric mesh, strictly forbidding any slimming of the waist or artificial bulking of the biceps to fit the flat-lay shirt's dimensions.