PHASE 1: VISUAL DECONSTRUCTION - **Fabric Physics:** The source garment is a woven cotton or cotton-blend poplin dress shirt. Unlike the target's current synthetic activewear, this material has high structural rigidity (low elasticity). It exhibits a semi-matte finish but requires sharp specular highlights on folds to define the black texture. It will not cling to the musculature like the current t-shirt; it must bridge over muscle valleys rather than sinking into them. - **Key Features:** The structured spread collar is critical and must replace the current crew neckline entirely. The vertical button placket must remain central but deform slightly with the torso twist. The curved "shirttail" hemline needs to be preserved, hanging freely rather than tucked. Rigid cuffs and distinct buttons are essential detail points. PHASE 2: FIT & DRAPE SIMULATION - **Body Mapping:** Due to the user's athletic build and the "leaning back/right" pose: * **Left Arm (Extended):** The fabric must exhibit tensile strain (pulling lines) extending from the left armpit across the pectoral muscle. The sleeve should not hang loose but follow the arm's vector. * **Right Arm (Relaxed):** Gravity will cause vertical draping. Expect bunching/stacking of the fabric just above the wrist cuff. * **Torso:** The shirt is a regular fit (not slim), so there should be an air gap between the fabric and the user's lower back/abs. The hemline should fall over the waistband of the shorts. - **Occlusion Handling:** The user has short hair and no jewelry, creating a "clean slate" for the upper body. The primary occlusion task is masking the existing green t-shirt collar entirely. The new collar must sit *around* the neck, occluding the lower neck skin that is currently visible above the crew neck, while sitting *behind* the jawline. PHASE 3: ENVIRONMENT & LIGHTING - **Light Match:** The target environment features strong, warm directional light coming from the upper-left (viewer's perspective), casting shadows to the right. The new black shirt must generate deep, distinct shadows on the user's right flank (under the relaxed arm). - **Color Calibration:** The source shirt is neutral black under cool light. It must be re-calibrated to absorb the ambient "peach/beige" bounce light from the background. The highlights on the black fabric must shift from cool white to a warmer, soft yellow/peach tone to integrate the garment into the scene. PHASE 4: IDENTITY PROTECTION - **Facial Lock:** Absolute freeze on the facial region above the thyroid cartilage (Adam's apple). The jawline definition and ear positions must remain pixel-perfect. - **Body Integrity:** Strictly forbidden to warp the user's athletic shoulder width or arm circumference. The garment must expand to accommodate the user's deltoids and biceps; the body mesh must not be compressed to fit the shirt. Skin tone on the arms and neck must remain unaltered.