PHASE 1: VISUAL DECONSTRUCTION - **Fabric Physics:** The source garment is a structured woven cotton or poplin blend. Unlike the user's current jersey knit t-shirt, this material has medium stiffness and low elasticity. It produces sharp, angular creases rather than soft folds. The surface has a matte finish with low specularity; it should diffuse light rather than reflect it shinily. - **Key Features:** The rolled-up sleeves with the "cuff" volume must be 3D reconstructed to sit around the elbow. The contrast black inner collar (visible at the neck) and the row of black buttons down the center placket are critical anchors. The single chest pocket on the left side and the curved "shirttail" hemline must be preserved. PHASE 2: FIT & DRAPE SIMULATION - **Body Mapping:** The user has a lean/slender build. The shirt should not cling to the torso but hang with a "regular fit" clearance, bridging the gap between the chest and the hips. Since the user's arms are slightly bent and relaxed at the sides, the fabric tension must simulate slight pulling across the shoulder blades. The rolled sleeves should settle just above the user's elbows, creating a distinct volumetric boundary between the fabric cuff and the user's bare forearm. - **Occlusion Handling:** The user's hands are positioned low near the hips; strictly layer the hands *over* the shirt if the hemline extends to that length. The user's neck and chin area must properly occlude the back of the new collar. The simulation must fully mask the existing white t-shirt, particularly at the neckline and sleeves, ensuring no white fabric "leaks" from underneath the red shirt. PHASE 3: ENVIRONMENT & LIGHTING - **Light Match:** The user's environment features a directional, somewhat dim light source coming from the upper-right (user's left), casting distinct shadows against the dark door behind. The red shirt must generate self-shadowing on the user's right side (image left) and deep ambient occlusion under the armpits and collar to match this high-contrast, low-light setting. - **Color Calibration:** The source image is studio-lit and hyper-saturated. The red channel must be desaturated and slightly cooled (blue-shifted) to match the cooler, grainier tonality of the user's room. A noise layer should be applied to the garment to match the ISO grain of the target photo. PHASE 4: IDENTITY PROTECTION - **Facial Lock:** The user's visible chin, jawline, lips, and neck skin above the collar bone must remain frozen and untouched. - **Body Integrity:** The user's slender torso width and arm thickness must be preserved; do not artificially bulk up the user to fill the shirt. The trousers (navy sweatpants with "SYDNEY" logo) must remain pixel-perfectly unchanged starting from where the new shirt's hem ends.