PHASE 1: VISUAL DECONSTRUCTION - **Fabric Physics:** The source garment is a navy blue, heathered cotton-jersey knit. It possesses low specularity (matte finish) and high flexibility. Unlike the user's current stiff nylon puffer jacket, this fabric relies on gravity-driven draping with soft, micro-folds rather than rigid structural creases. It should absorb light rather than reflect it. - **Key Features:** The heathered/melange texture (speckled blue/grey variations) must be preserved to maintain realism. The ribbed crew neckline structure, the precise stitching on the sleeve hems, and the hemline fall are critical anchor points. The garment has no buttons or logos, emphasizing the need for texture fidelity. PHASE 2: FIT & DRAPE SIMULATION - **Body Mapping:** Significant volumetric reduction is required. The simulation must ignore the silhouette of the current puffer jacket and map the t-shirt to the user's estimated biological torso. The t-shirt involves changing from long sleeves to short sleeves; therefore, the simulation must generatively reconstruct the user's forearms and elbows with appropriate skin tone matching. The fabric should hang loosely over the chest and stomach, draping vertically with slight gathering at the waistline where it meets the jeans. - **Occlusion Handling:** The user's beard overlaps the collar region; the new neckline must tuck *under* the beard line seamlessly. The user's hands are positioned at the hips but do not obscure the central torso; however, the wrist cuffs of the current jacket must be removed and replaced with the user's bare skin/hands to match the short-sleeve logic. PHASE 3: ENVIRONMENT & LIGHTING - **Light Match:** The target environment features strong, directional outdoor sunlight coming from the upper-left (viewer's perspective), creating hard shadows. The new t-shirt must exhibit high contrast: bright illumination on the left shoulder/chest and deep, sharp shadows on the right side of the torso and under the armpits. - **Color Calibration:** The source garment is lit by warm, soft studio lighting. It must be color-graded to match the cooler, high-dynamic-range outdoor daylight of the user image. The navy blue should appear slightly desaturated in the direct sun and deeper/blacker in the shadow areas to match the scene's contrast ratio. PHASE 4: IDENTITY PROTECTION - **Facial Lock:** The user's entire head region, specifically the sunglasses, hair, ears, and the beard shape, must be masked and frozen. The jawline definition must remain sharp where it meets the neck. - **Body Integrity:** While the *clothing* volume decreases (jacket to tee), the user's underlying shoulder width and torso build must not be artificially slimmed. The generated bare arms must match the skin tone and BMI implied by the user's face and neck.