PHASE 1: VISUAL DECONSTRUCTION - **Fabric Physics:** The source garment is a semi-structured woven fabric, likely cotton or linen blend with a matte finish. It possesses medium stiffness, meaning it resists micro-wrinkling but forms distinct, sharp folds at stress points (armpits, elbows). It has low specular reflection; light should diffuse softly across the surface rather than shine. - **Key Features:** The sharp collar structure and the button placket (center front) are critical rigid elements that must maintain geometry. The rolled-up sleeves creating a cuff effect at the elbow must be preserved. The loose, relaxed fit of the bodice contrasts with the user's current tight fitting top. PHASE 2: FIT & DRAPE SIMULATION - **Body Mapping:** The tight silhouette of the current halter top must be volumetrically expanded to accommodate the loose fit of the button-down shirt. The collar must encircle the base of the neck, replacing the halter neckline. Crucially, the sleeves must generate fabric covering the currently bare shoulders and upper arms, terminating just above the elbow bend. Due to the crossed-arm pose, the fabric must compress and bunch realistically between the user's inner biceps and the torso. - **Occlusion Handling:** This is a high-complexity occlusion scenario. The user's long, wavy hair falling over the shoulders must be segmented and layered *over* the new shirt collar and shoulders. The user's crossed arms and hands (specifically the left hand fingers and right forearm) are currently occluding the midsection; the new garment must be rendered *behind* these limbs. The tattoos on the forearms must remain visible, while the tattoos on the upper arms will be covered by the new sleeves. PHASE 3: ENVIRONMENT & LIGHTING - **Light Match:** The user is illuminated by a soft, broad studio light source coming from the upper-front-left, casting gentle shadows to the right. The black fabric of the shirt must adopt this lighting model, showing lighter diffuse highlights on the left shoulder and collar, and deeper shadows in the folds on the right side and under the crossed arms. - **Color Calibration:** The "black" of the source shirt must be color-graded to match the black point of the user's existing skirt to ensure a cohesive outfit. The shirt should not be rendered as void black (#000000) but rather a dark charcoal with visible texture noise to match the grain of the user image. PHASE 4: IDENTITY PROTECTION - **Facial Lock:** The user's entire head, including the sunglasses, jawline, and neck (above the thyroid cartilage), must remain pixel-perfectly frozen. The hair flow and volume must not be altered. - **Body Integrity:** Strictly forbid any warping or slimming of the user's arm width or waistline. The visible skin on the hands and forearms, including the snake tattoo on the left forearm and the linework tattoo on the right arm, must be preserved exactly as is without blurring or washing out.