PHASE 1: VISUAL DECONSTRUCTION - **Fabric Physics:** The source garment is a flannel/cotton blend button-down. It possesses medium weight with a matte finish and low specularity (no shine). The simulation must render a soft, slightly fuzzy surface texture typical of flannel, rather than the smooth cotton of the current t-shirt. Light should be absorbed rather than reflected. - **Key Features:** The red and black buffalo plaid pattern requires precise alignment across seams, specifically at the shoulder connection. The white 4-hole buttons, the single chest pocket on the wearer's left, the structured collar, and the buttoned cuffs must be preserved. The curved "shirttail" hemline is a structural essential. PHASE 2: FIT & DRAPE SIMULATION - **Body Mapping:** Due to the user's "hands-on-hips" pose, the long sleeves of the flannel shirt must exhibit significant creasing/bunching at the inner elbows (the cubital fossa) and tension lines across the deltoids. The torso of the shirt is looser than the current fitted t-shirt; it should drape somewhat vertically from the bust but bunch around the waist where the hands press against the fabric. The collar must sit higher and stiffer on the neck than the current crew neck. - **Occlusion Handling:** CRITICAL: The user has voluminous dark hair cascading over both shoulders and the upper chest; the red shirt must be rendered *underneath* these hair strands. The user's hands are placed at the waist; the shirt hem and lower sleeves must be occluded by the hands or simulated to bunch behind/around the wrists, ensuring the hands remain the top layer. PHASE 3: ENVIRONMENT & LIGHTING - **Light Match:** The user environment features natural, diffused daylight coming primarily from the left (viewer's perspective), casting soft shadows on the right side of the subject. The red flannel must reflect this directional lighting: brighter highlights on the left sleeve/shoulder, with deepening shadows in the fabric folds on the right side and under the bust. - **Color Calibration:** The source image is lit by flat, cool studio lighting. The target environment is warmer (balcony daylight). The red tone of the shirt requires a slight warm-shift temperature adjustment to blend with the ambient light reflected off the beige walls and tiled floor, preventing the "cut-and-paste" sticker effect. PHASE 4: IDENTITY PROTECTION - **Facial Lock:** The user's entire head region, specifically the jawline, facial expression, and the volume/flyaways of the hair, must be strictly frozen. The neck area above the new collar line must remain original. - **Body Integrity:** Strict prohibition on warping or slimming the user's waist or arm width. The garment must expand to accommodate the user's natural measurements. The visible skin tone on the legs and any exposed portion of the lower neck must remain untouched.