std_msgs/Header header
uint32  face_id      # track ID or 0-based detection index
string  emotion      # 'neutral' | 'happy' | 'surprised' | 'angry' | 'sad'
float32 confidence   # 0.0–1.0
float32 mouth_open   # mouth height / face height (0=closed)
float32 smile        # lip-corner elevation (positive=smile, negative=frown)
float32 brow_raise   # inner-brow to eye-top gap / face height (positive=raised)
float32 eye_open     # eye height / face height
