A 15-year-old female is brought to the clinic by her mother after a school counselor discovered multiple superficial linear cuts on the patient's forearms during a routine check-in. The patient reports she has been cutting for approximately six months, typically using a razor blade, and engages in the behavior 2-3 times per week. She states that cutting helps her manage overwhelming emotions, particularly after arguments with peers. She denies suicidal ideation, intent, or plan. She reports she carefully controls the depth of the cuts and avoids areas near major blood vessels. She has no history of suicide attempts. Which assessment approach is most critical to differentiate non-suicidal self-injury from suicidal self-harm in this adolescent?