A 34-year-old married man with a 10-year history of bipolar disorder type I presents to the psychiatry outpatient clinic with his wife. He reports feeling depressed for the past 3 weeks, with anhedonia, poor sleep, and persistent guilt about his past manic episodes. He denies current suicidal ideation but admits to passive death wishes. His wife mentions he has been giving away his possessions and has made a will despite having no serious medical illness. On examination, he appears psychomotor retarded with poor eye contact. He has had two previous suicide attempts—one by hanging 5 years ago and one by pesticide ingestion 2 years ago. His current medications include lithium (level 0.8 mEq/L) and sertraline 50 mg daily. Which of the following is the MOST critical intervention to reduce his imminent suicide risk?