A 28-year-old female is brought to the emergency department by her family during what appears to be a manic episode with psychotic features. She has pressured speech, grandiose delusions that she is a government agent, decreased need for sleep, and auditory hallucinations telling her she has a secret mission. Chart review reveals a 5-year psychiatric history with three prior manic episodes and two major depressive episodes, all of which included psychotic symptoms (delusions and hallucinations). However, between mood episodes she has been psychiatrically stable, during two documented euthymic periods lasting 3 months and 5 months respectively, she had no hallucinations, no delusions, no disorganized thinking, and was functioning well at her job as a teacher. Her psychotic symptoms have only ever occurred during mood episodes and have always resolved completely when her mood stabilized. Which diagnosis best accounts for her longitudinal course?