One-Day cTBS Over the Precuneus

Inclusion Criteria: * Age 18 years or older. * Able to speak, read, and understand English sufficiently to complete the study assessments and provide informed consent independently. * Diagnosis of major depressive disorder according to DSM-5-TR criteria, confirmed by a qualified physician. * Treatment-resistant depression, defined as an inadequate response to at least two adequate trials of antidepressant pharmacotherapy. * Patient Health Questionnaire-9 (PHQ-9) total score of 10 or higher. Exclusion Criteria: * Any condition identified through TMS safety screening that, in the judgment of a study physician, presents an unacceptable safety risk for TMS. Such conditions may include: * A history of a serious adverse reaction during TMS treatment. * A history of seizure. * A history of stroke. * A history of serious head injury or neurosurgery. * Metal in the head outside the mouth, such as shrapnel, surgical clips, or metal fragments. * An implanted device, such as a cardiac pacemaker, cochlear implant, medical pump, or intracardiac line. * Frequent or severe headaches. * Another brain-related condition or an illness that caused brain injury. * A family history of epilepsy. * Permanent tattoos on the head or neck. * Current recreational drug use. * Current pregnancy or possible pregnancy. * Use of a medication or combination of medications, a recent medication change, or medication withdrawal that, in the judgment of a study physician, presents an unacceptable safety risk, including a clinically significant increase in seizure risk. * Current or lifetime diagnosis of bipolar I disorder, bipolar II disorder, a schizophrenia spectrum disorder, or another primary psychotic disorder. * Active suicidal ideation with intent or plan requiring immediate clinical intervention, or another acute safety concern that cannot be safely managed within the study.