Sonia Health's AI therapist is being developed as a state machine that mirrors the structure of Cognitive Behavioral Therapy (CBT), which is centered around the cognitive model of CBT, describing the interconnectedness of situations, thoughts, behaviors, and emotions. The therapy approach aims to help clients become aware of, challenge, and reframe negative interpretations and thoughts. An AI therapist's main task is to respond to their client, requiring new context and information dependent on past interactions with the client, the stage of the ongoing session, the current topic being addressed, or the sentiment of the last client message. To achieve this, Sonia Health built a deep decision tree of structured retrieval and prompting for each stage using the LangChain framework, which provides customizable memory modules and agent constructors. The system also includes transitions between stages, emergency detection, and therapeutical worksheets to support personalized and effective treatment. The development of Sonia's AI therapy is being made accessible on the App Store, with the potential to positively impact millions of lives worldwide.