Is it permissible for a patient with chronic psychosis, whose hallucinations, dark thoughts, and depression are exacerbated by fasting, to break their fast?

The extent of illness that permits breaking the fast is explained in Fatwa no. 102013. If the harm you experience falls within this extent, then it is considered a valid harm that permits breaking the fast, and you must make up the missed days after recovery, as Allah Almighty says: "And whoever is ill or on a journey, then [he should make up] an equal number of other days." The determination of harm is to be made by a trustworthy Muslim doctor or through experience. However, if fasting does not cause you considerable harm, then your illness does not permit breaking the fast, and you must repent and make up for the days you broke your fast.