What is the ruling of Sharia on a civil engineer overseeing the construction of palaces for the corrupt?

It is permissible to engage in transactions—buying, selling, and leasing—with someone whose wealth is lawful, or whose wealth is a mixture of lawful and unlawful, whether they are a Muslim or a non-Muslim, a sinner or not a sinner, as long as such interaction does not involve assisting in a wrongdoing. This is based on the Almighty’s saying: (And cooperate in righteousness and piety, but do not cooperate in sin and aggression). However, it is not permissible to engage in transactions with someone whose entire wealth is unlawful, as this would be an affirmation of their injustice and their disposal of what they do not own.