I have a player who likes to find as many loopholes and vague rules as he can to try to get his way. He finally went too far. He was making a new character and was telling me about all the gear he had. When i asked him about how his character had all this OP gear he said his character made it. Meaning he did mechanics checks outside of a session and with out me there to check all the rules.
How do i handle this?