Okay-- well, I have a book recommendation for you, in that case.
But even before I do that-- which parent is "dialed in" to your child? It sounds like maybe it's Dad? By that I mean the parent that your child basically can't pull ANYTHING over on-- the one that knows what is happening in that head of his most of the time-- or at least well enough that the parent just KNOWS when the child is lying, etc. THAT parent just became the gut-checker for all parenting decisions and any stories that seem even remotely out of the ordinary and expected. And probably just for the routine stuff, too-- my daughter can easily convince her dad that all vegetables make her teeth hurt, but she certainly won't try it with me. I just give her "the look" and she kind of trails off into incoherently muttering under her breath. A single Spock-like raised eyebrow is particularly effective as a tool for quelling the worst of that sort of thing. Your mileage may vary, of course. LOL.
Book time.
The Manipulative Child.Horrible title-- but a transformative tool for parents of kids like this-- and the brighter they are, the more badly we need the help and insights. My dd was/is an extreme case. You have my sympathies.