If B didn’t say X can person A sue person B to compel performance of contract or just money back/damages?

Well first, my question more relates to the US Constitution's 1st Amendment, which guarantees freedom of speech from government/public interference, which is why a law could not compel someone to code something, but also, even in contract disputes between private parties, you will only be able to compel Specific Performance (doing an action) if you can show that monetary or other compensatory damages would be unable to properly compensate for the breach, and Specific Performance can never cover "personal obligations" such as continued employment.

If you had already written the code, but refused to turn it over, that might be possible to compel, but if it wasn't yet written I don't believe the courts would ever compel you to write that code as a form of compensation for contract breach.