What can I do if company won't file i-485 unless I commit another year if green card is approved?

If you have a copy of your I-140, you do not need to have the employer be involved in your I-485. You file that on your own.

There are several issues involved in this matter and as such, you need to speak to an attorney.The issue regarding a company's insistence that you work for them for a year may not be quite as unlawful as you may think. Just as you do not have to accept those terms, the company also is under no obligation to file a green card for you. And from an immigration stand point, if you accept those terms with full knowledge that you do not intend to honor it, and so, walk away once your green card is mailed, you may face DHS enforcement action because, DHS may allege that you committed fraud because, you never intended to work for the employer who filed your petition. Because, this is an employment based petition, you may think your case is not analogous to the situation where an alien married a US citizen and immediately walks away immediately after getting the green card, but DHS may not necessarily agree. Consult in detail with an experienced immigration lawyer.

The contract like this is absolutely lawful and perfectly enforceable. Moreover, it is perfectly reasonable for your employer to demand that you commit to work for them, at least, a year. After all, their petition to the U.S. Government states that you should be given a green card because this company needs you and you agree to work for them. If you are applying for a green card through your employer while you have no intention to work for that employer, you are committing immigration fraud on the Government of the United States. So I suggest you keep your rightful indignation in check: it isn't your company that "plays with peoples lives", it is you who is playing fast and loose with the law.

The default rule is that the employment is at will, meaning you can walk away at any time or your employer can let you go at any time. But if you enter into a contract, that contract is legally binding, and the employer can sue you for damages. They would have to prove that, as a result of your breach of this employment contract, the employer suffered certain damages because they lost a client or they had to hire and train someone else, which always costs money, etc. So an employment contract is legally binding. And it is not unreasonable for an employer to ask for one if they are to commit to the time and expense of sponsoring a green card. If you do not want to work for them, perhaps you can transfer your work visa to another employer and ask that employer to sponsor you (but they don't have to do that, of course). Basically, your employer has no obligation to sponsor your green card, so I do not see this request as anything unreasonable or unenforceable.