The manager said this quite common in silicon valley, even though this might not be enforceable. Therefore no one really bothers about it when hiring people/signing contracts. I looked up some agreements I can find on Internet and I can't find such broad claims reaching far beyond term of employment.
Is this common is Silicon Valley?
My worry is If I sign this and my next employer sees this, will they not hire me because they would worry a possible issue with ownership of work I do for them. Even if they don't see this agreement I feel I might end up signing contradicting agreement with my next employer.