A state law passed last year opened the door for cities and towns in Colorado to require developers to contribute to affordable housing and combat the state’s housing crisis. After researching, drafting, gathering feedback and tweaking a policy over the course of more than two years, Denver was the first community to walk through that door. The city’s long-in-the-works affordable housing mandate is now law after the Denver City Council voted to adopt a trio of bills codifying the new requirements on Monday.