Laments about corruption, physical insecurity and unresponsive bureaucrats are a staple of life in many countries in East and Central Africa, with one notable exception: Rwanda.The streets of its capital, Kigali, are impeccable, the roads are good, lights work and, unlike the traffic cops in Nairobi, Kampala or Dar es Salaam, police officers do not stop drivers simply to coerce bribes. Yet the architect of this miracle, President Paul Kagame, is in danger of reversing the gains that have made Rwanda a beacon of progress on the continent.For the most part, Mr. Kagame gets laudatory media coverage, especially in Africa, and it’s easy to see why. Sustained economic growth of around 8 percent over the last decade has brought real benefits to the Rwandan people — a strikingly impressive turnaround in the years since the 1994 genocide, when more than 800,000 people, the overwhelming majority of them members of the Tutsi minority, were killed in a 100-day rampage incited and organized by members of the previous, Hutu-dominated government.Today the word Rwanda is no longer synonymous with misery and death. The average life expectancy is 65 years, up from 48 in 1990, according to the World Health Organization. The percentage of children dying before their fifth birthday has fallen markedly, from 253 per 1,000 in 1995 to 55 per 1,000 in 2012. Most Rwandans have health insurance. There is almost universal access to basic education.