Marty Walsh rolled to a huge reelection win last year and just hosted a national gathering of the US Conference of Mayors, where he could bask in the glow of a city booming on the strength of its enviable position as a leader in areas driving the global economy.

But the city’s mayor knows better than to rest on Boston’s laurels, and Walsh, in a Codcast conversation with Bruce Mohl and me, was frank about the challenges facing Boston — from development and transportation gridlock to the state of its schools.

We sat down to talk on Thursday, a day before news broke that school Superintendent Tommy Chang will be shown the door after only three years on the job. The mayor — by all accounts the alpha figure in deciding he’d had enough of what has been a strained relationship with the superintendent his team hired — was obviously aware during our conversation that this news was coming. That offers an interesting context for considering Walsh’s remarks when we asked about a recent report showing that the district has made little progress over the last decade in getting off-track students who have struggled in the school system through to graduation.