The Boston Celtics have answered their most pressing question of the offseason. Jaylen Brown will be part of the franchise for the foreseeable future.

The Celtics’ wing has agreed to terms on a five-year supermax contract extension that will pay him up to $304 million, his agent said Tuesday.

It’s the richest contract in NBA history, surpassing the $264 million deal signed by Nuggets center Nikola Jokic last summer.

The deal was first reported by ESPN and confirmed to The Associated Press by Brown’s agent, Jason Glushon.

He averaged career highs of 26.6 points, 6.9 rebounds and 3.5 assists last season. But those numbers went down in the playoffs, when the Celtics lost to the Miami Heat in the Eastern Conference finals. In Game 7, Brown had 19 points on 8-of-23 shooting, making just one of nine 3-point attempts.

Still, the totality of his time in Boston has made him a key piece of the franchise’s current core that management wasn’t willing to risk seeing depart when his current four-year deal expires after next season.

By virtue of making the All-NBA second team — Brown’s first such honor in his career — he was eligible for the supermax extension.

From the moment this past season ended, Celtics president of basketball operations Brad Stevens has been adamant that he wanted to see Brown sign a long-term deal.

“He’s a big part of us. We believe in him and I’m thankful for him,” Stevens said last month. “I’m really thankful that when those guys have success they come back to work. And when they get beat, they own it and they come back to work. And so I know that’s what they’re about. And that’s hard to find.”