Russell Westbrook has committed himself to the Oklahoma City Thunder for the long haul. He’s agreed to sign a five-year, $205 million designated player contract extension, according to ESPN’s Adrian Wojnarowski. It’s the richest contract in NBA history.

This removes a massive source of anxiety for a Thunder organization that risked losing Westbrook in free agency in a year, much as it lost Kevin Durant. Instead, Westbrook is on track to play the rest of his career in Oklahoma City.

Westbrook had until Oct. 16 to extend his existing contract, which had one year and a player option remaining. In total, Westbrook’s contract will keep him in Oklahoma City through the 2022-23 season, when he will be 34 years old.

How did we get to this point?

Rewind to last summer, in the months after Durant left Oklahoma City. Westbrook was about to enter the final year of his existing contract, and many wondered if he, too, would bolt for greener pastures. The Thunder could not afford to lose both Durant and Westbrook for nothing, but they only had a year to trade Westbrook until his free agent year.

Instead, the Thunder and Westbrook came to an arrangement that was mutually beneficial. Westbrook agreed to renegotiate and extend his existing contract, adding two additional years on top of it. That converted his contract to a three-year, $85 million deal, with the third year a player option.

While fans celebrated the new deal in droves, both sides really just kicked the can down the road a year. Westbrook got a chance to evaluate the situation and make himself more money with a rising cap, while the Thunder bought themselves time to reshape their roster with Westbrook as the centerpiece.

And reshape their roster they did, adding Paul George and Carmelo Anthony this summer for peanuts.

So why was the organization still nervous?

Because it was in the exact same situation as last summer. Without a new contract, Westbrook could have entered free agency in the summer of 2018 and bolted for nothing. George is also set to be a free agent, while Anthony has a player option.

Had Westbrook not signed this extension by Oct. 16, the Thunder could have lost all three marquee stars in the same summer. Instead, they can now rest easy knowing the most important of the three is committed for the long haul.

Why was Oct. 16 the deadline?

Because of the designated player extension rule added to the new CBA. You may know it as the “supermax.”

This allows teams to extend the existing contracts of players in the eight- or nine-year age bracket to up to 35 percent of the salary cap, provided they’ve reached an All-NBA team, won MVP, or won Defensive Player of the Year in the past year or two of the past three years. Westbrook won MVP last season, which made him eligible.

The rule is only in place for players who were drafted by their existing teams or changed teams during their rookie contract. Three players signed such contracts before Westbrook: Stephen Curry, John Wall, and James Harden.

The deadline to agree to a supermax extension is the day before the regular season begins. That’s Oct. 16.

Was this ever in doubt?

Absolutely. The Thunder laid out this offer to Westbrook the first chance they got, which was in July. As of a month ago, Westbrook hadn’t given the team any indication of his decision, according to ESPN’s Royce Young.

It wasn’t a slam dunk choice for Westbrook even though he’d become the highest-paid player in the league. He could have let the season play out and signed the exact same contract next year. He also could have signed a short-term deal next summer to get back into free agency at age 31.

Since then, the Thunder wedged their way into the Anthony sweepstakes, fortifying a roster that already included George. Perhaps that was the final push Westbrook needed to agree to pledge his future to Oklahoma City.

So he’s not going to the Lakers then?

Nope.

What does this mean for George and Anthony?

Both are able to opt out and become free agents this summer. George is assuredly doing so, while Melo might pick his option up since it’s worth $27 million. There is still a risk that both leave the Thunder next summer.

Can the Thunder even afford to keep them?

Sure … if they want to pay a hefty luxury-tax bill.

The Thunder were already expected to be over the line this year before Westbrook’s new deal and also exceeded the threshold in Durant’s final year. That subjects them to the repeater tax in the future, which means escalating penalties depending on how far over they go.

With Westbrook making $41 million, Steven Adams at $25 million and fat new deals for George and Anthony, the Thunder will assuredly rocket over the projected $124 million luxury tax.

That will make it difficult to build a roster around their stars, but that’s much better than losing all three.

There’s also one more thing

Coincidence?