SANTA CLARA, Calif. -- The dramatic roller-coaster ride that has been the high-stakes contract negotiations between the San Francisco 49ers and wide receiver Brandon Aiyuk ended where it all began when this started more than six months ago -- with the Niners and Aiyuk sticking together for the long haul.

Aiyuk and the Niners on Thursday agreed to terms on a four-year, $120 million contract extension that will keep him in San Francisco through the 2028 season, sources told ESPN's Adam Schefter.

It's the same deal that has been on the table from the 49ers since Aug. 12, league sources told Schefter.

Aiyuk joins Miami Dolphins star Tyreek Hill as the fifth-highest-paid receivers in the NFL with an average annual value of $30 million per season.

The deal comes on the heels of perhaps the most contentious move yet in these negotiations as the Niners publicly declared Aiyuk healthy on Wednesday with coach Kyle Shanahan and general manager John Lynch saying they expected him to participate in practice.

Aiyuk did not practice Wednesday or Thursday, opening himself up to the possibility of team discipline. Thursday's agreement, however, ensures Aiyuk can spend the next 10 days preparing for the Sept. 9 opener against the New York Jets.

For nearly two years before the extension was finished, the Niners maintained they always intended to re-sign Aiyuk. There was plenty of doubt about that outcome in recent weeks after the wideout requested a trade just before the start of training camp on July 23.

Not long after, the Niners -- for the first time -- seemed serious about trading Aiyuk.

With strong interest from the Pittsburgh Steelers, Cleveland Browns and New England Patriots, the 49ers and Aiyuk evaluated their options. To make a deal work, a team was going to have to satisfy both the Niners as well Aiyuk's demands for a lucrative contract extension.

While each of those teams was seemingly able to check one of those boxes, neither could do both, which helped the Niners and Aiyuk return to the negotiating table to work out their differences.

The result was a long-awaited deal that ensures the Niners' top wideout isn't going anywhere as San Francisco pursues the franchise's sixth Lombardi Trophy that has narrowly evaded it in four of the past five seasons.

Now the Niners not only have their best receiver for another run at the Super Bowl, but they can keep him with quarterback Brock Purdy as part of the team's primary offensive foundation for the next five years.

In 2023, Aiyuk had a breakout season, leading the Niners in receiving yards (1,342) while finishing ninth in the NFL in receiving yards per game (83.9), second in yards per reception (17.9) and first in yards per target (12.9) on his way to a second-team All-Pro nod. His return also means the Niners could have the same starting 11 on offense from last year, with Aiyuk able to team with fellow wideouts Deebo Samuel and Jauan Jennings while rookies Ricky Pearsall and Jacob Cowing develop.

To reach this point, of course, it took plenty of time and patience on both sides. Soon after the 49ers lost Super Bowl LVIII in February, Aiyuk said he would stay in San Francisco "if it was the right move."

Asked what that would look like, Aiyuk said simply, "being a champion."

From there, things appeared to get more contentious after Lynch insisted at the league meetings in March that the team wanted to pay Aiyuk. After those comments, Aiyuk posted a series of emojis to his Instagram story that translated to "money talks, bulls--- walks."

April's NFL draft brought another important benchmark in the negotiations. At the time, Lynch and Shanahan made it clear that they would listen to calls on their receiver just as they would any other player but still had no desire to move on from Aiyuk.

"I've communicated on many occasions: our wish is that he's here and part of the Niners for the rest of his career," Lynch said in April. "We're working through that. ... I can say we're having good talks, and I'm just going to leave it at that."

Because of that, a trade involving Aiyuk was always going to require a substantial return coming to San Francisco. During draft weekend, no deals were ever close and Lynch and Shanahan again emphasized the desire to re-sign Aiyuk, even after spending their first-round pick (No. 31 overall) on Pearsall.

The Niners selecting Pearsall offered some insight into the state of the relationship between the team and Aiyuk, who played briefly with Pearsall at Arizona State. Moments after the pick. Aiyuk texted Lynch and Shanahan, "Fire pick, I can't lie."

While Aiyuk stayed away from the team's offseason program, he did not show up for the full-squad minicamp in early June, incurring more than $101,000 in fines as the negotiations reached a temporary stalemate.

In the meantime, other receivers around the league reeled in big contracts:

• The Philadelphia Eagles kept DeVonta Smith with a three-year, $75 million deal, with $51 million guaranteed;

• Detroit's Amon-Ra St. Brown inked for four years, $120.012 million, with $77 million guaranteed;

• Miami's Jaylen Waddle got three years for $84.75 million, with $76 million guaranteed;

• Philadelphia's A.J. Brown signed a three-year $96 million deal, with $84 million guaranteed;

• Minnesota's Justin Jefferson got a four-year, $140 million deal, with $110 million guaranteed;

• and Dallas' CeeDee Lamb signed a four-year deal earlier this week for $136 million, including $100 million guaranteed).

Those deals simultaneously provided an outline for a potential Aiyuk deal and drove his price higher, which contributed to his eventual trade request.

Just before the Niners opened training camp on July 23, Aiyuk officially requested a trade. Even after that, Lynch insisted that Aiyuk was likely to stick around at least through this season, with sources telling ESPN that other teams had reached out about trading for Aiyuk only to be told that the Niners had no interest in dealing him.

"We fully intend on Brandon being a Niner moving forward," Lynch said July 23. "We're always open to listen to things but like I said, we expect Brandon to be an integral part of our team like he has been and excited about that."

Aiyuk then reported to training camp with his teammates, though he did not participate in any practices. He did, however, take part in meetings and watched practices from the sideline.

Despite a wild week, an Aiyuk trade to the Steelers or any other team never materialized and the sides restarted the discussions that finally yielded an extension. Before Thursday's deal, Aiyuk was slated to play the 2024 season under the fifth-year option that came standard with the rookie contract he signed in 2020, which would have paid him $14.124 million.

This is the fifth year in a row that the 49ers have re-signed one of their stars either just before training camp or during: tight end George Kittle (2020), linebacker Fred Warner (2021), Samuel (2022) and Nick Bosa (2023).

Aiyuk is just the second first-round pick (along with Bosa) the Niners have made under Lynch and Shanahan to sign a second contract with the team.