OpenAI casts the break as a compliance and safety decision; Cursor says it wants to preserve a long-standing partnership, while Anthropic sees an opening to expand its role inside SpaceX. Musk, meanwhile, has treated the dispute as another front in his bitter fight with OpenAI’s leadership.

SpaceX completed its $60 billion acquisition of Cursor on Aug. 14, according to financial filings, placing the fast-growing AI coding tool under Elon Musk’s control.¹ That change of ownership triggered a narrow contractual window for OpenAI to act.

On Friday, OpenAI notified SpaceX that it would wind down the agreement supplying its models to Cursor, proposing a Nov. 12, 2026 shutoff date—the latest notice period allowed under the contract. The company said the decision was “incredibly tough,” but argued it could not trust SpaceX to follow its terms after what it described as earlier breaches by Musk-owned companies.² OpenAI said its concern is heightened by the forthcoming Astra model and the need for safeguards “at scale.”²

Cursor chief executive Michael Truell struck a more conciliatory note. OpenAI models account for roughly 5% of Cursor traffic, he said, adding that the companies were talking to resolve the matter. “Cursor was one of the very first users of OpenAI,” Truell wrote, calling the platform neutral infrastructure that Cursor had trusted for years.¹

Anthropic moved quickly to fill the gap. Co-founder Tom Brown said Cursor had been a trusted Claude partner since Sonnet 3.5 and pledged to “increase compute to support Claude models in Cursor.” Musk amplified that message with rocket emojis on X.Elon Musk (elonmusk)³

The rupture lands amid Musk’s long-running legal and personal battle with Sam Altman and Greg Brockman. Musk said he “couldn’t care less,” again accusing the OpenAI leaders of betraying the company’s nonprofit origins—claims OpenAI disputes.¹