OpenAI has notified SpaceX of its plan to terminate the contract supplying its models to Cursor, the popular AI coding platform, after SpaceX completed a $60 billion acquisition of Cursor’s parent company, Anysphere. The proposed end date is November 12, 2026, the latest allowed under the change-of-control provisions in the existing agreement.

The decision marks another chapter in the prolonged rivalry between OpenAI Chief Executive Sam Altman and SpaceX founder Elon Musk. OpenAI described the move as extremely difficult, noting its long relationship with Cursor and its interest in keeping models available to developers. At the same time, the company stated it lacks confidence that SpaceX will comply with its terms of service.

Contract Clause and Compliance Concerns Drive the Split

SpaceX finalized the all-stock purchase of Anysphere on August 14. The transaction valued Cursor at $60 billion and involved the exchange of approximately 389.3 million shares of SpaceX Class A stock. The deal ranks among the largest startup acquisitions to date and integrates Cursor into SpaceX’s broader AI efforts, including access to extensive GPU capacity.

OpenAI’s customized agreement with Cursor contained a limited window allowing termination after a change in ownership. The company exercised that right and selected the farthest available shutoff date so developers could continue using existing models for as long as possible. Future models, including the forthcoming Astra system, will not be supplied to Cursor.

In explaining the decision, OpenAI pointed to prior instances involving Musk-controlled companies. It cited breaches of contract terms by Twitter, now under SpaceX, after Musk’s acquisition of the platform. It also referenced Musk’s sworn admission earlier this year that xAI, now part of SpaceX, had violated OpenAI’s terms of service.

OpenAI emphasized that partnerships with large organizations typically require tailored contracts to maintain compliance and safety standards at scale. The company said it has worked with Cursor for nearly four years and holds respect for the product and its team.

Cursor Downplays Immediate Impact

Michael Truell, co-founder of Cursor and now a SpaceX executive, stated that OpenAI models account for roughly 5 percent of Cursor’s traffic. He noted that the companies remain in discussion and that Cursor was among the earliest users of OpenAI technology. Truell described the platform as neutral infrastructure that the team has trusted for years.

While the short-term operational effect appears limited, the loss removes one major model option from a tool long marketed for flexible access to leading systems. Cursor continues to offer models from other providers and benefits from SpaceX’s computing resources for its own development efforts.

Anthropic Chooses Continuity and Expansion

In contrast, Anthropic confirmed it will maintain and strengthen its relationship with Cursor. Tom Brown, co-founder of Anthropic, stated that Cursor has been a trusted partner since the release of Claude Sonnet 3.5. The company plans to increase the compute allocated to support Claude models inside the platform and expressed optimism about future collaboration under SpaceX ownership.

The stance differs from earlier Anthropic decisions. The company previously restricted access for xAI after its staff used Claude through Cursor and ended OpenAI’s access ahead of a major model launch, citing terms-of-service violations. In this case, Anthropic elected to deepen support rather than withdraw.

Musk Response and Broader Rivalry

Musk responded bluntly on the social platform X, writing that he could not care less about the decision. He reiterated longstanding criticisms of Altman and OpenAI President Greg Brockman, accusing them of transforming an open-source nonprofit into a closed entity.

The episode continues a series of disputes. Earlier this year a federal jury dismissed Musk’s $150 billion lawsuit against OpenAI on statute-of-limitations grounds. The latest development underscores how competitive pressures and ownership changes are reshaping access to frontier AI models across developer tools.

Developers using Cursor will retain OpenAI model access until the November 12 cutoff. After that date they will need to rely on alternative models available within the platform or other arrangements. The divergent choices by OpenAI and Anthropic illustrate the growing tendency among leading AI laboratories to treat distribution and partnership decisions as strategic levers in an intensifying race.