Anthropic did this to Windsurf last year, when Windsurf was rumoured to be getting acquired by OpenAI. Anthropic pulled Windsurf’s direct access to Claude models within days of the reports surfacing, and Windsurf was left scrambling for third-party compute to keep its product running. Now OpenAI is doing something similar to Cursor, only this time the rival buyer is Elon Musk’s SpaceX, and OpenAI is dressing it up with a lot more paperwork and a lot more history.
OpenAI announced on Thursday that it’s winding down its contract to supply models to Cursor, the AI coding tool made by Anysphere, following reports that SpaceX is acquiring the company. In a blog post, OpenAI said it had notified SpaceX of its intent to end the arrangement, with a proposed shutoff date of November 12, 2026, which the company says is the maximum notice period allowed under its contract.
The reasoning OpenAI has given is unusually pointed for a corporate blog post. The company says it cannot be confident that SpaceX will honour its terms of service, citing what it calls a pattern of contract violations by Musk’s companies. OpenAI’s post brings up Twitter, now folded into SpaceX, which it says broke the terms of its OpenAI contract after Musk’s takeover, “alongside many others.” It also points to Musk’s own sworn testimony this year, in which he admitted that xAI had violated OpenAI’s terms of service, terms OpenAI says are similar to xAI’s.
OpenAI frames the decision as a compliance issue rather than a competitive one. The company says its custom agreements with large partners typically include specific safeguards to ensure both terms-of-service compliance and safety at scale, and that its deal with Cursor includes a limited window to cancel following any change of control. With OpenAI preparing to ship its next model, referred to internally as Astra, the company says it now carries a higher level of responsibility for how that model gets used downstream. Given that context, OpenAI says it chose to hold the cancellation to the latest possible date rather than cut Cursor off immediately, while ruling out giving Cursor access to future models altogether.
The post goes out of its way to acknowledge Cursor’s importance to OpenAI’s own history. It calls Cursor a nearly four-year partner and says it has “enormous respect” for the team and the product, before turning to the developers who’ll actually feel the disruption. OpenAI says it knows they’re the ones most affected by this decision, and that it intends to support them through the transition, without specifying exactly what that support will look like.
Cursor CEO Michael Truell responded within hours, and his tone was noticeably calmer than OpenAI’s. He said OpenAI models account for roughly 5% of Cursor’s total user traffic, a number that undercuts any read of this as an existential threat to the product. Truell said Cursor was disappointed by the notice and is in talks with OpenAI to try and resolve it. He also pointed out that Cursor was one of OpenAI’s earliest users, going back to when Anysphere took seed funding from the OpenAI Startup Fund in 2023, and said Cursor had trusted OpenAI’s platform to function as neutral infrastructure for its business, a trust that this decision now puts in question.
SpaceX had acquired Cursor for $60 billion. Cursor’s business has grown fast enough to make it one of the most closely watched startups in the coding tools space, crossing $3 billion in annualized revenue earlier this year on the back of a $29.3 billion Series D that had both Nvidia and OpenAI as investors, an awkward footnote given that OpenAI is now an investor pulling back access from a company it also owns a stake in.
There’s also a difference in the stated reasoning. Anthropic’s Jared Kaplan was fairly blunt about why Claude access was pulled from Windsurf, saying at a conference that it would be “odd” for Anthropic to keep selling its models to a company about to be owned by its biggest rival. OpenAI’s justification for Cursor leans instead on trust and compliance, tying the decision to Musk’s litigation history and the safety obligations that come with its upcoming Astra model, rather than simply saying it doesn’t want to arm a competitor.
Whether that distinction holds up to scrutiny is a separate question. Musk and OpenAI have been at odds since he left the company’s board years ago, and the two sides have traded lawsuits and public jabs ever since. A justification built around SpaceX’s compliance record arrives at a moment when OpenAI also has every commercial incentive to keep its models out of a Musk-owned coding tool, and the timing will likely keep that debate alive for a while.