OpenAI's stated reason for ending the contract
OpenAI notified SpaceX on August 28, 2026, that it intends to wind down the contract supplying OpenAI models to Cursor, with a proposed shutoff date of November 12, 2026. In a public blog post, the company said the decision rests on its confidence that SpaceX, Cursor's new owner, will operate within OpenAI's terms of service. "We are making this choice because we cannot be confident that SpaceX will use our technology within our terms of service, based on our experience with Elon Musk's companies violating contracts," OpenAI wrote. The company said it is giving the maximum notice provided by the contract so developers retain access for as long as possible.
Contract trigger rooted in the SpaceX acquisition
The move follows SpaceX's $60 billion all-stock acquisition of Cursor's parent Anysphere, which was announced in June and closed on August 15, 2026. OpenAI's custom agreement with Cursor contained a change-of-control clause that opened a limited cancellation window, and OpenAI said it held the cancellation to the latest date permissible under the deal. OpenAI cited two prior episodes to justify its reasoning: it alleged that X, formerly Twitter and now part of SpaceX, broke the terms of its contract after Musk acquired the platform, and it pointed to earlier-2026 sworn testimony in which Musk acknowledged that xAI, also now part of SpaceX, had violated OpenAI's terms of service. The company added that its forthcoming model, Astra, raises the accountability bar, framing that as a reason to end the arrangement rather than extend it to a partner it does not trust.
Cursor's exposure and response
Cursor co-founder Michael Truell, now a SpaceX executive, framed the practical impact as limited, saying OpenAI models serve roughly 5% of Cursor user traffic. "Cursor was one of the very first users of OpenAI, we've worked closely with their team for years, and we've trusted their platform to be neutral infrastructure for our business," Truell wrote on X, adding that the teams are speaking to resolve the situation. Cursor itself continues to offer Grok models developed with SpaceX compute, along with frontier models from Anthropic and Google, while the editor itself remains unaffected by the cutoff.
Musk's reply and the Anthropic fill-in
In a post on X reported on August 29, 2026, Musk said he "couldn't care less" about OpenAI's decision and called Sam Altman and OpenAI President Greg Brockman "utterly untrustworthy" and accused them of having "stolen an open source nonprofit." Within hours, Anthropic co-founder and chief compute officer Tom Brown said Anthropic has partnered with Cursor since Sonnet 3.5 and will increase compute to support Claude models inside the editor; Musk replied to that post with two rocket emojis. OpenAI's Codex-side team lead Thibault Sottiaux said developers can keep using their own OpenAI API keys and retain access through OpenAI's IDE extensions for Cursor.
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