OpenAI caused something of a stir over the weekend when it announced plans to cut Cursor’s direct access to OpenAI models in November.The reason? Elon Musk.In a statement issued late on Friday, OpenAI pointed to two previous incidents involving Musk’s companies: Twitter breaking the terms of a data-licensing deal after Musk’s 2022 takeover of the social network, and Musk’s admission under oath earlier this year that xAI had partly used OpenAI models through distillation — conduct OpenAI says violated its terms of service. And now that SpaceX’s $60 billion deal to acquire Cursor has closed, OpenAI’s attentions are turning to Cursor.“This decision was incredibly tough, as we care deeply about our models being broadly available for developers,” the company wrote. “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.”While that in itself was big news for anyone following the day-to-day rough and tumble of the AI industry, what was particularly notable was the response of OpenAI’s arch rival. The Anthropic factorAs The New Stack noted in its coverage, Anthropic co-founder and “chief compute officer” Tom Brown moved fast, posting publicly within hours of OpenAI’s statement to confirm that it continues to see Cursor as a “trusted partner,” and will “continue to increase compute to support Claude models in Cursor.”Cursor has been a trusted partner of Anthropic since Sonnet 3.5. We’ll continue to increase compute to support Claude models in Cursor and are excited for what comes next with them at SpaceX.— Tom Brown (@NotTomBrown) August 29, 2026But anyone who has followed Anthropic’s recent history could be forgiven for wondering why.Take Windsurf. In May 2025, reports emerged that OpenAI was in talks to buy the AI coding tool for $3 billion. Anthropic didn’t hang around for the deal to close though, and within weeks, Windsurf said Anthropic had cut its direct access to Claude 3.5 Sonnet and Claude 3.7 Sonnet. Speaking at an event hosted by TechCrunch shortly after, Anthropic co-founder Jared Kaplan said that “it would be odd” for Anthropic to be selling Claude to OpenAI. As things transpired, the OpenAI deal fell through, and Google stepped in instead, paying $2.4 billion to hire Windsurf’s founders and R&D staff into DeepMind. “They cut them off ruthlessly when RUMORS of OpenAI potentially buying Windsurf surfaced.”In a social media post published on Sunday, Gergely Orosz, engineer and author of the Pragmatic Engineer newsletter, is quick to highlight the episode with Windsurf, which he noted had also been a “trusted partner” with Anthropic for some time. “They cut them off ruthlessly when RUMORS of OpenAI potentially buying Windsurf surfaced,” Orosz writes. “Now, SpaceX, an Ant(hropic) competitor bought Cursor — it’s still a trusted partner?”Then there’s xAI, the AI company Musk founded in 2023 to build Grok, which SpaceX acquired outright in a February transaction valuing xAI at $250 billion. In January this year, Kylie Robison reported that Anthropic had cut xAI staff off from Claude, which they’d been accessing through Cursor — with Cursor reportedly telling xAI it was “a new policy anthropic is enforcing for all its major competitors.” So Anthropic has previous form for moving fast, on rumor alone in Windsurf’s case, whenever a customer starts to resemble a competitor. Which makes this week’s public vote of confidence for a company now wholly owned by one of Anthropic’s actual rivals worth a second look.The compute dependencyWhat makes SpaceX different from the previous Windsurf and xAI episodes is that Anthropic is also buying a huge amount of compute from it.On May 6, Anthropic announced it had secured the entire output of SpaceX’s Colossus 1 data center near Memphis, Tennessee — more than 300 megawatts of compute and over 220,000 Nvidia GPUs. Anthropic had been hampered by limited compute availability, and the SpaceX deal, alongside other recent compute agreements, let it raise usage limits for Claude Pro and Max subscribers almost overnight.Two weeks later, the financial terms came out. Per SpaceX’s IPO filing, Anthropic agreed to pay $1.25 billion a month for compute across Colossus and Colossus II — about 325,000 Nvidia GPUs combined — scheduled to run through May 2029, subject to termination rights.SpaceX, for its part, said the arrangement would allow it to monetize some of its compute capacity while retaining enough to meet its own AI training and inference needs. As The New Stack reported in May, the deal also underscored just how central access to compute had become to competition between the leading AI labs. And it created an unusual commercial relationship: Anthropic was now buying a huge amount of compute from a company that also owned one of its direct AI rivals in xAI.And that is what makes Anthropic’s response to the Cursor acquisition so notable. In response to Tom Brown’s post on X on Saturday, Replit founder and CEO Amjad Masad points to the contrast between Anthropic’s support for Cursor now and its treatment of Windsurf last year, suggesting the latter had been harsher than OpenAI’s decision to cut Cursor off.“More likely answer is that you can’t do that here because you need the compute.”“Maybe you changed your ways, but we all remember what you did to Windsurf, which was infinitely nastier,” Masad writes. “More likely answer is that you can’t do that here because you need the compute.”Orosz essentially makes the same argument. If Anthropic was prepared to cut access when Windsurf merely looked likely to end up in OpenAI’s hands, why is it publicly promising MORE Claude capacity to Cursor after the company had actually been acquired by SpaceX?“SpaceX basically in this enviable position where one of its biggest competitors depends on its compute infra!”“Either SpaceX and Grok are not competitors to Anthropic (they are!); or, more likely, SpaceX leasing its Colossus 1 data center is more important to Anthropic than to stop offering Claude to SpaceX,” Orosz writes. “SpaceX basically in this enviable position where one of its biggest competitors depends on its compute infra!”And so this effectively highlights how strong a position SpaceX finds itself in. It now owns xAI and Cursor, putting it in direct competition with Anthropic in foundation models through Grok and in AI coding tools through Cursor, while Anthropic is simultaneously paying it billions of dollars for compute capacity supporting Claude. Whatever the stated rationale for treating Cursor as a “trusted partner,” that relationship leaves SpaceX with something neither Windsurf nor xAI had at the time Anthropic moved against them: a source of leverage over any decision on whether or not to cut access to Claude.The post SpaceX is in an “enviable position”: why Anthropic is sticking with Cursor as OpenAI cuts access appeared first on The New Stack.