OpenAI is so frustrated with Apple over a ChatGPT integration that failed to deliver the subscribers and prominence it expected that the company is now actively exploring legal action against the iPhone maker, Bloomberg News reported Thursday , citing people familiar with the matter.

According to Bloomberg, OpenAI has enlisted an outside law firm to work through its options, which could include sending Apple a formal breach-of-contract notice without necessarily escalating to a full lawsuit (at least not immediately). Any legal move would likely wait until after the conclusion of OpenAI’s ongoing trial with Elon Musk.

Still, it’s a reminder of what a difficult partner Apple can be for major software companies. The iPhone is an enormously attractive platform for growth, but it’s fully under Apple’s control — and companies that build there are only guests.…