This year’s watchOS 27 update to focus on stability, performance; one ‘ambitious’ project delayed

Apple’s upcoming watchOS 27 operating system will prioritise under the hood refinements over new tools and features, according to a new report detailing the company’s wearable strategy. Writing in his weekly Power On newsletter, Bloomberg’s Mark Gurman revealed that this year’s Apple Watch software refresh will focus largely on system stability, performance optimisation and smaller user-interface tweaks, rather than introducing a massive suite of new capabilities.

However, users can still look forward to a significant baseline upgrade: a major overhaul to the Apple Watch’s core heart-rate tracking system, Gurman said.

More accurate heart-rate tracking

While the report did not provide the exact technical details of the upgrade, the hardware improvements are expected to significantly boost how the Apple Watch collects biometric data. While Apple’s optical sensors are highly accurate, some have pointed out that competing dedicated fitness trackers like WHOOP often feel more precise because they refresh data at a more consistent, rapid frequency. The upcoming update aims to narrow this gap, providing users with more granular, real-time insights into their cardiovascular health throughout the day.

These tracking enhancements are also expected to serve as a critical foundation for Apple's long-term digital health strategy.

Project Mulberry may be delayed

The focus on stability for watchOS 27 comes as Apple grapples with severe delays to its one of the most ambitious health project in years.

Dubbed “Project Mulberry,” the internal initiative is an advanced, AI-powered health coaching service. The system is being built to act as a deeply integrated personal AI agent that can analyse a user’s lifelong Apple Health data to provide custom lifestyle pointers.

In its initial design, users would even be able to stream a live camera feed to the AI coach, allowing the software to analyse their physical posture and offer real-time athletic adjustments during workouts.

The service was originally slated to debut alongside a completely redesigned Health app during the iOS 26 software cycle. However, the project faced a massive shakeup after Eddy Cue, Apple's Senior Vice President of Services, officially took control of the company's dedicated health group.

Following the leadership transition, the scope of Project Mulberry was heavily scaled back. Gurman reports that features from the ambitious AI endeavor have now been officially pushed out of the initial fall launch window.

“I don’t expect features from that endeavor to launch until later in the iOS 27 update cycle,” Gurman claims.

The decision to delay the AI coach was reportedly driven by tight competition as leadership reportedly felt the software’s initial iterations simply weren’t polished or unique enough to successfully compete against established premium health and fitness subscription platforms already dominating the App Store.