Apple is expected to unveil the Apple Watch Ultra 4 and Apple Watch Series 12 tomorrow, and a late-breaking code discovery is shedding light on key features arriving with watchOS 27. The data points to four distinct areas of improvement: a dedicated Readiness app, more comprehensive strength training metrics, a new optical-sensing architecture, and a significant upgrade to internal storage.
Leaked code is often fragmentary, but when it comes from Apple’s own software development builds, it can reveal deliberate engineering intent before a live announcement. The details appear credible enough to offer a clear preview of the company’s next wearable hardware and software direction.
Readiness app set to join the Home Screen
One of the most notable discoveries is the existence of a new app simply named “Readiness.” Code in the watchOS 27 launcher reportedly places the Readiness app in the default Home Screen layout, directly after the Workout app. The Watch companion app on iOS 27 also references the Readiness app in its implementation for arranging apps, which indicates that the feature is designed to be a fully integrated part of the wearable experience, not just a hidden diagnostic tool.
No detailed user interface or onboarding text has been found, but the app’s name and location alongside Workout strongly suggest a function similar to the readiness scores popularized by Oura, Whoop, and Garmin. These platforms combine data such as resting heart rate, heart rate variability, sleep quality, and recent activity trends to give users a single score that reflects physical recovery and strain tolerance.
For years, Apple Watch has been incrementally building out health monitoring features, including sleep stages, heart rate alerts, and the Vitals app introduced in a previous watchOS release. Readiness appears to be a natural extension of that ecosystem, aiming to synthesize data into an actionable daily recommendation.
Update: Bloomberg’s Mark Gurman has weighed in, saying that Apple is expected to announce the Readiness app as a variant of the Vitals app. According to Gurman, the goal is to better compete with software from Whoop and Oura. The Vitals app already tracks overnight metrics such as heart rate, respiratory rate, wrist temperature, and sleep duration. A Readiness digest built on those same signals would give users a more holistic interpretation of whether they should push hard, take in extra recovery, or adjust their sleep schedule.
Strength workouts get a major upgrade
The second key finding revolves around strength training. Current watchOS allows users to start a traditional strength workout, but it mostly records heart rate, active calories, and duration. The new code suggests a complete reimagining of that experience, one that will transform Apple Watch into a far more valuable tool for lifters and athletes.
Evidence from the watchOS 27 code points to a system capable of describing individual sets and storing repetition counts, weight, equipment, body side, and duration for each set. That’s a level of specificity that rival strength training apps have offered for years, but Apple has been hesitant to implement natively, likely due to interface constraints and the difficulty of parsing manual input on a small screen.
If this new implementation ships as expected, users will be able to open the Workout app and select Strength Training, then begin a set-by-set log. They could potentially enter the load used, record how many reps were completed, note which side of the body performed the movement, and track rest periods. The data could then be consolidated in the Fitness app, where long-term progress can be charted alongside cardio, daily movement, and recovery markers.
Such a feature also aligns with Apple’s broader push into more athletic territory. CrossFit style workouts, Olympic lifting, and hypertrophy programs require detailed tracking for progression. Many serious athletes have turned to third-party platforms such as Strong, Hevy, or Fitbod, which integrate with Apple Health but are not built into watchOS. Offering this natively removes friction and makes the platform more compelling to a demographic that might otherwise choose a dedicated fitness wearable.
New optical sensor system
Another finding relates to a new optical-sensing system for the Apple Watch. The code documentation mentions an upgraded optical module, corroborating prior rumors that Apple Watch Ultra 4 and perhaps the Series 12 will include substantial internal changes. Optical sensors on Apple Watch have historically been used for heart rate measurement, oxygen saturation monitoring, and more recently for wrist temperature detection.
A new optical sensing system could improve the accuracy and responsiveness of photoplethysmography, the technique that uses light to measure blood flow. That would benefit many features, including heart rate zones during intense exercise, heart rate variability measurements used for readiness, and irregular rhythm notifications. With greater sensitivity, the watch could also potentially identify subtle health changes more quickly, which matters for people using the device as an early warning system.
Gurman’s comments about a “revamped heart rate sensing” align with this code discovery. Combined, they suggest Apple may be overhauling the way the watch reads pulse signals, possibly improving performance when the watch is loose, when the wearer is moving, or when workouts create vibration artifacts. Other wearables have introduced multi-LED arrays and higher frequency sampling to handle such conditions. Apple’s next generation may leverage an updated approach that extracts more accurate data from a wider range of skin tones, body sizes, and exercise intensities.
There is also the possibility that the new optical sensor prepares the watch for future non-invasive health monitoring, such as blood pressure or glucose tracking. Neither feature is believed to be ready for launch in this generation, but a more advanced optical foundation could be a prerequisite. For now, expect incremental improvements to existing metrics rather than a dramatic new sensor suite.
128GB storage on the next Apple Watch
The final major hint is the availability of 128GB of internal storage on Apple’s next-generation S-class chip. Previous Apple Watch models have carried considerably less capacity. The current S9 chip, for instance, is paired with 64GB of storage, and earlier models had significantly less. A jump to 128GB would double the available space, giving users more room for apps, music, podcasts, and other offline content.
On first glance, 128GB may seem excessive for a device that is designed to be a companion to the iPhone. But several factors made larger storage increasingly practical. Apple Music, Apple Podcasts, Audiobooks, and third-party media apps allow users to sync substantial libraries to the Watch for offline listening, and high-resolution audio files take up significant space. Furthermore, watchOS itself has grown heavier with each release, and Apple’s need to accommodate complex health measurements, workout routes, and new sensor data adds to the system footprint.
There are also camera-related possibilities. If the Ultra ever gains a camera for video calling, or if developers continue to create apps that leverage recorded video for form feedback, extra storage will be valuable. Even without such innovations, a 128GB chip may be a necessity for future watchOS feature expansions rather than a marketing point.
The S-class silicon inside the next Watch models will likely also improve performance and power efficiency. The move to 128GB indicates that the storage controller inside the system-on-chip has been redesigned, which often accompanies a move to newer fabrication processes. That could bring faster app launch times, smoother animations, and enhanced machine learning on device, all while maintaining or improving battery life.
Older models and watchOS 27 availability
Not every one of these advancements will be available to older Apple Watch generations. Hardware features such as the new optical-sensing system and the 128GB chip are tied to the next Watch models, which means Series 12 and Ultra 4 buyers will be the first to benefit. The strength workout improvements may rely on the updated processor, but they could also be delivered through software, perhaps to Apple Watch Series 9 and later.
The Readiness app is a more complex question. Many of the underlying metrics required for a readiness score are available on current models, including the Vitals app data. If Readiness is indeed a variant or a progressive interface layer over Vitals, it could be backwards compatible with watches that support watchOS 27. However, Apple has a history of reserving some health-oriented features for the latest hardware. The company may argue that the new optical sensor provides the accuracy needed to power Readiness, which would push this function to the newest models only. At this time, no official compatibility statement exists, but users of Apple Watch Series 9 and Ultra 2 will be watching closely.
The upcoming announcement is likely to clarify these details. According to the report, Apple will unveil the new watches this week, and the release notes of watchOS 27 will then finalize which devices get which experience. A feature that launches with the new models can sometimes be extended to older devices after developer feedback, but if the underlying hardware is truly required, backward compatibility will not be possible.
Apple appears to be responding to competitive pressure from both specialized fitness wearables and smartwatches running full health ecosystems. The Readiness app and expanded strength tracking directly challenge Oura and Whoop, which have made recovery and strain their primary selling points. Meanwhile, advanced optical sensing could narrow the gap on Garmin’s highly accurate workout metrics. Combined with 128GB storage and a new chip, the changes suggest Apple wants to turn the Watch from an everyday health companion to a professional-grade fitness instrument.
The final gaps in this puzzle will presumably be filled moments after the stage event concludes. For now, these four code-based findings offer an unusually detailed look at a major watchOS update. Whether you are a casual user who wants a simple wake-up alert or an elite athlete looking for set-by-set logging and deep recovery data, the next generation of Apple Watch is poised to deliver a meaningfully richer experience.
Source: 9to5Mac News