Another Partnership Quietly Begins on September 14th
On September 14th, the same day iOS 27 was released, Apple unveiled a beta version of its revamped assistant, "Siri AI." Behind the flashy keynote, a much bigger story was unfolding. The brain of Siri AI isn't an Apple-developed model, but rather Google's "Gemini." The two companies announced a multi-year agreement in January, but this is the first time the feature has actually reached users. As an engineer, following the details of this partnership reveals a design philosophy that goes beyond simply "adopting another company's model."
What is Siri AI?
Siri AI is a conversational assistant that understands personal contexts such as messages, emails, and photos, and can answer questions about what's displayed on the screen. It's also available as a standalone app and can handle cross-app operations (such as drafting emails or editing and sharing multiple photos). The English beta will be released first, with French, Japanese, Korean, Portuguese, and Spanish versions to be added in October or later. Supported devices are broad, starting with the iPhone 15 Pro, and will also be rolled out to iPad, Mac, Apple Watch, and Vision Pro.
Google's Gemini is running behind the scenes
This is the most important point I want to emphasize. According to multiple reports, the core of Siri AI is a 1.2 trillion parameter Gemini model customized by Google for Apple, running on Google Cloud via Apple's "Private Cloud Compute" privacy-protected infrastructure. Thomas Klein, head of Google Cloud, reportedly described his company as "the preferred cloud provider for Apple's next-generation AI model" at the Google Cloud Next 2026 conference. While users won't see any Google branding, some analysts suggest that the complex queries are actually being handled by Gemini running on NVIDIA's Blackwell B200 chip.
Why Apple Abandoned Its Own Model
Apple had been developing its own cloud model for many years, but according to reports, its scale remained at around 150 billion parameters, nearly eight times smaller than Google's customized model with 1.2 trillion parameters. Analysis suggests that attempting to run a frontier-level model on its own Private Cloud Compute would not meet Siri's required response speed. Acknowledging that they were "two years behind in developing their own" and deciding to continue in-house development while borrowing a frontier model is a rational choice for an engineering organization. In fact, the contract has a non-exclusive structure, and it reportedly includes "Any Model" extensibility, allowing other AI models to be integrated into Siri via the App Store in the future.
The Architecture's Inner Workings—Where Does "Apple" End and End?
What's technically interesting is how the lines of responsibility are drawn. Apple completely controls Siri's visual design, voice, and user experience, while Gemini functions solely as the inference engine. Apple's design is believed to process lightweight tasks on its own devices and Private Cloud Compute, routing only queries requiring heavier inference to Google. Gemini's Mixture-of-Experts architecture, which only invokes a small portion of the entire model for each query, is one reason why frontier-level models can be rented at a realistic cost.
How to interpret the 100 billion yen annual figure
According to Bloomberg, the contract is worth approximately $1 billion annually (about 150 billion yen), and analyst Gene Munster estimates the total multi-year contract could reach up to $5 billion. For comparison, Apple pays Google $20 billion annually for Safari's default search engine, making this Gemini contract about one-twentieth of that amount. However, this is an "initial price," and as with the search contract, the amount could easily increase as the integration deepens.
The Shadow of Antitrust Laws
A regulatory risk cannot be overlooked. Some analysts suggest that the partnership between Google and Apple, who already hold a $20 billion default search contract, and Apple's further deepening ties in the AI field could be mentioned in the U.S. Department of Justice's antitrust lawsuit against Google. The extent to which regulators will overlook the increasing commercial ties between the two companies will likely be a key focus going forward.
What Engineers Should Watch
The architecture of Siri AI serves as a valuable example for designing how to integrate other companies' frontier models into one's own products. It clearly separates the user experience layer from the model layer, maintains its own infrastructure for privacy protection (Private Cloud Compute), and outsources the inference itself. This "borrowing while self-sufficient" design philosophy is insightful for many companies that do not have their own frontier models. We should keep a close eye on the multilingual rollout after October and how concrete the Any Model concept becomes.