Apple's 37th Worldwide Developers Conference keynote — the last that Tim Cook will deliver as chief executive — opened Monday at Apple Park in Cupertino, unveiling a ground-up rebuild of Siri powered by Google's Gemini AI, a developer preview of homeOS, and the first betas of six operating systems. Cook, who announced in April that he will hand the chief executive role to hardware engineering chief John Ternus on September 1, framed the event as a reckoning with a two-year gap between promise and delivery on artificial intelligence.

The keynote arrived weeks after Apple agreed to a $250 million settlement with iPhone buyers who argued the company had advertised Siri features on the iPhone 16 that never shipped. The settlement received preliminary court approval on May 5, and a full approval hearing is scheduled for June 17. Apple denied wrongdoing, saying it resolved the matter "to stay focused on doing what we do best."

Siri Rebuilt From Scratch on a Trillion-Parameter Foundation

The headline announcement from the keynote is a complete overhaul of Siri built on a custom Gemini model that Apple and Google confirmed in January under a multi-year licensing deal reported by Bloomberg's Mark Gurman at roughly $1 billion a year. The rebuilt assistant arrives as a standalone app on iPhone, iPad, and Mac, surfaces inside the Dynamic Island with a "Search or Ask" prompt and a glowing cursor, and supports multi-step commands, persistent conversation history synced across devices via iCloud, and the ability to attach images and documents directly.

The new Siri can compose emails, retrieve nutritional data from food labels using the Camera app, and — when third-party AI apps are installed — hand questions off to services such as Claude or ChatGPT. iOS 27, iPadOS 27, and macOS 27 will also allow users to designate a third-party AI service as the default provider for Apple Intelligence features including Writing Tools and Image Playground, a meaningful opening of an ecosystem that has historically been tightly closed.

How Gemini-Powered Siri Routes Queries Across Three Tiers

The technical architecture behind the rebuilt Siri is a three-tier routing system that determines where each query is processed based on its complexity.

Simple requests — setting timers, playing music, controlling smart home devices — stay entirely on the device, handled by Apple's own smaller neural models with no data leaving the iPhone. Moderately complex requests escalate to Apple's Private Cloud Compute servers, which run on custom Apple Silicon hardware in sealed server nodes with stateless, ephemeral computation. This means user data is processed without being stored or accessible even to Apple staff.

The most demanding reasoning tasks travel further. According to a June 3 report from The Information, Apple found that running a trillion-parameter model inside Private Cloud Compute was too slow to be usable at the scale Siri requires. The heaviest queries will instead route to Google Cloud, where they run on Nvidia's Blackwell B200 graphics processors — hardware purpose-built for trillion-parameter inference. Apple acts as a privacy proxy at each transition: queries are anonymized, stripped of Apple ID linkage, and tokenized before reaching Google's infrastructure. Google is contractually barred from using these query streams to train future models.

The custom Gemini model at the top of this stack uses a mixture-of-experts architecture, which activates only a relevant subset of its 1.2 trillion total parameters for any given query. That design is why the arrangement is economically viable at scale: Apple gains the knowledge capacity of a frontier-tier model while paying inference costs closer to those of a much smaller system. The custom model is approximately eight times larger than the 150-billion-parameter models Apple had built in-house for cloud processing, and it was developed specifically for Apple's use case — users will see no Google branding anywhere in the experience.

What the Privacy Architecture Does and Does Not Guarantee

Apple and Google issued a joint statement in January stating that Apple Intelligence will "continue to run on Apple devices and Private Cloud Compute, while maintaining Apple's industry-leading privacy standards." Tim Cook reinforced this on the company's fiscal first-quarter 2026 earnings call: "We're not changing our privacy rules."

Security researchers and antitrust experts have raised more specific concerns. Nakash, chief executive of Ciphero, argued that Private Cloud Compute is "only as private as the weakest link," and that if Google retains any path to usage data for model improvement or debugging, "the privacy guarantee fundamentally breaks down." Apple published a technical white paper alongside the January announcement detailing the cryptographic protocols used to isolate query data, and has opened portions of Private Cloud Compute to independent researcher examination.

A separate concern involves the intersection of the Gemini deal with the ongoing Department of Justice antitrust appeal against Google. A federal court found in 2024 that Google had illegally maintained a search monopoly in part through exclusive default agreements with Apple. The remedies order explicitly prohibits Google from entering exclusive contracts for Gemini app distribution. Antitrust professor Rebecca Haw Allensworth of Vanderbilt University has argued the Gemini-Siri deal "essentially creates a second exclusive pipeline" that raises the same structural concerns. No enforcement action against the Gemini-Siri arrangement has been filed as of publication.

homeOS Developer Preview Gives Smart Home Developers a Head Start

For developers in the smart home and IoT space, Monday's keynote delivered a formal developer preview of homeOS — a new operating system purpose-built for Apple's upcoming smart home hardware lineup.

The HomePad, Apple's rumored hub combining a HomePod speaker with a 7-inch display and an A18 chip, is not shipping today. Apple is deliberately releasing the software platform ahead of the hardware, giving developers time to build and update apps before the HomePad's anticipated autumn launch alongside an updated HomePod mini and a refreshed Apple TV 4K. The device is described as capable of running FaceTime without requiring an iPhone — a meaningful change in how Apple positions home hardware in its ecosystem — and is expected to anchor a broader connected home strategy that also includes a new HomeKit security camera featuring Face ID.

Expanded HomeKit and Matter APIs are part of today's developer release, with particular attention paid to stability issues that arose after last year's HomeKit architecture migration broke a number of third-party integrations. Developers building Matter-compatible accessories will find new documentation directly relevant to those concerns. tvOS 27 also received smart home integration updates intended to work alongside the HomePad as a household hub.

What Changed in iOS 27 and the Rest of Apple's OS Family

Apple seeded developer betas for six operating systems immediately after the keynote: iOS 27, iPadOS 27, macOS 27, watchOS 27, tvOS 27, and visionOS 27. Public betas are expected in July, with full releases in September alongside the iPhone 18 lineup.

macOS 27 carries a "slight redesign" building on last year's Liquid Glass visual overhaul, according to Bloomberg's Mark Gurman, addressing shadows and transparency issues that drew criticism from Mac users. iOS 27 users should note that the iPhone 11 family loses eligibility, meaning owners of those devices will remain on iOS 26. visionOS 27 is light on new features but will receive the Siri and Apple Intelligence updates rolling out across the ecosystem.

The new Siri is expected to arrive as a gated beta when iOS 27 reaches public release in September, with some features rolling out gradually rather than on the first day of availability.

Cook's Last Keynote: AI Delivery After Two Years of Promises

Cook first promised a context-aware, personally intelligent Siri at WWDC 2024, and then failed to ship those features for nearly two years. A class action lawsuit followed, alleging that advertising for the iPhone 15 Pro and the entire iPhone 16 lineup had overpromised capabilities that were not yet functional when customers purchased those devices. The $250 million settlement Apple reached in May — covering eligible purchases made between June 10, 2024, and March 29, 2025 — means the Gemini-powered Siri keynote demo represents the first functional delivery of what Apple sold two years ago.

Internal leadership meetings at Apple, reported by Bloomberg, pushed the company toward a more aggressive AI posture after executives grew concerned the iPhone maker was falling behind OpenAI, Google, Anthropic, and Meta. The Gemini deal is the most visible result. For the roughly 1.5 billion active Apple device users, the September rollout will be the practical test of whether that reckoning produced a Siri worth the wait — and whether the three-tier routing architecture can deliver sub-second response times at the scale the iPhone install base demands.

Frequently Asked Questions

What did Apple announce at WWDC 2026?

Apple unveiled a rebuilt Siri powered by a custom 1.2-trillion-parameter Google Gemini model, a developer preview of homeOS for upcoming smart home hardware, and developer betas for six operating systems — iOS 27, iPadOS 27, macOS 27, watchOS 27, tvOS 27, and visionOS 27. The keynote was also Tim Cook's final as chief executive before he transitions to executive chairman on September 1.

How does Gemini-powered Siri work?

Siri now uses a three-tier routing system. Simple tasks stay on the device using Apple's own models. Moderately complex requests go to Apple's Private Cloud Compute servers. The heaviest reasoning tasks route to Google Cloud, running on Nvidia Blackwell B200 GPUs. At each step, Apple anonymizes and tokenizes queries so neither Apple staff nor Google can link requests to individual users.

What is homeOS?

homeOS is a new operating system Apple previewed at WWDC 2026 for its upcoming HomePad smart home hub — a device combining a HomePod speaker with a 7-inch display and an A18 chip. The HomePad hardware is not shipping yet; Apple released the software developer preview first so app developers can build and update their apps ahead of the HomePad's expected autumn 2026 launch.

When will the new Siri be available on iPhone?

The rebuilt Gemini-powered Siri is expected to arrive as a gated beta when iOS 27 reaches public release in September 2026, alongside the iPhone 18 lineup. Some features will roll out gradually rather than on the first day of availability. Developer betas are available now through the Apple Developer Program.