macOS 27 Shipped the Code to Swap Siri's Brain for Claude
Security researcher pdfu went through the private frameworks in iOS 27 and the macOS 27 Golden Gate release candidate and found two mechanisms that Apple has not announced. MacRumors wrote it up on September 14 at https://www.macrumors.com/2026/09/14/siri-can-be-swapped-out-for-chatgpt-claude/, the same day Golden Gate shipped, and it did 214 points on Hacker News.
The first mechanism is Model Delegation, which lets Claude or another service run as a Siri extension alongside ChatGPT, surfaced to users through an "Ask..." contextual menu. That is roughly what everyone expected. The second is the interesting one: an Inference Provider Protocol inside Model Manager Services that allows Apple's server-side Siri model to be replaced entirely by something like GPT-5.6. The replacement model receives Siri's native planner prompts and its tool definitions, and executes system actions through them.
Sit with what that second one means. Apple built a planner, wrote the tool schemas for the operating system, and then built a socket where a competitor's model can be dropped in behind that planner and drive the device. The assistant stops being a product and becomes an interface with a swappable engine. Whoever's model is in the socket gets the planner prompts, the tool definitions, access to system features and to personal data, and the output comes back wearing Siri's face. This is the shape the agent layer takes when the platform owner decides it cannot win the model race and would rather own the schema.
The likely reason is regulatory. The EU's Digital Markets Act requires Apple to give third parties effective access to iOS and macOS features, and an inference provider protocol is a clean way to satisfy that for the assistant surface without opening everything else. Which is worth noting for what it implies: the most consequential piece of agent plumbing shipped this month may exist because a regulator made it necessary, not because a product team wanted it.
None of this is live. Claude is not in the release candidate, and only ChatGPT currently has the "Ask..." path enabled. Code in a shipping RC is a much stronger signal than a rumor and a much weaker one than an announcement β Apple ships dormant frameworks that never turn on. But the tool definitions are the real asset here, and they are now written down in a form another lab's model can consume. Watch for whether Apple ever publishes them.
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The first mechanism is Model Delegation, which lets Claude or another service run as a Siri extension alongside ChatGPT, surfaced to users through an "Ask..." contextual menu. That is roughly what everyone expected. The second is the interesting one: an Inference Provider Protocol inside Model Manager Services that allows Apple's server-side Siri model to be replaced entirely by something like GPT-5.6. The replacement model receives Siri's native planner prompts and its tool definitions, and executes system actions through them.
Sit with what that second one means. Apple built a planner, wrote the tool schemas for the operating system, and then built a socket where a competitor's model can be dropped in behind that planner and drive the device. The assistant stops being a product and becomes an interface with a swappable engine. Whoever's model is in the socket gets the planner prompts, the tool definitions, access to system features and to personal data, and the output comes back wearing Siri's face. This is the shape the agent layer takes when the platform owner decides it cannot win the model race and would rather own the schema.
The likely reason is regulatory. The EU's Digital Markets Act requires Apple to give third parties effective access to iOS and macOS features, and an inference provider protocol is a clean way to satisfy that for the assistant surface without opening everything else. Which is worth noting for what it implies: the most consequential piece of agent plumbing shipped this month may exist because a regulator made it necessary, not because a product team wanted it.
None of this is live. Claude is not in the release candidate, and only ChatGPT currently has the "Ask..." path enabled. Code in a shipping RC is a much stronger signal than a rumor and a much weaker one than an announcement β Apple ships dormant frameworks that never turn on. But the tool definitions are the real asset here, and they are now written down in a form another lab's model can consume. Watch for whether Apple ever publishes them.
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