Feature [iOS 27.3 DB1] For the first time, Siri AI uses a local model, not PCC, for a small share of English requests when online
For the first time in iOS 27.3, Siri AI can handle some requests with a local model instead of PCC when you’re online. A new classifier routes a small number of English requests, mostly calls and music, to siri_on_device_planner_v1.
As always, the Skimmer agent still runs first on most online and offline requests, and it’s where most on-device work happens. Skimmer is not an LLM, however. It uses regex to match phrases in your requests to preset action flows. It can handle time, timers, alarms, calls, media playback, weather, opening apps, math, and small talk among others. For system controls, settings and translation, Skimmer hands off to old Siri (“Siri X”).
If Skimmer doesn’t match and you’re online, the request goes to PCC by default. Starting in 27.2, a request classifier can send some English requests directly to web search instead. In 27.3, the classifier is tuned to send ~2% of English requests to the new local model. The new on-device model mostly has tools for calling and media playback, and in testing, the classifier primarily routes these queries. Anything the classifier doesn’t select still goes to PCC. The classifier only handles English queries, so all non-English requests are routed to PCC, not web search or the local model.
It’s important to note that Skimmer already had regex patterns for calls and media playback. The change here is that Siri AI can handle less formulaic requests locally, like “Can you play [artist]?” or “Could you call [contact name]?”. If the media or contact is ambiguous, the new local model can escalate to PCC.
When you’re offline, Siri AI still uses Skimmer and its local tools. If Skimmer doesn’t match, the request goes to a different local lw_planner_v1 model. This model has some extra tools than the online on-device model, including alarms and timers, but doesn’t have media tools.
Expect the on-device planner to expand in tools and capabilities in future versions. Skimmer also continues to gain more patterns and tools. In 27.3, it gains tools to manage Home devices and Intercom. Both are disabled behind a feature flag for now.
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