macOS 26.4 Beta appears to have changed how built-in MacBook keyboard events are routed through IOHIDSystem. Third-party virtual HID devices loaded via DriverKit no longer receive events from the built-in keyboard. External keyboards are unaffected. This is already confirmed across multiple users: https://github.com/pqrs-org/Karabiner-Elements/issues/4402 One possible lead (from LLM-assisted code analysis, not independently verified): this could be related to a security policy referred to as com.apple.iohid.protectedDeviceAccess, which may block IOHIDDeviceOpen for the Apple Internal Keyboard via SPI transport (AppleHIDTransportHIDDevice). A GamePolicy check in IOHIDDeviceClass.m that gates HID device access could be involved. This is a hint, not a confirmed root cause. The impact goes well beyond a single project. Keyboard remapping on macOS is a thriving ecosystem — used for accessibility, ergonomics, developer productivity, and multilingual input. This is one of macOS's strengths as a platform. Many professionals
Topic:
App & System Services
SubTopic:
Core OS
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