BLE and a complete BLE Mesh stack, in pure Kern, verified on hardware

Kern reaches the device tier without a C dependency. sys.hci drives a Bluetooth controller over HCI_CHANNEL_USER, claiming the adapter exclusively the way a from-scratch host stack does, which is what mesh needs because it wants precise control of scanning and advertising rather than sharing with the kernel. It is verified against a real controller: hci_local_version returned HCI 5.2 and matched hciconfig exactly, revision included. sys.ble adds active LE scanning (parsing advertising reports into address, RSSI, flags, local name, manufacturer data and service UUIDs, deduplicated and merged with scan responses) and the advertising bearer that mesh provisioning rides on.

On top of that the BLE Mesh stack is complete: network layer with obfuscation, AES-CCM, replay protection, IV index, segmentation and relay; the access layer and a Generic OnOff model for real device messages; Secure Network Beacon; commissioning, revocation and configuration; Heartbeat publication and subscription for topology discovery; Friendship, so a Low Power Node can sleep while a Friend queues its messages; and the Proxy protocol with PDUs and SAR.

Provisioning is P-256 ECDH written from scratch in Kern, deliberately on 16-bit limbs rather than 32, because Kern integer arithmetic is overflow-checked and traps, so a 32×32 limb product would abort. It is verified against authority rather than itself: point doubling matches the standard vector in both coordinates, a derived public key matches one generated by OpenSSL, and the shared secret matches openssl pkeyutl -derive. Scalar multiplication is constant-time, which closes the provisioning timing side channel, and an invalid-curve hole found during the work was fixed.

The whole stack is pure Kern over the unsafe systems tier, no new C, TCB unchanged. Alongside it, sys.bluetooth gained a real RFCOMM implementation and sys.wifi stopped being a stub, which together retire the last stubs in the standard library.