This is the Rust userland library for Tock OS, providing safe abstractions over Tock syscalls (command, subscribe, allow) and a comprehensive set of driver APIs for peripherals such as GPIO, I2C, SPI, console, sensors, display, and networking. It includes a runtime with startup code for ARM, RISC-V, and x86 processes, a build system for generating Tock Binary Format (TBF) and TAB archives, and a full unit-testing framework with a fake kernel and fake drivers that enable testing Tock applications on a host machine. The architecture is trait-based, with drivers generic over a `Syscalls` implementation, allowing compile-time dependency injection for testing. This repo is not a standalone application but a library and framework for building Tock processes. It demonstrates high craftsmanship in its safe resource management patterns (e.g., `share::scope` for scoped buffer allocation) and includes a standalone micro-formatting crate (`ufmt`) that is 6-40x smaller than `core::fmt`.