A public systems-software engineering repository organised into ten tracks — modern C++, data structures and algorithms, computer architecture, Linux/POSIX internals, operating systems, embedded systems, real-time systems, backend and network systems, high-performance computing and systems security. Implementations include a toy ARM kernel in modern C++, a POSIX shell built from scratch, low-level process/IPC primitives and core data structures, with every project benchmarked and documented.