Procursus is a specialized build system and package repository infrastructure designed to compile open-source software into Debian packages (.deb) for Apple platforms (iOS, macOS, tvOS, watchOS). It functions as a cross-compilation environment, orchestrating the fetching, patching, compilation, signing, and packaging of hundreds of packages using a monolithic Makefile-based architecture. The system is primarily used by the jailbreak and iOS development communities to provide a Debian-like package management experience on non-Linux Apple operating systems. The architecture relies heavily on custom build macros, platform-specific patches, and Apple SDK integration. Key entry points include the central Makefile for orchestration, build_tools/ for helper scripts, and makefiles/*.mk for individual package definitions. The system manages complex dependency chains and security entitlements required for iOS/macOS compatibility. While it solves a difficult cross-platform packaging problem, the codebase is tightly coupled to Apple's internal APIs and SDK versions, requiring constant maintenance to keep pace with OS updates.