ZipStream-PHP is a PHP library for dynamically streaming ZIP archives directly to the client or any output stream without writing to disk on the server. It provides a clean API via the `ZipStream` class, which accepts files as strings, paths, streams, PSR-7 streams, or callbacks. The library supports DEFLATE and STORE compression, ZIP64 extensions for large archives, zero-header mode for streaming efficiency, and simulation modes to calculate output size without generating the archive. The architecture is monolithic but well-modularized: the main ZipStream orchestrates file entries, each handled by an internal `File` class, and binary data packing is abstracted through `PackField`. External dependencies are minimal (ext-mbstring, ext-zlib, optional PSR-7 packages), making it lightweight and easy to integrate. The codebase demonstrates strong engineering with comprehensive unit tests, static analysis (Psalm level 1), coding style enforcement, and CI/CD pipelines covering multiple PHP versions and OS platforms. Notable design choices include the use of PHP stream wrappers for custom output (CallbackStreamWrapper) and a simulation mode that enables accurate content-length headers without reading entire streams. Exception classes are well-defined, and the entire public API is fully documented with attributes and inline PHPDoc. The project is actively maintained with frequent commits, up-to-date dependency management, and a clear versioning and support policy.