This repository is the core library for @ngx-translate/core, a mature and widely-used internationalization (i18n) solution for Angular applications. It provides a comprehensive set of tools including a translation service, pipe, directive, and structural directive, all built on Angular's dependency injection and signal-based reactivity. The architecture follows a plugin pattern with injectable abstractions for loaders, compilers, parsers, and missing translation handlers, allowing users to customize behavior. Key features include hierarchical scoping (parent-child fallback and isolated subtrees), support for multiple translation loaders (including an HTTP loader in a companion package), and a signal-based `translate()` function that reactively updates when keys, parameters, or languages change. The library is thoroughly tested with over 30 spec files and maintains compatibility across Angular 16–21 via a compatibility matrix. The codebase demonstrates strong engineering practices: clean separation of concerns, well-defined interfaces, and extensive use of Angular's provider functions for configuration. While the library is feature-rich and production-ready, it carries some legacy patterns (deprecated content-as-key directive) and a large monolithic test file that could benefit from refactoring.