XState is a production-grade TypeScript library for creating, interpreting, and executing finite state machines and statecharts, based on the SCXML standard and the actor model. The repository is a monorepo (pnpm workspaces) containing the core `xstate` package, the lighter `@xstate/store` for event-sourced state management, and framework-specific bindings for React, Vue, Svelte, Solid, Preact, and Angular. It also includes `xstate-inspect` for debugging, `xstate-immer` for Immer integration, a graph analysis module for model-based testing, and many example applications and templates. The core engine provides `createMachine`, `createActor`, `setup()` for type-safe machine definitions, built-in actions (assign, sendTo, raise, etc.), guard combinators, and actor logic factories (`fromPromise`, `fromCallback`, `fromObservable`). The store sub-package offers atoms, source atoms, and composable extensions like persist and undo/redo. The codebase demonstrates high craftsmanship with extensive TypeScript type inference, well-encapsulated modules, and comprehensive test coverage. It is actively maintained with continuous CI/CD and version management via changesets.
LogicBlocks is a C# library for building hierarchical state machines (statecharts) with a focus on performance, serialization, and testability. It provides a `LogicBlock` base class that manages state transitions via input handlers (`IGet<TInput>`), supports pushdown automaton history, async task integration, and observable bindings. The library includes an `AutoBlock` extension for automatic state preallocation and serialization using Chickensoft's introspection and serialization frameworks, and a Roslyn source generator (`DiagramGenerator`) that produces PlantUML state diagrams from annotated state classes. The codebase is well-structured with extensive unit tests, clean separation of concerns, and a fluent API for bindings. It is designed for AOT environments and game development (Godot). The repository also contains a tutorial and a vending machine example.