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• Railway-oriented programming pattern for Dart: Core abstractions for building strongly-typed, declarative workflows in application-layer orchestration.
  • Railway<C, E>: Immutable builder for composing guards and steps into a type-safe workflow pipeline
  • RailwayGuard<C, E>: Interface for read-only validation operations that return Either<E, void>
  • RailwayStep<C, E>: Interface for state mutation operations that return Either<E, C>
  • Automatic short-circuiting on first error with Either-based result propagation
  • Single unified error type per railway (compile-time enforced, no runtime casting)
  • Sequential asynchronous execution with deterministic operation ordering
• Immutable builder pattern: Each guard() and step() call returns a new Railway instance, enabling safe reuse and composition
• Transaction-agnostic execution: Railways remain infrastructure-only with no built-in transaction management
• Comprehensive documentation: README with usage examples, error mapping patterns, and context immutability patterns
• Complete test coverage: 30 unit and integration tests covering builder, guards, steps, and execution engine
• Example workflow: Demonstration of user creation workflow with validation guards and mutation steps