requirements management

The third type parameter in Effect represents requirements - services and dependencies the effect needs to run:

Effect uses a powerful dependency injection system based on Context and Layer.

The primary reason to define services is testability. Every external dependency (API calls, databases, file systems, third-party SDKs) MUST be wrapped in a Context.Tag service so that tests can provide a test implementation instead of hitting real systems. This is how Effect achieves 100% test coverage — business logic depends only on service interfaces, and tests swap in test layers that control all I/O.

Questa abilità dovrebbe essere utilizzata quando l'utente chiede informazioni su "Servizi di effetti", "inserimento di dipendenze", "Effect.Tag", "Context.Tag", "Layer", "Effect.provide", "Effect.provideService", "implementazione del servizio", "gestione delle dipendenze", "Layer.succeed", "Layer.effect", "Layer.scoped", "componendo livelli", "Layer.merge", "Layer.provide", "servizi predefiniti", "layer memoizzazione", "testabilità", "livelli di test", "servizi simulati" o deve comprendere come Effect gestisce il parametro di tipo Requisiti (R). Fonte: andrueandersoncs/claude-skill-effect-ts.