The end to end journey for every user request originating from our apps traverses hundreds of hops across Meta’s distributed architecture such as client-libraries, privacy and security frameworks, microservices, data stores and hardware. These dependencies are interconnected, making our infra a massive, tightly-coupled graph. We aim to minimize the impact and the duration for dependency outages by making dependency health a core part of reliability at Meta. Dependency safety will enable us to protect the business, improve user experience on our apps and enhance incident response.