ESC Connect is a newly introduced feature in Pulumi ESC that allows users to integrate any secret source by building simple HTTPS adapter services, thus enabling access to secrets from proprietary systems, legacy tools, or third-party services without native ESC support. This capability allows developers to create custom adapters that fetch secrets from non-standard sources by handling requests from ESC, authenticating with signed JWT tokens for secure access, and returning the required secrets. The feature also includes support for automated secret rotation, ensuring seamless credential updates without downtime, and offers a deployable reference adapter implementation on AWS Lambda to showcase secure request validation. ESC Connect expands the flexibility of Pulumi ESC by allowing users to easily incorporate niche or custom secret management systems, with comprehensive documentation available to guide users in building these adapters and sharing them with the community.