This repository implements a web service called nightly.link that enables permanent, shareable download URLs for GitHub Actions build artifacts without requiring users to authenticate with GitHub. It acts as a proxy that redirects to time-limited download URLs provided by the GitHub API, using a GitHub App installation token for authorization. The architecture is a single Crystal web server using the Retour HTTP router, ECR templating, and SQLite for persisting repository-to-installation mappings. Key functionality includes resolving workflow files to their latest successful run's artifacts, direct artifact download by ID, and job log downloads. The codebase demonstrates clean separation of concerns, robust error handling, and a caching layer to reduce API calls.