Generic provider registry that allows registering named providers with config parsers and factory functions. Clean separation of concerns: each provider is self-contained with its own config type, validation, and lifecycle methods. The registration pattern (RegisterProvider, NewProvider) is reusable for any Go project needing pluggable backends.

Generates bootstrap shell scripts for VM initialization. Supports multiple Linux distributions (Debian, Ubuntu, Amazon Linux) and deployment targets (Docker Compose vs Helm/k3s). Includes Docker installation, SSH key injection, host tuning, SSH CA trust configuration, and runtime-specific setup. The function is parameterized via BootstrapOptions and could be extracted as a standalone library for provisioning scripts.

Full Hetzner Cloud provider implementation demonstrating several non-obvious patterns: SSH certificate-based authentication with a user-supplied CA key, local caching of SSH credentials with JSON serialization, instance identity lifecycle management (recreate on mismatch or SSH failure), firewall rule normalization and idempotent application, and label sanitization for Hetzner's constraints. The SSH retry/validation logic with certificate rotation is particularly well-crafted.

Clean, testable wrapper around the GitHub v3 API using go-github. Provides methods for issues, PRs, comments, collaborators, and SSH keys. Each method is thin and focused, with proper error handling. The test file provides a realistic fake HTTP server setup that can serve as a template for testing GitHub API clients.

Core GitHub Action logic that interprets webhook events (label, push, PR events) using a state machine (guessAction method) and dispatches up/down operations. Handles multi-variant deployments, marker-based PR comment updates with job/variant scoping, collaborator resolution, SSH key caching, templated URLs, and scheduled cleanup. The design cleanly separates event parsing from deployment orchestration.

Handles Docker Compose deployments via remote Docker context. Parses compose config to detect bind mounts, rewrites relative paths to remote paths, rsyncs source files, injects Caddy reverse proxy for TLS, and emits structured failure reports with container health diagnostics. The bind mount collection and rsync logic is a reusable pattern for any compose-based remote deployment system.