Concepts and Terminology

This section covers the core concepts and vocabulary used throughout Coasts. If you are new to Coasts, start here before diving into configuration or advanced usage.

• Coasts - self-contained runtimes of your project, each with its own ports, volumes, and worktree assignment.
• Run - creating a new Coast instance from the latest build, optionally assigning a worktree.
• Remove - tearing down a Coast instance and its isolated runtime state when you need a clean recreate or want to take Coasts down.
• Filesystem - the shared mount between host and Coast, host-side agents, and worktree switching.
• Private Paths - per-instance isolation for workspace paths that conflict across shared bind mounts.
• Coast Daemon - the local coastd control plane that executes lifecycle operations.
• Coast CLI - the terminal interface for commands, scripts, and agent workflows.
• Coastguard - the web UI launched with coast ui for observability and control.
• Ports - canonical ports vs dynamic ports and how checkout swaps between them.
• Primary Port & DNS - quick-links to your primary service, subdomain routing for cookie isolation, and URL templates.
• Assign and Unassign - switching a Coast between worktrees and the available assign strategies.
• Checkout - mapping canonical ports to a Coast instance and when you need it.
• Lookup - discovering which Coast instances match the agent's current worktree.
• Volume Topology - shared services, shared volumes, isolated volumes, and snapshotting.
• Shared Services - host-managed infrastructure services and volume disambiguation.
• Secrets and Extractors - extracting host secrets and injecting them into Coast containers.
• Builds - the anatomy of a coast build, where artifacts live, auto-pruning, and typed builds.
• Coastfile Types - composable Coastfile variants with extends, unset, omit, and autostart.
• Runtimes and Services - the DinD runtime, Docker-in-Docker architecture, and how services run inside a Coast.
• Bare Services - running non-containerized processes inside a Coast and why you should containerize instead.
• Bare Service Optimization - conditional installs, caching, private_paths, shared service connectivity, and assign strategies for bare services.
• Dynamic Port Environment Variables - the auto-injected <SERVICE>_DYNAMIC_PORT variables and how to use them in service commands.
• Logs - reading service logs from inside a Coast, the MCP tradeoff, and the Coastguard log viewer.
• Exec & Docker - running commands inside a Coast and talking to the inner Docker daemon.
• Agent Shells - containerized agent TUIs, the OAuth tradeoff, and why you should probably run agents on the host instead.
• MCP Servers - configuring MCP tools inside a Coast for containerized agents, internal vs host-proxied servers.
• Troubleshooting - doctor, daemon restart, project removal, and the factory-reset nuke option.