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.
• Filesystem — the shared mount between host and Coast, host-side agents, and worktree switching.
• 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.
• 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.