Coasts
Containerized Hosts
Localhost service isolation and orchestration for git worktrees.
Free, OSS, works with any harness, no AI upsells.
// the problem
Worktrees isolate code, not runtimes.
Your agents work in parallel, but your machine doesn't. Every worktree still runs on the same local environment — causing potential migration conflicts, port collisions, and competition for shared resources. So you validate sequentially, spin up cloud resources, or buy another laptop — while the bulk of your hardware sits idle.
Coasts are the local-first, free and open source solution to spawning parallel runtimes for your agents. A coast is a full runtime — its own ports, its own network, its own services. Run each stack in full isolation, or choose which resources to share across your coasts. Coasts work with any agentic coding solution — all you need is git worktrees.
// how it works
Three steps to parallel development.
install
define your environment
# Coastfile — point to your existing compose [coast] name = "my-project" compose = "./docker-compose.yml" [ports] web = 3000 db = 5432 api = 8080
For your agent
Let your agent configure the Coastfile for you
Copy a ready-made prompt you can paste into Cursor, Claude Code, or another agent. Run it in a chat opened in your project's directory.
orchestrate
For your agent
Teach your agent the Coasts workflow
Give it the context and conventions it needs to manage Coasts without extra back-and-forth. Run it in a chat opened in your project's directory.
// see it in action
From zero to parallel in minutes.
Watch how Coasts isolates full dev stacks so multiple agents can build, test, and iterate at the same time — without stepping on each other.
// works with everything
Your infrastructure, their favorite tools.
Coasts operates at the runtime level, not the harness or agent level. Claude Code, Cursor, Codex, Conductor, or whatever ships next month: if it uses worktrees, it works with Coasts. Let your team use whatever AI coding tools they like. Don't get locked-in to a harness by building your dev infra around it.
