Coasts Untangles the AI Coding Agent Chaos With Isolated Runtimes for Git Worktrees
As AI coding agents move from single-user experiments to production workflows, a new kind of bottleneck has emerged on developer laptops: too many agents, all trying to run the same project at once. Ports clash, databases get corrupted, and per-branch setup becomes fragile. Coasts, a Y Combinator–backed startup (Fall 2025), is introducing one of the more practical developer tools for AI agents to emerge from the current coding agent wave. A “Coast” – short for containerized host – is a local development runtime that lets developers run multiple fully isolated environments for the same project on one machine.
The core problem Coasts is tackling is a side effect of the shift to agentic software development. Modern workflows increasingly rely on multiple AI coding agents operating in parallel across git worktrees, each generating, testing, and iterating on changes simultaneously. In principle, git worktrees already allow a single repository to be checked out across multiple directories. In practice, the shared nature of localhost – a single default port, a single database file, a single set of service processes — makes true parallelism painful. Coasts fixes this by giving each worktree its own fully isolated runtime, so multiple agents can build and test side by side without stepping on each other.
Coasts was founded in 2025 by Dan Hyman, who serves as Founder and CTO. Hyman is a senior engineer and AWS/cloud infrastructure expert who has led teams building enterprise applications and large-scale systems. He also brings an unusually creative outside-tech background: in a previous life, he worked as a chef at a James Beard award–winning restaurant, an experience that tends to produce the kind of systems thinking (and high-pressure execution discipline) that serves developer-tools founders well. Coasts’ early product reflects that sensibility – pragmatic, well-scoped, and aimed at the kinds of daily pains that senior engineers immediately recognize.
The market for Coasts sits at the intersection of developer tools, B2B software, productivity, and the broader web development ecosystem. With coding agents like those from Anthropic, OpenAI, and specialized startups increasingly handling multi-step tasks across large repositories, developers are experimenting with running several agents in parallel to compress cycle time. But without isolation, those parallel runs tend to collapse into the classic “it works in my worktree, but breaks everywhere else” class of bug. Coasts positions itself as infrastructure for this new way of working: a thin, local runtime layer that makes parallel agent-driven development not just possible but pleasant.
The company is part of the Y Combinator Fall 2025 batch. With a two-person team, Coasts is prioritizing depth over breadth – focusing on making the core isolation primitive reliable, fast, and compatible with popular development stacks before expanding into more advanced orchestration features. That focus matters in developer tools, where early product quality and the right abstraction often determine whether a new category gets adopted or ignored.