Coasts tackles worktree runtime collisions

This feels less like a niche wrapper and more like infrastructure the AI-coding workflow stack has been missing: worktrees isolate files, but Coasts isolates the runtime too.

• –The core pain it solves is real for agentic dev: parallel branches often still fight over ports, databases, secrets, and shared state
• –Dynamic ports plus canonical host ports is the right compromise for both human convenience and agent automation
• –The “works with any harness” angle matters because teams rarely standardize on one editor or agent system
• –Docker-in-Docker lowers the abstraction gap, but it may also be the part most likely to need careful ops tuning in messy local setups
• –YC backing and an open-source posture give it credibility, but the product will live or die on how painless Coastfile setup feels in practice