Overview

trop is a small Rust CLI for reserving localhost ports in development worktrees. It is meant to replace hardcoded port numbers in scripts with stable, directory-aware reservations.

PORT=$(trop reserve)
npm run dev -- --port "$PORT"

The main guarantee is idempotence: the same worktree and tag get the same reservation on repeated calls, while different worktrees can reserve independently.

Use Cases

• Running several development worktrees at the same time.
• Giving concurrent local agents stable ports without a shared spreadsheet.
• Replacing fixed ports in just, npm, cargo, or shell scripts.
• Cleaning up stale reservations after a worktree is removed.

Model

Reservations are keyed by a directory and optional tag. trop stores reservations locally and coordinates concurrent callers with a SQLite-backed lock model.

The tool is intentionally local. It coordinates one user account on one machine; it does not try to enforce system-wide policy or broker ports across users, containers, or hosts.