dev-server sandbox instances

make dev-server starts the mux backend server, which uses a lockfile at:

• <MUX_ROOT>/server.lock (defaults to ~/.mux-dev/server.lock in development)

This means you can only run one dev server per mux root directory.

This skill documents the repo workflow for starting multiple dev-server instances in parallel (including from different git worktrees) by giving each instance its own temporary MUX_ROOT.

Quick start

make dev-server-sandbox

What it does

• Creates a fresh temporary MUX_ROOT directory