dev-server-sandbox
Run multiple isolated mux dev-server instances (temp MUX_ROOT + free ports)
Best use case
dev-server-sandbox is best used when you need a repeatable AI agent workflow instead of a one-off prompt.
Run multiple isolated mux dev-server instances (temp MUX_ROOT + free ports)
Teams using dev-server-sandbox should expect a more consistent output, faster repeated execution, less prompt rewriting.
When to use this skill
- You want a reusable workflow that can be run more than once with consistent structure.
When not to use this skill
- You only need a quick one-off answer and do not need a reusable workflow.
- You cannot install or maintain the underlying files, dependencies, or repository context.
Installation
Claude Code / Cursor / Codex
Manual Installation
- Download SKILL.md from GitHub
- Place it in
.claude/skills/dev-server-sandbox/SKILL.mdinside your project - Restart your AI agent — it will auto-discover the skill
How dev-server-sandbox Compares
| Feature / Agent | dev-server-sandbox | Standard Approach |
|---|---|---|
| Platform Support | Not specified | Limited / Varies |
| Context Awareness | High | Baseline |
| Installation Complexity | Unknown | N/A |
Frequently Asked Questions
What does this skill do?
Run multiple isolated mux dev-server instances (temp MUX_ROOT + free ports)
Where can I find the source code?
You can find the source code on GitHub using the link provided at the top of the page.
SKILL.md Source
# `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 ```bash make dev-server-sandbox ``` ## What it does - Creates a fresh temporary `MUX_ROOT` directory - Copies these files into the sandbox if present: - `providers.jsonc` (provider config) - `config.json` (project list) - Picks free ports (`BACKEND_PORT`, `VITE_PORT`) - Allows all hosts (`VITE_ALLOWED_HOSTS=all`) so it works behind port-forwarding domains - Runs `make dev-server` with those env overrides ## Options ```bash # Use a specific root to seed from (defaults to ~/.mux-dev then ~/.mux) SEED_MUX_ROOT=~/.mux-dev make dev-server-sandbox # Keep the sandbox root directory after exit (useful for debugging) KEEP_SANDBOX=1 make dev-server-sandbox # Pin ports (must be different) BACKEND_PORT=3001 VITE_PORT=5174 make dev-server-sandbox # Override which make binary to use MAKE=gmake make dev-server-sandbox ``` ## Security notes - `providers.jsonc` may contain API keys. - The sandbox root directory is created on disk (usually under your system temp dir). - This flow intentionally **does not** copy `secrets.json`.
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