costra

Run multiple Claude Code and Codex accounts side by side — each behind its own pxpipe proxy to save costs, with automatic port allocation and isolated config directories.

🎬 Demo

✨ Features

• 🔀 Multiple accounts, zero collisions — every account gets its own isolated config directory, so logins never clash
• 🔌 Stable, automatic port allocation — ports are assigned once from a configurable range and persisted per account
• 💸 Cost savings via pxpipe — each account runs behind its own pxpipe proxy; open its dashboard in the browser any time
• 🤖 Anthropic & OpenAI support — works with both Claude Code (claude) and Codex (codex)
• 🪶 Lightweight — plain Node.js, no runtime dependencies, script-friendly

📦 Install

npm install -g @martin-christensen/costra

Requires Node 20+ and the CLI you want to run (claude and/or codex) on your PATH.

🚀 Quick start

# Register accounts (stored in ~/.costra.json)
costra add work --provider anthropic --model claude-fable-5
costra add personal --provider anthropic
costra add oai --provider openai

# Launch — starts a pxpipe proxy in the background if needed (printing its
# URL), then launches the CLI
costra work
costra oai

# Open an account's pxpipe URL in the default browser
costra proxy open work

# Skip the pxpipe proxy entirely
costra work --no-proxy

# Pass extra arguments to the underlying CLI after --
costra work -- --resume

⚙️ How it works

For each account, costra:

1. Assigns a stable port from a configurable range (default 47800–47899), persisted in the account's config directory, skipping ports assigned to other accounts.
2. Ensures a pxpipe proxy is listening on that port (spawned detached, logs to pxpipe.log in the account's config dir) and prints its URL — open it in your browser any time with costra proxy open <account>.
3. Launches the provider's CLI with the right environment:

| Provider | CLI | Base URL env | Config dir env | Default config dir | | ----------- | -------- | -------------------- | ------------------- | ------------------------- | | anthropic | claude | ANTHROPIC_BASE_URL | CLAUDE_CONFIG_DIR | ~/.config-claude-<name> | | openai | codex | OPENAI_BASE_URL | CODEX_HOME | ~/.config-codex-<name> |

Because each account gets its own config directory, logins never collide — run as many accounts simultaneously as you like.

🧰 Commands

costra <account> [--no-proxy] [-- <cli args...>]
                                      Start proxy (if needed) and launch the CLI
costra add <account> [options]        Register an account
costra remove <account>               Unregister an account (config dir is kept)
costra list                           List configured accounts
costra status                         Show ports and proxy state per account
costra stop <account>                 Stop the account's background proxy
costra proxy <account>                Run the proxy in the foreground (debugging)
costra proxy open <account>           Open the account's pxpipe URL in the browser
costra version                        Show version and check npm for a newer one

costra --version / -v prints the bare version with no network access (script-friendly).

Launch options

| Option | Description | | ------------ | ----------------------------------------------- | | --no-proxy | Launch the CLI directly, without a pxpipe proxy |

add options

| Option | Description | | --------------------- | -------------------------------------------------- | | --provider <p> | anthropic (default) or openai | | --model <m> | Passed to the CLI as --model <m> | | --cli <binary> | Override the CLI binary | | --config-dir <path> | Override the account's config directory |

Update checks

Costra checks npm for a newer version at most once a day. The check runs in a detached background process, so commands are never delayed — when an update is found, a one-line notice is printed to stderr on the next run:

costra: update available 1.0.0 → 1.1.0 — run: npm install -g @martin-christensen/costra

The result is cached in ~/.costra-update.json (override with the COSTRA_UPDATE_CACHE env var). Set COSTRA_NO_UPDATE_CHECK=1 to disable update checks entirely.

🔧 Configuration

~/.costra.json (override the location with the COSTRA_CONFIG env var):

{
  "portRange": [47800, 47899],
  "accounts": {
    "work": { "provider": "anthropic", "model": "claude-fable-5" },
    "oai": { "provider": "openai" }
  }
}

🤝 Contributing

Contributions are welcome! Feel free to:

• 🐛 Open an issue for bugs or feature requests
• 🔀 Submit a pull request — run npm test before pushing
• 💡 Share ideas for new providers or workflows

🙏 Acknowledgments

costra stands on the shoulders of some great tools:

• Anthropic — for Claude Code, the agentic coding CLI this tool was born to multiplex
• OpenAI — for Codex, the second CLI citizen of costra
• pxpipe — for the proxy layer that makes the cost savings and traffic insight possible

📄 License

MIT © Martin Christensen