climax

A local browser + MCP surface for coding agents. Chat, live canvas, and multi-agent tabs — all running on your machine, orchestrated by any MCP- speaking CLI (Claude Code, codex, gemini, aider, cursor-agent…).

┌───────────────────────────────────────────────┐
│  http://127.0.0.1:8011                        │
│  ┌─────────────────────────────────────────┐  │
│  │                                         │  │
│  │      CANVAS  (sandboxed iframe —        │  │
│  │      agent-authored HTML, live)         │  │
│  │                                         │  │
│  └─────────────────────────────────────────┘  │
│  ┌─────────────────────────────────────────┐  │
│  │  Chat  ●  Canvas · Chat                 │  │
│  │  ...conversation with your agent...     │  │
│  │  [ type here                          ] │  │
│  └─────────────────────────────────────────┘  │
└───────────────────────────────────────────────┘
        ↑                        ↑
    WebSocket                  stdio
        ↓                        ↓
    backend  ←──── HTTP ──── mcp_server

Install

One line:

curl -fsSL https://climax.com.mx/install.sh | sh

Or with pip (pre-release for now — remove --pre once 0.1.0 ships):

pip install --pre python-climax

The PyPI name is python-climax because plain climax was already taken. The command and import name are still climax.

Then start it:

climax
# → http://127.0.0.1:8011

Open the URL. Click + agent in the browser to launch a coding agent — the backend spawns it with an ephemeral MCP config, so nothing to wire up by hand.

Optional: HTTPS via local.climax.com.mx

By default climax runs on plain HTTP at 127.0.0.1, which is fine for opening the UI directly. If you want to talk to climax from a page hosted on https://climax.com.mx (or any other HTTPS origin), browsers block the mixed-content request. For that case climax can serve HTTPS on a loopback DNS name — local.climax.com.mx — that resolves to 127.0.0.1 with a real Let's Encrypt certificate:

climax --tls
# → https://local.climax.com.mx:8011

--tls uses the bundled cert (if the release pipeline dropped one into climax/certs/) or you can pass --cert / --key explicitly. Traffic still never leaves your machine.

MCP tools exposed to the agent

The canvas iframe can talk back to the agent:

window.parent.postMessage({
  type: 'climax.event',
  name: 'submit',
  data: { /* whatever */ },
}, '*');

wait returns {stream:'canvas', name, data, ts} for canvas events and {stream:'chat', msg} for typed chat. One tool, both surfaces.

Multi-agent

Every MCP client identifies itself with an X-Climax-Agent header. The browser shows one tab per agent — canvas, chat, and pty terminal each. Click + agent to launch a new one from a preset (see climax/agents.toml). Bring-your-own preset via ~/.climax/agents.toml.

Development

git clone https://github.com/sheunaluko/climax
cd climax
pip install -e ".[dev]"
climax --host 127.0.0.1 --port 8011

Set PYTHON=/path/to/python ./start.sh for the convenience launcher (kills a stale instance on the port first).

Design notes

• Iframe is sandbox="allow-scripts allow-forms allow-popups" — no parent-frame access, no cookies. Safe for LLM-authored HTML.
• Backend state is per-agent in-memory; snapshots persist to a local SQLite file for offline reference.
• wait races both queues so agents never miss input on the wrong stream.

License

MIT — see LICENSE.