Open source Claude Code manager that spawns Codex/Gemini/OpenCode/Amp CLI and other coding agent CLIs in parallel across multiple tasks. For each run, cmux spawns an isolated openvscode instance via Docker or a configurable sandbox provider (like Morph/Daytona/E2B). The openvscode instance by default opens the git diff UI and a terminal with the running dev server (configurable via devcontainer.json).