Harness

Harness is minimal agent orchestration in the terminal.

Programmable, agent-agnostic, threaded, ergonomic, and fast.

What matters most

• Parallel threads across codex, claude, cursor, terminal, and critique.
• Workspace-scoped nim runs as its own process and is opened/streamed from the left rail like other live sessions, with inline first-run API key onboarding when required.
• One command palette (ctrl+p) to jump threads, run actions, and control workflow quickly.
• Toggle the bottom debug bar with cmd+p when you need runtime launch/auth context.
• Codex, Claude Code, and Cursor together in one workspace.
• Diff with Critique, with integrated terminals (harness diff + critique actions).
• Detached gateway sessions keep long-running work alive through reconnects.
• Rolling storage lifecycle policy keeps event/telemetry data bounded during long-lived sessions.
• Mux event-store maintenance runs in a managed background daemon with progress updates so cleanup does not block UI navigation.
• Gateway storage lifecycle policy updates from harness.config.jsonc apply without restarting the server.
• Deterministic visual-contract fixtures and viewport/input matrix e2e checks keep UI look-and-feel stable release-to-release.
• Command palette can open a GitHub thread entry in the left rail for the active project, then show full tracked-branch PR/review details in the main panel.
• Open the active project directly in local tools (iTerm2, Ghostty, Zed, Cursor, VSCode, Warp, Finder) or copy its path from the palette.
• Command-click links inside conversation terminal output: URLs open in browser, file-like paths open in your configured editor/open-in command.

Demo

Quick start

Prerequisites:

• Bun 1.3.9+
• At least one agent CLI (codex, claude, cursor, or critique)

Install and run:

# Bootstrap install
curl -fsSL https://raw.githubusercontent.com/jmoyers/harness/main/install.sh | bash

# Or run directly (no global install)
bunx @jmoyers/harness@latest

# Or install globally
bun add -g --trust @jmoyers/harness
harness

Use a named session when you want isolated state:

harness --session my-session

Named sessions automatically fall back to an available gateway port when the preferred port is already occupied. For deterministic restart/load diagnostics, you can still set an explicit non-default gateway port.

Standalone diff viewer (phase 1):

harness diff --help

Architecture (VTE path)

flowchart LR
    U[Keyboard + Command Palette] --> UI[Harness TUI]
    UI --> CP[Control Plane Stream API]
    CP --> TM[Thread Manager]
    TM --> AG[Agent Threads<br/>Codex / Claude / Cursor]
    TM --> PTY[Integrated PTY Terminals]
    PTY --> VTE[VTE Parser + Screen Model]
    VTE --> R[Terminal Renderer]
    TM --> DF[harness diff + Critique]
    DF --> R

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