HAR
Open Source harness for multi-agent coding workflows
HAR is an open-source, agent-agnostic harness for running fleets of coding agents in parallel across repositories. Each agent gets an isolated environment; changes pass deterministic validation gates and produce verifiable evidence, with full observability through a local dashboard called Mission Control. All configuration lives in a single committed contract file instead of scattered READMEs and per-tool config. Works with Claude Code, Cursor, Codex, and any MCP agent; installed via npm as @osfactory/har. Apache-2.0, 63 GitHub stars at time of check.
What is HAR?
HAR is an open-source, agent-agnostic harness for running fleets of coding agents in parallel, with isolated environments, deterministic validation gates, and a verifiable evidence trail per run.
Key features
- Isolated git worktree, branch, ports, and database per agent
- Deterministic launch/verify/teardown pipeline
- Verifiable proof artifact per run (not just a self-report)
- Local dashboard (Mission Control) for observability across repos and runs
- Single committed contract file instead of scattered config
- Works with Claude Code, Cursor, Codex, and any MCP agent
- Apache-2.0 licensed, installed via `npm install -g @osfactory/har`
Who it's for
- Teams running more than two coding agents in parallel on the same repository
- Reviewers who need proof a change was actually validated, not just a diff
- Projects that keep hitting merge or port collisions between concurrent agents
When not to use it
Not worth the setup overhead if you run a single agent interactively — the contract file and verify stage buy you nothing at that scale.
FAQ
Which coding agents does HAR support?
Any MCP-compatible agent, including Claude Code, Cursor, and Codex — it's agent-agnostic.
How does HAR prevent agents from stepping on each other?
Each agent runs in its own isolated git worktree with a dedicated branch, ports, and database.
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