LongHorizon-Harness

Loop Engineering for Computer-Use Agents

Give Claude Code, Codex, OpenCode, or DeepSeek Harness a goal once. Keep it working across desktop apps and the terminal for dozens of hours.

Plan → act → verify → checkpoint or recover → repeat — until the work is actually done.

Usage · The Loop · Computer Use · Results · Project Website · 简体中文

The model determines what an agent can do in one round. LongHorizon-Harness engineers the loop around it: what to do next, how to verify the result in the real computer, what progress to preserve, and how to continue after failure or context refresh.

A Loop Engineering system for Claude Code, Codex, OpenCode, and DeepSeek Harness. One-command install, ready to run.

LongHorizon-Harness turns existing agents into long-running computer-use systems. Across desktop apps and the terminal CLI, it continuously recovers the goal and verified state, selects the next bounded step, executes it with a fresh context, checks the actual result, and then checkpoints accepted progress or feeds failure evidence into the next round. It does not train a new model or replace an existing agent; it provides the durable execution loop around one.

✨ News

• [v0.1.8 · 2026-10-21] Fixes approvals after resuming historical runs, Markdown-formatted Manager routes, Claude Code MCP isolation, and non-UTF-8 CLI/DeepSeek output. Adds --final-response-timeout for slower closing replies. See the release notes for upgrade details and current Windows limitations.
• [v0.1.7 · 2026-08-20] A finished run is no longer a dead end: the workbench is now a conversation. Read the reply, type a follow-up, and the run continues on its own round ledger instead of replanning from scratch. A message you send mid-round is claimed by the very next round, so stopping and continuing never drops it. Also adds --reasoning-effort for every role (with --manager-reasoning-effort and friends to override one), forwarded to whichever backend exposes it. The transcript now reads in strict chronological order, and a graceful stop escalates to a force stop only when a worker ignores it.
• [v0.1.6 · 2026-08-15] Added OpenCode CLI support. LongHorizon-Harness can now run opencode run prompt as --agent opencode, with role-scoped read/write permissions, OpenCode API endpoint overrides, normalized JSON results, and CLI/config/doctor integration. The Web workbench can select OpenCode Harness and its model independently for each role.
• [v0.1.5 · 2026-08-14] Added phase-1 DeepSeek Harness CLI support. LongHorizon-Harness can now run dsh --profile headless as --agent deepseek_harness, with an isolated DSH_HOME, role-scoped read/write permissions, DeepSeek API endpoint overrides, normalized JSONL results, and CLI/config/doctor integration. The Web workbench can select DeepSeek Harness and its model independently for each role. GUI computer-use and MCP support will follow in a later phase; see the CLI setup.
• [v0.1.4 · 2026-08-11] The new Dashboard has landed: a React/FastAPI workbench you can drive entirely from the browser. Start a task, choose a backend and model per role, answer approvals, send an instruction mid-run, and stop or restart a run. Launch it with lh-harness web; see Run a task in the browser.
• [2026-08-10] Added the Terminal-Bench 2.1 evaluation.

🚀 We’re iterating rapidly. Stay tuned!

Video Demo

https://github.com/user-attachments/assets/ca8b77ce-9220-4d85-a272-b346009b2454

Loop Engineering for real computer environments.

Give LongHorizon-Harness an outcome. It repeatedly turns the remaining work into a bounded step, performs that step on the right computer surface, checks what actually happened, and carries the verified result into the next round.

flowchart LR
    S["Original goal +<br/>verified state"] --> P["Plan the next<br/>bounded step"]
    P --> A["Act in a desktop app or CLI<br/>with fresh context"]
    A --> V["Verify files, UI, logs, and tests<br/>in the real environment"]
    V -->|Pass| C["Checkpoint<br/>verified progress"]
    V -->|Fail| R["Record evidence<br/>and recover"]
    C --> D{"Task complete?"}
    R --> S
    D -->|No| S
    D -->|Yes| F["Verified result"]

This is Loop Engineering: designing the execution, verification, correction, and recovery loop around the agent — not just the prompt for a single turn.

This is the beginning of the README. Read the rest at the original. Read the full README ↗