Zenith: A Continuous-Improvement Harness for Long-Running Tasks

Zenith is an agent harness for work that may run for days or weeks, where the dominant failure mode is premature completion rather than inability to make progress. It runs a coding agent (Claude Code, Codex, or Hermes) as a multi-agent orchestrator over MCP/ACP: one orchestrator session reads task state each turn and decides whether to spawn workers and testers, register reusable skills, replan, or stop.

This repository contains the Zenith harness (zenith/) and the Intelligent Internet technical report (2026) behind it.

Read the report (PDF)

Abstract

Long-running agents often fail not because they cannot make progress, but because they stop before the task is truly complete. We tested five harness designs across eight long-horizon tasks to isolate the control mechanisms that matter: repeated gap-finding, revisable planning, independent verification, adaptive orchestration, and stopping discipline.

RALPH is the strongest simple baseline because it forces each new session to reopen the gap between the current project state and the original requirement. But RALPH is expensive and has no principled stopping rule.

Our Zenith method keeps the useful parts of repeated review while making the loop adaptive: the orchestrator dynamically allocates workers, testers, reusable skills, replanning, and stopping decisions. In this study, Zenith achieved the best mean rank while using less than half of RALPH's per-task cost.

Quick Start

Option 1 — Let your agent install it

Copy this prompt into Claude Code or Codex:

/goal Read the readme at https://github.com/Intelligent-Internet/zenith, detect if using Claude Code, Codex, or both, install requirements, install and run Zenith (i.e. uv run zenith, as in the readme), and create a new skill called /zenith — when used (along with an additional prompt) it will call the skill: the minimum skill content should be: """First read .claude/orchestrator_prompt.md and treat it as your primary role, then use Zenith to run this mission.""" Afterwards, you can add information about the Zenith harness, based on the readme and the technical report (inside the repo), and info on how to start Zenith if it's not already running. Change the skill to use .codex when using it in Codex. If both harnesses are available, make sure to add the skill to both of them correctly. In fact, there might be more harness options (Hermes, for example). See what is supported in zenith/src/zenith_harness/providers.py, and for those that you detect are present, add their skills correctly. When finished, confirm to me that Zenith is installed, running, and ready, explain a bit about Zenith, and why and when to use it.

This will:

• install Zenith with its requirements
• start Zenith using uv
• create a /zenith skill for each agent harness it detects

Then, in Claude Code or Codex, type:

/zenith <your instruction or query>

Option 2 — Install manually

Requirements

• Python 3.11+
• uv
• Node.js 22+ and npm
• Claude Code, Codex, or Hermes (see providers.py for the supported set)

Install

cd zenith
uv sync
uv run zenith --help

Install the ACP adapters globally for the agents you want Zenith to run: