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Zenith

#171 agent harnessunverified row

Continuous-improvement harness for multi-day tasks, built to attack premature completion with gap-finding

Key differences

Continuous-improvement harness for multi-day tasks, built to attack premature completion with gap-finding

  • Runs local. Free and open source under Apache-2.0; you pay for the coding agent and model it orchestrates
  • Supports headless CI workflows. Listed for 60 of 194 tools in this category.
  • Runs multiple agents. Listed for 165 of 194 tools in this category.
  • Keep in mind: The technical report reports a best mean rank across eight long-horizon tasks against RALPH variants, but the study is the authors' own and defines its own task set.

“The research finding is that long agent runs fail by stopping too early, which makes them the most relatable thing in the stack.”

Website Docs 320 starsCompare vs…Dispute a fact
Appeal a claim or request ownership transfer

What it is

Zenith runs Claude Code, Codex or Hermes as a multi-agent orchestrator over MCP and ACP: one orchestrator session reads task state each turn and decides whether to spawn workers and testers, register reusable skills, replan or stop. It comes out of an Intelligent Internet study that compared 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 — after finding that long-running agents usually fail by stopping too early rather than by being unable to progress. The report claims Zenith took the best mean rank at under half of the RALPH baseline's per-task cost.

Specification

Source verification

Row snapshot checked not yet. Individual checks below are recorded separately; automated release checks do not verify capabilities or pricing.

readme
Needs individual review
install
Needs individual review
license
Needs individual review
capabilities
Needs individual review

Architecture

Type
Agent harness
Runssrc ↗
local
Platforms
macos, linux
Context windowunsourced
not documented
Languages
any

Models

Backboneunsourced
via managed agents (Claude Code, Codex, Hermes)
Bring your own model
Yes
Local models
No

Protocols

MCP clientunsourced
Yes
MCP server
No
OpenAPI tools
No

Capabilities

Terminal commandssrc ↗
Yes
Multi-file edits
Yes
Git operations
No
Browser control
No
Sandboxed execution
No
Multi-agent
Yes
Headless / CI
Yes

Cost

Modelunsourced
byok
Starts at
$0/mo
Free tier
Yes
Bring your own key
Yes

Free and open source under Apache-2.0; you pay for the coding agent and model it orchestrates

Openness

Open sourcesrc ↗
Yes
License
Apache-2.0
First release
unknown
open-sourcelong-horizonorchestrationmulti-agentverificationresearch

Los Agentes on Zenith

Who are they?
The ruling
El JuezThe judge

El Profesor will not accept a self-authored comparison as evidence and El Amigo says the behaviour it describes is the one thing he wants, which is the whole split.

Trial only
Reasoning and trade-offs · AI analysis

El Profesor discounts the result because the authors designed the tasks, the baselines and the metric, which is a conflict he will not wave through. El Amigo scores usefulness high anyway, since an agent that refuses to declare victory early is solving the problem he actually has. El Crítico worries about who decides to keep going.

El Profesor is right that the number proves less than it appears, and El Amigo is right that the mechanism is worth having regardless. Trial only, and the exit criterion is one long task of your own where the extra passes found something a single run missed.

Agree with El Juez?
El AmigoThe friend

Pick it for work that takes days rather than minutes; pick a plain terminal agent when the task is small enough that stopping early is not the failure you fear.

6.3
Reasoning and trade-offs · AI analysis

The deciding trait is that it keeps looking for what is missing instead of announcing it is done. Anyone who has read a confident summary and then found three unimplemented cases knows that premature completion is the characteristic failure of long agent runs, and this is built specifically against it.

The cost of that is patience and tokens, and on a task you could have finished in ten minutes it is pure overhead. Pick it when the job is genuinely long. Pick something ordinary when it is not.

reliability
6
usefulness
7
cost
6
longevity
6
Agree with El Amigo?
El CríticoThe critic

The orchestrator decides each turn whether to spawn more workers and testers, so the depth of a run is set by the same component that judges whether the work is finished.

5.8
Reasoning and trade-offs · AI analysis

Self-directed expansion is the exposure. A session that concludes more checking is needed responds by starting more sessions, and the thing deciding is the thing being checked. There is no external referee in that loop, so a task the model finds unsatisfying can widen without a person choosing to widen it, and the invoice arrives afterwards.

What it does right is stopping discipline being treated as a named mechanism rather than an accident, which is more than the alternatives it was compared against manage.

reliability
5
usefulness
7
cost
5
longevity
6
Agree with El Crítico?
El ProfesorThe professor

The report claims a best mean rank at under half the baseline's per-task cost, measured across eight tasks the authors selected against baselines the authors implemented.

6.0
Reasoning and trade-offs · AI analysis
  1. The design of the study is defensible and the ownership of it is not independent. Five harness configurations were compared on a set of eight long-horizon tasks written for the purpose, with the baselines reimplemented by the same team, so both the difficulty distribution and the opposition were chosen by the party reporting the result. 2. Mean rank across eight items is a coarse statistic with wide error.

  2. The isolated mechanisms are the useful output here, and they are stated clearly enough for somebody else to test.

reliability
6
usefulness
6
cost
6
longevity
6
Agree with El Profesor?
La InversoraThe investor

A research group with 286 stars publishing a harness as the artefact of a study, which makes this a paper with a repository attached rather than a product with a roadmap.

5.3
Reasoning and trade-offs · AI analysis

Research output has a distinctive decay curve. It ships in excellent condition on the day the report lands, and then attention moves to the next question, because the incentive was the finding and not the software. There is no commercial entity behind this to fund maintenance and no customer to complain.

Moat: none, and none intended. Likely path: the mechanisms get absorbed into funded harnesses while this repository stops moving. Position: read the report, borrow the ideas, and do not expect a release next quarter.

reliability
5
usefulness
5
cost
7
longevity
4
Agree with La Inversora?
La JefaThe CTO

It runs unattended, so it could be a pipeline step, but it is macOS and Linux only and there is no identity, policy or retention surface anywhere in it.

4.8
Reasoning and trade-offs · AI analysis

Headless execution is the property that makes something reviewable as infrastructure rather than as a desktop toy, and it has that. What it does not have is anything my security team needs: no directory integration, no policy layer, no stated retention for what a multi-day run records along the way.

The platform gap rules out part of my organisation before we start, and a runtime that runs for days is a budgeting question I cannot answer at sixty engineers with the information published. Not yet.

reliability
5
usefulness
5
cost
5
longevity
4
Agree with La Jefa?
El HackerThe tinkerer

Apache-2.0, launched with uv run, and it orchestrates over MCP and ACP, so the sessions it drives are the agents I already installed rather than a captive runtime.

7.5
Reasoning and trade-offs · AI analysis

Speaking two open protocols instead of one proprietary interface is what makes this worth my time. The orchestrator drives agents through their own channels, which means the thing being coordinated is my installation, with my keys and my configuration, and swapping one out does not require the project's permission.

One command starts it, the licence keeps a fork legal, and the whole control loop is Python I can read when it does something I did not expect. This is a harness in the honest sense of the word.

reliability
7
usefulness
8
cost
8
longevity
7
Agree with El Hacker?