How is this different from guards and routers I already run?

It sits between perception and generation. Keep runtime supervision in Foreman, tool-call guardrails in jev-guard, context sieving in Winnow, and capability routing in JevRouter; this owns test-failure triage, doom-loop breaking, completion veto, effort governance, and model routing.

What actually stops the missing-package doom loop?

Sanitized assertion slices replace 500-line dumps, deterministic short-circuits fix dependencies and transient ports locally, entropy checks escalate borderline calls, and the abort gate exits nonzero on repeated repair loops instead of burning another large context.

What is the zero-key first run before I wire it into an agent?

Try the packaged runner triage sample with no install or key for local deterministic mode, then pip, npm, or cargo install for your runtime and jev-harness status to confirm the engine mode. Python and TypeScript cores carry no runtime dependencies.

When does the cloud Jev path even run?

Jev answers closed questions like triage category, severity, abort, target tier, and completion status without generative hallucination. The harness keeps cross-runtime parity across Python, TypeScript, and Rust with full offline fallback when no key is set.

How much does a live Jev triage call cost?

The README measures about $0.00002 per call at roughly 470 input tokens, against an estimated 50,000 frontier tokens for the missing-dependency case it replaces. Offline deterministic triage costs nothing and needs no key.

Which runtimes and integration surfaces does it ship?

Three runtimes, Python, TypeScript and Rust, callable as a CLI, an MCP server, git and CI hooks, and typed SDKs. The Python and TypeScript cores carry zero runtime dependencies, and pip, npm and cargo each install it.

How does the abort gate stop a doom loop?

When an agent repeats the same repair loop, a circuit breaker trips and the abort gate exits nonzero, stopping the loop instead of burning more frontier tokens. Sanitized assertion slices and deterministic short-circuits handle the simpler missing-package and transient failures locally.

CommunityJev Demos & Experiments

Jev Harness — ismaelsoilet

Decision layer for coding agents that triages test failures deterministically before spending frontier tokens. Offline heuristics handle missing packages, flaky transients, and loop breaking, with optional Jev micro-decisions and CLI, MCP, hook, and SDK use.

See highlights

Open github.com

Stars: 11
Language: Python
License: MIT
Published by: Community
Author: ismaelsoilet
Last verified: Oct 2026

ismaelsoilet/jev-harness

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Zero-dependency System One decision harness: 5 semantic gates saving frontier AI agent tokens on trivial errors & doom loops. Python + TypeScript + Rust. MCP-compatible.

Forks: 0
Last pushed: Updated Oct 2026

Repo stats from the GitHub API, cached Oct 2026.Homepage

This is one of several Jev listings for the same project. The canonical entry is Jev Harness — AntonioCoppe.

About this project

The Problem · How It Works · Where It Fits · Features · Quickstart · CLI · Astra-Jev effort governance · Integrations · SDKs (TS, Rust) · Git & CI guardrails · Economics & benchmarks · Architecture & roadmap · Contributing · Release · Changelog. Get running in seconds across any stack — zero external dependencies, zero API keys required for local deterministic mode:

Quoted from the project's README. Read the full README.

Tagscommunity awesomejev catalog-import

Works forJev for Classification Jev for Tool calling

Used inJev for Software & DevTools

Languages: Python

Highlights

Deterministic-first layer for triage, abort gating, completion veto, and effort governance.
Zero-trust sanitizing with short assertion slices, redaction, and injection masking.
Uncertain calls escalate via confidence margins while loops trip a circuit breaker.
Runs as CLI, MCP server, git and CI hooks, and typed SDKs across three runtimes.

Watch out

Deterministic heuristics cover known shapes first; ambiguous cases escalate and live calls need keys and budget. Copy reviewed against the repository README on 2026-10-04, not from running it.

Questions about this entry

Short answers drawn from the linked project or page.

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