MetaHarness
Mint a custom AI agent harness from any repo.
npx metaharness · open the Studio →
(Repo: ruvnet/metaharness · CLI: metaharness · Library: )
Agenten stärken
Der eigene Befehl des Herausgebers. Kein PlugMCP-Endpunkt.
Host a copy with our keys and logs.
npx -y @metaharness/[email protected]Claude Code hat keinen Installationslink für einen lokalen Befehl. Kopieren Sie den Befehl unten und führen Sie ihn in einem Terminal aus.
claude mcp add metaharness-host-copilot -- npx -y @metaharness/host-copilot@0.1.3In einem Terminal ausführen.
{ "mcpServers": { "metaharness-host-copilot": { "command": "npx", "args": [ "-y", "@metaharness/[email protected]" ] } }}claude_desktop_config.json
Remote-URL oder ein Befehl auf Ihrem Rechner? Worin sich die beiden Installationen unterscheiden
Auf PlugMCP ausführen
A new server you create. It is not this listing's official endpoint. Use the publisher install when you want their URL and their credentials.
StartenVom Herausgeber
npx metaharness · open the Studio →
(Repo: ruvnet/metaharness · CLI: metaharness · Library: )
GitHub Copilot (VSCode) host adapter for agent-harness-generator. Emits .vscode/mcp.json for the Copilot MCP client (ADR-032).
@ruvnet/agent-harness-generator
Explore the full animated walkthrough → · 12 chapters · 96-second full tour · 32-second preview
Every serious repo deserves its own agent. A repo-aware CLI, a repo-aware coding agent, a local MCP server, memory scoped to the project, skills generated from the actual file layout, governance policy, release verification, witness-signed provenance.
metaharness mints those, on demand, from a GitHub URL or a blank slate. It is not another agent framework. It is a factory for agent frameworks.
The model is replaceable. The harness is the product.
In under 60 seconds, in your browser, with nothing leaving your machine:
Output is an npm-publishable .zip with your name on it, your branding, your npx <your-name> CLI.
@metaharness/darwin/contrastive adds scoped proposals, actual probes, selective composition and metered experiment memory behind immutable caller policy. API guide. Independent paired confirmation adds unseen-task, statistical and regression checks. Public intent-classification evidence remains separate from general agent performance claims.@metaharness/arc-agi-3 owns exact observations,
persistent evidence-backed memory, belief-state exploration, guarded actions,
supervisor interventions, checkpoints, and hash-chained receipts.
@metaharness/arc-agi-3-chatgpt exposes that
controller as a remote MCP server and MCP Apps canvas for ChatGPT Developer
Mode. ChatGPT is the OpenAI reasoning host: neither package uses the OpenAI
API or an OPENAI_API_KEY. An opt-in ARC-specific AVO loop adds governed
candidate selection, lineage, memory, blocking supervision, and an explicitly
separate retrodiction arm. The frozen synthetic mechanism gate passes, and
one actor-declared-clean single-game smoke favored AVO 3.2676 to 0.3968, but that
non-competition result is not claim-eligible. All packages remain private and
experimental; no ARC performance claim is made until an official closed
scorecard satisfies the frozen controlled-ablation gate in
ADR-254.@metaharness/avo lets an agent repeatedly inspect, edit,
execute real tools, evaluate, repair/revert, branch, consult structured RVF
memory, and commit—while MetaHarness retains immutable capabilities, budgets,
promotion, quarantine, rollback, and signed replay receipts. Simple work stays
on Darwin's fast path. The runtime has a deterministic 205-action RVF
interruption proof; the stronger “AVO-class” claim remains blocked on the
preregistered 100-task unseen SWE-bench gate in ADR-251.
ADR-276 now enforces
that boundary at publication against the exact tag SHA and npm tarball,
protected claim semantics, measured cost, lineage roots, and two independent
graders.@metaharness/host-prime-agent, --host prime-agent) emits your
tools as project-scoped, Python-backed Prime Agent skills (.prime/agent/skills/ — the host has
no MCP) plus an install runbook. Fail-closed: Prime Agent can't enforce a deny-list itself,
so a non-empty deny-list ships a prominent SANDBOX-REQUIRED.md instead of silently dropping
your posture. From its design we also shipped RefineMutator — an evidence-backed proposer in
@metaharness/darwin that must cite the
failing traces behind each edit or propose nothing — and an opt-in --sessions crash-recoverable
JSONL session log whose Rust and TS (wasm) replays produce identical state hashes. Its PTC
("kernel as the only tool") claim is honestly deferred behind a pre-registered A/B in
evals-toolcall. See ADR-246 /
ADR-247. ($0)npx metaharness score <repo> reads
the repo (never runs it) and prints a one-screen report card — how well a
harness fits, how likely it is to build, how safe the tools are, and the
rough cost per run — so you know what you'll get before scaffolding.@metaharness/router
routes each request to the right model from your own results — same quality,
far less spend. Works out of the box with zero native deps; train it on your
data for a sharper fit (npm i @metaharness/router). Add the optional
@ruvector/tiny-dancer
to train a fast native model instead — same training data, no API change.@metaharness/field-memory is an experimental,
single-process-by-default packed-attractor layer with verified outcome caps,
support quarantine, decay, cost-aware choice, and no raw-episode API. Its
RuVector adapter fails closed unless a corrected flat-index wrapper is used.@metaharness/darwin) wired in —
run npm run evolve and the harness mutates its own config, tests each change in a
sandbox, and keeps only what measurably improves. The model stays frozen; the harness
evolves. Safe by default (no network, no API key; pure refactor/tuning behind a safety
gate). Validated on real SWE-bench Lite bug-fixing. --no-darwin to skip.--field-memory to scaffold a small bootstrap around the forthcoming
@metaharness/field-memory@^0.1.0 package. The generated harness uses packed
attractors, three distinct verifier-derived principals for support, no
hysteresis, and a bounded drift window. Principal independence depends on the
verifier's identity system.
It will not open storage or accept shared updates until the deployment
supplies an absolute storage path, a compatible adapter, and a principal
verifier backed by deployment authentication. Package influence caps are
centroid-local; fleet-wide admission and rate limits belong in that verifier.
The RuVector adapter requires a configuration-verified, in-place FlatIndex
with cosine distance and rejects HNSW or unverified legacy stores.
Minimum support quarantines routing but does not make stored singleton
aggregates confidential; protect field snapshots and registry storage.
A deployment-secret identity hash key of at least 32 bytes is also required
and must survive state restore. Conflicting package declarations or an
existing field module fail before disk writes, and harness upgrade reapplies
the opted-in overlay only after validating its exact, versioned manifest
contract. Unsupported overlay schemas require an explicit migration.
storage.writerScope: process requires one writer service; multi-process or
fleet use requires distributed. The flag is off by default, so existing
scaffold output is unchanged.@metaharness/weight-eft, metaharness weight-eft) takes the
complementary lever to Darwin's gradient-free evolution: it exports the harness's gold-resolved
archive into standard SFT/DPO sets and LoRA-tunes the open cheap tier (GLM/Qwen), so the
cost-cascade escalates to Opus/GPT less often. It attacks cost (fewer $0.50 escalations),
not the frontier ceiling — and stays honest about it. Strict train/eval-disjointness +
reward-hacking filters keep the lift real; the tune is a gene Darwin can prune if it overfits.
See ADR-198. ($0 / GPU-gated.)A generated harness is a starting point you own, not a fixed framework. Open it and make it yours:
harness doctor / harness validate keep it healthy as you trim.npm publish — now anyone on your team runs
npx @your-org/your-harness and gets the same repo-tuned agent. One
command, org-wide, versioned like any other dependency. (The 19
@metaharness/* examples are exactly this pattern,
published live.)Make older, cheaper models punch like frontier ones. The right harness isn't a pile of extra steps bolted onto an expensive model — it's putting the right model on each task and getting out of the way. Our DRACO benchmark proves it: a small, cheap model delivers frontier-quality research at roughly one-tenth the cost, and a smart router squeezes out the rest. Stop paying frontier prices for work a $0.10 model does just as well.
That router ships as @metaharness/router
— route(query) returns the cheapest model predicted to clear your quality bar,
learned from your own eval logs. npm i @metaharness/router.
# In the browser — zero install, nothing leaves the page
open https://ruvnet.github.io/metaharness/
# Or in the terminal — the same harness (behaviourally equivalent output)
npx metaharness my-bot --template vertical:coding --host claude-code
cd my-bot && npx . --help
Don't know what to pick? Run the wizard:
npx metaharness --wizard
Already have a repo you want a harness for?
harness analyze-repo . # local — deterministic analysis only
harness analyze-repo . --scaffold my-bot # materialise the recommended harness
No repository code is executed. Inferred build/test commands are emitted as trust: inferred · execution: disabled.
The same harness output runs on ten agent hosts — nine interactive, plus GitHub Actions (CI/CD):
MCP is included as a first-class adapter surface, not the identity. It is gated and default-deny (ADR-022):
off · local (stdio) · remote (HTTPS + auth)src/mcp/{server,tools,resources,prompts,policy,audit}.ts + a scannable .harness/mcp-policy.jsonharness mcp-scan <path> — "npm audit for agent tools": static-only scan flagging shell/network grants, missing audit/timeouts, wildcard permissions, unguarded secrets, unpinned deps. Exits 1 on any HIGH.npx metaharness --list
npx metaharness my-bot --template vertical:coding
Each ships bespoke domain agents (with system prompts), skills, commands, and per-host settings — all default-deny.
Don't want to pick flags? Each host and vertical has a dedicated
@metaharness/* wrapper — published, one npx away, no template/host
flags to remember. A scaffold from a wrapper is byte-identical to the
equivalent metaharness invocation.
Host integrations
Vertical workflows (ready-made multi-agent pods)
All 18 are live on npm under @metaharness. Source + per-package README:
examples-packages/ · plain-language deep-dive gists:
examples-packages/GISTS.md.
After scaffolding, every harness has a harness CLI:
21 subcommands total. Every one respects --help / -h. Shell completion: harness completions bash | zsh | fish.
📖 Full reference: docs/USAGE.md
v0.1.x beta — published and usable, with the credibility/doc reconciliation in issue #4 / ADR-042 in progress. The release pipeline is mature: CI matrix green across Rust × 3 OS + WASM × 3 OS + Node 20+22 × 3 OS + Bench + pack+install × 3 OS
node scripts/release.mjs <bump> --push) atomically bump 15 sources, run all gates, and tag.You (harness author)
└→ agent-harness-generator ← the factory
└→ Your harness (.zip) ← what you ship
├ npx <your-name> ← your identity
├ <your agents> ← your content
└ @metaharness/kernel ← shared primitives (Rust + WASM + NAPI-RS)
└→ Host adapter (Claude Code / Codex / pi.dev / Hermes / OpenClaw / RVM)
└→ LLM providers
You operate the factory. The factory produces your harness. Your users never see the factory — only the brand and CLI you ship. The kernel ships as @metaharness/kernel (Rust → wasm-pack + NAPI-RS); your content stays yours.
📖 Deeper: docs/ARCHITECTURE.md · docs/adrs/INDEX.md (220 ADRs)
git clone https://github.com/ruvnet/metaharness
cd metaharness
cargo test --workspace
cargo clippy --workspace --all-targets -- -D warnings
npm install
npm run build:wasm
npm test
node scripts/healthcheck.mjs
See CONTRIBUTING.md.
Which harness resolves the most benchmark per dollar, not just the highest raw score — ranked by a tunable
Value Score that blends capability and price. Tabs: SWE-bench Lite / Verified / Pro / DRACO /
SWE-ultralite (a fast n=25 model×mode scouting map). Every Darwin row is fully conformant (the solver never
sees gold tests during solving) and measured with the official swebench Docker harness, with Wilson 95% CIs.
Latest validated, conformant results (2026-06-26):
The same cheap→frontier empty-patch cascade (escalate only the empties to Opus) measures 55.6% on the full
SWE-bench Verified (500) — official swebench gold eval, conformant, ~56× cheaper than frontier-only — which
beats the Lite cascade (51.3%); the pattern generalizes across both splits. SWE-bench Verified cost is an
estimate (per-instance cost not captured in predictions). LiveCodeBench (n=100, contamination-resistant
post-cutoff window) lifts 44% → 62% via cost-cascade; caveats are honest: deepseek snapshot cutoff unpinned,
part of the lift is run-to-run variance (clean attributable lift +8 on the escalated tail), n=100 is directional
(not 1:1 with the official whole-release ~34%). Details in
packages/darwin-mode/bench/results/RESULTS.md (§33) and
LEARNINGS.md (§46b/§47).
Run your own harness and put it on the board — fork, add a measured row, open a PR. Conformance rules, the entry schema, and a step-by-step walkthrough are in SUBMISSIONS.md.
MIT — see LICENSE.
MetaHarness is a CLI and browser Studio that turns any GitHub repo (or a
blank slate) into a custom AI agent harness. The output is a branded,
npm-publishable package with its own npx <name> CLI, MCP server, memory,
governance policy, and Ed25519 witness-signed releases. Runs on ten hosts:
Claude Code, Codex, pi.dev, Hermes, OpenClaw, RVM, Copilot, OpenCode,
GitHub Actions, and Prime Agent.
Frameworks help developers build agents. MetaHarness helps repositories ship agents. The model is replaceable; the harness is the product.
No. The Studio is 100% client-side (GitHub Pages). The CLI runs locally. There is no MetaHarness account, no hosted backend, no telemetry.
No. metaharness analyze and metaharness genome are deterministic
static-analysis only. Inferred build/test commands are marked
trust: inferred · execution: disabled.
Ten today: Claude Code, Codex, pi.dev, Hermes, OpenClaw, RVM, Copilot, OpenCode, GitHub Actions, Prime Agent.
Rust, TypeScript / JavaScript, Python, and Go are detected deterministically via lockfile and manifest probing. Lexical scoring is the default; optional in-browser MiniLM embeddings via Transformers.js boost recall for unusual repos.
Yes — the generated harness ships with package.json, bin, a working
CLI, and harness validate to gate releases. harness sign adds the
Ed25519 witness; harness sbom emits SPDX-2.3.
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GitHub Copilot (VSCode) host adapter for agent-harness-generator. Emits .vscode/mcp.json for the Copilot MCP client (ADR-032).
{ "mcpServers": { "metaharness-host-copilot": { "command": "npx", "args": [ "-y", "@metaharness/[email protected]" ] } }}Tools
Noch keine Tool-Liste. Remote-Server erhalten eine nach dem ersten Health-Check.
FAQ
Kopieren Sie auf dieser Seite die stdio-Konfiguration für Cursor, Claude Desktop, Claude Code oder VS Code. Sie nutzt die Installation des Herausgebers, keinen PlugMCP-Proxy.
In diesem Eintrag ist keine erforderliche Umgebungsvariable aufgeführt.
@metaharness/host Copilot läuft lokal über stdio.
Zuletzt geprüft: 2026-11-08. GitHub Copilot (VSCode) host adapter for agent-harness-generator. Emits .vscode/mcp.json for the Copilot MCP client (ADR-032).