Branch-length batch covering tooling, the model layer, the Web App and the public surfaces. Highlights: - Changelog: a per-release `changelog/<version>/` tree, grouped by the surface each change touches, with a root CHANGELOG.md holding one line per release. - Dev startup: `scripts/dev-prebuild.mjs` serializes the skills+core prebuild behind a lock and keeps `pnpm install` current; `pnpm dev` runs server+web together. - AgentHub 0.3.3 -> 0.4.0: OmniMessage complete payloads carry one opaque `fidelity` object in place of item-level `signature`/`phase`, threaded verbatim through Trace, replay and resume; malformed classification adapted to the new error types. - Model layer: a model is always referenced by an explicit `(provider, model_id)` pair. The provider is never inferred, guessed or defaulted -- both the catalog inference and the unique-match config resolution are gone, and CLI, SDK, server routes and run_subagent all require the complete pair. Catalog gains the Qwen Token Plan, Qwen Pay-As-You-Go and Fireworks AI gateways, plus an expanded OpenRouter group. - Web App: catalog preset sync and per-group speed test on the Models page, positional slash commands, a markdown renderer, skill-library update reminders, and a vertically centred draft page whose upward menus size themselves to the room available. - Public surfaces: restructured READMEs, the penguin.ooo landing site and blog, refreshed benchmark results for both suites, and the demo videos playing on the landing page. Includes the fixes from a full review of the branch: 23 confirmed findings, among them a provider-inference bug that could send one vendor's API key to another vendor's endpoint, and an Escape handler that destroyed the composer's contents unrecoverably. Verified on the branch head: pnpm test (1127 passing, 7 packages), pnpm typecheck and pnpm format:check clean, Playwright e2e 14/14.
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PenguinHarness
With LangChain, you build agents by hand — at 1× speed.
With PenguinHarness, agents build agents — at 100×.
A zero-code Harness CLI and Web UI, connected to 1000+ models.
English | 简体中文
Why PenguinHarness
Three reasons, in deliberate order — from task quality, to how agents get built, to how they keep improving.
1. 🏆 Comparable quality, one to two orders of magnitude cheaper
A deliberately minimal toolset over clean low-level interfaces: fewer tool calls, fewer tokens — deeply tuned for open models like DeepSeek. Each harness on the model it is normally paired with, same tasks, head-to-head:
Best accuracy on data analysis — at 1/70 of Claude Code's cost.
2. ⚡ One sentence, and an Agent builds your Agent app
Type one sentence, and an Agent builds the complete Agent application for you — scaffold, code, and run instructions, end to end:
Collect the docs from https://github.com/ericbuess/claude-code-docs and build a RAG app that answers Claude Code questions as a configuration expert, citing its sources.
And this is the finished product — a docs expert with retrieval, cited sources that link to the original files, and example questions built in:
https://github.com/user-attachments/assets/9b7033e8-f08a-4c3f-bd33-547896664e6e
And generating this entire RAG app burned just $0.02 (¥0.2) of tokens — on DeepSeek V4 Pro.
3. 🧬 Self-evolution: it gets stronger with use
With PenguinHarness Skills, an Agent evaluates and optimizes itself: run the benchmark, find the lost points, ship version N+1 — with a snapshot before every round, and every request observable in the Trace view.
https://github.com/user-attachments/assets/922d13a6-5ffc-4685-9a39-352f02f9afc0
Supported Models
| Model | Providers |
|---|---|
| DeepSeek V4 | DeepSeek, OpenRouter, Fireworks AI, SiliconFlow, Qwen Token Plan |
| Kimi K3 | OpenRouter, Qwen Pay-As-You-Go |
| Kimi K2.6 | Moonshot AI |
| GLM 5.2 | Z.AI, OpenRouter, Fireworks AI, SiliconFlow, Qwen Token Plan, Qwen Pay-As-You-Go |
| Hunyuan 3 | OpenRouter |
| Qwen 3.8 Max | Qwen Token Plan (preview) |
| GPT 5.5 | OpenAI, OpenRouter |
| Gemini 3.5 Flash | Google Gemini, OpenRouter |
| Claude Opus 4.8 | Anthropic, OpenRouter |
Any OpenAI-protocol endpoint is supported: pick a preset above, or point a custom endpoint at any of the 1000+ online and local models.
Requirements
| Requirement | Supported |
|---|---|
| OS | Linux, macOS |
| Architecture | x64, arm64 |
| Runtime | bundled by the one-line installer (npm installs need Node >= 24) |
| Model | an API key for at least one model |
Installation
🌐 Web App — for humans
🚀 Install and launch the full experience (multi-session chat, Agent/skill/model management, usage stats, Trace observability, evaluation center):
curl -fsSL https://penguin.ooo/install.sh | sh
penguin web # start the service and open http://127.0.0.1:7364 (first login: admin / penguin-2026)
📦 Or via npm: npm install -g @prismshadow/penguin-cli. Configure models on the in-app Models page, then chat.
🤖 CLI & SDK — for agents
The same engine, scriptable — made to be driven by agents (and agents building agents):
penguin config model add --provider deepseek --model-id deepseek-v4-pro --api-key sk-... --set-default
penguin run -m "Create hello.txt containing Hello, Penguin" # one-shot task
penguin chat # interactive REPL (/compact, /exit, Ctrl-C to interrupt)
penguin server # headless service (same API the Web App uses)
import { createAgent, isCompleteModelMessage, userText } from "@prismshadow/penguin-core";
const agent = await createAgent({ agentId: "default_agent" });
const session = await agent.createSession({ workspaceDir: process.cwd() });
for await (const output of session.run([userText("Create hello.txt containing hi")], {
approve: async () => "allow", // per-tool-call approval
})) {
if (isCompleteModelMessage(output) && output.payload.type === "text") {
console.log(output.payload.text);
}
}
Roadmap
- Public release of the benchmark suite
- Desktop app
- Windows support
- More to come…
Development
pnpm install && pnpm build # build first: core's exports point at dist/
pnpm dev # backend + web app together (prefixed logs, deps built once)
See CONTRIBUTING.md for the full workspace guide: dev commands, quality gates, repo layout, and the changelog rule.
Citation
If you use PenguinHarness in your research, please cite:
@software{penguinharness2026,
author = {{PrismShadow Team}},
title = {PenguinHarness: Efficient Self-Improving Harness for Everyone},
year = {2026},
url = {https://github.com/Prism-Shadow/penguin-harness},
license = {Apache-2.0}
}
License
Apache-2.0 © 2026 Prism Shadow
Built with ❤️ by Yaowei Zheng (author of LlamaFactory), the PrismShadow AI Team, and Fable 5.