The JSONL retired-content admission matrix covers both historical V3 input and native V4 input across read/write and plain/zstd storage. V3 migration now prefixes unknown ignorable event identities with plugin:, while native V4 reads retain their stored identity. The shared expectation still required the unchanged V3 event tag and caused four deterministic CI failures. Select the expected event type by input generation while retaining the full payload, envelope, and immutable source-byte assertions. This corrects the test for the intended migration without weakening native admission or changing runtime behavior. The focused 20-case matrix now passes; restoring the old expectation reproduces the same four failures locally.
DeepSeek Harness
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DeepSeek Harness (dsh) is an open-source agent harness developed by DeepSeek AI.
It is built on an everything-is-a-plugin architecture and powered by Cordis, whose design is described in A Programming Paradigm for Spatiotemporal Composability.
Documentation: https://deepseek-harness.github.io/deepseek-harness/
Developer preview
DeepSeek Harness is in developer preview and iterating rapidly. THERE WILL BE COMPATIBILITY-BREAKING CHANGES.
Review the safety notice before running the project.
Run
Run from npm
Install Node.js, then run:
npx @deepseek-ai/dsh web
The command starts the Web UI at http://127.0.0.1:3080 by default and opens it in the default browser for a local launch. An SSH launch only prints the host URL because the SSH client or editor owns the local forwarded address. Pass --no-open to run the server without opening a browser. See Web UI guide.
Run from source
To run from a repository checkout:
git clone https://github.com/deepseek-ai/deepseek-harness.git
cd deepseek-harness
pnpm install
pnpm run build
pnpm dsh web
pnpm run build prepares the repository artifacts. pnpm dsh web uses those built artifacts without rebuilding.
Community and support
- Submit feedback or bug reports through GitHub Discussions.
- Add the
dsh-plugintopic to your plugin repository for discoverability. - Join DeepSeek Harness Discord community.
Contributing
See CONTRIBUTING.md.
Development
Start with the development guide and architecture documentation.
For agents, follow AGENTS.md.
Citation
@misc{deepseek-harness2026,
title={DeepSeek Harness: Everything is a Plugin},
author={DeepSeek-AI},
year={2026},
publisher={GitHub},
howpublished={\url{https://github.com/deepseek-ai/deepseek-harness}},
}
License
Third-party dependencies and their licenses are disclosed in THIRD_PARTY_NOTICES.md.