DeepSeek
DeepSeek Harness, also called dsh, is an open-source coding agent and agent development/runtime environment built on the Cordis plugin system. The Cordis kernel manages plugin mounting, unmounting and dependencies, while developers can swap or extend capabilities through configuration without changing the Harness source. Its append-only session log records system prompts, reasoning, tool calls and results, subagent scheduling and context injection; the Trajectory view supports inspection, resume, fork, search and replay from the same event stream. Four documented modes cover a full Standard coding agent, TypeScript-orchestrated Code mode, a two-tool Minimal benchmarking mode and a Creator mode for runtime inspection and custom presets. The project is in developer preview and explicitly warns that compatibility-breaking changes will occur.
Editorial verdict
Developers building or studying composable coding agents, custom agent modes, plugin ecosystems and traceable local-first runtimes.
Avoid production standardization when API stability is mandatory, or running it on sensitive systems without isolation, approval gates and reviewed integrations.
This is DeepSeek's own open agent harness rather than another API integration guide: it exposes the runtime architecture, trace history and extension surface needed to build customized coding agents.
Free MIT-licensed software; model APIs, external tools and infrastructure may incur separate costs
Self-hosted open source, DeepSeek API billing, Third-party model provider billing
The repository is MIT licensed. Production use must also follow the Safe Use Policy plus the terms and licenses of configured models, plugins, MCP servers, tools and dependencies.
Session data, tool records, files, paths, runtime logs, provider addresses and API keys are stored locally by default. Anonymized configuration and project lists may be reported, with an option to disable or redirect reporting; external models, web tools, MCP services and plugins may transmit data under their own policies.
Run the Web UI against a selected workspace with file editing, shell, search, planning, goals, subagents and workflows.
Compose or replace models, tools, storage, scheduling, loops and UI through Cordis configuration and plugins.
Inspect complete model context and tool activity, then resume, fork, search or replay from one event stream.
Use Minimal mode with persistent bash and str_replace_editor to benchmark models in a constrained environment.
Checked August 14, 2026. DeepSeek labels Harness a developer preview and warns of compatibility-breaking changes; recheck release status, package versions, plugin APIs and policies before production adoption.
AtomCode is a narrower Rust terminal coding agent with multi-model support and a smaller runtime surface.
DeerFlow focuses on research, coding and creation with sandboxes, memory, skills and messaging channels.
Existing coding agents can use DeepSeek's OpenAI- or Anthropic-compatible APIs without adopting the dsh runtime.
official · en · verified 2026-08-14
Confirms developer-preview status, plugin architecture, traceability, four runtime modes, quick start, source release and MIT positioning.
repository · en · verified 2026-08-14
Confirms public source, Cordis architecture, npm and source installation commands, compatibility warning and MIT license.
docs · en · verified 2026-08-14
Documents model-key configuration, workspace selection, file and command access, delegation, planning and permission approvals.
terms · en · verified 2026-08-14
Confirms local-default storage, optional anonymized reporting and third-party data-transfer boundaries.
terms · en · verified 2026-08-14
Documents isolation, human approval, prompt-injection, plugin trust and use-restriction requirements.
Last checked: 2026-08-14