Yichen Jiang
5d2c943d38
The executor collapse landed without telling the model it exists. Every tool contributes its own guidance section naming its tool, none of them qualify how that tool is reached, and they all render before the SDK (orders 100-199 against SDK_SECTION_ORDER 150), so the prompt said "Use the read tool" eleven times and never said only run_code is callable. A real session shows the consequence: the model emitted a native call, read `unknown tool "read"` for a tool the same prompt declares, and concluded the deployment was inconsistent rather than routing through run_code. The registry now contributes `tools:code-only` at order 99 -- ahead of the guidance band -- stating the rule, registered wherever `tools:sdk` is and rendering empty outside an effective `code`. `both` renders it empty because its native calls do execute, which is also why both-mode-turn no longer shares code-mode-turn's expected prompt. The denial itself now names the route back, since a bare UNKNOWN_TOOL for a declared tool is what misled the model.
DeepSeek Harness
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DeepSeek Harness (dsh) is an open-source coding agent built on the DeepSeek Harness SDK.
It uses an architecture where everything is a plugin.
Internal testing notice
DeepSeek Harness is under internal testing. Features and interfaces may change.
The internal build uploads all Session Logs by default to help diagnose reported problems. Set DSH_TELEMETRY_DISABLED=1 to disable telemetry. Send feedback through the internal WeChat group.
Run from source
Clone this repo, complete the dependency and API-key setup, then run:
pnpm dsh web
Use DeepSeek Harness
Web UI
Start the recommended local interface from the repository root:
pnpm dsh web
The command builds the repository before starting the Web UI, which is served at http://127.0.0.1:3080 by default.
Profiles
The source CLI boots profiles — ordered stacks of plugin-bundle patch layers under your own overrides in $DSH_HOME/profiles/<name>:
pnpm dsh --profile web # the browser UI
pnpm dsh plugin --profile tui add <package> # install a plugin into a custom profile
pnpm dsh --profile tui # boot it
The CLI reference describes profile layout, layer semantics, and config dump commands.
Headless
Run one task, print the final answer, and exit:
pnpm dsh --profile headless "summarize this workspace"
Automation and SDKs
From a source checkout with DEEPSEEK_API_KEY in the environment or its root .env, start the ACP automation server:
pnpm run demo:acp
The Python SDK drives a bundled JSON-RPC runtime. The examples cover the runnable headless, ACP, JSON-RPC, Code Mode, and self-referential compositions.
Why DeepSeek Harness
Built-in capabilities cover file reading, editing, and search; shell and persistent PTY execution; reusable skills; task tracking, goals, plans, todos, and background tasks; subagents and workflows; sandboxing and approvals; settings and credentials; persistent, resumable, forkable, and queryable sessions; LSP and web access; context compaction; and telemetry. Each composition selects the subset appropriate to its surface. The Web UI includes Plan Mode.
- Everything is a plugin. Models, tools, policies, storage, context management, and interfaces are composable Cordis plugins, so deployments can extend or replace behavior without forking the agent loop. See the architecture for the underlying design.
- Runs are reconstructable. Anything visible to the model is logged in the authoritative session stream; persistence, resume/fork/query, replay, telemetry, and UIs derive from the same events. See the session-log architecture.
- Code Mode (opt-in). It exposes a
run_codetool and a generated TypeScript SDK; only program output re-enters model context. See Code Mode. - Self-referential Cordis tools are opt-in. They let the agent inspect its live runtime and mount or unmount plugins while it runs. See the Cordis tools.
Community
Follow DeepSeek Harness on Twitter for project updates.
Development
Start with the development guide and read the architecture before changing packages.
For agents, follow AGENTS.md.
DeepSeek Harness is currently in internal testing.
License
Third-party dependencies and their licenses are disclosed in THIRD_PARTY_NOTICES.md.
Contributing
Read CONTRIBUTING.md before contributing to this repository.