Yichen Jiang
c56f23ae1f
A hand-damaged preset was silent until the worst moment. An unparsable composition listed as an ordinary selectable row and failed only at the next session start — set as default, every new session failed. A directory whose composition file was deleted vanished from the roster while still occupying its id: copy answered "delete the existing preset first" while remove answered "not found", a dead end. Discovery now owns health: every id-shaped directory is a roster slot, broken when its composition is missing or unloadable, checked with the loader's own entryListSchema dialect (!!js included) so health never rejects what the loader accepts. `broken` rides AgentPreset, the agentPreset.list entry, and the UI row; mount/recompose/standingKeyFor refuse broken up front with the discovery-reported reason, while resolve/read/remove still answer. The section renders marked red cards — unselectable, uncopyable, deletable, location kept on custom rows — and both pickers drop broken rows entirely. The cordis preset's persona now forbids editing the shipped install (corrupting cordis would disable the mode itself) and points authoring at $DSH_HOME/.agent-presets; its skill teaches preset.yml metadata, the copy-first workflow, the one-escalation sandbox reality, and honest verification. Exercised live: asked to edit the shipped composition the composed agent refuses citing both rules; asked for real presets (simple and complex) it lands them under the user root with one approved escalation each and self-checks with the loader dialect.
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.
Install
Clone the repository, then run the installer:
git clone <repo-url>
cd deepseek-harness
scripts/install.sh
The installer requires git and Node ^22.19 || >=24, offers to install pnpm when it is missing, prompts for a DeepSeek API key, builds the required repository artifacts, and launches the Web UI.
The default active checkout is ~/.dsh/source/current, and the launcher is linked into ~/.local/bin. Re-run the installer to update. scripts/install.sh owns alternate locations, update mechanics, and recovery options.
Use DeepSeek Harness
Web UI
For the recommended local interface, choose Web UI when the installer finishes. To start it later, or after updating the active checkout, build the repository and run:
(cd ~/.dsh/source/current && pnpm run build)
dsh web
The path above is the installer's default. If you set DSH_SOURCE or DSH_CURRENT, or reused an existing checkout, replace ~/.dsh/source/current with that checkout path; see scripts/install.sh for details. The Web UI is served at http://127.0.0.1:3080 by default.
Profiles
dsh boots profiles — ordered stacks of plugin-bundle patch layers under your own overrides in $DSH_HOME/profiles/<name>:
dsh --profile web # the browser UI (same as: dsh web)
dsh plugin --profile tui add <package> # install a plugin into a custom profile
dsh --profile tui # boot it
The CLI contract describes profile layout, layer semantics, and config dump commands.
Headless
Run one task, print the final answer, and exit:
dsh run "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.