Yichen Jiang e53f448650 fix(subagent): compose children from their parent's preset
Tool and prompt-section visibility is inherited along dsh-scope's parent
chain, and an agent's scope key is minted with no parent. Per-session agent
presets moved every model-facing row onto the agent plane and made
AgentPresets.mount() the one thing that binds that link, from the api-proxy's
session create, resume, and fork paths. The two in-process subagent drivers
installed only the per-child persona and tool filter, so a child's scope chain
had length one and its registry view resolved the global layer alone — which
is empty wherever a preset roster is composed. One-shot children reached the
model with no tools, continuable ones with only the host-plane `report`, and
neither carried its parent's persona, workspace context, or skill catalog.

AgentPresets.composeFrom() joins one agent to the standing composition another
already runs on. It is a bind, not a mount: the child gets its parent's exact
generation, so a composition edited since the parent started cannot fork it
onto another one, and it is synchronous, which is what lets a child creation
window use it. applyChildComposition() now takes the parent and performs the
join first, making a child composed without it unrepresentable at the call
sites. childSessionMeta() records the joined id so a cold read rebuilds the
composition the child actually ran under.

The audit that followed found two api-proxy readers on the wrong authority:
presenterScopeFor() and the live-agent branch of assertPresetUnchanged() both
read header.agentPreset, which goes stale the moment a blank session switches
preset. A switched session's cold transcript resolved presenters in the older
composition's layer and silently degraded to generic cards, and the gateway
refused to adopt a live session under the preset it actually runs while
accepting the one it left. Both now resolve through resolveSessionPreset(),
matching the resume branch fifteen lines above. The owning architecture Agent
Note carried the stale claim that the header records what a session runs; it
is corrected to name the header/log pair and its three readers.

Fixes #2165
2026-08-10 17:46:34 +08:00

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_code tool 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

BSD 3-Clause

Third-party dependencies and their licenses are disclosed in THIRD_PARTY_NOTICES.md.

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