Unofficial. This project has no tie to DeepSeek. It targets DeepSeek Harness 0.2.1-rc.2.

What is this?

DeepSeek Harness (DSH) is a desktop agent app. This package lets another agent drive it.

You get two small parts:

• A host plugin. It runs inside the DSH app. It serves a token-guarded loopback HTTP bridge.
• A stdio MCP server. Your MCP client (Claude Code, for example) starts it. It talks to the bridge.

Your client opens a normal DSH session, sends it messages, waits for the reply, and reads it. The session shows in the app like any other session. You can watch it, or take it over, any time ♡

Requirements

• DeepSeek Harness 0.2.1-rc.2, with a profile you can edit.
• Node.js ^22.19.0 or >=24.0.0.
• An MCP client that speaks stdio.

Install

1. Install the plugin

Use the dsh CLI. Replace default with the name of your profile.

dsh plugin --profile default add github:stellarie/dsh-session-bridge

The install builds the package from source, so it needs no separate build step.

Or edit the profile by hand. Add the package to the profile package.json. Then list it in the bundles, after @deepseek-ai/dsh-web-app.

{
  "dependencies": {
    "@stellarie/dsh-session-bridge": "github:stellarie/dsh-session-bridge"
  },
  "dsh": {
    "profile": {
      "bundles": [
        "@deepseek-ai/dsh-base",
        "@deepseek-ai/dsh-web-app",
        "@stellarie/dsh-session-bridge"
      ]
    }
  }
}

The package ships a cordis.patch.yml. It inserts the plugin row for you. Restart the app. The log shows session-bridge: serving http://127.0.0.1:…/session-bridge.

2. Register the MCP server

Point your MCP client at the copy inside the profile (<profile-dir> is your DSH profile directory):

claude mcp add dsh-session-bridge -- node <profile-dir>/node_modules/@stellarie/dsh-session-bridge/lib/mcp.js

Or run it from npm, with no profile install:

claude mcp add dsh-session-bridge -- npx -y -p @stellarie/dsh-session-bridge dsh-session-bridge-mcp

Any other MCP client works too. The command is dsh-session-bridge-mcp. The transport is stdio.

The MCP server reads the endpoint file on every call. An app restart needs no MCP restart.

Tools

Tool	What it does
dsh_list_sessions	List sessions: id, title, preset, working directory, running or idle.
dsh_open_session	Open a session in cwd. Reuses the newest idle session with the same preset and cwd. Pass reuse: false for a new one.
dsh_send	Send a message. Mode queue runs after the current turn. Mode steer joins the running turn. Returns afterSeq.
dsh_wait	Wait until the session ends a turn after afterSeq. Default 600 s, maximum 600 s.
dsh_read	Read your prompts and the assistant text after afterSeq. Tool calls and thinking are left out.
dsh_cancel	Interrupt the running turn. Queued messages stay queued.

A typical round trip:

dsh_open_session { cwd: "C:/repo", preset: "my-preset" }  → { sessionId, reused }
dsh_send         { sessionId, text: "Fix the failing test" } → { accepted, afterSeq: 41 }
dsh_wait         { sessionId, afterSeq: 41 }               → { ended: true, lastSeq: 58 }
dsh_read         { sessionId, afterSeq: 41 }               → { messages: [ … ] }

dsh_open_session defaults preset to yuu, the author's own preset. Pass your own preset id. See BACKLOG 1.

How the bridge stays safe (｀ω´)ゞ

The bridge gives full owner control of your sessions. Read this part, please.

Every request must pass these checks, in this order:

1. No Origin header. Browser pages always send one, so they are refused.
2. A loopback Host (127.0.0.1, localhost, or [::1]) with the server port.
3. A bearer token, compared in constant time.
4. POST only, with a JSON body of at most 1 MiB.
5. A method on the allowlist: create, prompt, page, projections, list, cancel.

The token is 32 random bytes. The plugin mints a new one at each start. It writes endpoint.json (url, token, pid, startedAt) with mode 0600 (POSIX) and deletes it on shutdown.

• Treat the endpoint file as a secret. Anyone who reads it can prompt your agents.
• The bridge listens only where the DSH web server listens. It adds no port of its own.
• The bridge speaks as the app owner. A prompt you send acts like a prompt you type in the app.

Configuration

Setting	Where	Default
endpointPath	plugin config in cordis.patch.yml	$DSH_HOME/session-bridge/endpoint.json
DSH_SESSION_BRIDGE_ENDPOINT	environment of the MCP server	unset
DSH_HOME	environment	~/.dsh

Set the same path on both sides when you move the file.

Develop

pnpm install
pnpm run typecheck
pnpm test
pnpm run build

The build writes lib/index.js (the plugin) and lib/mcp.js (the MCP server).

License

MIT © stellarie. Made with ♡ (๑˃ᴗ˂)ﻭ