No Fork Required: Add Codex, Claude Code, Files, and Terminal to DeepSeek Harness

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This is the installation and architecture reference. For project workflows, start with the Turning DSH into a Multi-Agent Project Workbench series.

DeepSeek Harness is useful as a conversation surface, but extending that surface can create an expensive maintenance choice: patch DSH core and keep rebasing, or keep switching between separate agent and developer tools.

There is now a third path. Five independently installable plugins add Codex, Claude Code, workspace files, and a terminal to official DSH. They use DSH's plugin system, so you can update DSH without carrying a fork.

The recording is an actual npm installation on official DSH, not a mockup: open the H.264 MP4 or review the acceptance evidence.

This walkthrough is for DSH users who want another conversation backend or a more complete coding workspace. It is not a Relay Events tutorial: the five plugins work without Relay's event runtime.

What Changes After Installation?

Install the Codex plugin and Codex appears in DSH's New Session mode menu. The session is backed by a Codex App Server Thread while DSH keeps its native conversation, composer, approval, question, and tool presentation.

Install the Claude plugin and Claude Code appears beside it. That backend uses the Claude Agent SDK and continues the same Claude session across DSH turns.

Install Workbench with Files and DSH gains a right-side workspace tree and text preview. Install Workbench with Terminal and DSH gains a bottom xterm surface. The terminal presentation is provider-neutral; the Codex plugin is the currently published provider in this suite.

These are separate capabilities. A user who only wants Codex does not need Claude, Workbench, Files, Terminal, or Relay Events.

Why the Boundary Matters

The two conversation backends are independent plugins. Workbench owns only the public side/bottom view contracts. Files and Terminal use those contracts instead of importing each other's implementation. Terminal accepts providers through a public registry rather than calling Codex code directly.

That separation has two practical consequences:

1. Official DSH remains an immutable dependency instead of a customized codebase.
2. Each plugin can be versioned, tested, installed, and eventually moved to a different repository without dragging the rest of Relay with it.

Relay is the maintainer and compatibility workspace for the suite. Relay Events remains optional and has a different job: durable waits, monitors, external events, routing, and delivery into the correct DSH session.

Install the npm Packages

The commands below were validated against official DeepSeek Harness 0.1.1-rc.2 at commit b150a551. Node.js 22.13 or newer and pnpm on PATH are required.

Stop a running DSH Web process, then install the combination you need.

Codex only:

pnpm dlx @deepseek-ai/dsh@0.1.1-rc.2 plugin --profile web add \
  relay-dsh-plugin-codex@next

Claude Code only:

pnpm dlx @deepseek-ai/dsh@0.1.1-rc.2 plugin --profile web add \
  relay-dsh-plugin-claude@next

Files and Terminal, with Codex providing the live terminal:

pnpm dlx @deepseek-ai/dsh@0.1.1-rc.2 plugin --profile web add \
  relay-dsh-plugin-workbench@latest \
  relay-dsh-plugin-files@latest \
  relay-dsh-plugin-terminal@latest \
  relay-dsh-plugin-codex@next

The backend release candidates are recommended during the current DSH preview: Codex next contains the bundled cross-platform App Server runtime, and Claude next contains the current model-selection synchronization fix. Check each npm page before pinning a production version.

Start DSH Web again:

pnpm dlx @deepseek-ai/dsh@0.1.1-rc.2 web

Codex and Claude still require their normal local authentication. The plugins do not collect credentials. Workbench itself is intentionally invisible until a view plugin registers a panel.

Install a GitHub Development Build

You can test an unreleased commit directly from GitHub:

pnpm dlx @deepseek-ai/dsh@0.1.1-rc.2 plugin --profile web add \
  github:yangbobo2021/relay-dsh-plugin-codex#main \
  github:yangbobo2021/relay-dsh-plugin-claude#main \
  github:yangbobo2021/relay-dsh-plugin-workbench#main \
  github:yangbobo2021/relay-dsh-plugin-files#main \
  github:yangbobo2021/relay-dsh-plugin-terminal#main

Use a tag or full commit SHA instead of #main when you need reproducible installs. GitHub packages must be listed explicitly because DSH's pnpm profile does not accept a GitHub package hidden as a transitive dependency.

Verify Before Starting Work

Open a new session and check the visible behavior:

• the mode menu contains only the backends you installed;
• Files appears after selecting a workspace and can preview a text file;
• Terminal appears in the bottom Workbench panel;
• a live terminal reports its provider clearly instead of silently falling back.

You can inspect package composition from the CLI as well:

dsh plugin --profile web why relay-dsh-plugin-codex
dsh plugin --profile web why relay-dsh-plugin-files
dsh plugin --profile web why relay-dsh-plugin-terminal

Each repository runs CI against an official DSH checkout. Tagged releases use the repository's npm release workflow; current Codex and Claude candidates publish SLSA provenance, and the Workbench-side repositories are configured to do the same on their next tagged release.

Who Does Not Need This?

If standard DSH agents and the existing conversation UI already cover your workflow, install nothing. If you only need a command prompt outside the conversation, a normal terminal is simpler. If your actual problem is waking a long-running session from email, a webhook, or a monitored condition, that is Relay Events territory rather than a reason to install every UI plugin.

Start with one capability. The Relay DSH plugin catalog links every repository, npm package, dependency rule, and troubleshooting guide. Issues and compatibility reports are welcome in the relevant plugin repository.