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Unity Plugin for DeepSeek Harness

Build Unity games with an AI agent. This plugin connects DeepSeek Harness to the Unity Game Engine, so you can describe what you want in plain language and the agent does the work inside the Unity Editor: creating projects, building scenes, writing and attaching C# scripts, importing your Asset Store purchases, running tests, and producing builds.

It talks to the Editor through Unity's official unity command-line tool, so everything happens in a real, running Editor and stays in sync with what you see on screen.

What you can do

• Start a game from scratch. "Create a new 3D project called SpaceRunner using the URP template" and the agent picks the template, creates the project, and opens the Editor.
• Build scenes by talking. Add GameObjects, position them, attach components, wire up prefabs. Scene commands round-trip in well under a second with no recompile.
• Write gameplay code. The agent creates C# scripts, waits for the recompile, and attaches them to the right objects. It can also run C# directly inside the Editor for anything that has no dedicated command.
• Put your Asset Store library to work. The agent can search the assets you own on the Unity Asset Store ("My Assets"), download them, and import them straight into the open project. See Using your Asset Store assets.
• See and test the result. Take screenshots of the Scene view, enter and exit Play mode, run EditMode and PlayMode tests.
• Ship it. Kick off player builds for your target platform.
• Learn from Unity's own playbooks. The plugin bundles Unity's official agent skill collection (UI, physics, optimization, multiplayer, package management, and more), so the agent follows Unity best practices instead of guessing.

Prerequisites

Before installing, make sure you have:

1. DeepSeek Harness 0.1.2-alpha.5 or newer. Older versions are not supported.

2. The unity command-line tool, installed, signed in, and with an activated license. Check with:

   unity auth status
   unity license status
   

3. Unity 6.0 or newer installed through the Unity Hub. Live control of the Editor requires Unity 6.

4. Python 3.9 or newer (only needed for the Asset Store feature; no extra packages required).

Each project you want the agent to drive needs the com.unity.pipeline package. You do not have to add it by hand: the agent can install it for you, or you can run it once yourself:

unity pipeline install --project-path /path/to/MyGame

Install

Add the plugin to the DeepSeek Harness profile you use:

dsh plugin --profile <name> add @opdsh/unity-plugin
dsh --profile <name>

That's it. Start the harness and ask the agent to make a Unity game.

dsh plugin --profile <name> add github:opdsh/unity-plugin  # from GitHub
dsh plugin --profile <name> add /path/to/unity-plugin      # local checkout

Installing from GitHub builds the package on install, which pnpm blocks until the package is allowlisted. If the first attempt fails with ERR_PNPM_GIT_DEP_PREPARE_NOT_ALLOWED, add this to the profile's pnpm-workspace.yaml and run the command again:

onlyBuiltDependencies:
  - "@opdsh/unity-plugin"

A local checkout installs as a link and needs no allowlist entry, but you must build it first with pnpm install && pnpm build.

To confirm the plugin loaded, run dsh --profile <name> --dump-config and look for the # == unity-plugin section.

Your first session

1. Open the Editor for your project, or let the agent create a new one.

2. Ask for something concrete, for example:

   Open the project at C:\Games\SpaceRunner, add a Player capsule at the origin with a Rigidbody, and write a script that moves it with WASD.

3. The agent checks which Editors are running, discovers the commands the Editor offers, makes the changes, and saves the scene.

Tips:

• The agent launches the Editor with the -automated flag so no dialog boxes block it. If you open the Editor yourself, that's fine too; the agent will find it.
• The first time a new project opens, Unity imports assets and can take a few minutes. The agent waits for the Editor to report "ready".
• Ask the agent to take a screenshot whenever you want to see what the scene looks like.

Using your Asset Store assets

Everything you have bought or claimed on the Unity Asset Store is available to the agent. It signs in with the same Unity account the unity CLI and Unity Hub already use, so there is nothing extra to set up.

Ask for an asset by name or by description:

Add the 2D Game Kit to this project.

Find a low-poly nature pack in my assets and import it.

The agent then:

1. Searches your "My Assets" library and picks the matching package.
2. Checks that the package supports your project's Unity version and warns you if it does not.
3. Downloads the .unitypackage from Unity's servers.
4. Imports it into the open project silently, with no import dialog.
5. Waits for any recompile to finish and tells you which folder under Assets/ the files landed in.

Only assets you already own are available this way. To use something new, buy or claim it on the Asset Store in your browser and it appears in your library right away. If your Unity sign-in has expired, the agent will ask you to run unity auth login or sign in through the Unity Hub, then continue.

The Asset Store feature works on Windows and macOS and needs Python 3.9 or newer.

Configuration

Most people never need to change anything. If you do:

In the web GUI: open Settings → Plugins → Plugin configuration and find the Unity Plugin card. There you can adjust the two timeouts and the output size cap. Changes apply immediately without a restart, and empty fields fall back to the defaults.

In the profile: for everything else (default project path, the path to the unity binary, CI credentials), edit the profile's cordis.patch.yml. A patch replaces the plugin's whole config block, so include every key you want to keep:

- insert:
    - id: unity
      name: '@opdsh/unity-plugin'
      config:
        unityBin: unity                    # path to the unity CLI if it is not on PATH
        projectPath: /abs/path/to/MyGame   # default project for Editor commands
        commandTimeoutMs: 120000           # per Editor command; must be > 0
        cliTimeoutMs: 600000               # for builds, tests, and other CLI calls; must be > 0
        graceMs: 5000
        outputMaxBytes: 512000             # must be > 0
        env: {}                            # e.g. UNITY_SERVICE_ACCOUNT_ID / SECRET for CI
        warmShell: true                    # keep one `unity shell` alive for fast Editor commands
        shellIdleMs: 300000                # close the idle shell after this long
        unitySkillsRepo: https://github.com/Unity-Technologies/skills  # '' disables the download
        unitySkillsRef: 87fac23d66a1f44f5e06c2935eccce0b40b9715a       # or a branch such as main

unitySkillsRef pins the version of Unity's official skills. The default is a tested commit; set it to main to follow the latest content. Skills are downloaded once per ref into <dshHome>/cache/unity-plugin/unity-skills; if the download fails, an existing cache keeps working.

Troubleshooting

What's included

Agent tools

Skills

• Unity's official skill collection, downloaded from Unity-Technologies/skills: unity-cli, new-unity-project, build-live-game, the UI family, package management, physics, optimization, multiplayer, and more.
• unity-workflow: how to drive the Editor safely with the tools above (check status first, bootstrap a project, the scene loop, tests and builds).
• unity-asset-store: search, download, and import assets you own from the Unity Asset Store.

A project- or user-level skill with the same name overrides a bundled one.

For contributors

pnpm install
pnpm typecheck
pnpm build

The build emits lib/index.mjs (the Node half the dsh Loader imports) and lib/client.js (the browser half, declared via dsh.client in package.json and served by the web GUI at /plugins/@opdsh/unity-plugin/client.js). The browser half loads only when the plugin is installed into a profile by package name; an absolute-path --patch overlay loads the Node half only.

To load from source against a deepseek-harness checkout without installing, write a patch overlay pointing at this checkout's entry point (absolute path; run pnpm install here first):

# dev.cordis.yml
- insert:
    - id: unity
      name: '/abs/path/to/unity-plugin/src/index.ts'

Then, from the deepseek-harness checkout:

pnpm dsh web --patch /abs/path/to/dev.cordis.yml

• Tools spawn the CLI through the harness subprocess service: argv only, never shell-interpreted; bounded collected output; tree-scoped termination; the abort signal is forwarded so tool timeouts kill the whole process tree.
• The four live-Editor tools (unity_status, unity_list_commands, unity_command, unity_eval) share a warm unity shell --protocol ndjson session per working directory, cutting per-call latency from roughly 600 ms of CLI start-up to single-digit milliseconds. Requests serialize per session; a timeout or cancellation mid-request kills the session and the next call respawns it; idle sessions are disposed after shellIdleMs. Set warmShell: false to fall back to one process per call. unity_cli always spawns per call because builds and tests run long and want raw streams.
• Every invocation passes --non-interactive, so a command that needs interactive input fails loudly instead of hanging the agent.
• The subprocess service scrubs credential-shaped environment variables from the child; CI service-account credentials must be passed explicitly via the env config field.
• commandTimeoutMs, cliTimeoutMs, and outputMaxBytes must be greater than zero. The settings card refuses to save invalid values, and a stored invalid value leaves the namespace on its last good one.
• Live-Editor tools return the CLI's uniform JSON envelope ({ success, command, data, errors, warnings }) as structured output, so they compose with Code Mode.
• Alternative integration: the CLI ships an MCP stdio server (unity mcp). Pointing @deepseek-ai/dsh-mcp-client at it works with zero code but forfeits render cards, config validation, and curated tool descriptions. This plugin exists to provide those.
• How the upstream Unity skills are fetched and patched: assets/UNITY-SKILLS-UPSTREAM.md.

Known limitations

• The Editor command set is discovered at runtime; the plugin does not pin or validate per-command parameter schemas.
• unity_cli starts one CLI process per call by design; only the four live-Editor tools use the warm session.
• The Asset Store feature works on Windows and macOS only.

License

MIT