unity-pluginDeepSeek Harness plugin

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unity-plugin

A DeepSeek Harness plugin that lets the agent build Unity games by driving the Unity Editor through the official unity CLI: project creation, live-Editor scene commands, in-Editor C# eval, tests, and builds.

What it registers

Tool	Purpose
unity_status	Report running Editor instances reachable via the Pipeline server.
unity_list_commands	Discover the connected Editor's command catalog with parameter schemas.
unity_command	Run one live-Editor command (create_gameobject, get_scene_hierarchy, save_scene, …); completes in under a second with no domain reload.
unity_eval	Execute C# inside the Editor process with full UnityEngine/UnityEditor access.
unity_cli	Raw escape hatch for every other CLI surface: projects create, open, pipeline install, templates list, editors, test, build, auth, license, logs.

When the dsh deployment has skill support (a composed skills service; the standard profiles do), the plugin mounts two skill roots through @deepseek-ai/dsh-skill-filesystem:

• Unity's official skill collection, fetched at plugin activation from Unity-Technologies/skills (unity-cli, new-unity-project, build-live-game, the ui family, package management, physics, optimization, multiplayer, and more) into <dshHome>/cache/unity-plugin/unity-skills. The fetch is a shallow git clone of the configured unitySkillsRef (default: a pinned known-good commit; set a branch such as main to snapshot newer content). Content is fetched once per configured ref; changing the ref re-fetches. If the fetch fails, an existing cache keeps serving; with no cache the plugin logs a warning and runs with only its own skills. Mechanism and upstream-defect handling: assets/UNITY-SKILLS-UPSTREAM.md.
• The plugin's own skills (assets/skills/): unity-workflow, the unity_* tool operating knowledge (status-first discipline, project bootstrap sequence, scene loop, build/test invocations), and unity-asset-store, search/download/install of the user's owned Asset Store purchases.

All mounted skills use the standard bundled rank, so a same-named project- or user-level skill overrides them.

When the deployment has user-settings support (a composed settings service; the standard profiles do), the plugin also registers the unity settings namespace (the user-editable subset: both timeouts and the output cap), and its browser half adds a Unity Plugin card to the dsh web GUI under Settings → Plugins → Plugin configuration. Values saved there override the composition config per user, mark themselves as overridden, and apply live: the tools and warm shell remount with the new values without a restart. Empty fields inherit the deployment configuration.

Live-Editor tools return the CLI's uniform JSON envelope ({ success, command, data, errors, warnings }) as structured output, so they compose cleanly with Code Mode.

Prerequisites

• DeepSeek Harness 0.1.2-alpha.5 or newer. That line moved the settings consumer API onto the settings service and replaced dsh-client-runtime with dsh-client-store; the plugin follows it and no longer loads on 0.1.1.
• The unity CLI installed and authenticated (unity auth status), with an activated license.
• A Unity 6.0+ Editor for live control; the target project needs the com.unity.pipeline package (unity pipeline install --project-path <p>; the agent can run this itself via unity_cli).

Install

Into a dsh profile (dsh plugin add passes the spec to pnpm add, so any spec pnpm accepts works):

sh
dsh plugin --profile <name> add @opdsh/unity-plugin      # from npm
dsh plugin --profile <name> add github:opdsh/unity-plugin  # from GitHub
dsh plugin --profile <name> add /path/to/unity-plugin      # local checkout
dsh --profile <name> --dump-config                         # verify the "# == unity-plugin" layer
dsh --profile <name>

Installing from GitHub (rather than npm) builds the package through its prepare script, which pnpm blocks until the package is allowlisted. The first attempt fails with ERR_PNPM_GIT_DEP_PREPARE_NOT_ALLOWED; add this to the profile's pnpm-workspace.yaml and re-run:

yaml
onlyBuiltDependencies:
  - "@opdsh/unity-plugin"

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

The bundle patch inserts the plugin with schema defaults. Override configuration from the profile's cordis.patch.yml (a patch replaces the row's whole config):

yaml
1- insert:
2    - id: unity
3      name: '@opdsh/unity-plugin'
4      config:
5        unityBin: unity
6        projectPath: /abs/path/to/MyGame   # default target for live-Editor tools
7        commandTimeoutMs: 120000           # must be > 0
8        cliTimeoutMs: 600000               # must be > 0
9        graceMs: 5000
10        outputMaxBytes: 512000             # must be > 0
11        env: {}                            # e.g. UNITY_SERVICE_ACCOUNT_ID/SECRET for CI
12        warmShell: true                    # live-Editor tools reuse one `unity shell` process
13        shellIdleMs: 300000                # idle warm session disposal
14        unitySkillsRepo: https://github.com/Unity-Technologies/skills  # '' disables the download
15        unitySkillsRef: 87fac23d66a1f44f5e06c2935eccce0b40b9715a       # or a branch, e.g. main

Development

sh
pnpm install
pnpm typecheck
pnpm build

The build emits two artifacts: lib/index.mjs (the Node half the dsh Loader imports) and lib/client.js (the browser half in the harness client-bundle shape, declared via dsh.client in package.json and served by the web GUI at /plugins/@opdsh/unity-plugin/client.js). The client-modules scan resolves the plugin by package name from the profile directory, so the browser half loads only when the plugin is installed into the profile (dsh plugin add); the absolute-path --patch dev overlay loads the Node half only.

To load from source against a deepseek-harness checkout without installing, write a patch overlay naming this checkout's entry point (the path must be absolute, and pnpm install must have run here first so the source imports resolve):

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

Then run it from the deepseek-harness checkout:

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

Design notes

• Tools spawn the CLI through the harness subprocess service (argv, never shell-interpreted; bounded collected output; tree-scoped termination; abort signal forwarded so tool timeouts kill the process tree).
• The four live-Editor tools (unity_status, unity_list_commands, unity_command, unity_eval) run through a warm unity shell --protocol ndjson session (one long-lived CLI process per working directory; {"id","argv"} request lines, {"id","exitCode","envelope"} responses), cutting per-call latency from ~600 ms of CLI start to single-digit milliseconds. Requests serialize per session; a tool timeout or cancellation mid-request kills the session tree (one request in a shared process cannot be cancelled alone) and the next call respawns it; idle sessions are disposed after shellIdleMs. Set warmShell: false to fall back to one CLI process per call (e.g. a CLI version without unity shell). unity_cli always spawns per call: builds and tests run long and want raw streams, not a serialized REPL turn.
• Every invocation runs with --non-interactive so a command needing interactive input fails loud 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: a timeout of zero or less is not a tool the registry will accept, so the schema refuses the value rather than letting it unregister the tools. The settings card marks such an entry invalid and blocks the save; a stored value that fails leaves the namespace on its last good one.
• Alternative integration: the CLI ships an MCP stdio server (unity mcp) exposing the same Editor commands. Connecting @deepseek-ai/dsh-mcp-client to it (command: unity, args: [mcp]) works with zero code, but forfeits dsh render cards, config validation, and curated tool descriptions. This plugin exists to provide those.

Known limitations

• The Editor command set is discovered at runtime; this plugin does not pin or validate per-command parameter schemas.
• unity_cli pays one CLI process start per call by design (see Design notes); only the four live-Editor tools use the warm session.