# Unity Package Management > Use when adding, removing, upgrading, or discovering Unity (UPM) packages programmatically from outside the Editor — headless or CI package installs via the C# UnityEditor.PackageManager.Client API, verifying package ids/versions against the Unity registry, or choosing which packages a game needs by genre, platform, and monetization. The Unity CLI does not manage UPM packages, so this skill covers that gap. Triggers on "install a Unity package", "add com.unity.*", "set up packages headless/CI", "which packages for a [genre] game". - Skill: `unity-technologies/unity-package-management` (Agent Skill, multi-file: 2 files) - Install (CLI): `npx skillmds@latest add unity-technologies/unity-package-management` - Raw SKILL.md: https://api.skillmd.com/api/skills/unity-technologies/unity-package-management/raw - Safety review: pending - Works with: Claude Code, Claude.ai, OpenAI Codex - Category: Integrations & APIs - Author: Unity-Technologies (https://skillmd.com/u/unity-technologies) - Updated: 2026-09-17 - Page: https://skillmd.com/skills/unity-technologies/unity-package-management --- # Unity Package Management (headless, via the C# Client API) Add, remove, upgrade, and discover UPM (Unity Package Manager) packages programmatically with `UnityEditor.PackageManager.Client`, driven headless from the terminal or CI. Do **not** hand-edit `Packages/manifest.json` — the Client API resolves dependencies and compatible versions correctly, whereas manual edits routinely break resolution. This complements the **`unity-cli`** skill (editor install, project creation, build/test): the CLI has **no** package-management command, so all package work goes through the Editor's C# API. ## When to use - Add / remove / upgrade one or more packages in an existing or freshly-created project. - Set up a project's packages non-interactively in CI. - Verify a package id exists, or find its available versions, before depending on it. - Decide which packages a game actually needs — see [references/select-packages.md](references/select-packages.md). ## Choosing what to install Install what the project actually needs, not everything; prefer packages the chosen template already provides (URP templates already include the render pipeline, Input System, etc.). The genre / look / platform / monetization → package mapping, plus how to search the registry, is in [references/select-packages.md](references/select-packages.md). Produce a **deduplicated list of package ids** and read it back to the user before installing. ## The `-quit` problem — why NOT `unity run` for installs `Client.Add` / `Client.AddAndRemove` are **asynchronous**: they return a `Request` that only completes on later `EditorApplication.update` ticks (the UPM child process marshals its result back on the Editor's main-loop pump, so a blocking `while (!req.IsCompleted)` busy-wait deadlocks it). The Editor must **stay alive** after `-executeMethod` returns, until the request finishes. `unity run` **cannot** be used for the installer: its default path injects `-quit` (see the reserved flags in the **`unity-cli`** skill). With `-quit`, the Editor quits the instant the method returns — before UPM resolves — so packages never install and the callback never runs. **Solution:** launch the **Editor binary directly** in `-batchmode` **without** `-quit`. The Editor stays alive, `EditorApplication.update` keeps ticking, the poll callback runs, and it calls `EditorApplication.Exit(code)` itself when done — which both quits and sets the process exit code. ## The installer script Write this to `Assets/Editor/ProjectBootstrap/PackageInstaller.cs`. It must live under an `Editor/` folder (or an Editor-only assembly) because it uses `UnityEditor`. ```csharp using System.Linq; using UnityEditor; using UnityEditor.PackageManager; using UnityEditor.PackageManager.Requests; using UnityEngine; namespace ProjectBootstrap { // Installs (and optionally removes) a fixed set of packages via the PackageManager // Client API, headless-safe. public static class PackageInstaller { // EDIT this list to match the package selection (see references/select-packages.md). static readonly string[] PackagesToAdd = { "com.unity.inputsystem", "com.unity.cinemachine", "com.unity.render-pipelines.universal", // "com.unity.package@1.2.3" // pin a version with @ when a minimum is required }; // Optionally drop packages in the same resolution pass (e.g. a template default you don't want). static readonly string[] PackagesToRemove = { }; const double TimeoutSeconds = 600; // UPM resolution + downloads can be slow static AddAndRemoveRequest _request; static double _deadline; // Invoke with: -executeMethod ProjectBootstrap.PackageInstaller.Install (NO -quit) public static void Install() { if (PackagesToAdd.Length == 0 && PackagesToRemove.Length == 0) { Debug.Log("[PackageInstaller] Nothing to do."); EditorApplication.Exit(0); return; } Debug.Log($"[PackageInstaller] Adding: {string.Join(", ", PackagesToAdd)}"); _request = Client.AddAndRemove(packagesToAdd: PackagesToAdd, packagesToRemove: PackagesToRemove); _deadline = EditorApplication.timeSinceStartup + TimeoutSeconds; EditorApplication.update += Poll; } static void Poll() { if (_request == null) return; if (!_request.IsCompleted) { if (EditorApplication.timeSinceStartup > _deadline) { EditorApplication.update -= Poll; Debug.LogError("[PackageInstaller] Timed out waiting for UPM."); EditorApplication.Exit(2); } return; } EditorApplication.update -= Poll; if (_request.Status == StatusCode.Success) { var names = _request.Result.Select(p => $"{p.name}@{p.version}"); Debug.Log($"[PackageInstaller] Resolved: {string.Join(", ", names)}"); EditorApplication.Exit(0); } else { Debug.LogError($"[PackageInstaller] Failed: {_request.Error?.message}"); EditorApplication.Exit(1); } } } } ``` `AddAndRemove` installs the whole set in a single UPM resolution pass — faster and less error-prone than one `Client.Add` per package. **Add / remove / upgrade with one script:** - **Add**: list the id in `PackagesToAdd`. - **Remove**: list the id in `PackagesToRemove`. - **Upgrade / pin**: add the id with `@` (e.g. `com.unity.cinemachine@2.9.7`). Without a version, resolution picks the latest compatible release. ## Discovering / verifying packages To confirm an id exists or list its versions before adding it, search the registry. The in-Editor `Client.SearchAll()` / `Client.Search("")` calls are also async, so they use the **same poll-and-`Exit` pattern and the same headless run** as the installer. Write `Assets/Editor/ProjectBootstrap/PackageSearch.cs`: ```csharp using System.Linq; using UnityEditor; using UnityEditor.PackageManager; using UnityEditor.PackageManager.Requests; using UnityEngine; namespace ProjectBootstrap { public static class PackageSearch { const double TimeoutSeconds = 120; static SearchRequest _request; static double _deadline; // Invoke with: -executeMethod ProjectBootstrap.PackageSearch.SearchAll (NO -quit) public static void SearchAll() { _request = Client.SearchAll(); // or Client.Search("com.unity.cinemachine") _deadline = EditorApplication.timeSinceStartup + TimeoutSeconds; EditorApplication.update += Poll; } static void Poll() { if (_request == null) return; if (!_request.IsCompleted) { if (EditorApplication.timeSinceStartup > _deadline) { EditorApplication.update -= Poll; Debug.LogError("[PackageSearch] Timed out."); EditorApplication.Exit(2); } return; } EditorApplication.update -= Poll; if (_request.Status == StatusCode.Success) { foreach (var p in _request.Result.OrderBy(p => p.name)) Debug.Log($"[PackageSearch] {p.name}@{p.versions.latestCompatible} {p.displayName}"); Debug.Log($"[PackageSearch] {_request.Result.Length} packages found."); EditorApplication.Exit(0); } else { Debug.LogError($"[PackageSearch] Failed: {_request.Error?.message}"); EditorApplication.Exit(1); } } } } ``` `_request.Result` is a `PackageInfo[]`; each entry exposes `name`, `displayName`, `description`, and `versions` (`.latest`, `.latestCompatible`, `.all`). For a terminal-only check without the Editor (a **known** id, not free-text search), query the registry directly — see [references/select-packages.md](references/select-packages.md#discovering-and-verifying-packages). ## Run it headless (direct Editor invocation, no `-quit`) Resolve the Editor binary from the version, then run it in batch mode. The script owns quitting via `EditorApplication.Exit`, so do **not** pass `-quit`: ```bash VERSION="" # e.g. 6000.0.47f1 (or an installed version) PROJECT="" METHOD="ProjectBootstrap.PackageInstaller.Install" # or ...PackageSearch.SearchAll # Install directory of that editor (Hub layout), via the unity CLI ED=$(unity editors path "$VERSION" --format json | python3 -c "import sys,json;print(json.load(sys.stdin)['data']['path'])") # Resolve the executable per-OS (handles both "dir containing Unity.app" and the ".app" itself) case "$(uname)" in Darwin) if [ -d "$ED/Unity.app" ]; then UNITY_BIN="$ED/Unity.app/Contents/MacOS/Unity"; elif [[ "$ED" == *.app ]]; then UNITY_BIN="$ED/Contents/MacOS/Unity"; else UNITY_BIN="$ED/Unity"; fi ;; Linux) UNITY_BIN="$ED/Editor/Unity" ;; *) UNITY_BIN="$ED/Editor/Unity.exe" ;; # Windows (Git Bash / MSYS); use Editor\Unity.exe in PowerShell esac "$UNITY_BIN" -batchmode -projectPath "$PROJECT" -executeMethod "$METHOD" -logFile - echo "Exit code: $?" # 0 = success, 1 = UPM error, 2 = timeout ``` `-logFile -` streams the Editor log (including the `[PackageInstaller]` / `[PackageSearch]` lines) to stdout so you can watch resolution progress and read any UPM error. If `unity editors path` output shape differs on your build, get the directory from `unity editors --installed --format json` instead. ## Verify ```bash # Every requested id should appear as a dependency cat "/Packages/manifest.json" ``` Confirm the run exited `0` and each package from the list is present in `manifest.json`. If a package fails to resolve, `_request.Error.message` is logged; read it and check the id/version against the registry. The Editor's own log (including the `[PackageInstaller]` lines) is the stdout you streamed with `-logFile -` above — read it there, not via `unity logs` (which shows the CLI's own log, not the Editor's). ## Import & save headlessly (generate `.meta` files) After a script or tool writes new `.cs`/asset files, Unity must **import** them so it generates the `.meta` file each asset needs — and every `.cs`/asset MUST be committed together with its `.meta`. Merely opening the project once (`unity open ""`) imports and generates them; use this method when you need it **headless** (in a script or CI). Unlike the package installer, this is **synchronous** — it finishes before returning — so it's safe to run via `unity run` (its injected `-quit` is harmless; the method also calls `EditorApplication.Exit` for a clean exit code). Write `Assets/Editor/ProjectBootstrap/ProjectSaver.cs`: ```csharp using UnityEditor; using UnityEngine; namespace ProjectBootstrap { public static class ProjectSaver { // Invoke with: -executeMethod ProjectBootstrap.ProjectSaver.SaveAll public static void SaveAll() { AssetDatabase.Refresh(ImportAssetOptions.ForceUpdate); AssetDatabase.SaveAssets(); Debug.Log("[ProjectSaver] Assets imported and saved."); EditorApplication.Exit(0); } } } ``` ```bash unity run "" --editor-version \ -- -executeMethod ProjectBootstrap.ProjectSaver.SaveAll ``` ## Notes - These editor scripts are a bootstrap convenience. Leave them in `Assets/Editor/ProjectBootstrap/` (they do nothing unless invoked) or delete them after setup — your call; mention it to the user. - All scripts live under `Editor/` because they use `UnityEditor`; they never ship in a build. - Monetization / backend packages (`com.unity.purchasing`, `com.unity.services.levelplay`, the UGS packages) install through this same mechanism, but do the actual **integration** via the dedicated skills: **implement-in-app-purchases**, **levelplay-unity-integration**, **build-live-game**.