Unity Package Management (Pipeline commands first, C# script as the fallback)

Add, remove, upgrade, and discover UPM (Unity Package Manager) packages with the package commands of the project's Pipeline package, run through unity command. Only when no Editor can answer those commands, fall back to UnityEditor.PackageManager.Client driven headless from a script (see Fallback). Do not hand-edit Packages/manifest.json: the Package Manager resolves dependencies and compatible versions correctly, whereas manual edits routinely break resolution.

This complements the unity-cli skill (editor install, project creation, build/test), which documents unity command, unity status and unity pipeline install.

Use the package commands first

The Pipeline package registers a package command group: add, remove, list, resolve, search and status. They need a running Editor whose project has com.unity.pipeline (add it with unity pipeline install, then unity open, then wait with unity status --until-ready). Each command's parameters come from the Editor, so read them before the first call. Don't guess a parameter name.