Run script and add files to Swift Package via BuildToolPlugin - swift

Question

Context
I recently took over a Swift project which relies on git submodules. One of my first task was to clean up the project, which means removing submodules, using Swift Packages.
On my way doing this i encounter a tricky submodule. It contains swift files and a WebPack project that's loaded in a WebView. Currently the project that imports this submodule has a custom build phase that runs npm ci + npm build to build the WebPack and copy the files into the app.
Question:
When i switch to using a Swift Package it should manage this custom build phase on its own. Is it possible to run npm ci + npm build in a BuildToolPlugin?
My current state is trying to run a shell script which simply creates a file:
#main
struct TSPlugin: BuildToolPlugin {
func createBuildCommands(context: PackagePlugin.PluginContext, target: PackagePlugin.Target) async throws -> [PackagePlugin.Command] {
let tsPath = context.pluginWorkDirectory
.appending (subpath: target.name)
.appending (subpath: "Seatmap")
print(tsPath)
print("here1")
let scriptPath = context.package.directory.appending(["..", "TSPlugin", "TEst.sh"])
print("here2")
return [
.prebuildCommand(
displayName: "Generating localized strings from source files",
executable: scriptPath,
arguments: [],
outputFilesDirectory: tsPath
)
]
}
}
#!/bin/bash
echo "come on"
touch easypeasy.txt
I rebuilt this in a demo project: https://github.com/Deitsch/SwiftPluginDemo