Subprocess does not quit after app exit

[xinnjie]

Describe the bug
A clear and concise description of what the bug is.

To Reproduce

1. Create new xcode project for mac SwiftUI app
2. Add these codes, subprocess dependency and run

import SwiftUI
import Subprocess
struct ContentView: View {
    var body: some View {
        VStack {
            Image(systemName: "globe")
                .imageScale(.large)
                .foregroundStyle(.tint)
            Text("Hello, world!")
        }
        .task {
          let configuration = Configuration(
                      executable: .path("/bin/sleep"),
                      arguments: ["60"]
                  )

          let _ = try! await Subprocess.run(
              configuration,
              output: .discarded,
              error: .discarded
          ) { _ in
          }
        }
        .padding()
    }
}

3. Open Activity Monitor app and search for sleep process, sleep subprocess shows up.
4. close mac app quickly
5. sleep sub process became orphan, and quit after 60 seconds

Expected behavior
A clear and concise description of what you expected to happen.
sleep subprocess quit quickly after parent mac app exit
Environment (please complete the following information):

• OS [e.g. macOS 15]
  macOS 15
• Swift version (run swift --version) [e.g. swiftlang-6.2.0.1.23 clang-1700.3.1.3]
  swift-driver version: 1.120.5 Apple Swift version 6.1.2 (swiftlang-6.1.2.1.2 clang-1700.0.13.5)
  Target: arm64-apple-macosx15.0
  Additional context
  Add any other context about the problem here.

[xinnjie]

It works great on command line app.
Add the test and run, sleep quit after I exit test manualy using ctrl-c

    @Test func testOrphanProcessIsKilledOnParentExit() async throws {
        let configuration = Configuration(
            executable: .path("/bin/sleep"),
            arguments: ["60"]
        )

        let _ = try await Subprocess.run(
            configuration,
            output: .discarded,
            error: .discarded
        ) { _ in
        }
    }

[iCharlesHu]

@xinnjie Thanks for the report! I suspect this might have something to do with SwiftUI app not calling Swift Task cancellation or Subprocess isn't handling this particular case gracefully. Subprocess relies on Swift Task cancellation to trigger teardown.

I'll investigate more.