A macOS 13+ `AppIntent` showcasing weird behaviour for list properties containing only a single `TransientAppEntity`

TransientAppEntity Weirdness Showcase.md

Test setup

Shortcuts app, add new workflow.

• First action: "TransientAppEntity Weirdness Showcase"
• Second action: "Get Items from List" with setting "First Item"

Test 1

1. Enter 2 as the Item count.
2. "Get Items from List" action: Select the [String] property
3. Run workflow: Result is "hello 0" (i.e. the first item in the list stored in that property)
4. "Get Items from List" action: Now select the [WeirdnessShowcaseAppEntity] property
5. Run workflow: Result is "hello 0" (i.e. the first item in the list stored in that property)

Test 2

1. Enter 1 as the Item count.
2. "Get Items from List" action: Select the [String] property
3. Run workflow: Result is "hello 0" (i.e. the first item in the list stored in that property)
4. "Get Items from List" action: Now select the [WeirdnessShowcaseAppEntity] property
5. Run workflow: Shortcuts displays an error "There was a problem running the shortcut"

---

What am I missing here? How can I make the property containing the TransientAppEntity behave correctly, i.e. just like the one holding the String?

TransientAppEntityWeirdnessShowcase.swift

import AppIntents
import Foundation

/// The `TransientAppEntityWeirdnessShowcase` intent below returns a `TransientAppEntity` (named
/// `ReturnValueAppEntity`) containing two properties: one is a `[String]`, the other is a
/// `[WeirdnessShowcaseAppEntity]`. I expect both to behave the same but they do not:
///
/// If the item count is set to 1, `stringItems` returns a list while `taeItems` returns the single
/// list item by itself, thus breaking any follow up actions expecting a list. If the item count is
/// 2 or more, both return lists.

@available(macOS 13.0, *)
struct TransientAppEntityWeirdnessShowcase: AppIntent {
  static var title: LocalizedStringResource = "TransientAppEntity Weirdness Showcase"
  static var description = IntentDescription("")

  @Parameter(title: "Item count")
  var count: Int

  static var parameterSummary: some ParameterSummary {
    Summary("Return \(\.$count) items each in this action's result properties")
  }

  func perform() async throws -> some IntentResult & ReturnsValue<ReturnValueAppEntity> {
    let rv = ReturnValueAppEntity()
    rv.stringItems = (0 ..< count).map { "hello \($0)" }
    rv.taeItems = (0 ..< count).map { _ in
      let e = WeirdnessShowcaseAppEntity()
      e.string = "hello"
      return e
    }

    return .result(value: rv)
  }
}

struct ReturnValueAppEntity: TransientAppEntity {
  static var typeDisplayRepresentation = TypeDisplayRepresentation(name: "ReturnValueAppEntity")

  var displayRepresentation: DisplayRepresentation {
    DisplayRepresentation(title: "ReturnValueAppEntity")
  }

  @Property(title: "[String]")
  var stringItems: [String]

  @Property(title: "[WeirdnessShowcaseAppEntity]")
  var taeItems: [WeirdnessShowcaseAppEntity]

  init() {}
}

struct WeirdnessShowcaseAppEntity: TransientAppEntity {
  static var typeDisplayRepresentation = TypeDisplayRepresentation(name: "WeirdnessShowcaseAppEntity")

  var displayRepresentation: DisplayRepresentation {
    DisplayRepresentation(title: "WeirdnessShowcaseAppEntity")
  }

  @Property(title: "Some string value")
  var string: String

  init() {}
}