How to conditionally build widget configuration parameters based on UserDefaults or other conditions

ConditionalDefaultEntity.swift

//
//  ConditionalDefaultEntity.swift
//  Mercury
//
//  Created by Kyle Bashour on 2/10/25.
//  Copyright © 2025 Kyle Bashour. All rights reserved.
//

import AppIntents

/// Provides a way to conditionally build widget configuration parameters based on "external" values.
///
/// You can't use if statements or other conditions inside the result builders, but you can query
/// whether an entity exists. This is a bit of a hack that conditionally provides a default entity
/// based on value returned from a closure, so you can read a boolean value out of something like
/// UserDefaults, Keychain, or elsewhere.
@available(iOS 17, *)
struct ConditionalDefaultEntity: AppEntity {
    static let typeDisplayRepresentation: TypeDisplayRepresentation = "Has queried value"
    static let defaultQuery = ConditionalDefaultEntityQuery()

    let displayRepresentation = DisplayRepresentation(title: "Has queried value")

    let id: UUID

    init(id: UUID) {
        self.id = UUID()
    }
}

@available(iOS 17, *)
struct ConditionalDefaultEntityQuery: EntityQuery {
    let valueProvider: @Sendable () -> Bool

    init() {
        valueProvider = { false }
    }

    init(valueProvider: @escaping @Sendable () -> Bool) {
        self.valueProvider = valueProvider
    }

    func entities(for identifiers: [ConditionalDefaultEntity.ID]) async throws -> [ConditionalDefaultEntity] {
        identifiers.map { ConditionalDefaultEntity(id: $0) }
    }

    func defaultResult() async -> ConditionalDefaultEntity? {
        valueProvider() ? ConditionalDefaultEntity(id: UUID()) : nil
    }
}

ExampleWidgetIntent.swift

//
//  ExampleWidgetIntent.swift
//  MercuryWidgetExtension
//
//  Created by Kyle Bashour on 2/10/25.
//  Copyright © 2025 Kyle Bashour. All rights reserved.
//

import AppIntents
import WidgetKit

@available(iOS 17, *)
struct ExampleWidgetIntent: WidgetConfigurationIntent {
    static var title: LocalizedStringResource = "My cool widget"
    static var isDiscoverable: Bool = false

    @Parameter(
        title: "Is value true",
        query: ConditionalDefaultEntityQuery {
            UserDefaults.standard.bool(forKey: "my-cool-value")
        }
    )
    var isValueTrue: ConditionalDefaultEntity?

    @Parameter(title: "Relevant if value is true")
    var trueRelevantValue: MyEntity?

    @Parameter(title: "Relevant if value is false")
    var falseRelevantValue: MyOtherEntity?

    static var parameterSummary: some ParameterSummary {
        When(\.$isValueTrue, .hasAnyValue) {
            Summary {
                \.$trueRelevantValue
            }
        } otherwise: {
            Summary {
                \.$falseRelevantValue
            }
        }
    }
}