fix

Author: dankinsoid

Sources/VDFlow/EmptyStep.swift

@@ -19,16 +19,15 @@ public struct EmptyStepsCollection: StepsCollection {
 		get { .none }
 		set {}
 	}
-	
-	public let none = EmptyStep()
+
 	public init() {}
 
 	public static func step<T>(for keyPath: WritableKeyPath<Self, StepID<T>>) -> AllSteps? {
 		AllSteps.none
 	}
 
-	public static func keyPath(for step: AllSteps) -> PartialKeyPath<EmptyStepsCollection> {
-		\.none
+	public static func keyPath(for step: AllSteps) -> PartialKeyPath<EmptyStepsCollection>? {
+		nil
 	}
 
 	public enum AllSteps: Codable, Hashable, Sendable, CaseIterable {
@@ -47,5 +46,5 @@ extension Never: StepsCollection {
 		set {}
 	}
 	public static func step<T>(for keyPath: WritableKeyPath<Self, StepID<T>>) -> AllSteps? { nil }
-	public static func keyPath(for step: Never) -> PartialKeyPath<Never> { }
+	public static func keyPath(for step: Never) -> PartialKeyPath<Never>? { }
 }

Sources/VDFlow/StepWrapper.swift

@@ -96,6 +96,11 @@ public struct StepWrapper<Parent: StepsCollection, Value>: Identifiable, StepWra
             .map { (id, $0) }
             .first
 	}
+
+	/// The key path for this step within the parent collection.
+	public var keyPath: WritableKeyPath<Parent, Value> {
+		Parent.keyPath(for: id)! as! WritableKeyPath<Parent, Value>
+	}
 }
 
 public extension StepWrapper where Value == EmptyStep {

Sources/VDFlow/StepsCollection.swift

@@ -37,7 +37,7 @@ public protocol StepsCollection {
 	static func step<T>(for keyPath: WritableKeyPath<Self, StepID<T>>) -> AllSteps?
 
 	/// Retrieves the key path for a specific step in the collection.
-	static func keyPath(for step: AllSteps) -> PartialKeyPath<Self>
+	static func keyPath(for step: AllSteps) -> PartialKeyPath<Self>?
 }
 
 extension StepsCollection {

Sources/VDFlowMacros/StepsMacro.swift

@@ -369,6 +369,30 @@ public struct StepsMacro: MemberAttributeMacro, ExtensionMacro, MemberMacro, Acc
 			"""
 		result.append(_lastMutateStepID)
 
+		let stepFunc: DeclSyntax =
+			   """
+			   public static func step<T>(for keyPath: WritableKeyPath<Self, StepID<T>>) -> AllSteps? {
+			      switch keyPath {
+			      \(raw: cases.map { "case \\.$\($0), \\._\($0): return .\($0)" }.joined(separator: "\n"))
+			      default:
+			       return nil
+			      }
+			   }
+			   """
+		result.append(stepFunc)
+
+		let needDefaultNil = !cases.contains("none") && isOptional
+		let keyPathFunc: DeclSyntax =
+			   """
+			   public static func keyPath(for step: AllSteps) -> PartialKeyPath<Self>? {
+			       switch step {
+			       \(raw: cases.map { "case .\($0): return \\.\($0)" }.joined(separator: "\n"))
+			       \(raw: needDefaultNil ? "default: return nil" : "")
+			       }
+			   }
+			   """
+		result.append(keyPathFunc)
+
 		guard canInitWithSelected else { return result }
 
 		let initialSelected: DeclSyntax =
@@ -403,27 +427,6 @@ public struct StepsMacro: MemberAttributeMacro, ExtensionMacro, MemberMacro, Acc
 			funcString += "}"
 			return DeclSyntax(stringLiteral: funcString)
 		}
-		let stepFunc: DeclSyntax =
-			   """
-			   public static func step<T>(for keyPath: WritableKeyPath<Self, StepID<T>>) -> AllSteps? {
-			     switch keyPath {
-			     \(raw: cases.map { "case \\.$\($0), \\._\($0): return .\($0)" }.joined(separator: "\n"))
-			     default:
-			      return nil
-			     }
-			   }
-			   """
-		result.append(stepFunc)
-
-		let keyPathFunc: DeclSyntax =
-			   """
-			   public static func keyPath(for step: AllSteps) -> PartialKeyPath<Self> {
-			       switch step {
-			       \(raw: cases.map { "case .\($0): return \\.\($0)" }.joined(separator: "\n"))
-			       }
-			   }
-			   """
-		result.append(keyPathFunc)
 		return result
 	}
 }