fix: address PR feedback for accessibility deferral

- Fix reduce bug in updateDeferredAccessibility where merge results were
  discarded (reduce(into:) → reduce() since merge returns a new value)
- Remove unused identifiers parameter from deferredAccessibilityReceiver
- Fix typo in doc comment ("through he" → "through the")
- Simplify customContent type to Accessibility.CustomContent
- Remove redundant needsAccessibilityUpdate invalidation
- Add AccessibilityDeferralTests covering merge chaining, apply/replace
  flow, and content generation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: RoyalPineapple

BlueprintUIAccessibilityCore/Sources/AccessibilityDeferral.swift

@@ -19,7 +19,7 @@ public struct AccessibilityDeferral {
         var rotorSequencer: AccessibilityComposition.RotorSequencer? { get set }
 
         /// Custom content that may be supplied in addition to the deferred content
-        var customContent: [BlueprintUI.Accessibility.CustomContent]? { get set }
+        var customContent: [Accessibility.CustomContent]? { get set }
 
         /// Content from an outside source that will be exposed via AccessibilityCustomContent
         var deferredAccessibilityContent: [AccessibilityDeferral.Content]? { get set }
@@ -53,7 +53,7 @@ public struct AccessibilityDeferral {
         /// Used to identify a specific `Source` element to inherit accessibility from.
         public var sourceIdentifier: AnyHashable
 
-        /// A stable identifier used to identify a given update pass through he view hierarchy. Content with matching updateIdentifiers should be combined.
+        /// A stable identifier used to identify a given update pass through the view hierarchy. Content with matching updateIdentifiers should be combined.
         internal var updateIdentifier: UUID?
         internal var inheritedAccessibility: AccessibilityComposition.CompositeRepresentation?
 
@@ -147,7 +147,7 @@ extension Element {
     }
 
     /// Creates a `ReceiverContainer` element to expose the deferred accessibility.
-    public func deferredAccessibilityReceiver(identifiers: [AnyHashable]) -> AccessibilityDeferral.ReceiverContainer {
+    public func deferredAccessibilityReceiver() -> AccessibilityDeferral.ReceiverContainer {
         AccessibilityDeferral.ReceiverContainer(wrapping: { self })
     }
 }
@@ -339,16 +339,14 @@ extension AccessibilityDeferral {
 
                 self.frameProvider = frameProvider
 
-                if var deferred = deferredAccessibilityContent?.compactMap({ $0.inheritedAccessibility }),
+                if let deferred = deferredAccessibilityContent?.compactMap({ $0.inheritedAccessibility }),
                    let first = deferred.first
                 {
-
                     mergeValues = deferred.dropFirst()
-                        .reduce(into: first) { result, value in
+                        .reduce(first) { result, value in
                             result.merge(with: value)
                         }
                 }
-                needsAccessibilityUpdate = true
             }
         }
     }

BlueprintUIAccessibilityCore/Tests/AccessibilityDeferralTests.swift

@@ -0,0 +1,195 @@
+import BlueprintUI
+import XCTest
+@testable import BlueprintUIAccessibilityCore
+
+
+class AccessibilityDeferralTests: XCTestCase {
+
+    // MARK: - CompositeRepresentation.merge chaining
+
+    func test_merge_multiple_representations() {
+        let rep1 = makeRepresentation(label: "Label 1", value: "Value 1", hint: "Hint 1")
+        let rep2 = makeRepresentation(label: "Label 2", value: "Value 2", hint: "Hint 2")
+        let rep3 = makeRepresentation(label: "Label 3", value: "Value 3", hint: "Hint 3")
+
+        let representations = [rep1, rep2, rep3]
+
+        // This mirrors the exact reduce pattern used in updateDeferredAccessibility
+        let merged = representations.dropFirst()
+            .reduce(representations.first!) { result, value in
+                result.merge(with: value)
+            }
+
+        XCTAssertEqual(merged.label, "Label 1, Label 2, Label 3")
+        XCTAssertEqual(merged.value, "Value 1, Value 2, Value 3")
+        XCTAssertEqual(merged.hint, "Hint 1, Hint 2, Hint 3")
+    }
+
+    func test_merge_two_representations() {
+        let rep1 = makeRepresentation(label: "First", value: "A")
+        let rep2 = makeRepresentation(label: "Second", value: "B")
+
+        let merged = rep1.merge(with: rep2)
+
+        XCTAssertEqual(merged.label, "First, Second")
+        XCTAssertEqual(merged.value, "A, B")
+    }
+
+    func test_merge_preserves_traits() {
+        let container = NSObject()
+        let element1 = UIAccessibilityElement(accessibilityContainer: container)
+        element1.accessibilityLabel = "Header"
+        element1.accessibilityTraits = .header
+
+        let element2 = UIAccessibilityElement(accessibilityContainer: container)
+        element2.accessibilityLabel = "Static"
+        element2.accessibilityTraits = .staticText
+
+        let rep1 = AccessibilityComposition.CompositeRepresentation([element1]) {}
+        let rep2 = AccessibilityComposition.CompositeRepresentation([element2]) {}
+
+        let merged = rep1.merge(with: rep2)
+
+        XCTAssertTrue(merged.traits.contains(.header))
+        XCTAssertTrue(merged.traits.contains(.staticText))
+    }
+
+    func test_merge_with_nil_returns_self() {
+        let rep = makeRepresentation(label: "Only", value: "One")
+        let merged = rep.merge(with: nil)
+
+        XCTAssertEqual(merged.label, "Only")
+        XCTAssertEqual(merged.value, "One")
+    }
+
+    // MARK: - Receiver apply / replace / merge
+
+    func test_apply_replaces_content_on_new_updateID() {
+        let receiver = TestReceiver()
+
+        var content1 = AccessibilityDeferral.Content(kind: .inherited(), identifier: "source1")
+        content1.updateIdentifier = UUID()
+        content1.inheritedAccessibility = makeRepresentation(label: "First")
+
+        receiver.apply(content: [content1], frameProvider: nil)
+
+        XCTAssertEqual(receiver.deferredAccessibilityContent?.count, 1)
+        XCTAssertEqual(receiver.deferredAccessibilityContent?.first?.inheritedAccessibility?.label, "First")
+    }
+
+    func test_apply_merges_content_on_same_updateID() {
+        let receiver = TestReceiver()
+        let sharedID = UUID()
+
+        var content1 = AccessibilityDeferral.Content(kind: .inherited(), identifier: "source1")
+        content1.updateIdentifier = sharedID
+        content1.inheritedAccessibility = makeRepresentation(label: "First")
+
+        var content2 = AccessibilityDeferral.Content(kind: .inherited(), identifier: "source2")
+        content2.updateIdentifier = sharedID
+        content2.inheritedAccessibility = makeRepresentation(label: "Second")
+
+        // First call replaces
+        receiver.apply(content: [content1], frameProvider: nil)
+        XCTAssertEqual(receiver.deferredAccessibilityContent?.count, 1)
+
+        // Second call with same updateID merges
+        receiver.apply(content: [content2], frameProvider: nil)
+        XCTAssertEqual(receiver.deferredAccessibilityContent?.count, 2)
+    }
+
+    func test_apply_clears_content_when_nil() {
+        let receiver = TestReceiver()
+
+        var content = AccessibilityDeferral.Content(kind: .inherited(), identifier: "source1")
+        content.updateIdentifier = UUID()
+        content.inheritedAccessibility = makeRepresentation(label: "Something")
+
+        receiver.apply(content: [content], frameProvider: nil)
+        XCTAssertEqual(receiver.deferredAccessibilityContent?.count, 1)
+
+        receiver.apply(content: nil, frameProvider: nil)
+        XCTAssertEqual(receiver.deferredAccessibilityContent?.count, 0)
+    }
+
+    func test_apply_propagates_actions_from_sources() {
+        let receiver = TestReceiver()
+
+        let container = NSObject()
+        let element = UIAccessibilityElement(accessibilityContainer: container)
+        element.accessibilityLabel = "Action Source"
+        element.accessibilityCustomActions = [
+            UIAccessibilityCustomAction(name: "Test Action") { _ in true },
+        ]
+
+        let rep = AccessibilityComposition.CompositeRepresentation([element]) {}
+
+        var content = AccessibilityDeferral.Content(kind: .inherited(), identifier: "source1")
+        content.updateIdentifier = UUID()
+        content.inheritedAccessibility = rep
+
+        receiver.apply(content: [content], frameProvider: nil)
+        XCTAssertEqual(receiver.accessibilityCustomActions?.first?.name, "Test Action")
+    }
+
+    // MARK: - Content customContent generation
+
+    func test_content_inherited_customContent() {
+        var content = AccessibilityDeferral.Content(kind: .inherited(.high), identifier: "id")
+        content.inheritedAccessibility = makeRepresentation(label: "Error Label", value: "Error Value")
+
+        let customContent = content.customContent
+        XCTAssertNotNil(customContent)
+        XCTAssertEqual(customContent?.label, "Error Label")
+        XCTAssertEqual(customContent?.value, "Error Value")
+        XCTAssertEqual(customContent?.importance, .high)
+    }
+
+    func test_content_error_customContent() {
+        var content = AccessibilityDeferral.Content(kind: .error, identifier: "id")
+        content.inheritedAccessibility = makeRepresentation(label: "Field", value: "is required")
+
+        let customContent = content.customContent
+        XCTAssertNotNil(customContent)
+        XCTAssertEqual(customContent?.importance, .high)
+    }
+
+    func test_content_nil_accessibility_returns_nil() {
+        let content = AccessibilityDeferral.Content(kind: .inherited(), identifier: "id")
+        XCTAssertNil(content.customContent)
+    }
+
+    // MARK: - Helpers
+
+    private func makeRepresentation(
+        label: String? = nil,
+        value: String? = nil,
+        hint: String? = nil
+    ) -> AccessibilityComposition.CompositeRepresentation {
+        let container = NSObject()
+        let element = UIAccessibilityElement(accessibilityContainer: container)
+        element.accessibilityLabel = label
+        element.accessibilityValue = value
+        element.accessibilityHint = hint
+        return AccessibilityComposition.CompositeRepresentation([element]) {}
+    }
+}
+
+// MARK: - Test Doubles
+
+private final class TestReceiver: UIView, AccessibilityDeferral.Receiver, AXCustomContentProvider {
+
+    var accessibilityCustomContent: [AXCustomContent]! = []
+
+    var customContent: [Accessibility.CustomContent]?
+
+    var rotorSequencer: AccessibilityComposition.RotorSequencer?
+
+    var deferredAccessibilityContent: [AccessibilityDeferral.Content]?
+
+    func updateDeferredAccessibility(frameProvider: AccessibilityDeferral.FrameProvider?) {
+        // No-op for unit testing the apply/replace/merge flow
+    }
+}
+
+extension TestReceiver: AccessibilityDeferral.DeferralView {}