fix: close Nearlight release blockers

Sources/Features/Conversation/TranscriptListView.swift

@@ -8,13 +8,22 @@ struct TranscriptListView: View {
     @State private var confirmClear = false
     @State private var followingLatest = true
     @State private var selectionActive = false
+    @State private var viewportHeight: CGFloat = 0
+    @State private var latestBottom: CGFloat = 0
+    @AccessibilityFocusState private var focusedEventID: String?
     @Environment(\.accessibilityReduceMotion) private var reduceMotion
     @Environment(\.dynamicTypeSize) private var typeSize
 
+    init(events: [TranscriptEvent], onClear: @escaping () -> Void) {
+        self.events = events
+        self.onClear = onClear
+        _followingLatest = State(initialValue: events.isEmpty)
+    }
+
     /// Auto-follow eligibility: never scroll while the user is selecting
     /// text or reading history.
     private var isFollowingEligible: Bool {
-        followingLatest && !selectionActive
+        followingLatest && !selectionActive && focusedEventID == nil
     }
     private static let deliveryMarkers = #"\[(?:appreciative|calm|concerned|curious|encouraging|excited|happy|joking|quiet|reassuring|reflective|sad|serious|surprised|sympathetic|urgent|whispering|laughter|sighing|breathing|neutral)\]\s*"#
 
@@ -44,13 +53,29 @@ struct TranscriptListView: View {
                                 .padding(.top, Nearlight.s24)
                         }
                         ForEach(events) { event in transcriptRow(event) }
-                        Color.clear.frame(height: 1).id("latest")
+                        GeometryReader { geometry in
+                            Color.clear.preference(
+                                key: TranscriptLatestBottomKey.self,
+                                value: geometry.frame(in: .named("transcriptScroll")).maxY
+                            )
+                        }
+                        .frame(height: 1)
+                        .id("latest")
                     }
                     .padding(.horizontal, Nearlight.s20)
                     .padding(.top, Nearlight.s16)
                     .padding(.bottom, Nearlight.s20)
                     .frame(minHeight: 200, alignment: .topLeading)
                 }
+                .coordinateSpace(name: "transcriptScroll")
+                .background {
+                    GeometryReader { geometry in
+                        Color.clear.preference(
+                            key: TranscriptViewportHeightKey.self,
+                            value: geometry.size.height
+                        )
+                    }
+                }
                 .scrollDismissesKeyboard(.interactively)
                 .defaultScrollAnchor(.top)
                 .simultaneousGesture(DragGesture().onChanged { _ in
@@ -61,15 +86,32 @@ struct TranscriptListView: View {
                     guard isFollowingEligible else { return }
                     proxy.scrollTo("latest", anchor: .bottom)
                 }
-                .onChange(of: events.count) { _, _ in
-                    guard isFollowingEligible else { return }
-                    proxy.scrollTo("latest", anchor: .bottom)
+                .onChange(of: events.count) { _, count in
+                    if count == 0 {
+                        selectionActive = false
+                        followingLatest = true
+                    } else if isFollowingEligible {
+                        proxy.scrollTo("latest", anchor: .bottom)
+                    }
                 }
                 .onChange(of: selectionActive) { _, active in
                     // Beginning text selection suspends auto-follow so the
                     // user's reading position is never disturbed.
                     if active { followingLatest = false }
                 }
+                .onChange(of: focusedEventID) { _, eventID in
+                    // VoiceOver focus on any transcript row means the user is
+                    // reading history. Only Latest resumes automatic following.
+                    if eventID != nil { followingLatest = false }
+                }
+                .onPreferenceChange(TranscriptViewportHeightKey.self) { height in
+                    viewportHeight = height
+                    updateFollowingEligibility(bottom: latestBottom, viewport: height)
+                }
+                .onPreferenceChange(TranscriptLatestBottomKey.self) { bottom in
+                    latestBottom = bottom
+                    updateFollowingEligibility(bottom: bottom, viewport: viewportHeight)
+                }
                 if !followingLatest && !events.isEmpty {
                     HStack {
                         Spacer()
@@ -77,6 +119,7 @@ struct TranscriptListView: View {
                             // Explicit Latest restores full eligibility,
                             // clearing any stale selection suspension.
                             selectionActive = false
+                            focusedEventID = nil
                             followingLatest = true
                             withAnimation(reduceMotion ? nil : Nearlight.standard) {
                                 proxy.scrollTo("latest", anchor: .bottom)
@@ -104,6 +147,17 @@ struct TranscriptListView: View {
         }
     }
 
+    private func updateFollowingEligibility(bottom: CGFloat, viewport: CGFloat) {
+        guard bottom > 0,
+              viewport > 0,
+              !selectionActive,
+              focusedEventID == nil else { return }
+        let shouldFollow = bottom <= viewport + 48
+        if followingLatest != shouldFollow {
+            followingLatest = shouldFollow
+        }
+    }
+
     private func transcriptRow(_ event: TranscriptEvent) -> some View {
         let isUser = event.role == .user
         let text = event.text.replacingOccurrences(of: Self.deliveryMarkers, with: "", options: .regularExpression)
@@ -141,6 +195,7 @@ struct TranscriptListView: View {
             Button("Copy message", systemImage: "doc.on.doc") { UIPasteboard.general.string = text }
         }
         .accessibilityElement(children: .combine)
+        .accessibilityFocused($focusedEventID, equals: event.id)
         .id(event.id)
     }
 
@@ -163,3 +218,19 @@ struct TranscriptListView: View {
         .monospacedDigit()
     }
 }
+
+private struct TranscriptViewportHeightKey: PreferenceKey {
+    static var defaultValue: CGFloat = 0
+
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
+        value = nextValue()
+    }
+}
+
+private struct TranscriptLatestBottomKey: PreferenceKey {
+    static var defaultValue: CGFloat = 0
+
+    static func reduce(value: inout CGFloat, nextValue: () -> CGFloat) {
+        value = nextValue()
+    }
+}