ios: let native scrolling handle Agent keyboard resizing

ios/Packages/Sybil/Sources/Sybil/SybilAgentView.swift

@@ -18,20 +18,20 @@ struct SybilAgentView: View {
 }
 
 // Draft edits and keyboard focus belong to the composer. The transcript observes
-// only room/render/scroll state; resizing is handled by its scroll geometry.
+// only room/render/scroll state; SwiftUI handles keyboard avoidance.
 private struct AgentTranscriptView: View {
     var room: SybilAgentRoom
     var topInset: CGFloat
     var latestRequest: Int
     @Environment(\.accessibilityReduceMotion) private var reduceMotion
     @State private var atLatest = true
-    @State private var isScrolling = false
+    @State private var scrollPhase: ScrollPhase = .idle
     @State private var historyLimit = 100
     @State private var historyStartID: String?
     @State private var scrollPosition = ScrollPosition()
     @State private var scrollTracking = AgentScrollTracking()
     @State private var appeared = false
-    private let bottomID = "agent-bottom"
+    private var isScrolling: Bool { scrollPhase.isScrolling }
 
     private var visibleReadingAnchor: AgentReadingAnchor? {
         scrollTracking.rowFrames.filter { $0.value.maxY > topInset && $0.value.minY < scrollTracking.metrics.height }
@@ -48,7 +48,6 @@ private struct AgentTranscriptView: View {
         let allMessages = transcript.messages
         let startIndex = transcript.startIndex
         let displayed = transcript.displayed
-        ScrollViewReader { proxy in
         ScrollView {
             LazyVStack(alignment: .leading, spacing: 15) {
                 if allMessages.count > displayed.count {
@@ -80,7 +79,7 @@ private struct AgentTranscriptView: View {
                     .foregroundStyle(SybilTheme.textMuted)
                     .accessibilityIdentifier("agent-typing")
                 }
-                    Color.clear.frame(height: 1).id(bottomID)
+                Color.clear.frame(height: 1)
             }
             .scrollTargetLayout()
             .padding(.horizontal, 16)
@@ -95,10 +94,13 @@ private struct AgentTranscriptView: View {
         .coordinateSpace(name: "agent-scroll")
         .scrollPosition($scrollPosition)
         .defaultScrollAnchor(.bottom, for: .initialOffset)
+        // Let SwiftUI follow size changes, including keyboard avoidance,
+        // without competing scrollTo calls from geometry updates.
+        .defaultScrollAnchor(atLatest ? .bottom : nil, for: .sizeChanges)
         .defaultScrollAnchor(.bottom, for: .alignment)
         .scrollDismissesKeyboard(.interactively)
         .onScrollPhaseChange { _, phase in
-                isScrolling = phase.isScrolling
+            scrollPhase = phase
         }
         .onScrollGeometryChange(for: AgentScrollMetrics.self) { geometry in
             AgentScrollMetrics(offset: geometry.contentOffset.y,
@@ -106,16 +108,16 @@ private struct AgentTranscriptView: View {
                 contentHeight: geometry.contentSize.height,
                 bottomInset: geometry.contentInsets.bottom, topInset: geometry.contentInsets.top,
                 visibleBottom: geometry.visibleRect.maxY)
-            } action: { previous, next in
+        } action: { _, next in
             #if DEBUG
             AgentRenderDiagnostics.record("scrollGeometry")
             #endif
             scrollTracking.metrics = next
             if scrollTracking.atBottom != next.atBottom { scrollTracking.atBottom = next.atBottom }
-                if isScrolling || next.contentHeight <= next.height { atLatest = next.atBottom }
-                if atLatest, !isScrolling,
-                   previous.height != next.height || previous.contentHeight != next.contentHeight || previous.bottomInset != next.bottomInset {
-                    proxy.scrollTo(bottomID, anchor: .bottom)
+            // Only user scrolling changes follow intent. Animated Latest
+            // navigation and native keyboard resizing must not cancel it.
+            if (isScrolling && scrollPhase != .animating) || next.contentHeight <= next.height {
+                atLatest = next.atBottom
             }
         }
         .onPreferenceChange(AgentRowFrames.self) { frames in
@@ -144,7 +146,7 @@ private struct AgentTranscriptView: View {
             if !atLatest {
                 Button {
                     atLatest = true
-                        withAnimation(reduceMotion ? nil : .easeOut(duration: 0.24)) { proxy.scrollTo(bottomID, anchor: .bottom) }
+                    withAnimation(reduceMotion ? nil : .easeOut(duration: 0.24)) { scrollPosition.scrollTo(edge: .bottom) }
                 } label: {
                     Label(room.unreadCount > 0 ? "\(room.unreadCount) unread" : "Latest", systemImage: "arrow.down")
                         .font(.sybil(.caption, weight: .semibold))
@@ -164,12 +166,11 @@ private struct AgentTranscriptView: View {
             if !loading && historyStartID == nil { historyStartID = displayed.first?.id }
         }
         .onChange(of: allMessages.count) { _, _ in
-                if atLatest { proxy.scrollTo(bottomID, anchor: .bottom) }
+            if atLatest { scrollPosition.scrollTo(edge: .bottom) }
         }
         .onChange(of: latestRequest) { _, _ in
             atLatest = true
-                proxy.scrollTo(bottomID, anchor: .bottom)
-            }
+            scrollPosition.scrollTo(edge: .bottom)
         }
         .modifier(AgentReadAcknowledgement(room: room, tracking: scrollTracking,
                                           atLatest: atLatest, isScrolling: isScrolling))

ios/Tests/SybilUITests/TranscriptFadeUITests.swift

@@ -123,6 +123,7 @@ final class TranscriptFadeUITests: XCTestCase {
         let followed = XCTNSPredicateExpectation(predicate: NSPredicate(format: "hittable == true"), object: latest)
         await fulfillment(of: [followed], timeout: 5)
         composer.tap()
+        XCTAssertTrue(app.keyboards.firstMatch.waitForExistence(timeout: 5))
         XCTAssertTrue(latest.isHittable)
         XCTAssertTrue(app.buttons["agent-attach"].isHittable)
         capture("agent-fade-latest-with-keyboard")
@@ -133,5 +134,27 @@ final class TranscriptFadeUITests: XCTestCase {
         try await Task.sleep(for: .milliseconds(500))
         let read = try await control(["action": "state"])
         XCTAssertEqual(read["readCursor"] as? Int, read["cursor"] as? Int)
+
+        // A reply still follows and settles as read while the keyboard is up.
+        try await control(["action": "reply", "content": "Reply with keyboard visible"])
+        let keyboardReply = app.staticTexts["Reply with keyboard visible"]
+        let keyboardFollowed = XCTNSPredicateExpectation(predicate: NSPredicate(format: "hittable == true"), object: keyboardReply)
+        await fulfillment(of: [keyboardFollowed], timeout: 5)
+        try await Task.sleep(for: .milliseconds(500))
+        let keyboardRead = try await control(["action": "state"])
+        XCTAssertEqual(keyboardRead["readCursor"] as? Int, keyboardRead["cursor"] as? Int)
+
+        // Interactive dismissal is user navigation; Latest must still return to
+        // the bottom, and presenting the keyboard again must keep it visible.
+        let dismissStart = scroll.coordinate(withNormalizedOffset: CGVector(dx: 0.5, dy: 0.9))
+        let dismissEnd = app.coordinate(withNormalizedOffset: CGVector(dx: 0.5, dy: 0.98))
+        dismissStart.press(forDuration: 0.1, thenDragTo: dismissEnd)
+        let dismissed = XCTNSPredicateExpectation(predicate: NSPredicate(format: "exists == false"), object: app.keyboards.firstMatch)
+        await fulfillment(of: [dismissed], timeout: 5)
+        if app.buttons["agent-jump-latest"].exists { app.buttons["agent-jump-latest"].tap() }
+        XCTAssertTrue(keyboardReply.isHittable)
+        composer.tap()
+        XCTAssertTrue(app.keyboards.firstMatch.waitForExistence(timeout: 5))
+        XCTAssertTrue(keyboardReply.isHittable)
     }
 }