diff --git a/Sources/TerminalWindowPortal.swift b/Sources/TerminalWindowPortal.swift
index e5ea21bc..d64cc7b1 100644
--- a/Sources/TerminalWindowPortal.swift
+++ b/Sources/TerminalWindowPortal.swift
@@ -23,9 +23,70 @@ final class WindowTerminalHostView: NSView {
     override var isOpaque: Bool { false }
 
     override func hitTest(_ point: NSPoint) -> NSView? {
+        if shouldPassThroughToSplitDivider(at: point) {
+            return nil
+        }
         let hitView = super.hitTest(point)
         return hitView === self ? nil : hitView
     }
+
+    private func shouldPassThroughToSplitDivider(at point: NSPoint) -> Bool {
+        guard let window else { return false }
+        let windowPoint = convert(point, to: nil)
+        guard let rootView = window.contentView else { return false }
+        return Self.containsSplitDivider(at: windowPoint, in: rootView)
+    }
+
+    private static func containsSplitDivider(at windowPoint: NSPoint, in view: NSView) -> Bool {
+        guard !view.isHidden else { return false }
+
+        if let splitView = view as? NSSplitView {
+            let pointInSplit = splitView.convert(windowPoint, from: nil)
+            if splitView.bounds.contains(pointInSplit) {
+                // Keep divider interactions reliable even when portal-hosted terminal frames
+                // temporarily overlap divider edges during rapid layout churn.
+                let expansion: CGFloat = 5
+                let dividerCount = max(0, splitView.arrangedSubviews.count - 1)
+                for dividerIndex in 0..<dividerCount {
+                    let first = splitView.arrangedSubviews[dividerIndex].frame
+                    let second = splitView.arrangedSubviews[dividerIndex + 1].frame
+                    let thickness = splitView.dividerThickness
+                    let dividerRect: NSRect
+                    if splitView.isVertical {
+                        guard first.width > 1, second.width > 1 else { continue }
+                        let x = max(0, first.maxX)
+                        dividerRect = NSRect(
+                            x: x,
+                            y: 0,
+                            width: thickness,
+                            height: splitView.bounds.height
+                        )
+                    } else {
+                        guard first.height > 1, second.height > 1 else { continue }
+                        let y = max(0, first.maxY)
+                        dividerRect = NSRect(
+                            x: 0,
+                            y: y,
+                            width: splitView.bounds.width,
+                            height: thickness
+                        )
+                    }
+                    let expandedDividerRect = dividerRect.insetBy(dx: -expansion, dy: -expansion)
+                    if expandedDividerRect.contains(pointInSplit) {
+                        return true
+                    }
+                }
+            }
+        }
+
+        for subview in view.subviews.reversed() {
+            if containsSplitDivider(at: windowPoint, in: subview) {
+                return true
+            }
+        }
+
+        return false
+    }
 }
 
 @MainActor
@@ -35,6 +96,7 @@ final class WindowTerminalPortal: NSObject {
     private weak var installedContainerView: NSView?
     private weak var installedReferenceView: NSView?
     private var installConstraints: [NSLayoutConstraint] = []
+    private var hasDeferredFullSyncScheduled = false
 
     private struct Entry {
         weak var hostedView: GhosttySurfaceScrollView?
@@ -226,8 +288,37 @@ final class WindowTerminalPortal: NSObject {
 
     func synchronizeHostedViewForAnchor(_ anchorView: NSView) {
         pruneDeadEntries()
-        guard let hostedId = hostedByAnchorId[ObjectIdentifier(anchorView)] else { return }
-        synchronizeHostedView(withId: hostedId)
+        let anchorId = ObjectIdentifier(anchorView)
+        let primaryHostedId = hostedByAnchorId[anchorId]
+        if let primaryHostedId {
+            synchronizeHostedView(withId: primaryHostedId)
+        }
+
+        // Failsafe: during aggressive divider drags/structural churn, one anchor can miss a
+        // geometry callback while another fires. Reconcile all mapped hosted views so no stale
+        // frame remains "stuck" onscreen until the next interaction.
+        synchronizeAllHostedViews(excluding: primaryHostedId)
+        scheduleDeferredFullSynchronizeAll()
+    }
+
+    private func scheduleDeferredFullSynchronizeAll() {
+        guard !hasDeferredFullSyncScheduled else { return }
+        hasDeferredFullSyncScheduled = true
+        DispatchQueue.main.async { [weak self] in
+            guard let self else { return }
+            self.hasDeferredFullSyncScheduled = false
+            self.synchronizeAllHostedViews(excluding: nil)
+        }
+    }
+
+    private func synchronizeAllHostedViews(excluding hostedIdToSkip: ObjectIdentifier?) {
+        guard ensureInstalled() else { return }
+        pruneDeadEntries()
+        let hostedIds = Array(entriesByHostedId.keys)
+        for hostedId in hostedIds {
+            if hostedId == hostedIdToSkip { continue }
+            synchronizeHostedView(withId: hostedId)
+        }
     }
 
     private func synchronizeHostedView(withId hostedId: ObjectIdentifier) {
@@ -261,12 +352,20 @@ final class WindowTerminalPortal: NSObject {
 
         let frameInWindow = anchorView.convert(anchorView.bounds, to: nil)
         let frameInHost = hostView.convert(frameInWindow, from: nil)
+        let hasFiniteFrame =
+            frameInHost.origin.x.isFinite &&
+            frameInHost.origin.y.isFinite &&
+            frameInHost.size.width.isFinite &&
+            frameInHost.size.height.isFinite
         let anchorHidden = Self.isHiddenOrAncestorHidden(anchorView)
         let tinyFrame = frameInHost.width <= 1 || frameInHost.height <= 1
+        let outsideHostBounds = !frameInHost.intersects(hostView.bounds)
         let shouldHide =
             !entry.visibleInUI ||
             anchorHidden ||
-            tinyFrame
+            tinyFrame ||
+            !hasFiniteFrame ||
+            outsideHostBounds
 
         let oldFrame = hostedView.frame
 #if DEBUG
@@ -301,7 +400,8 @@ final class WindowTerminalPortal: NSObject {
             dlog(
                 "portal.hidden hosted=\(portalDebugToken(hostedView)) value=\(shouldHide ? 1 : 0) " +
                 "visibleInUI=\(entry.visibleInUI ? 1 : 0) anchorHidden=\(anchorHidden ? 1 : 0) " +
-                "tiny=\(tinyFrame ? 1 : 0) frame=\(portalDebugFrame(frameInHost))"
+                "tiny=\(tinyFrame ? 1 : 0) finite=\(hasFiniteFrame ? 1 : 0) " +
+                "outside=\(outsideHostBounds ? 1 : 0) frame=\(portalDebugFrame(frameInHost))"
             )
 #endif
             hostedView.isHidden = shouldHide
@@ -316,6 +416,10 @@ final class WindowTerminalPortal: NSObject {
             if anchor.window !== currentWindow || anchor.superview == nil {
                 return hostedId
             }
+            if let reference = installedReferenceView,
+               !anchor.isDescendant(of: reference) {
+                return hostedId
+            }
             return nil
         }
 
diff --git a/vendor/bonsplit b/vendor/bonsplit
index 2bd60ba4..748d9c0f 160000
--- a/vendor/bonsplit
+++ b/vendor/bonsplit
@@ -1 +1 @@
-Subproject commit 2bd60ba40dc3350bd3c774b5f2de9f9b9c1b39fb
+Subproject commit 748d9c0fe12edebd5448b946ce2c23d7549cd073