diff --git a/Sources/BrowserWindowPortal.swift b/Sources/BrowserWindowPortal.swift
index 915467e2..10e0b8b0 100644
--- a/Sources/BrowserWindowPortal.swift
+++ b/Sources/BrowserWindowPortal.swift
@@ -1672,9 +1672,13 @@ final class WindowBrowserSlotView: NSView {
     func pinHostedWebView(_ webView: WKWebView) {
         guard webView.superview === self else { return }
 
+        let needsPlainWebViewFrameReset =
+            !Self.hasWebKitCompanionSubview(in: self, primaryWebView: webView) &&
+            Self.frameDiffersFromBounds(webView.frame, bounds: bounds)
         let needsFrameHosting =
             hostedWebView !== webView ||
             !hostedWebViewConstraints.isEmpty ||
+            needsPlainWebViewFrameReset ||
             !webView.translatesAutoresizingMaskIntoConstraints ||
             webView.autoresizingMask != [.width, .height]
         guard needsFrameHosting else {
@@ -1687,8 +1691,8 @@ final class WindowBrowserSlotView: NSView {
         hostedWebViewConstraints = []
         hostedWebView = webView
         // Attached Web Inspector mutates the moved WKWebView's frame directly.
-        // Re-pin only when hosting mode changes, not when WebKit resizes the page
-        // inside the slot for side-docked DevTools.
+        // Re-pin plain web views after cross-host reattach, but preserve the
+        // WebKit-managed split frame when docked DevTools siblings are present.
         webView.translatesAutoresizingMaskIntoConstraints = true
         webView.autoresizingMask = [.width, .height]
         webView.frame = bounds
@@ -1696,6 +1700,27 @@ final class WindowBrowserSlotView: NSView {
         layoutSubtreeIfNeeded()
     }
 
+    private static func frameDiffersFromBounds(_ frame: NSRect, bounds: NSRect, epsilon: CGFloat = 0.5) -> Bool {
+        abs(frame.minX - bounds.minX) > epsilon ||
+            abs(frame.minY - bounds.minY) > epsilon ||
+            abs(frame.width - bounds.width) > epsilon ||
+            abs(frame.height - bounds.height) > epsilon
+    }
+
+    private static func hasWebKitCompanionSubview(in host: NSView, primaryWebView: WKWebView) -> Bool {
+        var stack = host.subviews.filter { $0 !== primaryWebView }
+        while let current = stack.popLast() {
+            if current.isDescendant(of: primaryWebView) {
+                continue
+            }
+            if String(describing: type(of: current)).contains("WK") {
+                return true
+            }
+            stack.append(contentsOf: current.subviews)
+        }
+        return false
+    }
+
     func effectivePaneTopChromeHeight() -> CGFloat {
         paneTopChromeHeight
     }
@@ -1975,6 +2000,7 @@ final class WindowBrowserPortal: NSObject {
             guard let webView = entry.webView,
                   let containerView = entry.containerView,
                   !containerView.isHidden else { continue }
+            guard webView.superview === containerView else { continue }
             refreshHostedWebViewPresentation(
                 webView,
                 in: containerView,
@@ -2650,7 +2676,7 @@ final class WindowBrowserPortal: NSObject {
             containerView.setPaneTopChromeHeight(0)
             containerView.setSearchOverlay(nil)
             containerView.setDropZoneOverlay(zone: nil)
-            if !containerView.isHidden {
+            if !containerView.isHidden, webView.superview === containerView {
                 webView.browserPortalNotifyHidden(reason: reason)
             }
             containerView.isHidden = true