fix: preserve inherited appearance for WebKit refresh

Sources/Panels/BrowserPanelView.swift

@@ -264,9 +264,10 @@ struct BrowserPanelView: View {
     let paneOwnershipOverride: Bool?
     private let resolvedColorScheme: ColorScheme
     private let resolvedThemeBackgroundColor: NSColor
-    /// Inherited SwiftUI appearance is observed only to refresh WebKit's
-    /// system theme. It is never used to resolve browser toolbar colors.
-    @Environment(\.colorScheme) private var inheritedColorScheme
+    /// Appearance captured from the host before the parent injects the
+    /// surface-resolved scheme. It is observed only to refresh WebKit's system
+    /// theme and is never used to resolve browser toolbar colors.
+    private let inheritedColorScheme: ColorScheme
     @Environment(\.cmuxCanvasInlineBrowserHosting) private var canvasInlineBrowserHosting
     @Environment(\.paneDropZone) private var paneDropZone
     /// Held detector instance used to summarize installed browsers rather than
@@ -361,6 +362,7 @@ struct BrowserPanelView: View {
         portalPriority: Int,
         paneOwnershipOverride: Bool? = nil,
         resolvedColorScheme: ColorScheme,
+        inheritedColorScheme: ColorScheme,
         resolvedThemeBackgroundColor: NSColor,
         onRequestPanelFocus: @escaping () -> Void
     ) {
@@ -372,6 +374,7 @@ struct BrowserPanelView: View {
         self.portalPriority = portalPriority
         self.paneOwnershipOverride = paneOwnershipOverride
         self.resolvedColorScheme = resolvedColorScheme
+        self.inheritedColorScheme = inheritedColorScheme
         self.resolvedThemeBackgroundColor = resolvedThemeBackgroundColor
         self.onRequestPanelFocus = onRequestPanelFocus
         self._browserChromeStyle = State(initialValue: BrowserChromeStyle.resolve(

Sources/Panels/PanelContentView.swift

@@ -25,6 +25,10 @@ struct PanelContentView: View {
     let customSidebarUnread: SidebarUnreadModel = TerminalNotificationStore.shared.sidebarUnread
     let hasUnreadNotification: Bool
     let terminalAgentContext: String
+    /// Appearance inherited from the host before this view injects the
+    /// surface-resolved scheme for its rendered panel subtree. Browser WebKit
+    /// system theming may observe this value; browser chrome must not.
+    @Environment(\.colorScheme) private var inheritedColorScheme
     /// Explicit browser pane-ownership signal for hosts whose panels live outside
     /// the main `Workspace` tree (the Dock). `nil` keeps the main-area behavior.
     var paneOwnershipOverride: Bool? = nil
@@ -77,6 +81,7 @@ struct PanelContentView: View {
                     portalPriority: portalPriority,
                     paneOwnershipOverride: paneOwnershipOverride,
                     resolvedColorScheme: windowAppearance.resolvedColorScheme,
+                    inheritedColorScheme: inheritedColorScheme,
                     resolvedThemeBackgroundColor: windowAppearance.resolvedChromeBackgroundColor,
                     onRequestPanelFocus: onRequestPanelFocus
                 )

cmuxTests/BrowserChromeMetricsTests.swift

@@ -137,4 +137,23 @@ import Testing
             #expect(alpha == 1)
         }
     }
+
+    @Test
+    func inheritedAppearanceOnlyChangeKeepsBrowserChromeStableForWebKitRefresh() {
+        let surfaceScheme: ColorScheme = .light
+        let beforeRefresh = resolvedBrowserChromeColorScheme(
+            for: surfaceScheme,
+            ambientColorScheme: .dark
+        )
+        let afterRefresh = resolvedBrowserChromeColorScheme(
+            for: surfaceScheme,
+            ambientColorScheme: .light
+        )
+
+        // `BrowserPanelView` refreshes WebKit when this inherited value
+        // changes, while the toolbar authority must remain unchanged.
+        #expect(beforeRefresh == surfaceScheme)
+        #expect(afterRefresh == surfaceScheme)
+        #expect(afterRefresh == beforeRefresh)
+    }
 }