diff --git a/CHANGELOG.md b/CHANGELOG.md
index 88f48186b..6bc7610cd 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -30,6 +30,7 @@
 - System prompt now tags allowlisted owner numbers as the user identity to avoid mistaken “friend” assumptions.
 - LM Studio/Ollama replies now require <final> tags; streaming ignores content until <final> begins.
 - `process log` pagination is now line-based (omit `offset` to grab the last N lines).
+- macOS WebChat: assistant bubbles now update correctly when toggling light/dark mode.
 - macOS: avoid spawning a duplicate gateway process when an external listener already exists.
 - Node bridge: when binding to a non-loopback host (e.g. Tailnet IP), also listens on `127.0.0.1` for local connections (without creating duplicate loopback listeners for `0.0.0.0`/`127.0.0.1` binds).
 - UI perf: pause repeat animations when scenes are inactive (typing dots, onboarding glow, iOS status pulse), throttle voice overlay level updates, and reduce overlay focus churn.
diff --git a/apps/shared/ClawdisKit/Sources/ClawdisChatUI/ChatTheme.swift b/apps/shared/ClawdisKit/Sources/ClawdisChatUI/ChatTheme.swift
index c676efd58..c6e00045b 100644
--- a/apps/shared/ClawdisKit/Sources/ClawdisChatUI/ChatTheme.swift
+++ b/apps/shared/ClawdisKit/Sources/ClawdisChatUI/ChatTheme.swift
@@ -6,7 +6,39 @@ import AppKit
 import UIKit
 #endif
 
+#if os(macOS)
+private extension NSAppearance {
+    var isDarkAqua: Bool {
+        self.bestMatch(from: [.aqua, .darkAqua]) == .darkAqua
+    }
+}
+#endif
+
 enum ClawdisChatTheme {
+    #if os(macOS)
+    static func resolvedAssistantBubbleColor(for appearance: NSAppearance) -> NSColor {
+        // NSColor semantic colors don't reliably resolve for arbitrary NSAppearance in SwiftPM.
+        // Use explicit light/dark values so the bubble updates when the system appearance flips.
+        appearance.isDarkAqua
+            ? NSColor(calibratedWhite: 0.18, alpha: 0.88)
+            : NSColor(calibratedWhite: 0.94, alpha: 0.92)
+    }
+
+    static func resolvedOnboardingAssistantBubbleColor(for appearance: NSAppearance) -> NSColor {
+        appearance.isDarkAqua
+            ? NSColor(calibratedWhite: 0.20, alpha: 0.94)
+            : NSColor(calibratedWhite: 0.97, alpha: 0.98)
+    }
+
+    static let assistantBubbleDynamicNSColor = NSColor(
+        name: NSColor.Name("ClawdisChatTheme.assistantBubble"),
+        dynamicProvider: resolvedAssistantBubbleColor(for:))
+
+    static let onboardingAssistantBubbleDynamicNSColor = NSColor(
+        name: NSColor.Name("ClawdisChatTheme.onboardingAssistantBubble"),
+        dynamicProvider: resolvedOnboardingAssistantBubbleColor(for:))
+    #endif
+
     static var surface: Color {
         #if os(macOS)
         Color(nsColor: .windowBackgroundColor)
@@ -78,9 +110,7 @@ enum ClawdisChatTheme {
 
     static var assistantBubble: Color {
         #if os(macOS)
-        let base = NSColor.controlBackgroundColor
-        let blended = base.blended(withFraction: 0.18, of: .white) ?? base
-        return Color(nsColor: blended).opacity(0.88)
+        Color(nsColor: self.assistantBubbleDynamicNSColor)
         #else
         Color(uiColor: .secondarySystemBackground)
         #endif
@@ -88,9 +118,7 @@ enum ClawdisChatTheme {
 
     static var onboardingAssistantBubble: Color {
         #if os(macOS)
-        let base = NSColor.controlBackgroundColor
-        let blended = base.blended(withFraction: 0.22, of: .white) ?? base
-        return Color(nsColor: blended)
+        Color(nsColor: self.onboardingAssistantBubbleDynamicNSColor)
         #else
         Color(uiColor: .secondarySystemBackground)
         #endif
diff --git a/apps/shared/ClawdisKit/Tests/ClawdisKitTests/ChatThemeTests.swift b/apps/shared/ClawdisKit/Tests/ClawdisKitTests/ChatThemeTests.swift
new file mode 100644
index 000000000..26352a411
--- /dev/null
+++ b/apps/shared/ClawdisKit/Tests/ClawdisKitTests/ChatThemeTests.swift
@@ -0,0 +1,29 @@
+@testable import ClawdisChatUI
+import Foundation
+import Testing
+
+#if os(macOS)
+import AppKit
+#endif
+
+#if os(macOS)
+private func luminance(_ color: NSColor) throws -> CGFloat {
+    let rgb = try #require(color.usingColorSpace(.deviceRGB))
+    return 0.2126 * rgb.redComponent + 0.7152 * rgb.greenComponent + 0.0722 * rgb.blueComponent
+}
+#endif
+
+@Suite struct ChatThemeTests {
+    @Test func assistantBubbleResolvesForLightAndDark() throws {
+        #if os(macOS)
+        let lightAppearance = try #require(NSAppearance(named: .aqua))
+        let darkAppearance = try #require(NSAppearance(named: .darkAqua))
+
+        let lightResolved = ClawdisChatTheme.resolvedAssistantBubbleColor(for: lightAppearance)
+        let darkResolved = ClawdisChatTheme.resolvedAssistantBubbleColor(for: darkAppearance)
+        #expect(try luminance(lightResolved) > luminance(darkResolved))
+        #else
+        #expect(Bool(true))
+        #endif
+    }
+}