SCAL-324146 Fix: Dark mode resets to light on client-side navigation when isDarkMode URL param is set

src/components/DevDocTemplate/index.tsx

@@ -108,6 +108,14 @@ const DevDocTemplate: FC<DevDocTemplateProps> = (props) => {
         if (typeof window === 'undefined') return false;
         // In-product (embedded) presentation always uses light mode — product UI has no theme toggle.
         if (!isPublicSite(location.search)) return false;
+        // URL param takes highest priority (set by embedding product to pass its theme).
+        const urlParams = new URLSearchParams(window.location.search);
+        const darkModeParam = urlParams.get('isDarkMode');
+        if (darkModeParam !== null) {
+            const isDark = darkModeParam === 'true';
+            localStorage.setItem('themeMode', isDark ? 'dark' : 'light');
+            return isDark;
+        }
         /* themeMode is only written when the user explicitly clicks the toggle.
            If absent, follow OS preference fresh every load. */
         const explicitChoice = localStorage.getItem('themeMode');
@@ -265,6 +273,7 @@ const isVersionedIframe = VERSION_DROPDOWN.some(
                 const newDarkMode = darkModeParam === 'true';
                 setDarkMode(newDarkMode);
                 localStorage.setItem('theme', newDarkMode ? 'dark' : 'light');
+                localStorage.setItem('themeMode', newDarkMode ? 'dark' : 'light');
             }
         }
     }, [location.search]);