WebUI: Store durable settings in client data API

src/webui/www/private/index.html

@@ -29,6 +29,7 @@
     <script defer src="scripts/monkeypatch.js?v=${CACHEID}"></script>
     <script defer src="scripts/cache.js?v=${CACHEID}"></script>
     <script defer src="scripts/localpreferences.js?v=${CACHEID}"></script>
+    <script defer src="scripts/client-data.js?v=${CACHEID}"></script>
     <script defer src="scripts/color-scheme.js?v=${CACHEID}"></script>
     <script defer src="scripts/mocha-init.js?locale=${LANG}&v=${CACHEID}"></script>
     <script defer src="scripts/lib/clipboard-copy.js"></script>

src/webui/www/private/scripts/addtorrent.js

@@ -44,9 +44,10 @@ window.qBittorrent.AddTorrent ??= (() => {
     let source = "";
 
     const LocalPreferences = new window.qBittorrent.LocalPreferences.LocalPreferences();
+    const clientData = window.parent.qBittorrent.ClientData;
 
     const getCategories = () => {
-        const defaultCategory = LocalPreferences.get("add_torrent_default_category", "");
+        const defaultCategory = clientData.getCached("add_torrent_default_category") ?? "";
         const categorySelect = document.getElementById("categorySelect");
         for (const name of window.parent.qBittorrent.Client.categoryMap.keys()) {
             const option = document.createElement("option");
@@ -311,10 +312,7 @@ window.qBittorrent.AddTorrent ??= (() => {
 
         if (document.getElementById("setDefaultCategory").checked) {
             const category = document.getElementById("category").value.trim();
-            if (category.length === 0)
+            clientData.set({ add_torrent_default_category: category.length > 0 ? category : null });
-                LocalPreferences.remove("add_torrent_default_category");
-            else
-                LocalPreferences.set("add_torrent_default_category", category);
         }
     };
 

src/webui/www/private/scripts/client-data.js

@@ -0,0 +1,128 @@
+/*
+ * Bittorrent Client using Qt and libtorrent.
+ * Copyright (C) 2025 Thomas Piccirello <thomas@piccirello.com>
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
+ *
+ * In addition, as a special exception, the copyright holders give permission to
+ * link this program with the OpenSSL project's "OpenSSL" library (or with
+ * modified versions of it that use the same license as the "OpenSSL" library),
+ * and distribute the linked executables. You must obey the GNU General Public
+ * License in all respects for all of the code used other than "OpenSSL".  If you
+ * modify file(s), you may extend this exception to your version of the file(s),
+ * but you are not obligated to do so. If you do not wish to do so, delete this
+ * exception statement from your version.
+ */
+
+"use strict";
+
+window.qBittorrent ??= {};
+window.qBittorrent.ClientData ??= (() => {
+    const exports = () => {
+        return {
+            getCached: (...args) => instance.getCached(...args),
+            get: (...args) => instance.get(...args),
+            set: (...args) => instance.set(...args),
+        };
+    };
+
+    // this is exposed as a singleton
+    class ClientData {
+        /**
+         * @type Map<string, any>
+         */
+        #cache = new Map();
+
+        /**
+         * @param {string[]} keys
+         * @returns {Record<string, any>}
+         */
+        async #fetch(keys) {
+            return await fetch("api/v2/app/clientData", {
+                    method: "POST",
+                    body: new URLSearchParams({
+                        keys: JSON.stringify(keys)
+                    })
+                })
+                .then(async (response) => {
+                    if (!response.ok)
+                        return;
+
+                    return await response.json();
+                });
+        }
+
+        /**
+         * @param {Record<string, any>} data
+         */
+        async #set(data) {
+            await fetch("api/v2/app/setClientData", {
+                    method: "POST",
+                    body: new URLSearchParams({
+                        data: JSON.stringify(data)
+                    })
+                })
+                .then((response) => {
+                    if (!response.ok)
+                        throw new Error("Failed to store client data");
+                });
+        }
+
+        /**
+         * @param {string} key
+         * @returns {any}
+         */
+        getCached(key) {
+            return this.#cache.get(key);
+        }
+
+        /**
+         * @param {string[]} keys
+         * @returns {Record<string, any>}
+         */
+        async get(keys = []) {
+            const keysToFetch = keys.filter((key) => !this.#cache.has(key));
+            if (keysToFetch.length > 0) {
+                const fetchedData = await this.#fetch(keysToFetch);
+                for (const [key, value] of Object.entries(fetchedData))
+                    this.#cache.set(key, value);
+            }
+
+            return Object.fromEntries(keys.map((key) => ([key, this.#cache.get(key)])));
+        }
+
+        /**
+         * @param {Record<string, any>} data
+         */
+        async set(data) {
+            try {
+                await this.#set(data);
+            }
+            catch (err) {
+                console.error(err);
+                return;
+            }
+
+            // update cache
+            for (const [key, value] of Object.entries(data))
+                this.#cache.set(key, value);
+        }
+    }
+
+    const instance = new ClientData();
+
+    return exports();
+})();
+Object.freeze(window.qBittorrent.ClientData);

src/webui/www/private/scripts/client.js

@@ -31,6 +31,7 @@ window.qBittorrent.Client ??= (() => {
         return {
             setup: setup,
             initializeCaches: initializeCaches,
+            initializeClientData: initializeClientData,
             closeWindow: closeWindow,
             closeFrameWindow: closeFrameWindow,
             getSyncMainDataInterval: getSyncMainDataInterval,
@@ -56,15 +57,47 @@ window.qBittorrent.Client ??= (() => {
     const tagMap = new Map();
 
     let cacheAllSettled;
+    let clientDataPromise;
     const setup = () => {
         // fetch various data and store it in memory
+        clientDataPromise = window.qBittorrent.ClientData.get([
+            "show_search_engine",
+            "show_rss_reader",
+            "show_log_viewer",
+            "speed_in_browser_title_bar",
+            "show_top_toolbar",
+            "show_status_bar",
+            "show_filters_sidebar",
+            "hide_zero_status_filters",
+            "color_scheme",
+            "full_url_tracker_column",
+            "use_alt_row_colors",
+            "use_virtual_list",
+            "dblclick_complete",
+            "dblclick_download",
+            "dblclick_filter",
+            "search_in_filter",
+            "qbt_selected_log_levels",
+            "add_torrent_default_category",
+        ]);
+
         cacheAllSettled = Promise.allSettled([
             window.qBittorrent.Cache.buildInfo.init(),
             window.qBittorrent.Cache.preferences.init(),
-            window.qBittorrent.Cache.qbtVersion.init()
+            window.qBittorrent.Cache.qbtVersion.init(),
+            clientDataPromise,
         ]);
     };
 
+    const initializeClientData = async () => {
+        try {
+            await clientDataPromise;
+        }
+        catch (error) {
+            console.error(`Failed to initialize client data. Reason: "${error}".`);
+        }
+    };
+
     const initializeCaches = async () => {
         const results = await cacheAllSettled;
         for (const [idx, result] of results.entries()) {
@@ -224,8 +257,8 @@ let queueing_enabled = true;
 let serverSyncMainDataInterval = 1500;
 let customSyncMainDataInterval = null;
 let useSubcategories = true;
-const useAutoHideZeroStatusFilters = LocalPreferences.get("hide_zero_status_filters", "false") === "true";
+let useAutoHideZeroStatusFilters = false;
-const displayFullURLTrackerColumn = LocalPreferences.get("full_url_tracker_column", "false") === "true";
+let displayFullURLTrackerColumn = false;
 
 /* Categories filter */
 const CATEGORIES_ALL = "b4af0e4c-e76d-4bac-a392-46cbc18d9655";
@@ -251,6 +284,8 @@ const TRACKERS_WARNING = "82a702c5-210c-412b-829f-97632d7557e9";
 // Map<trackerHost: String, Map<trackerURL: String, torrents: Set>>
 const trackerMap = new Map();
 
+const clientData = window.qBittorrent.ClientData;
+
 let selectedTracker = LocalPreferences.get("selected_tracker", TRACKERS_ALL);
 let setTrackerFilter = () => {};
 
@@ -259,7 +294,13 @@ let selectedStatus = LocalPreferences.get("selected_filter", "all");
 let setStatusFilter = () => {};
 let toggleFilterDisplay = () => {};
 
-window.addEventListener("DOMContentLoaded", (event) => {
+window.addEventListener("DOMContentLoaded", async (event) => {
+    await window.qBittorrent.Client.initializeClientData();
+    window.qBittorrent.ColorScheme.update();
+
+    useAutoHideZeroStatusFilters = clientData.getCached("hide_zero_status_filters") === true;
+    displayFullURLTrackerColumn = clientData.getCached("full_url_tracker_column") === true;
+
     window.qBittorrent.LocalPreferences.upgrade();
 
     let isSearchPanelLoaded = false;
@@ -406,6 +447,13 @@ window.addEventListener("DOMContentLoaded", (event) => {
         LocalPreferences.set(`filter_${filterListID.replace("FilterList", "")}_collapsed`, filterList.classList.toggle("invisible").toString());
     };
 
+    const highlightSelectedStatus = () => {
+        const statusFilter = document.getElementById("statusFilterList");
+        const filterID = `${selectedStatus}_filter`;
+        for (const status of statusFilter.children)
+            status.classList.toggle("selectedFilter", (status.id === filterID));
+    };
+
     new MochaUI.Panel({
         id: "Filters",
         title: "Panel",
@@ -427,35 +475,35 @@ window.addEventListener("DOMContentLoaded", (event) => {
     initializeWindows();
 
     // Show Top Toolbar is enabled by default
-    let showTopToolbar = LocalPreferences.get("show_top_toolbar", "true") === "true";
+    let showTopToolbar = clientData.getCached("show_top_toolbar") !== false;
     if (!showTopToolbar) {
         document.getElementById("showTopToolbarLink").firstElementChild.style.opacity = "0";
         document.getElementById("mochaToolbar").classList.add("invisible");
     }
 
     // Show Status Bar is enabled by default
-    let showStatusBar = LocalPreferences.get("show_status_bar", "true") === "true";
+    let showStatusBar = clientData.getCached("show_status_bar") !== false;
     if (!showStatusBar) {
         document.getElementById("showStatusBarLink").firstElementChild.style.opacity = "0";
         document.getElementById("desktopFooterWrapper").classList.add("invisible");
     }
 
     // Show Filters Sidebar is enabled by default
-    let showFiltersSidebar = LocalPreferences.get("show_filters_sidebar", "true") === "true";
+    let showFiltersSidebar = clientData.getCached("show_filters_sidebar") !== false;
     if (!showFiltersSidebar) {
         document.getElementById("showFiltersSidebarLink").firstElementChild.style.opacity = "0";
         document.getElementById("filtersColumn").classList.add("invisible");
         document.getElementById("filtersColumn_handle").classList.add("invisible");
     }
 
-    let speedInTitle = LocalPreferences.get("speed_in_browser_title_bar") === "true";
+    let speedInTitle = clientData.getCached("speed_in_browser_title_bar") === true;
     if (!speedInTitle)
         document.getElementById("speedInBrowserTitleBarLink").firstElementChild.style.opacity = "0";
 
     // After showing/hiding the toolbar + status bar
-    window.qBittorrent.Client.showSearchEngine(LocalPreferences.get("show_search_engine") !== "false");
+    window.qBittorrent.Client.showSearchEngine(clientData.getCached("show_search_engine") !== false);
-    window.qBittorrent.Client.showRssReader(LocalPreferences.get("show_rss_reader") !== "false");
+    window.qBittorrent.Client.showRssReader(clientData.getCached("show_rss_reader") !== false);
-    window.qBittorrent.Client.showLogViewer(LocalPreferences.get("show_log_viewer") === "true");
+    window.qBittorrent.Client.showLogViewer(clientData.getCached("show_log_viewer") === true);
 
     // After Show Top Toolbar
     MochaUI.Desktop.setDesktopSize();
@@ -572,13 +620,6 @@ window.addEventListener("DOMContentLoaded", (event) => {
             window.qBittorrent.Filters.clearStatusFilter();
     };
 
-    const highlightSelectedStatus = () => {
-        const statusFilter = document.getElementById("statusFilterList");
-        const filterID = `${selectedStatus}_filter`;
-        for (const status of statusFilter.children)
-            status.classList.toggle("selectedFilter", (status.id === filterID));
-    };
-
     const updateCategoryList = () => {
         const categoryList = document.getElementById("categoryFilterList");
         if (!categoryList)
@@ -1221,7 +1262,7 @@ window.addEventListener("DOMContentLoaded", (event) => {
 
     document.getElementById("showTopToolbarLink").addEventListener("click", (e) => {
         showTopToolbar = !showTopToolbar;
-        LocalPreferences.set("show_top_toolbar", showTopToolbar.toString());
+        clientData.set({ show_top_toolbar: showTopToolbar });
         if (showTopToolbar) {
             document.getElementById("showTopToolbarLink").firstElementChild.style.opacity = "1";
             document.getElementById("mochaToolbar").classList.remove("invisible");
@@ -1235,7 +1276,7 @@ window.addEventListener("DOMContentLoaded", (event) => {
 
     document.getElementById("showStatusBarLink").addEventListener("click", (e) => {
         showStatusBar = !showStatusBar;
-        LocalPreferences.set("show_status_bar", showStatusBar.toString());
+        clientData.set({ show_status_bar: showStatusBar });
         if (showStatusBar) {
             document.getElementById("showStatusBarLink").firstElementChild.style.opacity = "1";
             document.getElementById("desktopFooterWrapper").classList.remove("invisible");
@@ -1272,7 +1313,7 @@ window.addEventListener("DOMContentLoaded", (event) => {
 
     document.getElementById("showFiltersSidebarLink").addEventListener("click", (e) => {
         showFiltersSidebar = !showFiltersSidebar;
-        LocalPreferences.set("show_filters_sidebar", showFiltersSidebar.toString());
+        clientData.set({ show_filters_sidebar: showFiltersSidebar });
         if (showFiltersSidebar) {
             document.getElementById("showFiltersSidebarLink").firstElementChild.style.opacity = "1";
             document.getElementById("filtersColumn").classList.remove("invisible");
@@ -1288,7 +1329,7 @@ window.addEventListener("DOMContentLoaded", (event) => {
 
     document.getElementById("speedInBrowserTitleBarLink").addEventListener("click", (e) => {
         speedInTitle = !speedInTitle;
-        LocalPreferences.set("speed_in_browser_title_bar", speedInTitle.toString());
+        LocalPreferences.set("speed_in_browser_title_bar", speedInTitle);
         if (speedInTitle)
             document.getElementById("speedInBrowserTitleBarLink").firstElementChild.style.opacity = "1";
         else
@@ -1298,19 +1339,19 @@ window.addEventListener("DOMContentLoaded", (event) => {
 
     document.getElementById("showSearchEngineLink").addEventListener("click", (e) => {
         window.qBittorrent.Client.showSearchEngine(!window.qBittorrent.Client.isShowSearchEngine());
-        LocalPreferences.set("show_search_engine", window.qBittorrent.Client.isShowSearchEngine().toString());
+        clientData.set({ show_search_engine: window.qBittorrent.Client.isShowSearchEngine() });
         updateTabDisplay();
     });
 
     document.getElementById("showRssReaderLink").addEventListener("click", (e) => {
         window.qBittorrent.Client.showRssReader(!window.qBittorrent.Client.isShowRssReader());
-        LocalPreferences.set("show_rss_reader", window.qBittorrent.Client.isShowRssReader().toString());
+        clientData.set({ show_rss_reader: window.qBittorrent.Client.isShowRssReader() });
         updateTabDisplay();
     });
 
     document.getElementById("showLogViewerLink").addEventListener("click", (e) => {
         window.qBittorrent.Client.showLogViewer(!window.qBittorrent.Client.isShowLogViewer());
-        LocalPreferences.set("show_log_viewer", window.qBittorrent.Client.isShowLogViewer().toString());
+        clientData.set({ show_log_viewer: window.qBittorrent.Client.isShowLogViewer() });
         updateTabDisplay();
     });
 
@@ -1367,7 +1408,7 @@ window.addEventListener("DOMContentLoaded", (event) => {
     // main window tabs
 
     const showTransfersTab = () => {
-        const showFiltersSidebar = LocalPreferences.get("show_filters_sidebar", "true") === "true";
+        const showFiltersSidebar = clientData.getCached("show_filters_sidebar") !== false;
         if (showFiltersSidebar) {
             document.getElementById("filtersColumn").classList.remove("invisible");
             document.getElementById("filtersColumn_handle").classList.remove("invisible");

src/webui/www/private/scripts/color-scheme.js

@@ -36,12 +36,12 @@ window.qBittorrent.ColorScheme ??= (() => {
         };
     };
 
-    const LocalPreferences = new window.qBittorrent.LocalPreferences.LocalPreferences();
     const colorSchemeQuery = window.matchMedia("(prefers-color-scheme: dark)");
+    const clientData = window.parent.qBittorrent.ClientData;
 
     const update = () => {
         const root = document.documentElement;
-        const colorScheme = LocalPreferences.get("color_scheme");
+        const colorScheme = clientData.getCached("color_scheme");
         const validScheme = (colorScheme === "light") || (colorScheme === "dark");
         const isDark = colorSchemeQuery.matches;
         root.classList.toggle("dark", ((!validScheme && isDark) || (colorScheme === "dark")));
@@ -52,5 +52,3 @@ window.qBittorrent.ColorScheme ??= (() => {
     return exports();
 })();
 Object.freeze(window.qBittorrent.ColorScheme);
-
-window.qBittorrent.ColorScheme.update();

src/webui/www/private/scripts/dynamicTable.js

@@ -65,6 +65,7 @@ window.qBittorrent.DynamicTable ??= (() => {
         return 0;
     };
 
+    const clientData = window.qBittorrent.ClientData ?? window.parent.qBittorrent.ClientData;
     let DynamicTableHeaderContextMenuClass = null;
 
     if (typeof LocalPreferences === "undefined")
@@ -75,7 +76,7 @@ window.qBittorrent.DynamicTable ??= (() => {
             this.dynamicTableDivId = dynamicTableDivId;
             this.dynamicTableFixedHeaderDivId = dynamicTableFixedHeaderDivId;
             this.dynamicTableDiv = document.getElementById(dynamicTableDivId);
-            this.useVirtualList = useVirtualList && (LocalPreferences.get("use_virtual_list", "false") === "true");
+            this.useVirtualList = useVirtualList && (clientData.getCached("use_virtual_list") === true);
             this.fixedTableHeader = document.querySelector(`#${dynamicTableFixedHeaderDivId} thead tr`);
             this.hiddenTableHeader = this.dynamicTableDiv.querySelector("thead tr");
             this.table = this.dynamicTableDiv.querySelector("table");
@@ -730,7 +731,7 @@ window.qBittorrent.DynamicTable ??= (() => {
         }
 
         setupAltRow() {
-            const useAltRowColors = (LocalPreferences.get("use_alt_row_colors", "true") === "true");
+            const useAltRowColors = clientData.getCached("use_alt_row_colors") !== false;
             if (useAltRowColors)
                 document.getElementById(this.dynamicTableDivId).classList.add("altRowColors");
         }
@@ -1805,7 +1806,7 @@ window.qBittorrent.DynamicTable ??= (() => {
                     ? "dblclick_download"
                     : "dblclick_complete";
 
-                if (LocalPreferences.get(prefKey, "1") !== "1")
+                if (clientData.getCached(prefKey) === "0")
                     return true;
 
                 if (state.includes("stopped"))

src/webui/www/private/scripts/search.js

@@ -107,8 +107,7 @@ window.qBittorrent.Search ??= (() => {
     });
 
     const init = () => {
-        // load "Search in" preference from local storage
+        document.getElementById("searchInTorrentName").value = (window.qBittorrent.ClientData.getCached("search_in_filter") === "names") ? "names" : "everywhere";
-        document.getElementById("searchInTorrentName").value = (LocalPreferences.get("search_in_filter") === "names") ? "names" : "everywhere";
         const searchResultsTableContextMenu = new window.qBittorrent.ContextMenu.ContextMenu({
             targets: "#searchResultsTableDiv tbody tr",
             menu: "searchResultsTableMenu",
@@ -804,7 +803,8 @@ window.qBittorrent.Search ??= (() => {
     };
 
     const searchInTorrentName = () => {
-        LocalPreferences.set("search_in_filter", getSearchInTorrentName());
+        // don't await this
+        window.qBittorrent.ClientData.set({ search_in_filter: getSearchInTorrentName() });
         searchFilterChanged();
     };
 

src/webui/www/private/views/createtorrent.html

@@ -138,7 +138,7 @@
             return option;
         };
 
-        const init = () => {
+        const init = async () => {
             const pieceSizeSelect = document.getElementById("pieceSize");
             pieceSizeSelect.appendChild(createSizeOption(0));
             for (let i = 4; i <= 17; ++i)
@@ -163,7 +163,7 @@
                 submit();
             });
 
-            loadPreference();
+            await loadPreference();
             window.qBittorrent.pathAutofill.attachPathAutofill();
         };
 
@@ -207,11 +207,13 @@
                 comments: document.getElementById("comments").value,
                 source: document.getElementById("source").value,
             };
-            LocalPreferences.set("torrent_creator", JSON.stringify(preference));
+            window.parent.qBittorrent.ClientData.set({ torrent_creator: preference });
         };
 
-        const loadPreference = () => {
+        const loadPreference = async () => {
-            const preference = JSON.parse(LocalPreferences.get("torrent_creator") ?? "{}");
+            const clientData = await window.parent.qBittorrent.ClientData.get(["torrent_creator"]);
+            const preference = clientData.torrent_creator ?? {};
+
             document.getElementById("sourcePath").value = preference.sourcePath ?? "";
             document.getElementById("torrentFormat").value = preference.torrentFormat ?? "hybrid";
             document.getElementById("pieceSize").value = preference.pieceSize ?? 0;

src/webui/www/private/views/filters.html

@@ -261,7 +261,7 @@
         });
 
         document.getElementById("Filters_pad").addEventListener("dblclick", (event) => {
-            if (LocalPreferences.get("dblclick_filter", "1") !== "1")
+            if (window.qBittorrent.ClientData.getCached("dblclick_filter") === "0")
                 return;
 
             const filterItem = event.target.closest("li");

src/webui/www/private/views/log.html

@@ -185,7 +185,7 @@
         let logFilterTimer = -1;
         let inputtedFilterText = "";
         let selectBox;
-        let selectedLogLevels = JSON.parse(LocalPreferences.get("qbt_selected_log_levels")) || ["1", "2", "4", "8"];
+        let selectedLogLevels = window.qBittorrent.ClientData.getCached("qbt_selected_log_levels") ?? ["1", "2", "4", "8"];
 
         const init = () => {
             for (const option of document.getElementById("logLevelSelect").options)
@@ -276,7 +276,8 @@
             if (selectedLogLevels !== value) {
                 tableInfo[currentSelectedTab].last_id = -1;
                 selectedLogLevels = value;
-                LocalPreferences.set("qbt_selected_log_levels", JSON.stringify(selectedLogLevels));
+                // don't await this
+                window.qBittorrent.ClientData.set({ qbt_selected_log_levels: selectedLogLevels });
                 logFilterChanged();
             }
         };

src/webui/www/private/views/preferences.html

@@ -2215,10 +2215,8 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
             document.getElementById("locale_select").value = selected;
         };
 
-        const updateColoSchemeSelect = () => {
+        const updateColoSchemeSelect = (colorScheme) => {
             const combobox = document.getElementById("colorSchemeSelect");
-            const colorScheme = LocalPreferences.get("color_scheme");
-
             if (colorScheme === "light")
                 combobox.options[1].selected = true;
             else if (colorScheme === "dark")
@@ -2230,20 +2228,31 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
         const loadPreferences = () => {
             window.parent.qBittorrent.Cache.preferences.init()
                 .then((pref) => {
+                    const clientData = window.parent.qBittorrent.ClientData;
+                    const colorScheme = clientData.getCached("color_scheme");
+                    const fullUrlTrackerColumn = clientData.getCached("full_url_tracker_column");
+                    const useVirtualList = clientData.getCached("use_virtual_list");
+                    const hideZeroStatusFilters = clientData.getCached("hide_zero_status_filters");
+                    const dblclickDownload = clientData.getCached("dblclick_download");
+                    const dblclickComplete = clientData.getCached("dblclick_complete");
+                    const dblclickFilter = clientData.getCached("dblclick_filter");
+                    const useAltRowColors = clientData.getCached("use_alt_row_colors");
+
                     // Behavior tab
                     // Language
                     updateWebuiLocaleSelect(pref.locale);
-                    updateColoSchemeSelect();
+                    updateColoSchemeSelect(colorScheme);
+
                     document.getElementById("statusBarExternalIP").checked = pref.status_bar_external_ip;
                     document.getElementById("performanceWarning").checked = pref.performance_warning;
-                    document.getElementById("displayFullURLTrackerColumn").checked = (LocalPreferences.get("full_url_tracker_column", "false") === "true");
+                    document.getElementById("displayFullURLTrackerColumn").checked = fullUrlTrackerColumn === true;
-                    document.getElementById("useVirtualList").checked = (LocalPreferences.get("use_virtual_list", "false") === "true");
+                    document.getElementById("useVirtualList").checked = useVirtualList === true;
-                    document.getElementById("hideZeroFiltersCheckbox").checked = (LocalPreferences.get("hide_zero_status_filters", "false") === "true");
+                    document.getElementById("hideZeroFiltersCheckbox").checked = hideZeroStatusFilters === true;
-                    document.getElementById("dblclickDownloadSelect").value = LocalPreferences.get("dblclick_download", "1");
+                    document.getElementById("dblclickDownloadSelect").value = dblclickDownload ?? "1";
-                    document.getElementById("dblclickCompleteSelect").value = LocalPreferences.get("dblclick_complete", "1");
+                    document.getElementById("dblclickCompleteSelect").value = dblclickComplete ?? "1";
-                    document.getElementById("dblclickFiltersSelect").value = LocalPreferences.get("dblclick_filter", "1");
+                    document.getElementById("dblclickFiltersSelect").value = dblclickFilter ?? "1";
                     document.getElementById("confirmTorrentDeletion").checked = pref.confirm_torrent_deletion;
-                    document.getElementById("useAltRowColorsInput").checked = (LocalPreferences.get("use_alt_row_colors", "true") === "true");
+                    document.getElementById("useAltRowColorsInput").checked = useAltRowColors !== false;
                     document.getElementById("filelog_checkbox").checked = pref.file_log_enabled;
                     document.getElementById("filelog_save_path_input").value = pref.file_log_path;
                     document.getElementById("filelog_backup_checkbox").checked = pref.file_log_backup_enabled;
@@ -2658,6 +2667,7 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
 
         const applyPreferences = () => {
             const settings = {};
+            const clientData = {};
             // Validate form data
 
             // Behavior tab
@@ -2665,21 +2675,21 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
             settings["locale"] = document.getElementById("locale_select").value;
             const colorScheme = Number(document.getElementById("colorSchemeSelect").value);
             if (colorScheme === 0)
-                LocalPreferences.remove("color_scheme");
+                clientData.color_scheme = null;
             else if (colorScheme === 1)
-                LocalPreferences.set("color_scheme", "light");
+                clientData.color_scheme = "light";
             else
-                LocalPreferences.set("color_scheme", "dark");
+                clientData.color_scheme = "dark";
             settings["status_bar_external_ip"] = document.getElementById("statusBarExternalIP").checked;
             settings["performance_warning"] = document.getElementById("performanceWarning").checked;
-            LocalPreferences.set("full_url_tracker_column", document.getElementById("displayFullURLTrackerColumn").checked.toString());
+            clientData.full_url_tracker_column = document.getElementById("displayFullURLTrackerColumn").checked;
-            LocalPreferences.set("use_virtual_list", document.getElementById("useVirtualList").checked.toString());
+            clientData.use_virtual_list = document.getElementById("useVirtualList").checked;
-            LocalPreferences.set("hide_zero_status_filters", document.getElementById("hideZeroFiltersCheckbox").checked.toString());
+            clientData.hide_zero_status_filters = document.getElementById("hideZeroFiltersCheckbox").checked;
-            LocalPreferences.set("dblclick_download", document.getElementById("dblclickDownloadSelect").value);
+            clientData.dblclick_download = document.getElementById("dblclickDownloadSelect").value;
-            LocalPreferences.set("dblclick_complete", document.getElementById("dblclickCompleteSelect").value);
+            clientData.dblclick_complete = document.getElementById("dblclickCompleteSelect").value;
-            LocalPreferences.set("dblclick_filter", document.getElementById("dblclickFiltersSelect").value);
+            clientData.dblclick_filter = document.getElementById("dblclickFiltersSelect").value;
             settings["confirm_torrent_deletion"] = document.getElementById("confirmTorrentDeletion").checked;
-            LocalPreferences.set("use_alt_row_colors", document.getElementById("useAltRowColorsInput").checked.toString());
+            clientData.use_alt_row_colors = document.getElementById("useAltRowColorsInput").checked;
             settings["file_log_enabled"] = document.getElementById("filelog_checkbox").checked;
             settings["file_log_path"] = document.getElementById("filelog_save_path_input").value;
             settings["file_log_backup_enabled"] = document.getElementById("filelog_backup_checkbox").checked;
@@ -3170,6 +3180,11 @@ Use ';' to split multiple entries. Can use wildcard '*'.)QBT_TR[CONTEXT=OptionsD
             settings["i2p_inbound_length"] = Number(document.getElementById("i2pInboundLength").value);
             settings["i2p_outbound_length"] = Number(document.getElementById("i2pOutboundLength").value);
 
+            window.parent.qBittorrent.ClientData.set(clientData)
+                .catch((error) => {
+                    alert("QBT_TR(Unable to save web client preferences, qBittorrent is probably unreachable.)QBT_TR[CONTEXT=HttpServer]");
+                });
+
             // Send it to qBT
             window.parent.qBittorrent.Cache.preferences.set(settings)
                 .then(() => {

src/webui/www/webui.qrc

@@ -390,6 +390,7 @@
         <file>private/scripts/addtorrent.js</file>
         <file>private/scripts/cache.js</file>
         <file>private/scripts/client.js</file>
+        <file>private/scripts/client-data.js</file>
         <file>private/scripts/color-scheme.js</file>
         <file>private/scripts/contextmenu.js</file>
         <file>private/scripts/dynamicTable.js</file>