diff --git a/src/app/(dashboard)/dashboard/settings/components/AppearanceTab.tsx b/src/app/(dashboard)/dashboard/settings/components/AppearanceTab.tsx
index 5afb230437..3c5d685530 100644
--- a/src/app/(dashboard)/dashboard/settings/components/AppearanceTab.tsx
+++ b/src/app/(dashboard)/dashboard/settings/components/AppearanceTab.tsx
@@ -221,9 +221,7 @@ export default function AppearanceTab() {
 
         <div className="pt-4 border-t border-border">
           <div className="mb-3">
-            <p className="font-medium">
-              {getSettingsLabel("sidebarVisibility", "Hide sidebar items")}
-            </p>
+            <p className="font-medium">{t("sidebarVisibilityToggle")}</p>
             <p className="text-sm text-text-muted">
               {getSettingsLabel(
                 "sidebarVisibilityDesc",
@@ -249,7 +247,7 @@ export default function AppearanceTab() {
                     >
                       <p className="font-medium">{item.label}</p>
                       <Toggle
-                        checked={hiddenSidebarSet.has(item.id)}
+                        checked={!hiddenSidebarSet.has(item.id)}
                         onChange={() => toggleSidebarItem(item.id)}
                         disabled={loading}
                       />
diff --git a/src/app/(dashboard)/dashboard/settings/components/ProxyTab.tsx b/src/app/(dashboard)/dashboard/settings/components/ProxyTab.tsx
index bc5ae5c47e..6d3ffafee1 100644
--- a/src/app/(dashboard)/dashboard/settings/components/ProxyTab.tsx
+++ b/src/app/(dashboard)/dashboard/settings/components/ProxyTab.tsx
@@ -1,7 +1,7 @@
 "use client";
 
 import { useState, useEffect, useRef } from "react";
-import { Card, Button, ProxyConfigModal } from "@/shared/components";
+import { Card, Button, ProxyConfigModal, Toggle } from "@/shared/components";
 import { useTranslations } from "next-intl";
 import ProxyRegistryManager from "./ProxyRegistryManager";
 
@@ -11,6 +11,8 @@ export default function ProxyTab() {
   const mountedRef = useRef(true);
   const t = useTranslations("settings");
   const tc = useTranslations("common");
+  const [debugMode, setDebugMode] = useState(false);
+  const [loading, setLoading] = useState(true);
 
   const loadGlobalProxy = async () => {
     try {
@@ -22,6 +24,21 @@ export default function ProxyTab() {
     } catch {}
   };
 
+  const updateDebugMode = async (value: boolean) => {
+    try {
+      const res = await fetch("/api/settings", {
+        method: "PATCH",
+        headers: { "Content-Type": "application/json" },
+        body: JSON.stringify({ debugMode: value }),
+      });
+      if (res.ok) {
+        setDebugMode(value);
+      }
+    } catch (err) {
+      console.error("Failed to update debugMode:", err);
+    }
+  };
+
   useEffect(() => {
     mountedRef.current = true;
     async function init() {
@@ -40,6 +57,19 @@ export default function ProxyTab() {
     };
   }, []);
 
+  useEffect(() => {
+    fetch("/api/settings")
+      .then((res) => {
+        if (!res.ok) throw new Error(`HTTP error ${res.status}`);
+        return res.json();
+      })
+      .then((data) => {
+        setDebugMode(data.debugMode === true);
+        setLoading(false);
+      })
+      .catch(() => setLoading(false));
+  }, []);
+
   return (
     <>
       <div className="flex flex-col gap-6">
@@ -78,6 +108,18 @@ export default function ProxyTab() {
         </Card>
 
         <ProxyRegistryManager />
+        <Card className="p-6 mt-4">
+          <div className="flex items-center justify-between">
+            <div>
+              <p className="font-medium">{t("debugToggle")}</p>
+            </div>
+            <Toggle
+              checked={debugMode}
+              onChange={() => updateDebugMode(!debugMode)}
+              disabled={loading}
+            />
+          </div>
+        </Card>
       </div>
 
       <ProxyConfigModal
diff --git a/src/app/api/settings/__tests__/settings.test.ts b/src/app/api/settings/__tests__/settings.test.ts
new file mode 100644
index 0000000000..c8d06b2fa7
--- /dev/null
+++ b/src/app/api/settings/__tests__/settings.test.ts
@@ -0,0 +1,64 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { PATCH } from "../route";
+
+// Mock the localDb functions used in the route
+vi.mock("../../../../lib/localDb", () => {
+  const original = vi.importActual("../../../../lib/localDb");
+  return {
+    ...original,
+    getSettings: vi.fn(),
+    updateSettings: vi.fn(),
+  };
+});
+
+import { getSettings, updateSettings } from "../../../../lib/localDb";
+
+// Helper to create a Request with JSON body
+function createPatchRequest(body: unknown) {
+  return new Request("http://localhost/api/settings", {
+    method: "PATCH",
+    headers: { "Content-Type": "application/json" },
+    body: JSON.stringify(body),
+  });
+}
+
+describe("PATCH /api/settings", () => {
+  beforeEach(() => {
+    vi.resetAllMocks();
+    // Default settings before each test
+    (getSettings as any).mockResolvedValue({
+      debugMode: false,
+      hiddenSidebarItems: [],
+    });
+    // Mock updateSettings to merge updates into the original
+    (updateSettings as any).mockImplementation(async (updates: Record<string, unknown>) => {
+      const current = await (getSettings as any)();
+      return { ...current, ...updates };
+    });
+  });
+
+  it("toggles debugMode via PATCH", async () => {
+    const req = createPatchRequest({ debugMode: true });
+    const res = await PATCH(req as any);
+    expect(res.status).toBe(200);
+    const json = await res.json();
+    expect(json.debugMode).toBe(true);
+    // Ensure password is not leaked
+    expect(json).not.toHaveProperty("password");
+    // Verify DB update called with correct payload
+    expect(updateSettings).toHaveBeenCalledOnce();
+    const calledWith = (updateSettings as any).mock.calls[0][0];
+    expect(calledWith.debugMode).toBe(true);
+  });
+
+  it("updates hiddenSidebarItems via PATCH", async () => {
+    const req = createPatchRequest({ hiddenSidebarItems: [] });
+    const res = await PATCH(req as any);
+    expect(res.status).toBe(200);
+    const json = await res.json();
+    expect(json.hiddenSidebarItems).toEqual([]);
+    expect(updateSettings).toHaveBeenCalledOnce();
+    const calledWith = (updateSettings as any).mock.calls[0][0];
+    expect(calledWith.hiddenSidebarItems).toEqual([]);
+  });
+});
diff --git a/src/i18n/messages/en.json b/src/i18n/messages/en.json
index dc9105da85..7aa80d86ec 100644
--- a/src/i18n/messages/en.json
+++ b/src/i18n/messages/en.json
@@ -1678,6 +1678,8 @@
     "darkMode": "Dark Mode",
     "lightMode": "Light Mode",
     "systemTheme": "System Theme",
+    "debugToggle": "Enable Debug Mode",
+    "sidebarVisibilityToggle": "Show Sidebar Items",
     "enableCache": "Enable Cache",
     "cacheTTL": "Cache TTL",
     "maxCacheSize": "Max Cache Size",
diff --git a/src/shared/validation/settingsSchemas.ts b/src/shared/validation/settingsSchemas.ts
index 9fea61ae3d..4517b33d5a 100644
--- a/src/shared/validation/settingsSchemas.ts
+++ b/src/shared/validation/settingsSchemas.ts
@@ -26,6 +26,7 @@ export const updateSettingsSchema = z.object({
   requireAuthForModels: z.boolean().optional(),
   blockedProviders: z.array(z.string().max(100)).optional(),
   hideHealthCheckLogs: z.boolean().optional(),
+  debugMode: z.boolean().optional(),
   hiddenSidebarItems: z.array(z.enum(HIDEABLE_SIDEBAR_ITEM_IDS)).optional(),
   // Routing settings (#134)
   fallbackStrategy: z