diff --git a/apps/dashboard/src/lib/extension-store-url.ts b/apps/dashboard/src/lib/extension-store-url.ts
index 2aadb20..9f74170 100644
--- a/apps/dashboard/src/lib/extension-store-url.ts
+++ b/apps/dashboard/src/lib/extension-store-url.ts
@@ -3,7 +3,7 @@ export const CHROME_EXTENSION_STORE_URL =
 	"https://chromewebstore.google.com/detail/celjddfjncnnkgfgldobcahfiimlebll/" as const;
 
 export const FIREFOX_EXTENSION_STORE_URL =
-	"https://addons.mozilla.org/en-US/firefox/addon/diffkit/" as const;
+	"https://addons.mozilla.org/addon/diffkit/" as const;
 
 function isFirefoxFamilyUserAgent(ua: string): boolean {
 	// Desktop Firefox: "Firefox/123"; Firefox iOS: "FxiOS/123"; avoid relying on siteConfig.
diff --git a/apps/dashboard/src/routes/_protected/settings/index.tsx b/apps/dashboard/src/routes/_protected/settings/index.tsx
index 2372b50..752c567 100644
--- a/apps/dashboard/src/routes/_protected/settings/index.tsx
+++ b/apps/dashboard/src/routes/_protected/settings/index.tsx
@@ -1,9 +1,19 @@
-import { MoonIcon, SunIcon, SystemIcon } from "@diffkit/icons";
+import {
+	CheckIcon,
+	DownloadIcon,
+	MoonIcon,
+	SunIcon,
+	SystemIcon,
+} from "@diffkit/icons";
 import { Button } from "@diffkit/ui/components/button";
+import { Logo } from "@diffkit/ui/components/logo";
 import { cn } from "@diffkit/ui/lib/utils";
 import { createFileRoute, Link } from "@tanstack/react-router";
 import { useTheme } from "next-themes";
+import { useEffect, useState } from "react";
 import { signOutToLogin } from "#/lib/auth-actions";
+import { isDiffKitExtensionPresent } from "#/lib/diffkit-extension-detect";
+import { getExtensionStoreInstallUrl } from "#/lib/extension-store-url";
 import { useHasMounted } from "#/lib/use-has-mounted";
 
 const themeOptions = [
@@ -40,6 +50,13 @@ function GeneralSettingsPage() {
 				<ThemePicker />
 			</SettingsSection>
 
+			<SettingsSection
+				title="Browser extension"
+				description="Automatically redirect GitHub pages to DiffKit."
+			>
+				<ExtensionCard />
+			</SettingsSection>
+
 			<SettingsSection
 				title="Repository access"
 				description="Manage which GitHub organizations and repositories DiffKit can access."
@@ -229,3 +246,60 @@ function SystemThemePreview() {
 		</div>
 	);
 }
+
+function ExtensionCard() {
+	const hasMounted = useHasMounted();
+	const [installed, setInstalled] = useState(false);
+
+	useEffect(() => {
+		if (!hasMounted) return;
+
+		setInstalled(isDiffKitExtensionPresent());
+
+		if (isDiffKitExtensionPresent()) return;
+
+		const el = document.documentElement;
+		const observer = new MutationObserver(() => {
+			if (isDiffKitExtensionPresent()) {
+				setInstalled(true);
+				observer.disconnect();
+			}
+		});
+		observer.observe(el, {
+			attributes: true,
+			attributeFilter: ["data-diffkit-extension"],
+		});
+		return () => observer.disconnect();
+	}, [hasMounted]);
+
+	const installHref = getExtensionStoreInstallUrl();
+
+	return (
+		<div className="flex items-center justify-between gap-4 rounded-xl border border-border/70 px-4 py-3.5">
+			<div className="flex min-w-0 items-center gap-3">
+				<Logo className="size-5 shrink-0" aria-hidden />
+				<div className="min-w-0">
+					<p className="text-sm font-medium">DiffKit Extension</p>
+					<p className="text-sm text-muted-foreground">
+						{installed
+							? "The extension is installed and active."
+							: "Redirect GitHub PRs, issues, and matching pages to DiffKit."}
+					</p>
+				</div>
+			</div>
+			{installed ? (
+				<span className="flex shrink-0 items-center gap-1.5 text-sm text-emerald-600 dark:text-emerald-400">
+					<CheckIcon size={14} strokeWidth={2} />
+					Installed
+				</span>
+			) : (
+				<Button asChild variant="outline" size="sm" className="shrink-0">
+					<a href={installHref} target="_blank" rel="noopener noreferrer">
+						<DownloadIcon size={14} strokeWidth={2} />
+						Install
+					</a>
+				</Button>
+			)}
+		</div>
+	);
+}
diff --git a/extensions/diffkit-redirect/dashboard-presence.js b/extensions/diffkit-redirect/dashboard-presence.js
index 8a202e6..68a5f58 100644
--- a/extensions/diffkit-redirect/dashboard-presence.js
+++ b/extensions/diffkit-redirect/dashboard-presence.js
@@ -2,10 +2,20 @@
  * Runs on DiffKit web app origins so the site can detect the extension via DOM
  * (`data-diffkit-extension` on <html>). Content scripts cannot share `window`
  * with the page, but DOM attributes are visible to the app.
+ *
+ * Guard: Firefox may inject content scripts beyond the manifest `matches` when
+ * the user grants broader host permissions, so we verify the origin explicitly.
  */
 (function markDiffKitExtensionPresent() {
   try {
-    document.documentElement.dataset.diffkitExtension = "1";
+    const origin = location.origin;
+    if (
+      origin === "https://diff-kit.com" ||
+      origin === "http://localhost:3000" ||
+      origin === "http://127.0.0.1:3000"
+    ) {
+      document.documentElement.dataset.diffkitExtension = "1";
+    }
   } catch {
     // ignore
   }