fix(auth): custom-domain login lands on guild home + guild logo favicon

apps/web/src/app/api/auth/discord/callback/route.ts

@@ -30,7 +30,7 @@ export async function GET(request: NextRequest) {
 
   const cookieStore = await cookies();
   const storedState = cookieStore.get("oauth_state")?.value;
-  const returnTo = safeRelativePath(cookieStore.get("oauth_return_to")?.value, "/dashboard");
+  const returnToCookie = cookieStore.get("oauth_return_to")?.value;
 
   // Clear the one-shot CSRF cookies regardless of outcome.
   cookieStore.delete("oauth_state");
@@ -40,6 +40,8 @@ export async function GET(request: NextRequest) {
   const host = await requestHostname();
   const onCustomDomain = Boolean(host) && !isPrimaryHostname(host!);
   const base = onCustomDomain ? `https://${host}` : appBaseUrl();
+  // The dashboard is primary-only; default custom-domain logins to the guild home.
+  const returnTo = safeRelativePath(returnToCookie, onCustomDomain ? "/" : "/dashboard");
   const errorUrl = new URL("/?auth=error", base);
 
   if (!code || !state || !storedState || state !== storedState) {

apps/web/src/app/api/auth/discord/login/route.ts

@@ -22,12 +22,19 @@ export const dynamic = "force-dynamic";
 export async function GET(request: NextRequest) {
   const state = crypto.randomUUID();
 
+  const host = await requestHostname();
+  const onCustomDomain = host != null && !isPrimaryHostname(host);
+
   // Same-origin relative redirect only (rejects "//", backslashes, control chars).
-  const returnTo = safeRelativePath(request.nextUrl.searchParams.get("returnTo"), "/dashboard");
+  // The dashboard lives only on the primary host, so on a custom domain default
+  // to the guild's branded home ("/") instead of "/dashboard".
+  const returnTo = safeRelativePath(
+    request.nextUrl.searchParams.get("returnTo"),
+    onCustomDomain ? "/" : "/dashboard",
+  );
 
-  const host = await requestHostname();
   let app: { clientId: string; redirectUri: string } | undefined;
-  if (host && !isPrimaryHostname(host)) {
+  if (onCustomDomain) {
     const oauth = await resolveHostOAuth(host);
     if (!oauth) {
       // No usable per-guild OAuth app for this custom domain — fall back to the

apps/web/src/app/layout.tsx

@@ -6,6 +6,8 @@ import { SiteFooter } from "@/components/site-footer";
 import { SiteHeader } from "@/components/site-header";
 import { ThemeProvider } from "@/components/theme-provider";
 import { getCurrentUser } from "@/lib/auth";
+import { logoUrl, parseBranding } from "@/lib/branding";
+import { getGuildByDomain, isPrimaryHostname, requestHostname } from "@/lib/custom-domain";
 import { getDirection, getLocale } from "@/i18n";
 import "./globals.css";
 
@@ -28,7 +30,7 @@ const spaceMono = Space_Mono({
   display: "swap",
 });
 
-export const metadata: Metadata = {
+const DEFAULT_METADATA: Metadata = {
   title: "MSK Forms: application forms with a status loop",
   description:
     "Build application forms, collect submissions, and let applicants track their status live. With a Discord bot any server can invite.",
@@ -38,6 +40,28 @@ export const metadata: Metadata = {
   },
 };
 
+/**
+ * Host-aware metadata: on a guild's verified custom domain, use that guild's
+ * name and (if set) its logo as the browser favicon, so the tab looks like the
+ * guild's own site. Falls back to the MSK Forms defaults everywhere else.
+ */
+export async function generateMetadata(): Promise<Metadata> {
+  const host = await requestHostname();
+  if (!host || isPrimaryHostname(host)) return DEFAULT_METADATA;
+
+  const guild = await getGuildByDomain(host);
+  if (!guild) return DEFAULT_METADATA;
+
+  const logo = logoUrl(guild.id, parseBranding(guild.branding));
+  return {
+    ...DEFAULT_METADATA,
+    title: guild.name,
+    ...(logo
+      ? { icons: { icon: [{ url: logo, type: "image/webp" }], apple: logo } }
+      : {}),
+  };
+}
+
 export default async function RootLayout({
   children,
 }: Readonly<{ children: React.ReactNode }>) {