fix(register): preserve ?redirect= through cross-origin sign-in flows

src/pages/login/login-page.test.tsx

@@ -41,4 +41,19 @@ describe("LoginPage", () => {
     })
     expect(screen.getByText("Sign up")).toBeInTheDocument()
   })
+
+  it("preserves ?redirect= on the Sign up link", async () => {
+    await renderWithFileRoutes(<></>, {
+      initialLocation:
+        "/login?redirect=https%3A%2F%2Fhera-streamer-invitational-2026.criticalbit.gg%2F",
+      routerContext: unauthContext,
+    })
+    const link = await screen.findByRole("link", { name: "Sign up" })
+    // TanStack Router serializes search params alphabetically and re-encodes —
+    // the important thing is that the redirect target survives the hop, not
+    // the exact encoding.
+    expect(link.getAttribute("href")).toMatch(
+      /^\/register\?redirect=.*hera-streamer-invitational-2026\.criticalbit\.gg/
+    )
+  })
 })

src/pages/login/login-page.tsx

@@ -177,7 +177,11 @@ export function LoginPage() {
         <CardFooter className="justify-center">
           <p className="text-muted-foreground text-sm">
             Don't have an account?{" "}
-            <Link to="/register" className="text-primary underline">
+            <Link
+              to="/register"
+              search={redirect ? { redirect } : {}}
+              className="text-primary underline"
+            >
               Sign up
             </Link>
           </p>

src/pages/register/register-page.tsx

@@ -1,5 +1,5 @@
 import { useState } from "react"
-import { Link, useNavigate } from "@tanstack/react-router"
+import { Link, useNavigate, useSearch } from "@tanstack/react-router"
 import { LoaderCircle } from "lucide-react"
 import { toast } from "sonner"
 import { Button } from "@/components/ui/button"
@@ -22,6 +22,8 @@ import { submitConsents, type ConsentInput } from "@/lib/consent"
 export function RegisterPage() {
   const auth = useAuth()
   const navigate = useNavigate()
+  const search = useSearch({ from: "/register" })
+  const redirect = (search as { redirect?: string }).redirect
   const [email, setEmail] = useState("")
   const [password, setPassword] = useState("")
   const [confirmPassword, setConfirmPassword] = useState("")
@@ -70,9 +72,17 @@ export function RegisterPage() {
         // Swallow — user is signed up; they'll be prompted again on profile.
       }
       // Refresh the AuthContext (reads /auth/me with the new cookie) before
-      // navigating, so /profile's beforeLoad sees isAuthenticated=true.
+      // navigating, so the destination's beforeLoad sees isAuthenticated=true.
       await auth.checkAuth()
-      await navigate({ to: "/profile" })
+      const target = redirect ?? "/profile"
+      if (target.startsWith("http")) {
+        // Cross-origin redirect (e.g. from a consumer app like
+        // hera-streamer-…) — must be a hard nav since useNavigate only
+        // handles in-app routes.
+        window.location.href = target
+        return
+      }
+      await navigate({ to: target })
     } catch (error) {
       const message = await getErrorMessage(error, "Registration failed")
       toast.error(message)

src/routes/register.tsx

@@ -1,7 +1,14 @@
 import { createFileRoute, redirect } from "@tanstack/react-router"
 import { RegisterPage } from "@/pages/register/register-page"
 
+type RegisterSearch = {
+  redirect?: string
+}
+
 export const Route = createFileRoute("/register")({
+  validateSearch: (search: Record<string, unknown>): RegisterSearch => ({
+    redirect: (search.redirect as string) || undefined,
+  }),
   beforeLoad: ({ context }) => {
     if (context.auth.isAuthenticated) {
       throw redirect({ to: "/profile" })