feat: add sign-out redirect URL and enhance sign-in redirect handling

frontend/.env.example

@@ -8,3 +8,4 @@ NEXT_PUBLIC_CLERK_SIGN_IN_FORCE_REDIRECT_URL=/boards
 NEXT_PUBLIC_CLERK_SIGN_UP_FORCE_REDIRECT_URL=/boards
 NEXT_PUBLIC_CLERK_SIGN_IN_FALLBACK_REDIRECT_URL=/boards
 NEXT_PUBLIC_CLERK_SIGN_UP_FALLBACK_REDIRECT_URL=/boards
+NEXT_PUBLIC_CLERK_AFTER_SIGN_OUT_URL=/

frontend/src/app/sign-in/[[...rest]]/page.tsx

@@ -1,13 +1,25 @@
 "use client";
 
+import { useSearchParams } from "next/navigation";
 import { SignIn } from "@clerk/nextjs";
 
+import { resolveSignInRedirectUrl } from "@/auth/redirects";
+
 export default function SignInPage() {
+  const searchParams = useSearchParams();
+  const forceRedirectUrl = resolveSignInRedirectUrl(
+    searchParams.get("redirect_url"),
+  );
+
   // Dedicated sign-in route for Cypress E2E.
   // Avoids modal/iframe auth flows and gives Cypress a stable top-level page.
   return (
     <main className="flex min-h-screen items-center justify-center bg-slate-50 p-6">
-      <SignIn routing="path" path="/sign-in" forceRedirectUrl="/activity" />
+      <SignIn
+        routing="path"
+        path="/sign-in"
+        forceRedirectUrl={forceRedirectUrl}
+      />
     </main>
   );
 }

frontend/src/auth/redirects.test.ts

@@ -0,0 +1,44 @@
+import { afterEach, describe, expect, it, vi } from "vitest";
+
+import { resolveSignInRedirectUrl } from "@/auth/redirects";
+
+describe("resolveSignInRedirectUrl", () => {
+  afterEach(() => {
+    vi.unstubAllEnvs();
+  });
+
+  it("uses env fallback when redirect is missing", () => {
+    vi.stubEnv("NEXT_PUBLIC_CLERK_SIGN_IN_FALLBACK_REDIRECT_URL", "/boards");
+
+    expect(resolveSignInRedirectUrl(null)).toBe("/boards");
+  });
+
+  it("defaults to /dashboard when no env fallback is set", () => {
+    expect(resolveSignInRedirectUrl(null)).toBe("/dashboard");
+  });
+
+  it("allows safe relative paths", () => {
+    expect(resolveSignInRedirectUrl("/dashboard?tab=ops#queue")).toBe(
+      "/dashboard?tab=ops#queue",
+    );
+  });
+
+  it("rejects protocol-relative urls", () => {
+    vi.stubEnv("NEXT_PUBLIC_CLERK_SIGN_IN_FALLBACK_REDIRECT_URL", "/activity");
+
+    expect(resolveSignInRedirectUrl("//evil.example.com/path")).toBe("/activity");
+  });
+
+  it("rejects external absolute urls", () => {
+    vi.stubEnv("NEXT_PUBLIC_CLERK_SIGN_IN_FALLBACK_REDIRECT_URL", "/activity");
+
+    expect(resolveSignInRedirectUrl("https://evil.example.com/steal")).toBe(
+      "/activity",
+    );
+  });
+
+  it("accepts same-origin absolute urls and normalizes to path", () => {
+    const url = `${window.location.origin}/boards/new?src=invite#top`;
+    expect(resolveSignInRedirectUrl(url)).toBe("/boards/new?src=invite#top");
+  });
+});

frontend/src/auth/redirects.ts

@@ -0,0 +1,31 @@
+const DEFAULT_SIGN_IN_REDIRECT = "/dashboard";
+
+function isSafeRelativePath(value: string): boolean {
+  return value.startsWith("/") && !value.startsWith("//");
+}
+
+export function resolveSignInRedirectUrl(rawRedirect: string | null): string {
+  const fallback =
+    process.env.NEXT_PUBLIC_CLERK_SIGN_IN_FALLBACK_REDIRECT_URL ??
+    DEFAULT_SIGN_IN_REDIRECT;
+
+  if (!rawRedirect) return fallback;
+
+  if (isSafeRelativePath(rawRedirect)) {
+    return rawRedirect;
+  }
+
+  if (typeof window === "undefined") {
+    return fallback;
+  }
+
+  try {
+    const parsed = new URL(rawRedirect, window.location.origin);
+    if (parsed.origin !== window.location.origin) {
+      return fallback;
+    }
+    return `${parsed.pathname}${parsed.search}${parsed.hash}`;
+  } catch {
+    return fallback;
+  }
+}

frontend/src/components/providers/AuthProvider.tsx

@@ -7,12 +7,19 @@ import { isLikelyValidClerkPublishableKey } from "@/auth/clerkKey";
 
 export function AuthProvider({ children }: { children: ReactNode }) {
   const publishableKey = process.env.NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY;
+  const afterSignOutUrl =
+    process.env.NEXT_PUBLIC_CLERK_AFTER_SIGN_OUT_URL ?? "/";
 
   if (!isLikelyValidClerkPublishableKey(publishableKey)) {
     return <>{children}</>;
   }
 
   return (
-    <ClerkProvider publishableKey={publishableKey}>{children}</ClerkProvider>
+    <ClerkProvider
+      publishableKey={publishableKey}
+      afterSignOutUrl={afterSignOutUrl}
+    >
+      {children}
+    </ClerkProvider>
   );
 }

frontend/src/proxy.ts

@@ -8,18 +8,40 @@ const isClerkEnabled = () =>
     process.env.NEXT_PUBLIC_CLERK_PUBLISHABLE_KEY,
   );
 
-// Public routes must include Clerk sign-in paths to avoid redirect loops.
+// Public routes include home and sign-in paths to avoid redirect loops.
-const isPublicRoute = createRouteMatcher(["/sign-in(.*)"]);
+const isPublicRoute = createRouteMatcher(["/", "/sign-in(.*)", "/sign-up(.*)"]);
+
+function isClerkInternalPath(pathname: string): boolean {
+  // Clerk may hit these paths for internal auth/session refresh flows.
+  return pathname.startsWith("/_clerk") || pathname.startsWith("/v1/");
+}
+
+function requestOrigin(req: Request): string {
+  const forwardedProto = req.headers.get("x-forwarded-proto");
+  const forwardedHost = req.headers.get("x-forwarded-host");
+  const host = forwardedHost ?? req.headers.get("host");
+  const proto = forwardedProto ?? "http";
+  if (host) return `${proto}://${host}`;
+  return new URL(req.url).origin;
+}
+
+function returnBackUrlFor(req: Request): string {
+  const { pathname, search, hash } = new URL(req.url);
+  return `${requestOrigin(req)}${pathname}${search}${hash}`;
+}
 
 export default isClerkEnabled()
   ? clerkMiddleware(async (auth, req) => {
+      if (isClerkInternalPath(new URL(req.url).pathname)) {
+        return NextResponse.next();
+      }
       if (isPublicRoute(req)) return NextResponse.next();
 
       // In middleware, `auth()` resolves to a session/auth context (Promise in current typings).
       // Use redirectToSignIn() (instead of protect()) for unauthenticated requests.
       const { userId, redirectToSignIn } = await auth();
       if (!userId) {
-        return redirectToSignIn({ returnBackUrl: req.url });
+        return redirectToSignIn({ returnBackUrl: returnBackUrlFor(req) });
       }
 
       return NextResponse.next();
@@ -28,7 +50,7 @@ export default isClerkEnabled()
 
 export const config = {
   matcher: [
-    "/((?!_next|[^?]*\\.(?:html?|css|js(?!on)|jpe?g|webp|png|gif|svg|ttf|woff2?|ico|csv|docx?|xlsx?|zip|webmanifest)).*)",
+    "/((?!_next|_clerk|v1|[^?]*\\.(?:html?|css|js(?!on)|jpe?g|webp|png|gif|svg|ttf|woff2?|ico|csv|docx?|xlsx?|zip|webmanifest)).*)",
     "/(api|trpc)(.*)",
   ],
 };