feat(confidence-engine): establish authenticated product boundary

lib/supabase/api-auth.js

@@ -0,0 +1,13 @@
+import { getAuthenticatedUser } from "@/lib/supabase/server.js";
+
+export function unauthorizedResponse() {
+  return Response.json({ error: "Unauthorized" }, { status: 401 });
+}
+
+export function withAuthenticatedApi(handler) {
+  return async function authenticatedApiHandler(request, context) {
+    const user = await getAuthenticatedUser();
+    if (!user) return unauthorizedResponse();
+    return handler(request, context);
+  };
+}

lib/supabase/browser.js

@@ -0,0 +1,14 @@
+"use client";
+
+import { createBrowserClient } from "@supabase/ssr";
+
+export function createClient() {
+  return createBrowserClient(
+    process.env.NEXT_PUBLIC_SUPABASE_URL,
+    process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY,
+  );
+}
+
+export function magicLinkRedirectTo(origin) {
+  return `${origin}/auth/callback`;
+}

lib/supabase/server.js

@@ -0,0 +1,33 @@
+import { createServerClient } from "@supabase/ssr";
+import { cookies } from "next/headers";
+
+function getSupabaseConfig() {
+  return {
+    url: process.env.NEXT_PUBLIC_SUPABASE_URL,
+    key: process.env.NEXT_PUBLIC_SUPABASE_ANON_KEY,
+  };
+}
+
+export function createServerSupabaseClient() {
+  const cookieStore = cookies();
+  const { url, key } = getSupabaseConfig();
+  return createServerClient(url, key, {
+    cookies: {
+      getAll() {
+        return cookieStore.getAll();
+      },
+      setAll(cookiesToSet) {
+        try {
+          cookiesToSet.forEach(({ name, value, options }) => cookieStore.set(name, value, options));
+        } catch {
+          // Server Components cannot write cookies; middleware refreshes sessions.
+        }
+      },
+    },
+  });
+}
+
+export async function getAuthenticatedUser() {
+  const { data: { user } } = await createServerSupabaseClient().auth.getUser();
+  return user;
+}