Add guest cart drawer, Continue handoff, and shared customer login.

Co-authored-by: Cursor <cursoragent@cursor.com>

lib/shared-auth-cookie.ts

@@ -0,0 +1,123 @@
+/** Shared auth cookies so storefront + customer.{domain} share one login. */
+
+export const SHARED_ACCESS_TOKEN_KEY = "meshkee_customer_access_token";
+export const SHARED_REFRESH_TOKEN_KEY = "meshkee_customer_refresh_token";
+
+const CHUNK_SIZE = 2800;
+const MAX_CHUNKS = 24;
+
+function cookieDomain(): string | undefined {
+  if (typeof window === "undefined") return undefined;
+  const host = window.location.hostname.toLowerCase();
+  if (host === "localhost" || host === "127.0.0.1") return undefined;
+  const parts = host.split(".").filter(Boolean);
+  if (parts.length < 2) return undefined;
+  return `.${parts.slice(-2).join(".")}`;
+}
+
+function readRawCookie(name: string): string | null {
+  if (typeof document === "undefined") return null;
+  const prefix = `${name}=`;
+  const match = document.cookie.split("; ").find((row) => row.startsWith(prefix));
+  if (!match) return null;
+  return match.slice(prefix.length);
+}
+
+function writeRawCookie(name: string, value: string | null) {
+  if (typeof document === "undefined") return;
+  const domain = cookieDomain();
+  if (value == null) {
+    let cookie = `${name}=; path=/; max-age=0; SameSite=Lax`;
+    if (domain) cookie += `; domain=${domain}`;
+    document.cookie = cookie;
+    return;
+  }
+  const maxAge = 60 * 60 * 24 * 30;
+  let cookie = `${name}=${value}; path=/; max-age=${maxAge}; SameSite=Lax`;
+  if (domain) cookie += `; domain=${domain}`;
+  document.cookie = cookie;
+}
+
+function clearChunkedCookie(name: string) {
+  writeRawCookie(name, null);
+  const n = Number(readRawCookie(`${name}_n`) || "0");
+  writeRawCookie(`${name}_n`, null);
+  for (let i = 0; i < Math.max(n, MAX_CHUNKS); i++) {
+    writeRawCookie(`${name}_${i}`, null);
+  }
+}
+
+function writeCookie(name: string, value: string | null) {
+  clearChunkedCookie(name);
+  if (value == null || value === "") return;
+
+  const encoded = encodeURIComponent(value);
+  if (encoded.length <= 3500) {
+    writeRawCookie(name, encoded);
+    return;
+  }
+
+  const chunks: string[] = [];
+  for (let i = 0; i < encoded.length; i += CHUNK_SIZE) {
+    chunks.push(encoded.slice(i, i + CHUNK_SIZE));
+  }
+  writeRawCookie(`${name}_n`, String(chunks.length));
+  chunks.forEach((chunk, i) => writeRawCookie(`${name}_${i}`, chunk));
+}
+
+function readCookie(name: string): string | null {
+  const n = Number(readRawCookie(`${name}_n`) || "0");
+  if (n > 0) {
+    let encoded = "";
+    for (let i = 0; i < n; i++) {
+      const part = readRawCookie(`${name}_${i}`);
+      if (part == null) return null;
+      encoded += part;
+    }
+    try {
+      return decodeURIComponent(encoded);
+    } catch {
+      return null;
+    }
+  }
+
+  const raw = readRawCookie(name);
+  if (raw == null) return null;
+  try {
+    return decodeURIComponent(raw);
+  } catch {
+    return null;
+  }
+}
+
+export function writeSharedAuthCookies(accessToken: string, refreshToken?: string) {
+  writeCookie(SHARED_ACCESS_TOKEN_KEY, accessToken);
+  if (refreshToken) writeCookie(SHARED_REFRESH_TOKEN_KEY, refreshToken);
+}
+
+export function clearSharedAuthCookies() {
+  writeCookie(SHARED_ACCESS_TOKEN_KEY, null);
+  writeCookie(SHARED_REFRESH_TOKEN_KEY, null);
+}
+
+export function readSharedAccessToken(): string | null {
+  return readCookie(SHARED_ACCESS_TOKEN_KEY);
+}
+
+export function readSharedRefreshToken(): string | null {
+  return readCookie(SHARED_REFRESH_TOKEN_KEY);
+}
+
+export function hydrateLocalTokensFromSharedCookies(
+  accessKey = SHARED_ACCESS_TOKEN_KEY,
+  refreshKey = SHARED_REFRESH_TOKEN_KEY,
+): boolean {
+  if (typeof window === "undefined") return false;
+  if (localStorage.getItem(accessKey)) return false;
+  const access = readSharedAccessToken();
+  if (!access) return false;
+  localStorage.setItem(accessKey, access);
+  const refresh = readSharedRefreshToken();
+  if (refresh) localStorage.setItem(refreshKey, refresh);
+  return true;
+}