feat(clients): scaffold top-level Clients section with sub-nav around Accounts

backend/src/middleware/requireCustomerPortal.js

@@ -0,0 +1,62 @@
+/**
+ * Customer portal feature-flag gate.
+ *
+ * Blocks every /api/customer/* and /api/admin/customers/* endpoint
+ * when the `customerPortal` flag is off. Returns 410 Gone so the
+ * frontend can distinguish "feature has been disabled" from "you
+ * don't have access" (which would be 403) — useful for the customer
+ * dashboard's auto-redirect on a soft-kill scenario.
+ *
+ * Reads the flag via customerAccountsService.isCustomerPortalEnabled
+ * (which itself reads from the maintainer's feature_flags table),
+ * so a single source of truth.
+ */
+
+const customerAccountsService = require('../services/customerAccountsService');
+const logger = require('../utils/logger');
+
+async function isEnabled() {
+  try {
+    return await customerAccountsService.isCustomerPortalEnabled();
+  } catch (err) {
+    // Defensive: if the lookup throws (DB unavailable, table missing
+    // mid-migration), fail closed so an enabled-by-default fallback
+    // can't accidentally expose customer surfaces during boot.
+    logger.warn('requireCustomerPortal: feature flag lookup failed, treating as off', {
+      error: err?.message,
+    });
+    return false;
+  }
+}
+
+/**
+ * Customer-facing endpoints. Returns 410 with a code the frontend
+ * can interpret to clear stale session storage + redirect to
+ * /admin/login.
+ */
+async function requireCustomerPortalEnabled(req, res, next) {
+  if (await isEnabled()) return next();
+  return res.status(410).json({
+    error: 'Customer portal is disabled',
+    code: 'CUSTOMER_PORTAL_DISABLED',
+  });
+}
+
+/**
+ * Admin-facing /api/admin/customers/* endpoints. Same gate, same
+ * status code — keeps the contract consistent across both halves of
+ * the customer-portal surface. The sidebar UI already hides the
+ * entry, but a stale tab or direct API call must also be blocked.
+ */
+async function requireCustomerPortalEnabledAdmin(req, res, next) {
+  if (await isEnabled()) return next();
+  return res.status(410).json({
+    error: 'Customer portal is disabled',
+    code: 'CUSTOMER_PORTAL_DISABLED',
+  });
+}
+
+module.exports = {
+  requireCustomerPortalEnabled,
+  requireCustomerPortalEnabledAdmin,
+};