Login UI provides clear user feedback

Login forms without loading indicators let users click submit repeatedly while the first request is still in flight, triggering duplicate authentication attempts that can corrupt session state, burn through brute-force lockout counters, double-charge billing events on post-login redirects, and produce inconsistent MFA challenges. Missing error feedback forces users to guess why authentication failed, driving them to password managers that may paste stale credentials and accelerating account lockouts tracked under OWASP A07 (Identification & Authentication Failures). Inaccessible form labels also breach WCAG 2.2 SC 1.3.1 (Info and Relationships) and SC 4.1.2 (Name, Role, Value), excluding screen-reader users from your product.

Disable the submit button and show a spinner or skeleton while the authentication request is pending, render server-returned error messages in an aria-live="polite" region next to the form, and bind every input to a visible <label htmlFor>. Wire this into your login component file such as src/app/(auth)/login/page.tsx or src/components/auth/LoginForm.tsx:

const [pending, setPending] = useState(false);
const [error, setError] = useState<string | null>(null);

async function onSubmit(data: FormData) {
  setPending(true);
  setError(null);
  const res = await signIn(data);
  setPending(false);
  if (!res.ok) setError(res.message);
}

return (
  <form onSubmit={handleSubmit(onSubmit)}>
    <label htmlFor="email">Email</label>
    <input id="email" {...register('email')} disabled={pending} />
    {error && <p role="alert" aria-live="polite">{error}</p>}
    <button type="submit" disabled={pending}>
      {pending ? 'Signing in…' : 'Sign in'}
    </button>
  </form>
);

• ID: saas-authentication.session-management.login-ui-feedback
• Severity: info
• What to look for: Examine the login and registration components. Check for: a loading/pending state when the form is submitting (prevents double-submission), clear error display for failed attempts, and accessible form labels. This is a UX observation, not a security check. Count all instances found and enumerate each.
• Pass criteria: Login form shows a loading state during submission and displays error messages clearly when login fails. At least 1 implementation must be confirmed.
• Fail criteria: Login form has no loading indicator, allows double-submission, or displays no feedback on failure.
• Skip (N/A) when: No UI components (API-only project). Signal: no frontend, no login form.
• Detail on fail: "Login form at src/app/(auth)/login/page.tsx has no loading state — users can submit multiple times while the request is pending".
• Remediation: Clear loading states prevent duplicate submissions that can cause confusing behavior. This is an informational note — address as part of general UX polish. Add loading state to the login form component in src/app/login/page.tsx or src/components/auth/LoginForm.tsx.