diff --git a/bun.lock b/bun.lock
index e5bfbdfe..cdf7d437 100644
--- a/bun.lock
+++ b/bun.lock
@@ -235,7 +235,7 @@
     },
     "packages/auth": {
       "name": "@wrnexus/auth",
-      "version": "0.8.22",
+      "version": "0.8.23",
       "dependencies": {
         "@wrnexus/authz": "workspace:*",
         "@wrnexus/captcha": "workspace:*",
diff --git a/packages/auth/assets/client/auth.js b/packages/auth/assets/client/auth.js
index 1744ac3f..1ee18894 100644
--- a/packages/auth/assets/client/auth.js
+++ b/packages/auth/assets/client/auth.js
@@ -413,7 +413,32 @@
     const pending = new Map();
     let expired = false;
     let disposed = false;
+    let expiryTimer;
+    const expiresAt = Number(saved?.mfaExpiresAt);
+    const expire = () => {
+      if (disposed) return;
+      expired = true;
+      window.clearTimeout(expiryTimer);
+      sessionStorage.removeItem(MFA_STORAGE_KEY);
+      if (tokenInput) tokenInput.value = "";
+      form?.querySelectorAll("input, button").forEach((control) => {
+        control.disabled = true;
+      });
+      setMessage(
+        status,
+        "Your sign-in request has expired. Sign in again to get a fresh verification request.",
+        true,
+      );
+      const restart = element.querySelector("[data-auth-mfa-restart]");
+      if (restart) restart.hidden = false;
+    };
+    const checkExpiry = () => {
+      // Old stored challenges have no verifiable deadline: require fresh sign-in.
+      if (saved?.mfaToken && (!Number.isFinite(expiresAt) || expiresAt <= Date.now())) expire();
+      return expired;
+    };
     const restoreToken = () => {
+      checkExpiry();
       if (!expired && tokenInput && !tokenInput.value && saved?.mfaToken)
         tokenInput.value = String(saved.mfaToken);
     };
@@ -433,6 +458,7 @@
     const sendCode = async (selected) => {
       if (disposed || expired || !isOtp(selected)) return;
       restoreToken();
+      if (expired) return;
       if (!tokenInput?.value) {
         setMessage(status, "Sign-in verification has expired. Start again.", true);
         const restart = element.querySelector("[data-auth-mfa-restart]");
@@ -476,10 +502,11 @@
           );
       } finally {
         pending.delete(selected);
-        if (!disposed && method() === selected) setFormBusy(form, false);
+        if (!disposed && !expired && method() === selected) setFormBusy(form, false);
       }
     };
     const updateMethod = () => {
+      if (checkExpiry()) return;
       const selected = method();
       setFormBusy(form, false);
       if (challengeInput) challengeInput.value = "";
@@ -524,13 +551,12 @@
     };
     const onError = (event) => {
       if (event.target !== form || event.detail?.code !== "mfa-transaction-expired") return;
-      expired = true;
-      sessionStorage.removeItem(MFA_STORAGE_KEY);
-      if (tokenInput) tokenInput.value = "";
-      const restart = element.querySelector("[data-auth-mfa-restart]");
-      if (restart) restart.hidden = false;
+      expire();
     };
     updateMethod();
+    if (!expired && Number.isFinite(expiresAt)) {
+      expiryTimer = window.setTimeout(expire, Math.max(0, expiresAt - Date.now()));
+    }
     // Capture native change before the shared Radio emits its component output.
     form?.addEventListener("change", onMethodChange, true);
     form?.addEventListener("submit", onSubmit, true);
@@ -538,6 +564,7 @@
     element.addEventListener("wrn:error", onError);
     flowCleanups.set(element, () => {
       disposed = true;
+      window.clearTimeout(expiryTimer);
       form?.removeEventListener("change", onMethodChange, true);
       form?.removeEventListener("submit", onSubmit, true);
       element.removeEventListener("wrn:success", onSuccess);
diff --git a/packages/auth/components/TwoFactorChallenge.wrn b/packages/auth/components/TwoFactorChallenge.wrn
index 89503234..51529f4f 100644
--- a/packages/auth/components/TwoFactorChallenge.wrn
+++ b/packages/auth/components/TwoFactorChallenge.wrn
@@ -51,8 +51,15 @@ component TwoFactorChallenge {
         <p data-error="_form" role="alert" class="m-0 hidden rounded-[var(--wrn-radius-sm)] bg-[color-mix(in_srgb,var(--wrn-color-danger)_10%,transparent)] p-3 text-sm text-[var(--wrn-color-danger)]"></p>
         <Button type="submit" label="{submitLabel}" variant="solid" color="{color}" size="{size}" fullWidth="true" />
       </form>
-      <a href='{signInHref}' data-auth-mfa-restart hidden class="mt-4 text-sm text-[var(--wrn-color-primary)] underline">Sign-in verification expired. Back to sign in</a>
-      <a href='{recoveryHref}' class="mt-4 inline-flex text-sm text-[var(--wrn-color-primary)] hover:underline">Account recovery options</a>
+      <nav class="wrn-auth-mfa-links" aria-label="Sign-in help">
+        <a href='{signInHref}' data-auth-mfa-restart hidden>Back to sign in</a>
+        <a href='{recoveryHref}'>Account recovery options</a>
+      </nav>
     </section>
   }
+  style {
+    .wrn-auth-mfa-links { display: flex; flex-direction: column; align-items: flex-start; gap: 0.75rem; margin-top: 1.25rem; }
+    .wrn-auth-mfa-links a { color: var(--wrn-color-primary); font-size: 0.875rem; }
+    .wrn-auth-mfa-links a:hover { text-decoration: underline; }
+  }
 }
diff --git a/packages/auth/package.json b/packages/auth/package.json
index 5f73c3f5..6e9ec5e8 100644
--- a/packages/auth/package.json
+++ b/packages/auth/package.json
@@ -1,6 +1,6 @@
 {
   "name": "@wrnexus/auth",
-  "version": "0.8.22",
+  "version": "0.8.23",
   "description": "Complete authentication, account security, MFA, passkeys, recovery, devices, risk, and audit system for WRNexusJS.",
   "type": "module",
   "sideEffects": false,
diff --git a/packages/auth/src/engine.ts b/packages/auth/src/engine.ts
index e5d1acea..421ef194 100644
--- a/packages/auth/src/engine.ts
+++ b/packages/auth/src/engine.ts
@@ -490,6 +490,7 @@ export function createAuthEngine(options: AuthEngineOptions): AuthEngine {
         message: "Additional verification is required but no verification method is available",
       };
     }
+    const mfaExpiresAt = now() + 5 * 60_000;
     const mfaToken = await issueToken(user.id, "login-mfa", {
       ttlMs: 5 * 60_000,
       metadata,
@@ -500,6 +501,7 @@ export function createAuthEngine(options: AuthEngineOptions): AuthEngine {
       message: "Complete two-step verification to finish signing in.",
       user: publicUser(user),
       mfaToken,
+      mfaExpiresAt,
       requires: { mfa: methods },
     };
   }
@@ -1081,6 +1083,7 @@ export function createAuthEngine(options: AuthEngineOptions): AuthEngine {
             risk,
           };
         }
+        const mfaExpiresAt = now() + 5 * 60_000;
         const mfaToken = await issueToken(user.id, "login-mfa", {
           ttlMs: 5 * 60_000,
           metadata: {
@@ -1099,6 +1102,7 @@ export function createAuthEngine(options: AuthEngineOptions): AuthEngine {
           user: publicUser(user),
           risk,
           mfaToken,
+          mfaExpiresAt,
           requires: { captcha: risk.requireCaptcha, mfa: methods },
         };
       }
@@ -1961,6 +1965,7 @@ export function createAuthEngine(options: AuthEngineOptions): AuthEngine {
       account = await engine.linkOAuth(user.id, providerName, normalizedProfile, tokens);
       if (await hasMfa(user.id)) {
         const methods = await availableMfaMethods(user.id);
+        const mfaExpiresAt = now() + 5 * 60_000;
         const mfaToken = await issueToken(user.id, "login-mfa", {
           ttlMs: 5 * 60_000,
           metadata: { oauthProvider: providerName },
@@ -1970,6 +1975,7 @@ export function createAuthEngine(options: AuthEngineOptions): AuthEngine {
           code: "mfa-required",
           user: publicUser(user),
           mfaToken,
+          mfaExpiresAt,
           requires: { mfa: methods },
         };
       }
diff --git a/packages/auth/src/types.ts b/packages/auth/src/types.ts
index be33fb69..054ba0be 100644
--- a/packages/auth/src/types.ts
+++ b/packages/auth/src/types.ts
@@ -505,6 +505,8 @@ export interface AuthResult {
   session?: AuthSession;
   risk?: AuthRiskDecision;
   mfaToken?: string;
+  /** Absolute expiry of the pending sign-in challenge, in epoch milliseconds. */
+  mfaExpiresAt?: number;
   requires?: {
     captcha?: boolean;
     mfa?: AuthMfaMethod[];
diff --git a/packages/auth/test/engine.test.ts b/packages/auth/test/engine.test.ts
index 94ade447..93622a7d 100644
--- a/packages/auth/test/engine.test.ts
+++ b/packages/auth/test/engine.test.ts
@@ -863,6 +863,7 @@ describe("authentication engine", () => {
       requires: { mfa: ["totp"] },
     });
     expect(await engine.beginMfaOtp(firstLogin.mfaToken!, "email-otp")).toBeUndefined();
+    expect(firstLogin.mfaExpiresAt).toBe(now() + 5 * 60_000);
 
     expect((await engine.verifyEmail(verificationToken)).ok).toBe(true);
     const secondLogin = await engine.login({
diff --git a/packages/auth/test/mfa-runtime.test.ts b/packages/auth/test/mfa-runtime.test.ts
index 2c0e4202..51894390 100644
--- a/packages/auth/test/mfa-runtime.test.ts
+++ b/packages/auth/test/mfa-runtime.test.ts
@@ -2,12 +2,39 @@ import { expect, test } from "bun:test";
 import { readFileSync } from "node:fs";
 import { Window, type HTMLInputElement, type HTMLElement } from "happy-dom";
 
+test("expired and legacy MFA requests are rejected on mount before entering a code", async () => {
+  for (const deadline of [undefined, Date.now() - 1]) {
+    const window = new Window({ url: "https://sso.example.test/mfa" });
+    try {
+      window.sessionStorage.setItem(
+        "wrnexus.auth.mfa",
+        JSON.stringify({ mfaToken: "old-challenge", mfaExpiresAt: deadline }),
+      );
+      window.document.body.innerHTML = `<section data-auth-mfa-challenge><form data-auth-mfa-form>
+        <input name="mfaToken"><input type="radio" name="method" value="totp"><input name="code"><p data-auth-mfa-status hidden></p><button type="submit">Verify</button>
+        </form><a data-auth-mfa-restart hidden href="/login">Back to sign in</a></section>`;
+      window.eval(readFileSync(new URL("../assets/client/auth.js", import.meta.url), "utf8"));
+      (window as any).WRNexusAuth.mount(window.document);
+      expect(window.document.querySelector("button")!.disabled).toBe(true);
+      expect(window.document.querySelector<HTMLElement>("[data-auth-mfa-restart]")!.hidden).toBe(
+        false,
+      );
+      expect(window.document.querySelector("[data-auth-mfa-status]")!.textContent).toContain(
+        "Sign in again",
+      );
+      expect(window.sessionStorage.getItem("wrnexus.auth.mfa")).toBeNull();
+    } finally {
+      await window.happyDOM.close();
+    }
+  }
+});
+
 test("selecting delivery radios sends once, ignores stale responses, and never sends for local methods", async () => {
   const window = new Window({ url: "https://sso.example.test/mfa" });
   try {
     window.sessionStorage.setItem(
       "wrnexus.auth.mfa",
-      JSON.stringify({ mfaToken: "synthetic-test-challenge" }),
+      JSON.stringify({ mfaToken: "synthetic-test-challenge", mfaExpiresAt: Date.now() + 300_000 }),
     );
     window.document.body.innerHTML = `<section data-auth-mfa-challenge data-mfa-initial-method="totp"><form data-auth-mfa-form>
       <input name="mfaToken"><input name="challengeId"><input name="code">
@@ -63,6 +90,7 @@ test("MFA radios preserve allowed methods and restore continuation without reviv
       "wrnexus.auth.mfa",
       JSON.stringify({
         mfaToken: "synthetic-test-challenge",
+        mfaExpiresAt: Date.now() + 300_000,
         requires: { mfa: ["totp"] },
       }),
     );