diff --git a/src/components/frontend/session/SessionExpiryBanner.tsx b/src/components/frontend/session/SessionExpiryBanner.tsx
index 3ff6e12..89682e4 100644
--- a/src/components/frontend/session/SessionExpiryBanner.tsx
+++ b/src/components/frontend/session/SessionExpiryBanner.tsx
@@ -16,6 +16,13 @@ import {
 } from "@/lib/session/countdown";
 import { SESSION_EXTENDED_EVENT } from "@/hooks/useGameTick";
 
+/**
+ * Stable id for the one-shot "session expiring" heads-up toast. A fixed id lets
+ * us dismiss it deterministically (e.g. on sign-out) instead of relying on the
+ * opaque id returned by `toast.info`. Mirrors MissionReminderToasts.
+ */
+const SESSION_EXPIRY_TOAST_ID = "session-expiry-warning";
+
 interface SessionExpiryBannerProps {
   /** Absolute expiry (ms since epoch), server-computed from the JWT `exp`. */
   sessionExp: number | null;
@@ -70,6 +77,7 @@ export function SessionExpiryBanner({
     toastFiredRef.current = true;
     const minutes = Math.round(warnMs / 60_000);
     toast.info(`Your session expires in about ${minutes} min.`, {
+      id: SESSION_EXPIRY_TOAST_ID,
       action: {
         label: "Extend",
         onClick: () => void extendSession(),
@@ -83,6 +91,20 @@ export function SessionExpiryBanner({
     if (phase === "warn") fireToast();
   }, [phase, warnMs, fireToast]);
 
+  // The heads-up toast is only relevant while we're in the warn window. Dismiss it
+  // when the user extends (phase leaves "warn") or dismisses the banner, and again
+  // on unmount (sign-out swaps the shell for the landing page) — otherwise the
+  // duration:Infinity toast lingers for a signed-out user and its Extend button 403s.
+  useEffect(() => {
+    if (!visible) toast.dismiss(SESSION_EXPIRY_TOAST_ID);
+  }, [visible]);
+
+  useEffect(() => {
+    return () => {
+      toast.dismiss(SESSION_EXPIRY_TOAST_ID);
+    };
+  }, []);
+
   const extendSession = useCallback(async () => {
     setExtending(true);
     setError(null);