diff --git a/frontend/src/hooks.server.ts b/frontend/src/hooks.server.ts
index c8f4ec3..18c3d63 100644
--- a/frontend/src/hooks.server.ts
+++ b/frontend/src/hooks.server.ts
@@ -7,6 +7,7 @@ import {
 	setSessionCookie,
 	clearSessionCookie,
 	setChildSessionCookie,
+	setActiveChild,
 	clearActiveChild,
 	PLATFORM_SESSION_COOKIE,
 	clearPlatformSession
@@ -81,6 +82,11 @@ export const handle: Handle = async ({ event, resolve }) => {
 					if (freshToken !== childToken) {
 						setChildSessionCookie(event.cookies, activeId, freshToken);
 					}
+					// Sliding expiry: pb_active has the same 5-day maxAge as the
+					// token cookies but was previously never re-set, so it aged
+					// out 5 days after join/switch despite daily use. Re-set it
+					// on every authenticated request to keep it alive.
+					setActiveChild(event.cookies, activeId);
 					return resolve(event);
 				}
 			} catch {