feat(terminal): add session grace expiry tests and improve detach logic (#14127)

Co-authored-by: Cursor <cursoragent@cursor.com>

agent/utils/terminal/session.go

@@ -314,7 +314,17 @@ func (s *Session) detach(a *attachment, clean, revalidate bool, cursor uint64) {
 		if !s.Persistent || revalidate {
 			timeout = revalidateGrace
 		}
-		s.grace = time.AfterFunc(timeout, s.Close)
+		// Stop cannot cancel a fired timer; a racing Attach clears s.grace.
+		var grace *time.Timer
+		grace = time.AfterFunc(timeout, func() {
+			s.mu.Lock()
+			expired := s.grace == grace
+			s.mu.Unlock()
+			if expired {
+				s.Close()
+			}
+		})
+		s.grace = grace
 	}
 	s.mu.Unlock()
 	if clean {

frontend/src/components/terminal/dock/index.vue

@@ -18,6 +18,7 @@
         size="w-70"
         :show-close="false"
         :modal="false"
+        modal-penetrable
         @opened="claim"
     >
         <template #header>

frontend/src/components/terminal/host.vue

@@ -7,6 +7,7 @@
                         :ref="(el: any) => store.setInstance(item.key, el)"
                         @session="(id: string) => store.setSessionId(item.key, id)"
                         @expired="store.onExpired(item.key)"
+                        @reconnect="store.reconnect(item.key)"
                     />
                 </Teleport>
             </template>

frontend/src/components/terminal/index.vue

@@ -31,7 +31,7 @@ const { currentNode } = useGlobalStore();
 
 // session: agent side session id known (fresh or reattached)
 // expired: the agent no longer has the session; a reconnect must open a new one
-const emit = defineEmits(['session', 'expired']);
+const emit = defineEmits(['session', 'expired', 'reconnect']);
 
 // Close codes of the agent's session protocol (agent/utils/terminal/session.go).
 const CLOSE_SESSION_NOT_FOUND = 4404;
@@ -56,6 +56,7 @@ let closing = false;
 let reconnecting = false;
 let reconnectNoticeShown = false;
 let revalidating = false;
+let expired = false;
 let reconnectStartedAt = 0;
 let reconnectDelay = 1000;
 let reconnectTimer: ReturnType<typeof setTimeout> | null = null;
@@ -279,6 +280,7 @@ function resizeTerminal() {
     if (terminalElement.value.clientWidth <= 0 || terminalElement.value.clientHeight <= 0) {
         return;
     }
+    if (terminalElement.value.closest('.terminal-host')) return;
 
     fitAddon.fit();
     if (isWsOpen()) {
@@ -484,6 +486,7 @@ const closeRealTerminal = (ev: CloseEvent) => {
                 '31',
                 ev.code === 1000 ? 'The connection has been disconnected.' : i18n.global.t('terminal.sessionExpired'),
             );
+            expired = true;
             emit('expired');
             return;
         case CLOSE_ATTACHED_ELSEWHERE:
@@ -602,6 +605,13 @@ function sendMsg(data: string, line: string = '') {
 
 function onTermData(data: string) {
     if (!data) return;
+    if (expired) {
+        if (isEnterInputData(data)) {
+            expired = false;
+            emit('reconnect');
+        }
+        return;
+    }
     if (aiNotice.value.loading) return;
     sendMsg(data, isEnterInputData(data) ? getCurrentTerminalLine() : '');
 }