fix: resolve activity tracking and UI race conditions

- Remove LastActive reset on emergency promotion to preserve actual activity state
- Fix UI rejection count race by tracking whether rejection was already counted
- Optimize browser detection to avoid redundant string searches

session_manager.go

@@ -1226,10 +1226,8 @@ func (sm *SessionManager) transferPrimaryRole(fromSessionID, toSessionID, transf
 	// Promote target session
 	toSession.Mode = SessionModePrimary
 	toSession.hidRPCAvailable = false
-	// Reset LastActive for all emergency promotions to prevent immediate re-timeout
-	if strings.HasPrefix(transferType, "emergency_") {
-		toSession.LastActive = time.Now()
-	}
+	// For manual transfers, preserve the session's actual LastActive timestamp
+	// Emergency promotions inherit the observer's activity state - no free time
 	sm.primarySessionID = toSessionID
 
 	// ALWAYS set lastPrimaryID to the new primary to support WebRTC reconnections
@@ -1476,16 +1474,19 @@ func extractBrowserFromUserAgent(userAgent string) *string {
 	ua := strings.ToLower(userAgent)
 
 	// Check for common browsers (order matters - Chrome contains Safari, etc.)
+	// Optimize Safari check by caching Chrome detection
+	hasChrome := strings.Contains(ua, "chrome")
+
 	if strings.Contains(ua, "edg/") || strings.Contains(ua, "edge") {
 		return &BrowserEdge
 	}
 	if strings.Contains(ua, "firefox") {
 		return &BrowserFirefox
 	}
-	if strings.Contains(ua, "chrome") {
+	if hasChrome {
 		return &BrowserChrome
 	}
-	if strings.Contains(ua, "safari") && !strings.Contains(ua, "chrome") {
+	if strings.Contains(ua, "safari") {
 		return &BrowserSafari
 	}
 	if strings.Contains(ua, "opera") || strings.Contains(ua, "opr/") {

ui/src/components/AccessDeniedOverlay.tsx

@@ -1,4 +1,4 @@
-import { useEffect, useState, useCallback } from "react";
+import { useEffect, useState, useCallback, useRef } from "react";
 import { useNavigate } from "react-router";
 import { XCircleIcon } from "@heroicons/react/24/outline";
 
@@ -30,6 +30,7 @@ export default function AccessDeniedOverlay({
   const { maxRejectionAttempts } = useSettingsStore();
   const [countdown, setCountdown] = useState(10);
   const [isRetrying, setIsRetrying] = useState(false);
+  const hasCountedRef = useRef(false);
 
   const handleLogout = useCallback(async () => {
     try {
@@ -50,7 +51,15 @@ export default function AccessDeniedOverlay({
   }, [navigate, setUser, clearSession, clearNickname]);
 
   useEffect(() => {
-    if (!show) return;
+    if (!show) {
+      hasCountedRef.current = false;
+      setCountdown(10);
+      return;
+    }
+
+    // Only count rejection once per showing
+    if (hasCountedRef.current) return;
+    hasCountedRef.current = true;
 
     const newCount = incrementRejectionCount();