diff --git a/src/auth/auth.controller.ts b/src/auth/auth.controller.ts
index eff3f53..ba5837d 100644
--- a/src/auth/auth.controller.ts
+++ b/src/auth/auth.controller.ts
@@ -127,9 +127,9 @@ export class AuthController {
                     throw new HttpException('Agent account not configured. Contact administrator.', 403);
                 }
 
-                // Check for duplicate login
+                // Check for duplicate login — strict: one device only
                 const existingSession = await this.sessionService.isSessionLocked(agentConfig.ozonetelAgentId);
-                if (existingSession && existingSession !== memberId) {
+                if (existingSession) {
                     throw new HttpException('You are already logged in on another device. Please log out there first.', 409);
                 }