diff --git a/requirements.txt b/requirements.txt
index 0e49a54..6e32cdb 100644
--- a/requirements.txt
+++ b/requirements.txt
@@ -7,7 +7,7 @@ websockets>=13.0
 python-multipart>=0.0.17
 psutil>=6.0.0
 aiofiles>=24.0.0
-apscheduler>=3.10.0
+apscheduler>=3.10.0,<4.0.0
 pywinpty>=2.0.0; sys_platform == "win32"
 
 # Dev dependencies
diff --git a/server/services/scheduler_service.py b/server/services/scheduler_service.py
index bb4fdfa..239f6cd 100644
--- a/server/services/scheduler_service.py
+++ b/server/services/scheduler_service.py
@@ -285,6 +285,20 @@ class SchedulerService:
                 ).delete()
                 db.commit()
 
+                # Check for active manual-start overrides that prevent auto-stop
+                active_start_override = db.query(ScheduleOverride).filter(
+                    ScheduleOverride.schedule_id == schedule_id,
+                    ScheduleOverride.override_type == "start",
+                    ScheduleOverride.expires_at > now,
+                ).first()
+
+                if active_start_override:
+                    logger.info(
+                        f"Skipping scheduled stop for {project_name}: "
+                        f"active manual-start override (expires {active_start_override.expires_at})"
+                    )
+                    return
+
                 # Stop agent
                 await self._stop_agent(project_name, project_dir)