Fix scheduler cleanup edge cases

agent/internal/scheduler/scheduler.go

@@ -202,13 +202,24 @@ func (w *checkWorker) Wait() {
 }
 
 func (w *checkWorker) loop(initial config.CheckConfig) {
+	cfg := initial
+	stoppedNotified := false
+	notifyStopped := func() {
+		if stoppedNotified {
+			return
+		}
+		stoppedNotified = true
+		if w.hooks.OnStopped != nil {
+			w.hooks.OnStopped(cfg.ID)
+		}
+	}
 	defer func() {
+		notifyStopped()
 		if w.onDone != nil {
 			w.onDone(w)
 		}
 		w.wg.Done()
 	}()
-	cfg := initial
 	t := time.NewTimer(time.Hour)
 	stopTimer(t)
 	defer t.Stop()
@@ -249,9 +260,6 @@ func (w *checkWorker) loop(initial config.CheckConfig) {
 	}
 
 	if !arm(cfg, true) {
-		if w.hooks.OnStopped != nil {
-			w.hooks.OnStopped(cfg.ID)
-		}
 		return
 	}
 
@@ -261,18 +269,12 @@ func (w *checkWorker) loop(initial config.CheckConfig) {
 			stopping = true
 			ctxDone = nil
 			if !running {
-				if w.hooks.OnStopped != nil {
-					w.hooks.OnStopped(cfg.ID)
-				}
 				return
 			}
 		case <-stopCh:
 			stopping = true
 			stopCh = nil
 			if !running {
-				if w.hooks.OnStopped != nil {
-					w.hooks.OnStopped(cfg.ID)
-				}
 				return
 			}
 		case next := <-w.updateCh:
@@ -307,9 +309,6 @@ func (w *checkWorker) loop(initial config.CheckConfig) {
 				}
 			}
 			if stopping {
-				if w.hooks.OnStopped != nil {
-					w.hooks.OnStopped(cfg.ID)
-				}
 				return
 			}
 			if runAfterCurrent {