fix: throttle desktop monitoring dispatch

server/internal/tenant/app/desktop_task_service_test.go

@@ -203,6 +203,44 @@ func TestBuildCountPublishTasksByStatusesQueryHidesDeletedPublishRecords(t *test
 	}
 }
 
+func TestLeaseNextQueuedMonitorTaskSQLSerializesPerClientPlatform(t *testing.T) {
+	t.Parallel()
+
+	normalized := normalizeSQLForDesktopTaskTest(leaseNextQueuedMonitorTaskSQL())
+	for _, fragment := range []string{
+		"NOT EXISTS ( SELECT 1 FROM desktop_tasks AS active",
+		"active.target_client_id = $3",
+		"active.platform_id = dt.platform_id",
+		"active.status = 'in_progress'",
+		"active.desktop_id <> dt.desktop_id",
+		"recent.status IN ('succeeded', 'failed', 'unknown', 'aborted')",
+		"recent.updated_at >= now() - interval '30 seconds'",
+	} {
+		if !strings.Contains(normalized, fragment) {
+			t.Fatalf("monitor lease query missing %q: %s", fragment, normalized)
+		}
+	}
+}
+
+func TestLeaseQueuedDesktopTaskByIDSQLSerializesMonitorPerClientPlatform(t *testing.T) {
+	t.Parallel()
+
+	normalized := normalizeSQLForDesktopTaskTest(leaseQueuedDesktopTaskByIDSQL())
+	for _, fragment := range []string{
+		"dt.kind <> 'monitor' OR NOT EXISTS",
+		"active.target_client_id = $4",
+		"active.platform_id = dt.platform_id",
+		"active.status = 'in_progress'",
+		"active.desktop_id <> dt.desktop_id",
+		"recent.status IN ('succeeded', 'failed', 'unknown', 'aborted')",
+		"recent.updated_at >= now() - interval '30 seconds'",
+	} {
+		if !strings.Contains(normalized, fragment) {
+			t.Fatalf("task-specific lease query missing %q: %s", fragment, normalized)
+		}
+	}
+}
+
 func recoverDesktopTaskSelectColumns(query string) []string {
 	re := regexp.MustCompile(`(?is)select\s+(.*?)\s+from\s+desktop_tasks`)
 	match := re.FindStringSubmatch(query)