fix: gate scheduler task concurrency

cmd/gitea-dynamic-runner/controller.go

@@ -85,8 +85,12 @@ func runController(ctx context.Context) error {
 		return err
 	}
 	registry := runnerfacade.NewRegistry()
+	gate := taskscheduler.NewSingleFlightGate()
 	giteaClient := giteaactions.NewClient(giteaactions.DefaultHTTPClient(), config.GiteaURL, config.GiteaUUID, config.GiteaToken)
-	facade := &runnerfacade.Facade{Registry: registry, Capabilities: capabilities, Upstream: giteaClient}
+	facade := &runnerfacade.Facade{
+		Registry: registry, Capabilities: capabilities, Upstream: giteaClient,
+		OnTerminal: func(taskassignment.Assignment) { gate.Release() },
+	}
 	bootstrap := runnerbootstrap.Bootstrap{
 		Capabilities: capabilities, FacadeURL: config.FacadeURL, FacadeSPIFFEID: config.FacadeSPIFFEID,
 	}
@@ -99,7 +103,7 @@ func runController(ctx context.Context) error {
 		labels = append(labels, string(taskassignment.BackendVM))
 	}
 	poller := taskscheduler.Poller{
-		Client: giteaClient,
+		Client: giteaClient, Gate: gate,
 		Scheduler: &taskscheduler.Scheduler{TrustDomain: config.TrustDomain, Dispatcher: assignmentqueue.Publisher{
 			JetStream: producerJS, SubjectBase: config.SubjectBase,
 		}},