Add Run control event stream

platform/service/control_events.go

@@ -0,0 +1,77 @@
+package service
+
+import (
+	"sync"
+
+	"browser.local/platform/domain"
+	"browser.local/platform/validator"
+)
+
+const defaultRunControlEventRetrySeconds = 5
+
+type RunControlEventSubscription struct {
+	Initial *domain.RunControlEvent
+	Events  <-chan domain.RunControlEvent
+	Cancel  func()
+}
+
+func (svc *CoreService) SubscribeRunControlEvents(request domain.RunControlStreamRequest) (RunControlEventSubscription, error) {
+	request = domain.CopyRunControlStreamRequest(request)
+	if err := validator.ValidateRunControlStreamRequest(request); err != nil {
+		return RunControlEventSubscription{}, err
+	}
+	if err := svc.validateRunSession(request.RunEndpointID, request.SessionToken); err != nil {
+		return RunControlEventSubscription{}, err
+	}
+
+	updates := make(chan domain.RunControlEvent, 8)
+	var initial *domain.RunControlEvent
+	svc.controlStreamMu.Lock()
+	if latest, exists := svc.controlStreamEvents[request.RunEndpointID]; exists && latest.Sequence > request.LastEventSeq {
+		copy := domain.CopyRunControlEvent(latest)
+		initial = &copy
+	}
+	svc.controlStreamWaiters[request.RunEndpointID] = append(svc.controlStreamWaiters[request.RunEndpointID], updates)
+	svc.controlStreamMu.Unlock()
+
+	var once sync.Once
+	cancel := func() {
+		once.Do(func() {
+			svc.controlStreamMu.Lock()
+			waiters := svc.controlStreamWaiters[request.RunEndpointID]
+			for index, candidate := range waiters {
+				if candidate == updates {
+					waiters = append(waiters[:index], waiters[index+1:]...)
+					break
+				}
+			}
+			if len(waiters) == 0 {
+				delete(svc.controlStreamWaiters, request.RunEndpointID)
+			} else {
+				svc.controlStreamWaiters[request.RunEndpointID] = waiters
+			}
+			svc.controlStreamMu.Unlock()
+			close(updates)
+		})
+	}
+	return RunControlEventSubscription{Initial: initial, Events: updates, Cancel: cancel}, nil
+}
+
+func (svc *CoreService) publishRunControlEvent(runEndpointID string, eventType string) {
+	if runEndpointID == "" || eventType == "" {
+		return
+	}
+	svc.controlStreamMu.Lock()
+	sequence := svc.controlStreamSeq[runEndpointID] + 1
+	svc.controlStreamSeq[runEndpointID] = sequence
+	event := domain.RunControlEvent{RunEndpointID: runEndpointID, Sequence: sequence, Type: eventType, ServerTime: svc.now(), RetrySeconds: defaultRunControlEventRetrySeconds}
+	svc.controlStreamEvents[runEndpointID] = event
+	waiters := append([]chan domain.RunControlEvent(nil), svc.controlStreamWaiters[runEndpointID]...)
+	svc.controlStreamMu.Unlock()
+	for _, waiter := range waiters {
+		select {
+		case waiter <- event:
+		default:
+		}
+	}
+}