Add domain states and event runtime (T-002)

core/application/event.go

@@ -0,0 +1,51 @@
+package application
+
+// EventType identifies an application event consumed by UI adapters.
+type EventType string
+
+const (
+	EventCatalogRefreshed  EventType = "CatalogRefreshed"
+	EventCatalogRejected   EventType = "CatalogRejected"
+	EventDownloadStarted   EventType = "DownloadStarted"
+	EventDownloadProgress  EventType = "DownloadProgress"
+	EventDownloadPaused    EventType = "DownloadPaused"
+	EventDownloadCompleted EventType = "DownloadCompleted"
+	EventDownloadFailed    EventType = "DownloadFailed"
+	EventInstallCompleted  EventType = "InstallCompleted"
+	EventInstallRolledBack EventType = "InstallRolledBack"
+	EventAppStarted        EventType = "AppStarted"
+	EventAppExited         EventType = "AppExited"
+	EventLicenseChanged    EventType = "LicenseChanged"
+)
+
+var validEventTypes = map[EventType]struct{}{
+	EventCatalogRefreshed:  {},
+	EventCatalogRejected:   {},
+	EventDownloadStarted:   {},
+	EventDownloadProgress:  {},
+	EventDownloadPaused:    {},
+	EventDownloadCompleted: {},
+	EventDownloadFailed:    {},
+	EventInstallCompleted:  {},
+	EventInstallRolledBack: {},
+	EventAppStarted:        {},
+	EventAppExited:         {},
+	EventLicenseChanged:    {},
+}
+
+// Valid reports whether eventType is part of the documented event contract.
+func (eventType EventType) Valid() bool {
+	_, ok := validEventTypes[eventType]
+	return ok
+}
+
+// Event is the common envelope delivered from background use cases to adapters.
+//
+// Payload is event-specific and will be replaced by concrete payload types as
+// the corresponding use cases are implemented.
+type Event struct {
+	Type      EventType
+	RequestID string
+	AppID     string
+	Payload   any
+}