Implement resumable download queue (T-301)

core/application/download_event.go

@@ -0,0 +1,45 @@
+package application
+
+// DownloadStartedPayload begins one transfer attempt. A later attempt may
+// reset Done when a remote entity cannot be safely resumed.
+type DownloadStartedPayload struct {
+	Attempt    uint64
+	Done       int64
+	TotalKnown bool
+	Total      int64
+}
+
+// DownloadProgressPayload reports monotonic progress within one attempt.
+type DownloadProgressPayload struct {
+	Attempt       uint64
+	Done          int64
+	TotalKnown    bool
+	Total         int64
+	SpeedBytesSec int64
+}
+
+// DownloadPausedPayload maps to domain queued while preserving pause intent.
+type DownloadPausedPayload struct {
+	Attempt uint64
+	Done    int64
+}
+
+// DownloadCompletedPayload means bytes are durably downloaded but still
+// untrusted. T-302 must verify the signed Catalog identity, size and hashes.
+type DownloadCompletedPayload struct {
+	Attempt uint64
+	Done    int64
+	Path    string
+}
+
+// DownloadFailedPayload carries a stable low-level transfer/storage code.
+type DownloadFailedPayload struct {
+	Attempt   uint64
+	Done      int64
+	ErrorCode string
+}
+
+// DownloadCanceledPayload confirms cleanup and suppresses the old attempt.
+type DownloadCanceledPayload struct {
+	Attempt uint64
+}

core/application/event.go

@@ -11,6 +11,7 @@ const (
 	EventDownloadPaused    EventType = "DownloadPaused"
 	EventDownloadCompleted EventType = "DownloadCompleted"
 	EventDownloadFailed    EventType = "DownloadFailed"
+	EventDownloadCanceled  EventType = "DownloadCanceled"
 	EventInstallCompleted  EventType = "InstallCompleted"
 	EventInstallRolledBack EventType = "InstallRolledBack"
 	EventAppStarted        EventType = "AppStarted"
@@ -26,6 +27,7 @@ var validEventTypes = map[EventType]struct{}{
 	EventDownloadPaused:    {},
 	EventDownloadCompleted: {},
 	EventDownloadFailed:    {},
+	EventDownloadCanceled:  {},
 	EventInstallCompleted:  {},
 	EventInstallRolledBack: {},
 	EventAppStarted:        {},

core/application/event_test.go

@@ -11,6 +11,7 @@ func TestEventTypeValid(t *testing.T) {
 		EventDownloadPaused,
 		EventDownloadCompleted,
 		EventDownloadFailed,
+		EventDownloadCanceled,
 		EventInstallCompleted,
 		EventInstallRolledBack,
 		EventAppStarted,