feat: rotate unsequenced client output safely

internal/client/spool/events.go

@@ -33,6 +33,13 @@ type EventInput struct {
 	CreatedAt   time.Time
 }
 
+const (
+	// These match the CommandEvent oneof field numbers, allowing the runtime to
+	// reconstruct the envelope without a second event-kind translation table.
+	EventKindOutput           uint32 = 5
+	EventKindOutputTruncation uint32 = 10
+)
+
 type Event struct {
 	IssueUUID    domain.UUID
 	LocalOrdinal uint64