work towards decoupling api from router

internal/common/events.go

@@ -0,0 +1,26 @@
+package common
+
+import (
+	"encoding/json"
+)
+
+type Event struct {
+	Type  string `json:"type"`
+	Data  any    `json:"data,omitempty"`
+	Error string `json:"error,omitempty"`
+}
+
+func (e Event) ToJSON() ([]byte, error) {
+	return json.Marshal(e)
+}
+
+type EventDestination interface {
+	Send(event Event) error
+	Is(dest EventDestination) bool
+}
+
+type EventRouter interface {
+	HandleEvent(event Event, source EventDestination)
+	AddEventDestination(dest EventDestination)
+	RemoveEventDestination(dest EventDestination)
+}