Introduced stop signals and dependency gating for operations. Added mechanism to RMASS message sending protocol (Confirmed Working)

plugins/rmass/actions/getrmassattachmenturl.py

@@ -4,6 +4,11 @@ kind = "action"
 
 alias = "getrmassattachmenturl"
 
+depends = [
+    "synapsegetroomalias",
+    "synapsegetattachment",
+]
+
 showstatus = True
 
 resolve = {
@@ -47,4 +52,10 @@ filters = [
         "filtervalue": "m.text",
         "print": f"No image detected. Bypassing attachment push",
     },
+    {
+        "filterkey": "event_id",
+        "operator": "==",
+        "filtervalue": {"outputs": "db_event_id"},
+        "print": f"Message already delivered. Bypassing {name}",
+    },
 ]