Implement reactions and image sync

core/realtime/compose_ws.py

@@ -162,6 +162,15 @@ async def compose_ws_application(scope, receive, send):
         return
 
     await send({"type": "websocket.accept"})
+
+    # TODO(reactions): stream incremental reaction add/remove events over WS
+    # instead of relying on message row refresh polling windows.
+    # TODO(edits): add edit event envelopes so compose can update message text
+    # in place when upstream supports edits.
+    # TODO(retractions): add retract/delete event envelopes and tombstone UI.
+    # TODO(capability): surface per-service capability notices (e.g. "edited
+    # locally but upstream protocol does not support edits").
+
     last_ts = 0
     limit = 100
     last_typing_key = ""