apps/chat/integrations/mattermost/client.py

@@ -156,9 +156,14 @@ class MattermostClient:
 
         return channel_id
 
-    def post_message(self, channel_id: str, message: str) -> str:
+    def post_message(self, channel_id: str, message: str, sender_uuid: UUID) -> str:
         """
         Post a message to the given channel using the admin token.
+
+        Every post is authored by the single service account, not the real
+        sender — there are no per-user tokens. `sender_uuid` is stamped into
+        the post's `props` so it can be recovered later in `get_posts()`;
+        Mattermost's own `user_id` on the post is always the service account.
         Returns the opaque mattermost_post_id string.
         """
         try:
@@ -166,6 +171,7 @@ class MattermostClient:
                 options={
                     "channel_id": channel_id,
                     "message": message,
+                    "props": {"sender_uuid": str(sender_uuid)},
                 }
             )
             return post["id"]

apps/chat/services/message.py

@@ -7,7 +7,7 @@ from apps.chat.events.publishers.push import PushPublisher
 from apps.chat.events.publishers.websocket import WebSocketPublisher
 from apps.chat.exceptions import ConversationClosedError
 from apps.chat.integrations.mattermost.client import MattermostClient
-from apps.chat.models import Conversation, ConversationStatus, MattermostAccountMapping
+from apps.chat.models import Conversation, ConversationStatus
 from apps.chat.services.account import AccountService
 from apps.chat.services.storage import StorageService
 
@@ -62,7 +62,9 @@ class MessageService:
         else:
             mm_message = text or ""
 
-        post_id = self._mm.post_message(conversation.mattermost_channel_id, mm_message)
+        post_id = self._mm.post_message(
+            conversation.mattermost_channel_id, mm_message, sender_uuid
+        )
 
         event = MessageSentEvent(
             chat_uuid=conversation_uuid,
@@ -99,19 +101,14 @@ class MessageService:
             since=since,
         )
 
-        mm_user_ids = {p["user_id"] for p in raw_posts if p.get("user_id")}
-        mappings = {
-            m.mattermost_user_id: m.user_uuid
-            for m in MattermostAccountMapping.objects.filter(
-                mattermost_user_id__in=mm_user_ids
-            )
-        } if mm_user_ids else {}
+        return [self._normalize_post(p) for p in raw_posts]
 
-        return [self._normalize_post(p, mappings) for p in raw_posts]
-
-    def _normalize_post(self, post: dict, mappings: dict) -> dict:
-        mm_uid = post.get("user_id")
-        sender_uuid = mappings.get(mm_uid)
+    def _normalize_post(self, post: dict) -> dict:
+        sender_uuid_raw = (post.get("props") or {}).get("sender_uuid")
+        try:
+            sender_uuid = UUID(sender_uuid_raw) if sender_uuid_raw else None
+        except ValueError:
+            sender_uuid = None
         msg = post.get("message", "")
         created_ms = post.get("create_at")
         created_at = (

apps/chat/tests/test_conversation_close.py

@@ -109,4 +109,4 @@ def test_send_message_after_reopen_succeeds():
     result = svc.send(conv.uuid, sender_uuid, "text", text="hello again")
 
     assert result["post_id"] == "post-1"
-    mm_client.post_message.assert_called_once_with("ch-close", "hello again")
+    mm_client.post_message.assert_called_once_with("ch-close", "hello again", sender_uuid)

apps/chat/tests/test_messages.py

@@ -3,7 +3,7 @@ from unittest.mock import Mock
 
 import pytest
 
-from apps.chat.models import Conversation, MattermostAccountMapping
+from apps.chat.models import Conversation
 from apps.chat.services.message import MessageService
 
 
@@ -36,7 +36,7 @@ def test_send_text_message():
 
     result = svc.send(conv.uuid, sender_uuid, "text", text="Hello world")
 
-    mm_client.post_message.assert_called_once_with("ch-send-text", "Hello world")
+    mm_client.post_message.assert_called_once_with("ch-send-text", "Hello world", sender_uuid)
     storage.get_download_url.assert_not_called()
     ws_publisher.publish.assert_called_once()
 
@@ -62,7 +62,9 @@ def test_send_image_message():
     result = svc.send(conv.uuid, sender_uuid, "image", object_key=object_key)
 
     storage.get_download_url.assert_called_once_with(object_key)
-    mm_client.post_message.assert_called_once_with("ch-send-image", f"image:{object_key}")
+    mm_client.post_message.assert_called_once_with(
+        "ch-send-image", f"image:{object_key}", sender_uuid
+    )
     assert result["url"] == download_url
     assert result["message_type"] == "image"
 
@@ -71,11 +73,7 @@ def test_send_image_message():
 def test_list_messages_normalized():
     conv = Conversation.objects.create(mattermost_channel_id="ch-list")
     sender_uuid = uuid.uuid4()
-    mm_user_id = "mm-user-xyz"
-
-    MattermostAccountMapping.objects.create(
-        user_uuid=sender_uuid, mattermost_user_id=mm_user_id
-    )
+    mm_user_id = "mm-service-bot"  # every post is authored by the service account
 
     object_key = "voice/def456/clip.ogg"
     raw_posts = [
@@ -83,12 +81,14 @@ def test_list_messages_normalized():
             "id": "p1",
             "user_id": mm_user_id,
             "message": "First message",
+            "props": {"sender_uuid": str(sender_uuid)},
             "create_at": 1700000000000,
         },
         {
             "id": "p2",
             "user_id": mm_user_id,
             "message": f"voice:{object_key}",
+            "props": {"sender_uuid": str(sender_uuid)},
             "create_at": 1700000001000,
         },
         {
@@ -130,7 +130,7 @@ def test_list_messages_normalized():
 
     system_msg = messages[2]
     assert system_msg["post_id"] == "sys1"
-    assert system_msg["sender_uuid"] == sender_uuid
+    assert system_msg["sender_uuid"] is None
     assert system_msg["mattermost_message_type"] == "system_add_to_channel"