filter messages on client side

apps/chat/integrations/mattermost/client.py

@@ -156,15 +156,6 @@ class MattermostClient:
 
         return channel_id
 
-    @staticmethod
-    def _is_system_post(post: dict) -> bool:
-        """
-        Mattermost auto-generates posts like "user-x added to the channel"
-        (type e.g. "system_add_to_channel") whenever channel membership
-        changes. Real user-sent posts have an empty type.
-        """
-        return post.get("type", "").startswith("system_")
-
     def post_message(self, channel_id: str, message: str) -> str:
         """
         Post a message to the given channel using the admin token.
@@ -190,8 +181,8 @@ class MattermostClient:
     ) -> list[dict]:
         """
         Fetch posts from a channel and return them in chronological order.
-        System posts (channel membership changes, etc.) are excluded — only
-        real user-sent posts are returned.
+        Includes Mattermost system posts (channel membership changes, etc.)
+        as-is, with their raw `type` intact — callers filter if they need to.
 
         `since` is a Unix timestamp in **milliseconds**. When provided,
         `page` is ignored and all posts after that timestamp are returned.
@@ -211,30 +202,19 @@ class MattermostClient:
         posts_map: dict = data.get("posts", {})
 
         # Mattermost returns newest-first; reverse to get chronological order.
-        return [
-            posts_map[pid]
-            for pid in reversed(order)
-            if pid in posts_map and not self._is_system_post(posts_map[pid])
-        ]
+        return [posts_map[pid] for pid in reversed(order) if pid in posts_map]
 
     def get_latest_post_id(self, channel_id: str) -> str | None:
         """
-        Return the ID of the most recent real (non-system) post in the
-        channel, or None if there are none yet.
+        Return the ID of the most recent post in the channel, or None if empty.
         Used to derive `has_unread` against a stored last_read_mattermost_post_id.
         """
         try:
             data = self._driver.posts.get_posts_for_channel(
-                channel_id, params={"page": 0, "per_page": 20}
+                channel_id, params={"page": 0, "per_page": 1}
             )
         except Exception as exc:
             raise MattermostError(f"Fetching latest post failed: {exc}") from exc
 
         order: list[str] = data.get("order", [])
-        posts_map: dict = data.get("posts", {})
-
-        for pid in order:  # newest-first
-            post = posts_map.get(pid)
-            if post and not self._is_system_post(post):
-                return pid
-        return None
+        return order[0] if order else None

apps/chat/serializers/messages.py

@@ -12,6 +12,7 @@ class MessageSerializer(serializers.Serializer):
     post_id = serializers.CharField()
     sender_id = serializers.UUIDField(allow_null=True)
     message_type = serializers.CharField(default="text")
+    mattermost_message_type = serializers.CharField(default="", allow_blank=True)
     text = serializers.CharField(allow_null=True, required=False)
     url = serializers.CharField(allow_null=True, required=False)
     created_at = serializers.DateTimeField(allow_null=True, required=False)

apps/chat/services/message.py

@@ -72,6 +72,7 @@ class MessageService:
             "post_id": post_id,
             "sender_id": sender_id,
             "message_type": message_type,
+            "mattermost_message_type": "",
             "text": text,
             "url": file_url,
             "created_at": None,
@@ -118,6 +119,7 @@ class MessageService:
             "post_id": post.get("id"),
             "sender_id": sender_id,
             "message_type": "file" if is_url else "text",
+            "mattermost_message_type": post.get("type", ""),
             "text": None if is_url else msg,
             "url": msg if is_url else None,
             "created_at": created_at,

apps/chat/tests/test_mattermost_client.py

@@ -21,20 +21,8 @@ def _post(post_id, msg="hi", post_type="", user_id="u1"):
     }
 
 
-def test_get_posts_excludes_system_posts():
+def test_get_posts_keeps_chronological_order():
     # Mattermost order is newest-first.
-    posts_map = {
-        "p1": _post("p1", "real message"),
-        "sys1": _post("sys1", "user-x added to the channel", post_type="system_add_to_channel"),
-    }
-    client = _make_client({"order": ["sys1", "p1"], "posts": posts_map})
-
-    result = client.get_posts("chan-1")
-
-    assert [p["id"] for p in result] == ["p1"]
-
-
-def test_get_posts_keeps_chronological_order_with_no_system_posts():
     posts_map = {
         "p1": _post("p1", "first"),
         "p2": _post("p2", "second"),
@@ -46,28 +34,20 @@ def test_get_posts_keeps_chronological_order_with_no_system_posts():
     assert [p["id"] for p in result] == ["p1", "p2"]
 
 
-def test_get_latest_post_id_skips_leading_system_post():
-    # sys1 is newest (e.g. someone was just added), p1 is the latest real message.
+def test_get_posts_includes_system_posts_with_raw_type():
     posts_map = {
-        "sys1": _post("sys1", "user-y added to the channel", post_type="system_add_to_channel"),
         "p1": _post("p1", "real message"),
+        "sys1": _post("sys1", "user-x added to the channel", post_type="system_add_to_channel"),
     }
     client = _make_client({"order": ["sys1", "p1"], "posts": posts_map})
 
-    assert client.get_latest_post_id("chan-1") == "p1"
+    result = client.get_posts("chan-1")
+
+    assert [p["id"] for p in result] == ["p1", "sys1"]
+    assert result[1]["type"] == "system_add_to_channel"
 
 
-def test_get_latest_post_id_returns_none_when_only_system_posts_exist():
-    posts_map = {
-        "sys1": _post("sys1", "user-x added to the channel", post_type="system_add_to_channel"),
-        "sys2": _post("sys2", "user-y added to the channel", post_type="system_add_to_channel"),
-    }
-    client = _make_client({"order": ["sys2", "sys1"], "posts": posts_map})
-
-    assert client.get_latest_post_id("chan-1") is None
-
-
-def test_get_latest_post_id_returns_newest_real_post_when_no_system_posts():
+def test_get_latest_post_id_returns_newest_post_id():
     posts_map = {
         "p1": _post("p1", "first"),
         "p2": _post("p2", "second"),
@@ -75,3 +55,9 @@ def test_get_latest_post_id_returns_newest_real_post_when_no_system_posts():
     client = _make_client({"order": ["p2", "p1"], "posts": posts_map})
 
     assert client.get_latest_post_id("chan-1") == "p2"
+
+
+def test_get_latest_post_id_returns_none_when_empty():
+    client = _make_client({"order": [], "posts": {}})
+
+    assert client.get_latest_post_id("chan-1") is None

apps/chat/tests/test_messages.py

@@ -90,6 +90,13 @@ def test_list_messages_normalized():
             "message": "http://minio.local/chat/file.pdf",
             "create_at": 1700000001000,
         },
+        {
+            "id": "sys1",
+            "type": "system_add_to_channel",
+            "user_id": mm_user_id,
+            "message": "user-x added to the channel",
+            "create_at": 1700000002000,
+        },
     ]
 
     mm_client = Mock()
@@ -99,12 +106,13 @@ def test_list_messages_normalized():
 
     messages = svc.list_messages(conv.id, page=0, per_page=20)
 
-    assert len(messages) == 2
+    assert len(messages) == 3
 
     text_msg = messages[0]
     assert text_msg["post_id"] == "p1"
     assert text_msg["sender_id"] == sender_uuid
     assert text_msg["message_type"] == "text"
+    assert text_msg["mattermost_message_type"] == ""
     assert text_msg["text"] == "First message"
     assert text_msg["url"] is None
 
@@ -112,5 +120,10 @@ def test_list_messages_normalized():
     assert file_msg["post_id"] == "p2"
     assert file_msg["sender_id"] == sender_uuid
     assert file_msg["message_type"] == "file"
+    assert file_msg["mattermost_message_type"] == ""
     assert file_msg["url"] == "http://minio.local/chat/file.pdf"
     assert file_msg["text"] is None
+
+    system_msg = messages[2]
+    assert system_msg["post_id"] == "sys1"
+    assert system_msg["mattermost_message_type"] == "system_add_to_channel"