diff --git a/plugins/platforms/simplex/adapter.py b/plugins/platforms/simplex/adapter.py
index 9c3d22a429fa..9965a8d0adfb 100644
--- a/plugins/platforms/simplex/adapter.py
+++ b/plugins/platforms/simplex/adapter.py
@@ -354,13 +354,22 @@ async def _handle_new_chat_item(self, wrapper: dict) -> None:
             logger.debug("SimpleX: ignoring event with no chat_id")
             return
 
-        # Sender — for groups the message includes a chatItemMember sub-object
-        member = chat_item.get("chatItemMember") or {}
+        # Sender — current simplex-chat reports the group member under
+        # chatItem.chatDir.groupMember; older payloads used chatItemMember.
+        chat_dir = chat_item.get("chatDir") or {}
+        member = chat_dir.get("groupMember") or chat_item.get("chatItemMember") or {}
         if is_group and member:
-            sender_id = str(member.get("memberId") or member.get("id") or chat_id)
+            member_profile = member.get("memberProfile") or {}
+            sender_id = str(
+                member.get("memberId")
+                or member.get("groupMemberId")
+                or member.get("id")
+                or chat_id
+            )
             sender_name = (
                 member.get("displayName")
                 or member.get("localDisplayName")
+                or member_profile.get("displayName")
                 or sender_id
             )
         else:
diff --git a/tests/gateway/test_simplex_plugin.py b/tests/gateway/test_simplex_plugin.py
index 1048168aa6e6..61ed6a809981 100644
--- a/tests/gateway/test_simplex_plugin.py
+++ b/tests/gateway/test_simplex_plugin.py
@@ -263,6 +263,38 @@ async def test_handle_event_filters_own_corr_id():
     assert own not in adapter._pending_corr_ids  # discarded
 
 
+@pytest.mark.asyncio
+async def test_group_sender_from_chatdir_groupmember():
+    """current simplex-chat reports the group sender under
+    chatItem.chatDir.groupMember, not the legacy chatItemMember key."""
+    from gateway.config import PlatformConfig
+    cfg = PlatformConfig(enabled=True, extra={"ws_url": "ws://localhost:5225"})
+    adapter = SimplexAdapter(cfg)
+    captured = AsyncMock()
+    adapter.handle_message = captured  # type: ignore
+
+    wrapper = {
+        "chatInfo": {"type": "group", "groupInfo": {"groupId": 7, "displayName": "hermes-agent"}},
+        "chatItem": {
+            "content": {"msgContent": {"type": "text", "text": "hello"}},
+            "meta": {"itemStatus": {"type": "rcvNew"}},
+            "chatDir": {
+                "type": "groupRcv",
+                "groupMember": {
+                    "memberId": "memb-abc",
+                    "memberProfile": {"displayName": "Brandon"},
+                },
+            },
+        },
+    }
+    await adapter._handle_new_chat_item(wrapper)
+
+    captured.assert_awaited_once()
+    event_obj = captured.await_args[0][0]
+    assert event_obj.source.user_id == "memb-abc"
+    assert event_obj.source.user_name == "Brandon"
+
+
 # ---------------------------------------------------------------------------
 # 9. Standalone (out-of-process) send for cron
 # ---------------------------------------------------------------------------