fix(msteams): secure inbound defaults and ref persistence

Default Microsoft Teams inbound auth validation to enabled, update the README to match, and prevent denied senders from persisting conversation refs before allowlist checks pass.

Made-with: Cursor

tests/test_msteams.py

@@ -147,6 +147,40 @@ async def test_handle_activity_ignores_group_messages(make_channel):
     assert ch._conversation_refs == {}
 
 
+@pytest.mark.asyncio
+async def test_handle_activity_denied_sender_does_not_store_ref(make_channel, tmp_path):
+    ch = make_channel(allowFrom=["allowed-user"])
+
+    activity = {
+        "type": "message",
+        "id": "activity-denied",
+        "text": "Hello from denied user",
+        "serviceUrl": "https://smba.trafficmanager.net/amer/",
+        "conversation": {
+            "id": "conv-denied",
+            "conversationType": "personal",
+        },
+        "from": {
+            "id": "29:user-id",
+            "aadObjectId": "aad-user-1",
+            "name": "Bob",
+        },
+        "recipient": {
+            "id": "28:bot-id",
+            "name": "nanobot",
+        },
+        "channelData": {
+            "tenant": {"id": "tenant-id"},
+        },
+    }
+
+    await ch._handle_activity(activity)
+
+    assert ch.bus.inbound == []
+    assert ch._conversation_refs == {}
+    assert not (tmp_path / "state" / "msteams_conversations.json").exists()
+
+
 @pytest.mark.asyncio
 async def test_handle_activity_mention_only_uses_default_response(make_channel):
     ch = make_channel()
@@ -520,6 +554,7 @@ async def test_start_logs_install_hint_when_pyjwt_missing(make_channel, monkeypa
 def test_msteams_default_config_includes_restart_notify_fields():
     cfg = MSTeamsChannel.default_config()
 
+    assert cfg["validateInboundAuth"] is True
     assert "restartNotifyEnabled" not in cfg
     assert "restartNotifyPreMessage" not in cfg
     assert "restartNotifyPostMessage" not in cfg