diff --git a/nanobot/channels/msteams.py b/nanobot/channels/msteams.py
index fc25f2fbb..d2addacca 100644
--- a/nanobot/channels/msteams.py
+++ b/nanobot/channels/msteams.py
@@ -70,6 +70,7 @@ class ConversationRef:
     activity_id: str | None = None
     conversation_type: str | None = None
     tenant_id: str | None = None
+    updated_at: float | None = None
 
 
 class MSTeamsChannel(BaseChannel):
@@ -288,7 +289,9 @@ class MSTeamsChannel(BaseChannel):
             activity_id=activity_id or None,
             conversation_type=conversation_type or None,
             tenant_id=str((channel_data.get("tenant") or {}).get("id") or "") or None,
+            updated_at=time.time(),
         )
+
         self._save_refs()
 
         await self._handle_message(
@@ -493,6 +496,14 @@ class MSTeamsChannel(BaseChannel):
     def _save_refs(self) -> None:
         """Persist conversation references."""
         try:
+            stale_keys = [
+                key
+                for key, ref in self._conversation_refs.items()
+                if self._is_stale_or_unsupported_ref(ref)
+            ]
+            for key in stale_keys:
+                self._conversation_refs.pop(key, None)
+
             data = {
                 key: {
                     "service_url": ref.service_url,
@@ -501,6 +512,7 @@ class MSTeamsChannel(BaseChannel):
                     "activity_id": ref.activity_id,
                     "conversation_type": ref.conversation_type,
                     "tenant_id": ref.tenant_id,
+                    "updated_at": ref.updated_at,
                 }
                 for key, ref in self._conversation_refs.items()
             }
@@ -508,6 +520,21 @@ class MSTeamsChannel(BaseChannel):
         except Exception as e:
             logger.warning("Failed to save MSTeams conversation refs: {}", e)
 
+    def _is_stale_or_unsupported_ref(self, ref: ConversationRef) -> bool:
+        """Reject unsupported refs and prune old refs."""
+        service_url = (ref.service_url or "").strip().lower()
+        conversation_type = (ref.conversation_type or "").strip().lower()
+        updated_at = ref.updated_at or 0.0
+        max_age_seconds = 30 * 24 * 60 * 60
+
+        if "webchat.botframework.com" in service_url:
+            return True
+        if conversation_type and conversation_type != "personal":
+            return True
+        if updated_at and updated_at < time.time() - max_age_seconds:
+            return True
+        return False
+
     async def _get_access_token(self) -> str:
         """Fetch an access token for Bot Framework / Azure Bot auth."""
 
diff --git a/tests/test_msteams.py b/tests/test_msteams.py
index b4ed59092..3dbfdfb2f 100644
--- a/tests/test_msteams.py
+++ b/tests/test_msteams.py
@@ -1,4 +1,5 @@
 import json
+import time
 
 import pytest
 
@@ -551,6 +552,38 @@ async def test_start_logs_install_hint_when_pyjwt_missing(make_channel, monkeypa
     assert errors == ["PyJWT not installed. Run: pip install nanobot-ai[msteams]"]
 
 
+def test_save_refs_prunes_webchat_and_stale_refs(make_channel):
+    ch = make_channel()
+    now = time.time()
+    ch._conversation_refs = {
+        "teams-good": ConversationRef(
+            service_url="https://smba.trafficmanager.net/amer/",
+            conversation_id="teams-good",
+            conversation_type="personal",
+            updated_at=now,
+        ),
+        "webchat-bad": ConversationRef(
+            service_url="https://webchat.botframework.com/",
+            conversation_id="webchat-bad",
+            conversation_type=None,
+            updated_at=now,
+        ),
+        "teams-stale": ConversationRef(
+            service_url="https://smba.trafficmanager.net/amer/",
+            conversation_id="teams-stale",
+            conversation_type="personal",
+            updated_at=now - (31 * 24 * 60 * 60),
+        ),
+    }
+
+    ch._save_refs()
+
+    assert set(ch._conversation_refs) == {"teams-good"}
+    saved = json.loads(ch._refs_path.read_text(encoding="utf-8"))
+    assert set(saved) == {"teams-good"}
+    assert saved["teams-good"]["updated_at"] == pytest.approx(now)
+
+
 def test_msteams_default_config_includes_restart_notify_fields():
     cfg = MSTeamsChannel.default_config()