diff --git a/plugins/memory/honcho/session.py b/plugins/memory/honcho/session.py
index 76cf4e94598b4..367b6e58f1572 100644
--- a/plugins/memory/honcho/session.py
+++ b/plugins/memory/honcho/session.py
@@ -56,6 +56,12 @@ def _auth_error_message(exc: BaseException) -> str:
     )
 
 
+_REAUTH_REQUIRED_MESSAGE = (
+    "Honcho OAuth grant is revoked and cannot be refreshed; "
+    "re-authenticate with 'hermes honcho setup'."
+)
+
+
 @dataclass
 class HonchoSession:
     """
@@ -219,6 +225,23 @@ class HonchoSessionManager:
         self._auth_notice_emitted = True
         return self._auth_failure
 
+    def _reauth_required(self) -> bool:
+        """True when the OAuth grant is dead and only a new login can fix it.
+
+        Reads the config and compares the refresh-token digest, so a re-login
+        flips this back to False with no network call — recovery is immediate.
+        """
+        try:
+            from plugins.memory.honcho import oauth
+            from plugins.memory.honcho.client import resolve_config_path
+
+            host = getattr(self._config, "host", "") or ""
+            if not host:
+                return False
+            return oauth.reauth_required(resolve_config_path(), host)
+        except Exception:
+            return False
+
     def _force_reauth(self) -> bool:
         """Rotate the OAuth token after a server-side 401 and rebind the client.
 
@@ -512,6 +535,15 @@ class HonchoSessionManager:
         if not session.messages:
             return True
 
+        new_messages = [m for m in session.messages if not m.get("_synced")]
+        if not new_messages:
+            return True
+
+        # A dead grant cannot authenticate; skip the call until re-login.
+        if self._reauth_required():
+            self._record_auth_failure(HonchoAuthError(_REAUTH_REQUIRED_MESSAGE))
+            return False
+
         user_peer = self._get_or_create_peer(session.user_peer_id)
         assistant_peer = self._get_or_create_peer(session.assistant_peer_id)
         honcho_session = self._sessions_cache.get(session.honcho_session_id)
@@ -521,10 +553,6 @@ class HonchoSessionManager:
                 session.honcho_session_id, user_peer, assistant_peer
             )
 
-        new_messages = [m for m in session.messages if not m.get("_synced")]
-        if not new_messages:
-            return True
-
         honcho_messages = []
         for msg in new_messages:
             peer = user_peer if msg["role"] == "user" else assistant_peer
@@ -750,6 +778,12 @@ class HonchoSessionManager:
         if not session:
             return ""
 
+        # A dead grant cannot authenticate; skip the call until re-login.
+        if self._reauth_required():
+            exc = HonchoAuthError(_REAUTH_REQUIRED_MESSAGE)
+            self._record_auth_failure(exc)
+            raise exc
+
         target_peer_id = self._resolve_peer_id(session, peer)
         if target_peer_id is None:
             return ""
diff --git a/tests/honcho_plugin/test_auth_recovery.py b/tests/honcho_plugin/test_auth_recovery.py
index 15a0e4dd4a396..ef26f1e6552cd 100644
--- a/tests/honcho_plugin/test_auth_recovery.py
+++ b/tests/honcho_plugin/test_auth_recovery.py
@@ -398,6 +398,82 @@ class TestSyncAuthRetry:
         assert mgr._auth_failure is None
 
 
+# ---------------------------------------------------------------------------
+# dead grant: skip calls entirely until re-login
+# ---------------------------------------------------------------------------
+
+
+def _kill_grant(tmp_path, monkeypatch) -> Path:
+    """Revoke the grant on a tmp config and point the manager's path at it."""
+    from plugins.memory.honcho import client as client_mod
+
+    path = tmp_path / "honcho.json"
+    _write(path, {"hosts": {"hermes": _host_block()}})
+    monkeypatch.setattr(oauth, "_REFRESH_RETRY_DELAY_SECONDS", 0)
+    monkeypatch.setattr(
+        oauth, "_http_post_form_status",
+        lambda *a, **k: (400, {"error": "invalid_grant"}),
+    )
+    oauth.ensure_fresh_token(path, "hermes", now=1000)
+    assert oauth.reauth_required(path, "hermes") is True
+    monkeypatch.setattr(client_mod, "resolve_config_path", lambda: path)
+    return path
+
+
+def _relogin(path: Path) -> None:
+    oauth.install_grant(
+        path, "hermes",
+        {"access_token": "hch-at-fresh", "refresh_token": "hch-rt-fresh", "expires_in": 3600},
+        client_id="hermes-desktop",
+        token_endpoint="http://localhost:8000/oauth/token",
+    )
+
+
+class TestDeadGrantSkipsCalls:
+    def test_dead_grant_issues_no_dialectic_call(self, tmp_path, monkeypatch):
+        _kill_grant(tmp_path, monkeypatch)
+        peer = _FlakyPeer(failures=0)
+        mgr = _make_manager(peer)
+        with pytest.raises(HonchoAuthError):
+            mgr.dialectic_query("k", "q")
+        assert peer.calls == 0
+        assert mgr.pop_auth_notice() is not None
+
+    def test_relogin_resumes_dialectic_without_waiting(self, tmp_path, monkeypatch):
+        path = _kill_grant(tmp_path, monkeypatch)
+        peer = _FlakyPeer(failures=0)
+        mgr = _make_manager(peer)
+        with pytest.raises(HonchoAuthError):
+            mgr.dialectic_query("k", "q")
+        assert peer.calls == 0
+
+        _relogin(path)
+        assert mgr.dialectic_query("k", "q") == "synthesized answer"
+        assert peer.calls == 1
+        assert mgr._auth_failure is None
+
+    def test_dead_grant_issues_no_sync_call(self, tmp_path, monkeypatch):
+        _kill_grant(tmp_path, monkeypatch)
+        flaky = _FlakyHonchoSession(failures=0)
+        mgr, session = _make_sync_manager(flaky)
+        assert mgr._flush_session(session) is False
+        assert flaky.calls == 0
+        assert mgr._auth_failure is not None
+
+    def test_relogin_resumes_sync_without_waiting(self, tmp_path, monkeypatch):
+        path = _kill_grant(tmp_path, monkeypatch)
+        flaky = _FlakyHonchoSession(failures=0)
+        mgr, session = _make_sync_manager(flaky)
+        assert mgr._flush_session(session) is False
+        assert flaky.calls == 0
+
+        _relogin(path)
+        assert mgr._flush_session(session) is True
+        assert flaky.calls == 1
+        assert all(m["_synced"] for m in session.messages)
+        assert mgr._auth_failure is None
+
+
 # ---------------------------------------------------------------------------
 # one-time user-facing notice
 # ---------------------------------------------------------------------------