fix(honcho): require strict True for pin_peer_name to survive MagicMock configs (#15162)

CI caught that ``test_session_manager_prefers_runtime_user_id_over_config_peer_name``
in ``tests/agent/test_memory_user_id.py`` failed after this branch: that
test passes a ``MagicMock`` for ``config``, where
``mock.pin_peer_name`` silently returns another ``MagicMock`` — truthy by
default.  My ``getattr(..., "pin_peer_name", False)`` fallback was
supposed to guard against callers that haven't added the new attr, but
MagicMock *does* have the attr — it just returns a live mock for it.

Tightened the gate to ``getattr(..., False) is True``.  Real configs
built via ``HonchoClientConfig.from_global_config`` always yield a
proper boolean, so strict equality matches the pinned case and rejects
both the unset-attr fallback and MagicMock stand-ins.  Added a comment
explaining why ``is True`` is intentional, not paranoid.

Also tightened the ``peer_name`` existence check to
``getattr(..., None)`` so a MagicMock with ``peer_name`` left at its
default (also truthy) doesn't spuriously enable pinning either.

Verified against both the new ``test_pin_peer_name.py`` suite (13/13
pass) and the previously-failing
``TestHonchoUserIdScoping`` (3/3 pass).  Zero behaviour change for real
``HonchoClientConfig`` values.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

plugins/memory/honcho/session.py

@@ -284,10 +284,16 @@ class HonchoSessionManager:
         # identity and we should keep it unified across platforms — see
         # #14984.  Opt into that with ``hosts.<host>.pinPeerName: true`` in
         # ``honcho.json`` (or root-level ``pinPeerName: true``).
-        pin_peer_name = bool(
-            self._config
-            and self._config.peer_name
-            and getattr(self._config, "pin_peer_name", False)
+        # `is True` (not `bool(...)`) is deliberate: several multi-user tests
+        # pass a ``MagicMock`` for ``config`` where ``mock.pin_peer_name``
+        # silently returns another MagicMock — truthy by default.  Requiring
+        # strict ``True`` keeps pinning as opt-in even for callers that
+        # haven't updated their mocks yet; real configs built via
+        # ``from_global_config`` always produce a proper boolean.
+        pin_peer_name = (
+            self._config is not None
+            and bool(getattr(self._config, "peer_name", None))
+            and getattr(self._config, "pin_peer_name", False) is True
         )
         if self._runtime_user_peer_name and not pin_peer_name:
             user_peer_id = self._sanitize_id(self._runtime_user_peer_name)