test(state): cover update_session_model overwrite + getattr-guard text path

Follow-up to LengR's #35181 salvage:
- gateway text-path uses getattr(self, '_session_db', None) to match the
  picker callback path (defensive for object.__new__() gateway test pattern).
- add SessionDB.update_session_model test asserting it overwrites the
  COALESCE-pinned model and survives subsequent token updates (#34850).

gateway/run.py

@@ -10704,10 +10704,11 @@ class GatewayRunner:
 
         # Persist the new model to the session DB so the dashboard
         # shows the updated model (#34850).
-        if self._session_db is not None:
+        _sess_db = getattr(self, "_session_db", None)
+        if _sess_db is not None:
             try:
                 _sess_entry = self.session_store.get_or_create_session(source)
-                self._session_db.update_session_model(
+                _sess_db.update_session_model(
                     _sess_entry.session_id, result.new_model
                 )
             except Exception as exc:

scripts/release.py

@@ -46,6 +46,7 @@ ACP_REGISTRY_MANIFEST = REPO_ROOT / "acp_registry" / "agent.json"
 # Auto-extracted from noreply emails + manual overrides
 AUTHOR_MAP = {
     "drpelagik@gmail.com": "SeaXen",
+    "lengr@users.noreply.github.com": "LengR",
     "metalclaudbot@gmail.com": "HashClawAI",
     "tonybear55665566@gmail.com": "TonyPepeBear",
     "kaspersniels@gmail.com": "nielskaspers",

tests/test_hermes_state.py

@@ -152,6 +152,30 @@ class TestSessionLifecycle:
         session = db.get_session("s1")
         assert session["model"] == "anthropic/claude-opus-4.6"
 
+    def test_update_session_model_overwrites_existing(self, db):
+        """A mid-session /model switch must overwrite the stored model.
+
+        update_token_counts uses COALESCE(model, ?) (first-writer-wins), so
+        the dashboard kept showing the original model after a switch (#34850).
+        update_session_model sets the column unconditionally.
+        """
+        db.create_session(session_id="s1", source="telegram",
+                          model="xiaomi/mimo-v2.5-pro")
+        # Token updates never change the model once set.
+        db.update_token_counts("s1", input_tokens=10, output_tokens=5,
+                               model="xiaomi/mimo-v2.5-pro")
+        assert db.get_session("s1")["model"] == "xiaomi/mimo-v2.5-pro"
+
+        # Explicit switch overwrites it.
+        db.update_session_model("s1", "xiaomi/mimo-v2.5")
+        assert db.get_session("s1")["model"] == "xiaomi/mimo-v2.5"
+
+        # And a subsequent token update does NOT revert it (COALESCE no-ops
+        # because the column is now non-NULL).
+        db.update_token_counts("s1", input_tokens=10, output_tokens=5,
+                               model="xiaomi/mimo-v2.5-pro")
+        assert db.get_session("s1")["model"] == "xiaomi/mimo-v2.5"
+
     def test_parent_session(self, db):
         db.create_session(session_id="parent", source="cli")
         db.create_session(session_id="child", source="cli", parent_session_id="parent")