diff --git a/api/models.py b/api/models.py
index 8015809b..f4a70db0 100644
--- a/api/models.py
+++ b/api/models.py
@@ -3425,12 +3425,17 @@ def _apply_sidebar_state_db_override_metadata(sessions: list[dict], metadata: di
                 state_last = float(state_db_last_message_at or 0)
             except (TypeError, ValueError):
                 state_last = 0.0
+            # ``current_last`` intentionally includes ``updated_at``: if a
+            # sidecar metadata-only write happened after the state.db append,
+            # keep the conservative anti-resurrection guard and wait for a
+            # newer settled state.db message before overlaying counts again.
             if state_count > current_count and (state_last <= 0 or state_last > current_last):
+                try:
+                    existing_actual = max(0, int(session.get('actual_message_count') or 0))
+                except (TypeError, ValueError):
+                    existing_actual = 0
                 session['message_count'] = state_count
-                session['actual_message_count'] = max(
-                    state_count,
-                    int(session.get('actual_message_count') or 0) if str(session.get('actual_message_count') or '').isdigit() else 0,
-                )
+                session['actual_message_count'] = max(state_count, existing_actual)
                 if state_last > 0:
                     session['last_message_at'] = max(float(session.get('last_message_at') or 0), state_last)
                     session['updated_at'] = max(float(session.get('updated_at') or 0), state_last)
diff --git a/tests/test_session_sidebar_cache.py b/tests/test_session_sidebar_cache.py
index 11896363..c6a328e8 100644
--- a/tests/test_session_sidebar_cache.py
+++ b/tests/test_session_sidebar_cache.py
@@ -1,10 +1,23 @@
 import threading
 from types import SimpleNamespace
 
+import pytest
+
 import api.routes as routes
 from api import session_events
 
 
+@pytest.fixture(autouse=True)
+def _isolated_session_list_cache_state():
+    routes._session_list_cache_clear()
+    with routes._SESSIONS_CACHE_LOCK:
+        routes._SESSIONS_CACHE_INFLIGHT.clear()
+    yield
+    routes._session_list_cache_clear()
+    with routes._SESSIONS_CACHE_LOCK:
+        routes._SESSIONS_CACHE_INFLIGHT.clear()
+
+
 class _StageRecorder:
     def __init__(self):
         self.stages = []
@@ -74,8 +87,9 @@ def test_session_list_cache_key_separates_profile_and_all_profiles():
     assert calls == ["default", "other", "default_all"]
 
 
-def test_session_list_cache_singleflight_rebuild_once():
+def test_session_list_cache_singleflight_rebuild_once(monkeypatch):
     routes._session_list_cache_clear()
+    monkeypatch.setattr(routes, "_session_list_cache_source_stamp", lambda _key: ("stable",))
 
     started = threading.Event()
     release = threading.Event()
@@ -121,8 +135,9 @@ def test_session_list_cache_singleflight_rebuild_once():
     assert calls == 1
 
 
-def test_session_list_cache_follower_wait_stage_when_rebuild_inflight():
+def test_session_list_cache_follower_wait_stage_when_rebuild_inflight(monkeypatch):
     routes._session_list_cache_clear()
+    monkeypatch.setattr(routes, "_session_list_cache_source_stamp", lambda _key: ("stable",))
 
     started = threading.Event()
     release = threading.Event()
diff --git a/tests/test_webui_state_db_reconciliation.py b/tests/test_webui_state_db_reconciliation.py
index 11daacee..8815e104 100644
--- a/tests/test_webui_state_db_reconciliation.py
+++ b/tests/test_webui_state_db_reconciliation.py
@@ -125,6 +125,36 @@ def _install_test_session(monkeypatch, tmp_path, sid, sidecar_messages):
     return session
 
 
+def test_sidebar_state_db_overlay_preserves_numeric_actual_count():
+    import api.models as models
+
+    sid = "webui_float_actual_count"
+    sessions = [
+        {
+            "session_id": sid,
+            "source_tag": "webui",
+            "message_count": 2,
+            "actual_message_count": 5.0,
+            "last_message_at": 1001.0,
+            "updated_at": 1001.0,
+        }
+    ]
+
+    models._apply_sidebar_state_db_override_metadata(
+        sessions,
+        {
+            sid: {
+                "_state_db_source": "webui",
+                "_state_db_message_count": 4,
+                "_state_db_last_message_at": 1003.0,
+            }
+        },
+    )
+
+    assert sessions[0]["message_count"] == 4
+    assert sessions[0]["actual_message_count"] == 5
+
+
 def test_tail_cancelled_partial_blocks_state_db_replay():
     from api.models import merge_session_messages_append_only