fix(db): validate cached project connections

app/native/wndb/connection.py

@@ -20,6 +20,17 @@ def _close_connection(connection: pg.Connection) -> None:
         connection.close()
 
 
+def _is_healthy(connection: pg.Connection) -> bool:
+    if _is_closed(connection):
+        return False
+    try:
+        with connection.cursor() as cur:
+            cur.execute("SELECT 1")
+    except pg.Error:
+        return False
+    return True
+
+
 def _get_project_lock(name: str) -> RLock:
     with _registry_lock:
         lock = _project_locks.get(name)
@@ -32,7 +43,7 @@ def _get_project_lock(name: str) -> RLock:
 def open_connection(name: str) -> pg.Connection:
     with _get_project_lock(name):
         connection = g_conn_dict.get(name)
-        if connection is None or _is_closed(connection):
+        if connection is None or not _is_healthy(connection):
             if connection is not None:
                 _close_connection(connection)
             connection = pg.connect(
@@ -47,8 +58,9 @@ def is_connection_open(name: str) -> bool:
         connection = g_conn_dict.get(name)
         if connection is None:
             return False
-        if _is_closed(connection):
+        if not _is_healthy(connection):
             del g_conn_dict[name]
+            _close_connection(connection)
             return False
         return True