fix(core): restore adapter command behavior

harness/tht/adapters/dwh/postgres.py

@@ -1,7 +1,7 @@
 """Direct PostgreSQL implementation of the DWH port."""
 
 from tht.config import DatabaseConfig
-from sqlalchemy.exc import SQLAlchemyError
+from sqlalchemy.exc import OperationalError, SQLAlchemyError
 
 from tht.db import execute, sampling
 from tht.db.connection import can_create_in_schema, make_engine, ping, writable_tables
@@ -22,8 +22,10 @@ class PostgresDwhAdapter:
     def health(self) -> DwhHealth:
         try:
             ping(self._engine)
+        except OperationalError as exc:
+            return DwhHealth(ok=False, detail=str(exc.orig), error_kind="connection")
         except SQLAlchemyError as exc:
-            return DwhHealth(ok=False, detail=str(exc))
+            return DwhHealth(ok=False, detail=str(exc), error_kind="connection")
         writable = tuple(writable_tables(self._engine, self._config.db_schema))
         can_create = can_create_in_schema(self._engine, self._config.db_schema)
         return DwhHealth(ok=True, database=self._config.database, schema=self._config.db_schema,