fix(core): preserve adapter command contracts

harness/tht/adapters/dwh/thoth_rest.py

@@ -22,8 +22,10 @@ class ThothRestDwhAdapter:
             result = self._client.ping()
         except RestError as exc:
             return DwhHealth(ok=False, detail=str(exc))
-        ok = bool(result.get("db_connected", True))
-        return DwhHealth(ok=ok, detail=None if ok else str(result))
+        ok = bool(result.get("db_connected") and result.get("schema_accessible"))
+        return DwhHealth(ok=ok, detail=None if ok else str(result),
+                         database=self._database.database, schema=self._database.db_schema,
+                         endpoint=self._client.cfg.base_url, read_only=True)
 
     def introspect(self) -> PhysicalSchema:
         return introspect_rest(
@@ -44,10 +46,10 @@ class ThothRestDwhAdapter:
         except RestError as exc:
             raise ExecutionError(str(exc)) from exc
 
-    def distinct_values(self, table: str, column: str) -> DistinctValues:
+    def distinct_values(self, table: str, column: str, *, limit: int) -> DistinctValues:
         try:
             return sampling.distinct_values_rest(
-                self._client, self._database.db_schema, table, column
+                self._client, self._database.db_schema, table, column, max_values=limit
             )
         except RestError as exc:
             raise ExecutionError(str(exc)) from exc