feat: expose the telemetry schema SQL to downstreams

tests/unit/test_package.py

@@ -25,3 +25,15 @@ def test_ocr_public_surface_exported():
     ):
         assert hasattr(polygateway, name), name
         assert name in polygateway.__all__, name
+
+
+def test_telemetry_schema_sql_exported():
+    """issue #13: manual 档下游需要主动索取"库要求的最小 schema"的顶层入口。
+
+    同时钉住公共面**只增这一个名字**: `missing_columns_warning` 是 recorder 内部
+    共用的文案构造函数,导出它等于多一份永久承诺(库承诺公共面只增不删)。
+    """
+    assert "telemetry_schema_sql" in polygateway.__all__
+    assert callable(polygateway.telemetry_schema_sql)
+    assert "missing_columns_warning" not in polygateway.__all__
+    assert not hasattr(polygateway, "missing_columns_warning")