整理了初始化过程，现在更容易被继承了。

sync_state_machine/config/runtime_config.py

@@ -3,7 +3,7 @@
 Prefer importing from `sync_state_machine.config` directly.
 """
 
-from .datasource_config import ApiDataSourceConfig, DbDataSourceConfig, JsonlDataSourceConfig, DataSourceConfig
+from .datasource_config import ApiDataSourceConfig, JsonlDataSourceConfig, DataSourceConfig
 from .persist_config import PersistConfig
 from .logging_config import LoggingConfig
 from .strategy_config import (
@@ -17,6 +17,7 @@ from .pipeline_config import PipelineRunConfig, DEFAULT_NODE_TYPES
 from .builder import (
     build_default_config,
     build_config,
+    build_config_from_file,
     apply_config_overrides,
     apply_env_overrides,
     config_snapshot,
@@ -24,7 +25,6 @@ from .builder import (
 
 __all__ = [
     "ApiDataSourceConfig",
-    "DbDataSourceConfig",
     "JsonlDataSourceConfig",
     "DataSourceConfig",
     "PersistConfig",
@@ -38,6 +38,7 @@ __all__ = [
     "DEFAULT_NODE_TYPES",
     "build_default_config",
     "build_config",
+    "build_config_from_file",
     "apply_config_overrides",
     "apply_env_overrides",
     "config_snapshot",