ETL API¶

Entrypoints and Runtime Contracts¶

`loom.etl.runner`	Runner API for compiling and executing ETL pipelines.
`loom.etl.runtime`	Runtime contracts used by executor and backend implementations.

Declarative Authoring¶

`loom.etl.declarative`	I/O declaration API for ETL sources, targets, and file formats.
`loom.etl.pipeline`	User-facing alias for ETL pipeline declaration primitives.
`loom.etl.schema`	Schema, contracts, and table-reference primitives for ETL.

Execution Infrastructure¶

`loom.etl.storage`	Storage config, location mapping, and routing.
`loom.etl.checkpoint`	Checkpoint storage API for ETL pipeline intermediates.
`loom.etl.observability`	Observability public API for ETL runtime hooks and persisted records.

Backends¶

`loom.etl.backends._historify`	Backend-agnostic SCD Type 2 transform and HistorifyBackend Protocol.
`loom.etl.backends.polars`	Polars backend for the Loom ETL framework.
`loom.etl.backends.spark`	PySpark backend for the Loom ETL framework.

Testing¶

`loom.etl.testing`	ETL testing utilities — stubs, runners, scenario, and pytest fixtures.
`loom.etl.testing.spark`	Spark testing utilities and pytest fixtures for the Loom ETL framework.