Choose a workflow

Interface	Input	Behavior and intended use
`fit_global_lines`	`Spectrum`	Caller-preprocessed; no host; in-memory result. Best for developing one global model.
`fit_local`	`Spectrum`	Caller-preprocessed; no host; in-memory result. Best for targeted, independent windows.
`fit_global_lines_workflow`	Spectrum file/row	Galactic correction; optional host; in-memory result. Best for one file-based object.
`fit_object_to_store`	File, `SpectrumData`, or `Spectrum`	Galactic correction except caller-preprocessed `Spectrum`; optional host; run bundle and QA. Best for reproducible single-object work.
`fit_batch`	Parquet/FITS sample	Galactic correction; optional host; resumable run bundle. Best for surveys and production samples.

Recommended path

Start with qsospec.fit_global_lines() while developing a model.
Use qsospec.fit_object_to_store() when outputs and QA must be archived.
Use qsospec.fit_batch() after the single-object configuration is scientifically validated.
Use local fitting only when independent windows are intentional.

The complete workflow descriptions are in User Guide.