Create a custom recipe

For a group of narrow lines, start with the registry helper:

custom = qsospec.recipes.generic_narrow_lines(
    ["nev_3427", "neiii_3870"],
    id="my_narrow_complex",
    label="My narrow complex",
    fit_window=(3350.0, 3950.0),
    fit_windows=((3350.0, 3950.0),),
    qa_labels=("nev_3427", "neiii_3870"),
)

result = qsospec.fit_global_lines(
    spectrum,
    complexes=[custom],
)

For full control, construct immutable qsospec.ComponentRecipe and qsospec.ComplexRecipe objects. Define component roles, multiplicity, velocity/FWHM bounds, required lines, coverage mode, fit windows, and backend.

Common failures

• Unknown line ID: inspect qsospec.lines.list().

• Complex skipped: check total window coverage, valid pixels, edge margins, and required line centers.

• Component disabled: component-adaptive recipes retain only covered lines.

Next: Recipe reference and Configuration API.