Reports

read, read_all, write and convert return a Report of everything they decided:

• choices: what a policy or the data decided (nifti_form = sform (code 1), geometry = reused from source (unchanged), ...);
• warnings: things that are probably fine but worth knowing (qform and sform disagree, a header of another format is not written, ...);
• dropped: what the target format cannot store and was left out.

image.meta.user = {"study": "A"}
report = medvol.write(image, "out.nii.gz")
print(report)

write nifti out.nii.gz
  choice: geometry = reused from source (unchanged)
  dropped: user: the format has no place for arbitrary metadata

With on_loss="error", a drop raises medvol.LossError instead, before anything is written:

try:
    medvol.write(image, "out.nii.gz", on_loss="error")
except medvol.LossError as error:
    print(error)            # user: the format has no place for arbitrary metadata

Reading also appends the report to the image's history (action: converted, the tool and version, the choices as settings, warnings and drops as warnings), so a .mla file records how it was made:

image.meta.history[-1]
# {'action': 'converted', 'tool': 'medvol 1.0.0', 'from': 'nifti',
#  'settings': {'nifti_form': 'sform (code 1)'}, 'time': '2026-11-06T12:29:50Z'}

The CLI prints the report of every conversion.