Convert raising 'xlsx' type is not supported.

[MatheusAbdias]

Bug

The _guess_format method in _DocumentConversionInput class is incorrectly identifying XLSX files as "application/zip" format.

Steps to Reproduce

1. Create an instance of DoclingConvert with XLSX support:

converter = DoclingConvert(allowed_formats=[InputFormat.XLSX])
result = converter.convert(path)
result.document.save_as_markdown(Path("./output.md"))

The _guess_format method in _DocumentConversionInput is returning "application/zip"

class _DocumentConversionInput):
    def _guess_format(self, obj: Path | DocumentStream) -> InputFormat | None: ...

Inside the _guess_format filetype.guess_mime is returning application/zip.
...

Docling version

ocling version: 2.24.0
Docling Core version: 2.20.0
Docling IBM Models version: 3.4.0
Docling Parse version: 3.4.0
Python: cpython-312 (3.12.8)
Platform: Linux-6.6.75-2-MANJARO-x86_64-with-glibc2.41
...

Python version

Python 3.12.8
...

[MatheusAbdias]

While investigating this issue, I found the python-magic library which correctly identifies the XLSX file type. I've tested it with the same file and it returns the proper mime type. However, this solution requires installing libmagic as a system dependency. Would it be acceptable to add this dependency to the project?

[cau-git]

@MatheusAbdias Thanks for your suggestion. This comes back to #802, where we track this issue more broadly.

We want to avoid working with libmagic since it is under GPL-license, hence we cannot distribute it. We try to avoid system library dependencies that we cannot bundle.