Worked on the DS4SD/docling repository to improve the reliability of MS Excel file ingestion by addressing the handling of invisible sheets. Using Python and backend development skills, implemented logic to set the content layer to INVISIBLE for hidden sheets, ensuring that only visible data is processed during file parsing. This adjustment prevents erroneous data extraction and aligns the workflow with user expectations for Excel handling. Updated the test suite to cover this scenario, reducing the risk of regression and supporting robust file processing. The work delivered a targeted bug fix that enhances data integrity for downstream analytics and document ingestion pipelines.