Free-form metadata object. A multipart/form-data request sends it as a JSON-encoded string. A write replaces the whole object: only the pitcher namespace and aiAnalysis are kept when the payload leaves them out, so send back every other key you want to keep. That includes pptx_data, the PPTX's extracted slide data, which a conversion needs: once a write drops it, turning conversion on is refused. PPTX-to-Sections conversion is controlled by three keys that work as a set: pitcher_auto_convert_to_sections: true is the only one that starts a conversion, either on an upload that carries PPTX content, or when a later metadata write turns it on for a viewable PPTX (the write keeps the file's extracted pptx_data, and is refused with the reason when the file cannot be converted yet). pitcher_auto_convert_include_sections (name the section groups after the PPTX's own sections) and pitcher_auto_convert_use_scribble_pdfjs only shape that conversion and do nothing on their own. Progress is reported in pitcher_sections_conversion_status.