What a per-file extractor is handed. Readers are lazy so a snippet pays only for what it opens.
Just the file name, e.g. sheet.msg.json.
sheet.msg.json
Path relative to the <kind>/<pkg>/ root, e.g. de/sheet.msg.json.
<kind>/<pkg>/
de/sheet.msg.json
What a per-file extractor is handed. Readers are lazy so a snippet pays only for what it opens.