alt Hacker NewsI gave a blanket ban on pdftotext to my agents. The output can get so mangled that a smart human wouldn’t untangle it. Did you try understanding the output from pdftotext yourself?
My approach is just ocr-ing with Terra or Gemini flash + checking citations with source both ways. But if I wanted to avoid llm calls, I’d just tell Fable to build a pdf reader directly from pdf binary format. Should be way more robust.
A PDF is a command stream designed for rendering. Interpreting the command stream to get the positions of each glyph is deterministic and existing libraries (I use both pdf_oxide and lopdf) do that fine. Once you have glyph positions, you need to use various heuristics to reconstruct words, paragraphs, columns, headers and footers, etc. For example, in a patent document, there's two columns with a gutter in the middle of line numbers. If you interpret the document as having a single line, you'll get numbers mixed up with the text, which can throw off efforts to find particular phrases. PDF builders also insert all sorts of weird crap into the OCR layers that has to get normalized out.
It's just a pretty pedestrian data-munging problem where there's no closed form perfect solution and you have to use various heuristics to get the right result.