Built a document processing system in Make.com to handle email attachments end-to-end. Extracts text via PDF.co, processes with OpenAI, and outputs structured JSON. Fixed key failure points: proper binary handling (no .dat issues), AI inside iterator for 1:1 mapping, strict JSON schema, automated file renaming, and organized Google Drive storage. Added logging and fallback paths to prevent silent errors. Result: stable, scalable automation with zero manual handling.