Construction runs on documents: tender packs, permit applications, site surveys, BIM exports, and drawing sets at A0 and larger. This pipeline processes 100,000 of them every month, and after a year in production I can tell you the thing most people get wrong about systems like this: the hard part is not the PDFs. What actually breaks at scale is everything around them: orchestration under load, retries that silently double your costs, one corrupt file poisoning a batch, and third-party services failing at the worst moment.

The pipeline is built around one principle: one run per document. Every document moves through the system independently, is traceable end to end, and fails alone. A malformed file, a scanned page that needs OCR, an oversized A0 drawing that has to be tiled before processing: each is handled by its own stage in a waterfall, and a failure is isolated, logged, and retried without touching the other 99,999. At volume, failure modes are not edge cases. They are Tuesday.