Imagine one brilliant clerk handed a warehouse of boxes and told: read everything, remember everything, then tell me what matters. However brilliant, the answer arrives unverifiable: you can't tell the remembered from the imagined. That is, roughly, what “paste the documents into a chatbot” does, at scale, with your case.
This engine is built on the opposite model: a room full of clerks, each given one small, bounded task: read this one document, pull the dates from this one page, compare these two names. Each comes with defined inputs, defined outputs, and a supervisor's ledger recording every completion. The AI is used the same way a good clerk is: for one task at a time, with its work checked before it's filed.
The pipeline's spine (cataloguing, custody, text, filing) is deterministic: run it twice, get the same answer twice. The AI sits inside that spine as a replaceable part, never as the foundation. Each document's progress is written to the ledger stage by stage, so a run interrupted overnight resumes exactly where it stopped, and only the piece that failed is retried, not the whole matter.
This discipline is why the two things lawyers care about move together. Accuracy: small steps produce checkable claims, and every claim is verified against the source before it's stored. Cost: nothing is re-read, models see only what their one task requires, and there is no monolithic read-the-whole-corpus prompt anywhere in the system.