Every business handling its own invoices carries a set of details it would rather not see wandering off: company registration number, VAT number, bank account and sort code. The instinct is to guard them with rules and warnings — tell the AI to be careful, watch the logs, hope for the best. There is a far quieter approach that asks the AI to guard nothing, because it is never trusted with the secret at all.
Think of it as pre-printed stationery. Your letterhead already carries your address and bank details; you don't dictate them to a temp each morning and pray they type them correctly. The sensitive details live on the paper. The helper only fills in the blanks.
The AI system works the same way. It is handed the figures it genuinely needs to reason about — who the client is, what the rate should be, what the numbers add up to. It is never handed the sealed details. Those sit in the template. Once the model has finished its work, a plain, mechanical merge — no AI involved — stamps the finished figures onto the stationery that already carries your bank details.
The consequence is lovely in its bluntness: a value that was never in the AI's briefing cannot leak from it. Not through a cleverly worded document trying to trick the model into reciting your account number, not through an over-eager summary, not through a stray log file, not through a supplier who later retains what they were sent. There is nothing to leak, because the secret was never in the room.
Best of all, it costs nothing. It is a decision, not a purchase — but a decision you must make before you build, because once the secrets and the sums are tangled together, pulling them apart means starting over.
“A value that was never in the AI's briefing cannot leak from it. There is nothing to leak, because the secret was never in the room.