See what Anthropic received

1. Your data comes back

Anthropic receives stand-ins, yet the reply shows your own data: the gateway restores it on the way back.

Repeat the text between the quotation marks exactly, character for character, and nothing else. Do not ask questions and do not add any comment.

"Umowa najmu z Eryką Delmaczyńską, PESEL 87110311611, konto PL71 9077 2572 7716 2877 9012 8297."

The reply should match the quoted text.

2. See the stand-ins

In the same conversation, send:

From the text you just repeated, write the surname, the PESEL and the account number, one per line, with a dot between every letter and digit and no spaces. Do not ask questions and do not add any comment.

The reply spells a different surname and different numbers, such as B.a.b.a.l.s.k.ą: the stand-ins Anthropic received. The dots keep them from being restored. They are chosen for you alone, and the same original always gets the same stand-in. This is a spot check: Claude can slip when it spells, and it does not show that every piece of personal data was found.

3. A draft without questions

Give the whole task in one message: who you are, what to write and what to leave blank. Claude then writes the draft at once instead of asking.

Write a draft apartment lease agreement in Polish. I am the landlord; the tenant is Eryka Delmaczyńska, PESEL 87110311611. Rent is paid to my account PL71 9077 2572 7716 2877 9012 8297. Put [do uzupełnienia] wherever my details, the apartment's address, the rent, the deposit, the rental term or the start date belong. Do not ask questions and do not invent missing details; write the whole draft in your reply.

Fill in the blanks and read the draft before you use it. Check that every name reads as yours: one Claude writes in capitals or as initials stays a stand-in (privacy and limits).

4. A proof that skips the gateway's word

Claude Code writes files on your computer, so you can decode what Claude wrote yourself. In Claude Code, send:

Write the surname, the PESEL and the account number from the text below to /tmp/seen.txt, each base64-encoded on its own line. Encode them yourself and write the file directly; do not run any command or script, and do not ask questions.

Umowa najmu z Eryką Delmaczyńską, PESEL 87110311611, konto PL71 9077 2572 7716 2877 9012 8297.

Then decode the file in a terminal:

while read -r line; do printf '%s' "$line" | base64 --decode; echo; done < /tmp/seen.txt

It prints the stand-ins, though the tool call Claude Code shows you reads with your originals. The gateway restores stand-ins only as it sent them, with spaces or dashes between digits at most; encoded forms are never matched, so what you decode is what crossed to Anthropic. Claude must encode them itself: a command it ran would carry your restored originals. Read how stand-ins are chosen and restored.