Privacy

Privacy Policy

Last updated · 2026-09-20

Most privacy policies are a list of promises. This one is mostly a description of an architecture, because for the things that matter Tansu is built so that we cannot read your data rather than merely undertaking not to.

Who we are

Tansu is operated by Zeroth World Ventures LLC. This policy covers the Tansu website (tansu.xyz) and the Tansu application (app.tansu.xyz). Questions: privacy@tansu.xyz.

What we cannot see

Everything you keep in Tansu — passwords, documents, images, notes, and the titles you give them — is encrypted on your own device before it leaves. The key is derived from your passkey and, if you set one, your recovery phrase. Neither ever reaches our servers.

What our servers hold is ciphertext we have no key for. We cannot sort it, search it, or say what any of it is. If we were compelled to hand over everything we have about you, that is what would be handed over.

This has a cost, and you should know it before you store anything. If you lose your passkey and never set a recovery phrase, your data cannot be recovered — not by you, and not by us. There is no support process that can reset it. A member of staff who could let you back in could also let themselves in, and for as long as that door exists the sentence above is false.

What we do hold

An account identifier we generate. It is a random string and says nothing about you.
Your passkey's public key. By definition public: it can verify a signature but cannot produce one.
If you sign in with Google or Apple: the provider's immutable identifier for you (sub). We key your account on that rather than on your email address, because an address can change hands. We do not store your email address.
Wrapped key material — two encrypted blobs we cannot open. We hold them so that a new device can get your account back.
An audit log of what was done on your behalf: which task, which account, when, and whether you approved it. Entries sit on a hash chain your own device verifies, so we cannot remove one without it showing.
If you enable notifications: a push subscription endpoint. Notification contents are encrypted end-to-end; the push provider sees only that something needs you.

Some of the above is more than we would like. We keep a written list of every field we store in the clear and what it would take to stop storing it, and we work through it. Where a field is still there, it is because something the product does today needs it — not because nobody looked.

Signing in with Google or Apple

We request only openid and email. That tells us which account you are and nothing else — no access to your mail, files, contacts, or anything else in that account.

A provider sign-in answers who you are. It is not the key. Signing in with Google does not open anything you have stored: the encryption key is still derived from your passkey and your recovery phrase, and Google is party to neither. Google Workspace API data is never requested, received, used, or transferred.

When an agent acts for you

A task you approve produces a permission with a boundary: named accounts, named sites, an action list, a spending limit, an expiry, and revocation at any time. The agent runs in a hardware-isolated environment whose identity your device verifies before any key is released, and that environment is destroyed when the task ends.

The model driving that agent never receives your credentials in the clear. Decryption happens inside the isolated environment, and what the model sees are placeholders.

This website and your approximate location

The public website (tansu.xyz) tailors its examples to where you are: a restaurant near you, your home team, your local currency. To do that it reads the approximate location our hosting provider attaches to every request — worked out from your connection’s IP address — and looks up the nearest large city. We do not store or log that lookup, we do not send it to anyone else, and it is never tied to an account (there are no accounts on the public website). Our hosting provider sees your request, as it does for any web page. This happens on the public website only, not inside the app.

The site sets no cookies.

Who else is involved

Hosting and DNS — providers who carry ciphertext they have no key for.
Confidential inference — when a task needs a model, it runs inside an attested hardware-isolated environment. What that does and does not prove is written down in our public documentation rather than summarised here.
Sign-in providers — Google and Apple, if you choose to use them.

We do not sell data, and we do not run advertising. That is not only a promise; it is why the agent can work for one side. An agent paid by a merchant is a salesperson.

Your choices

Export everything. The app has an endpoint that returns everything we hold about you — not a curated view. A privacy claim nobody can check is a slogan.
Delete anything, or everything. Deleting an item removes the ciphertext. Deleting your account removes all of it.
Stop everything at once. One control voids every permission in force and destroys the environments running under them.
Depending on where you live, you may also have rights of access, correction, portability, and erasure. Write to privacy@tansu.xyz and we will act within 30 days.

Retention

Ciphertext is kept until you delete it or close your account. Audit entries are kept for as long as the account exists, because an audit log you can be talked out of is not an audit log. Everything is removed within 30 days of account closure.

Children

Tansu is not for anyone under 18, and we do not knowingly hold data belonging to a child.

Changes

If we change this policy in a way that affects what we can see, we will say so in the app before the change takes effect — not in a footer.