> ## Documentation Index
> Fetch the complete documentation index at: https://docs.klio.tech/llms.txt
> Use this file to discover all available pages before exploring further.

# What Klio keeps

> What belongs in a shared workplace, what is stripped before it is written, and what is retired once it stops being true.

A memory layer is defined as much by what it refuses to keep as by what it
stores. This page is the honest version of both.

## Keep vs. never keep

<Columns cols={2}>
  <Card title="Worth keeping" icon="check">
    * **Decisions** — what was chosen, and why
    * **Repo rules** — conventions the work must hold to
    * **Plans** — the shape of work in flight
    * **Durable facts** about the project or the people on it
  </Card>

  <Card title="Never stored" icon="ban">
    * **Secrets** — keys, tokens, credentials
    * **Personal data** — redacted before write
    * **Transcripts, tool calls, file contents**
    * **Anything a newer decision has retired**
  </Card>
</Columns>

The test for whether something belongs: *would the next agent be worse off
without it?* A decision passes. A log line of a file being read does not.

## Redaction fails closed

Secrets and personal data are stripped **before** anything is persisted — not
on the way out. If content cannot be made safe, the write is rejected rather
than stored in a degraded form.

<Warning>
  This is a backstop, not a licence. Redaction is pattern-based, and no
  pattern set catches everything. Do not deliberately route credentials or
  customer PII through memory tools on the assumption that they will be caught.
  Prompt your agents not to send them in the first place.
</Warning>

## Superseding

When a newer memory contradicts an older one, the older one is superseded and
stops surfacing in recall. The chain is retained — the history of what was
believed when is not deleted — but only current truth comes back from a query.

This is what keeps recall sharp over months. Without it, a store accumulates
contradictions and the agent picks between them arbitrarily.

To retract something explicitly rather than waiting for it to be contradicted,
use [`forget`](/tools/forget) with the memory id from a prior recall.

## Deduplication

Near-identical writes are collapsed rather than stored twice. Agents are
repetitive by nature — several of them working the same project will write the
same conclusion in slightly different words, and without dedup the store fills
with paraphrases of a single fact.

<Note>
  Dedup is similarity-based, so it is a judgement call rather than an exact
  match. Two genuinely distinct facts phrased almost identically can be
  collapsed. If you need both, make the wording meaningfully different or scope
  them to different [spaces](/concepts/scope).
</Note>

## Where it physically lives

<Tabs>
  <Tab title="Klio Cloud">
    Memory lives on Klio's infrastructure, encrypted in transit and at rest at
    the infrastructure level, isolated per org. Secrets and PII are redacted
    before storage.

    The encryption keys are ours, and Cloud writes are not hash-chained. If your
    threat model requires keys you hold, self-host.
  </Tab>

  <Tab title="Self-hosted">
    Memory lives in your own Postgres, on your own hardware. It is encrypted at
    rest under a key **you** own, and every write is chained with SHA-256 so the
    history is tamper-evident and independently inspectable.

    Nothing leaves your estate. See [Self-hosting](/self-host/install).
  </Tab>
</Tabs>

<Info>
  The user-held key and the hash chain are properties of the **self-hosted**
  engine specifically. Anywhere you see those claims, they refer to self-hosting
  — Klio Cloud makes the weaker guarantees described above.
</Info>