/hindsight-docs

Memory Defense

Hindsight scrubs secrets and PII from retain content using a 45-pattern regex set. Each match is replaced with a [REDACTED:type] marker before content reaches memory units or the document body. The feature is configured per bank and disabled by default.

How it works

Memory Defense is opt-in per bank. The extension is always present, but it sits dormant until you give a bank a policy that turns it on. When a policy is set, every memory the agent writes to that bank is scanned before it lands in storage. When the scanner recognizes a credential, an API key, a database connection string, or a known PII format, the matched substring is replaced with a redaction marker like [REDACTED:github_token].

The scrubbed version is what actually gets stored. Memory units and document bodies persist the redacted text, so future recall responses, exports, and reflect operations never see the original secret.

A policy only affects future retain calls on the bank where it is set. Existing memories are not retroactively scanned when you add or change a policy.

Configuring Memory Defense

Memory Defense is configured per bank via the bank's memory_defense config field. You can set the policy at bank creation time or update it later via PATCH /v1/{tenant}/banks/{bank_id}/config.

The open-source version implements the sensitive_data rule with two possible actions:

• redact — replace each matched secret with a [REDACTED:type] marker and store the scrubbed memory.
• block — drop any item that contains a match. If every item in a retain request is blocked, the call returns 422.

A minimal policy:

{
  "memory_defense": {
    "enabled": true,
    "rules": [
      { "on": "sensitive_data", "action": "redact" }
    ]
  }
}

Once that policy is on a bank, every retain to that bank is screened with the 45 redaction patterns documented below.

:::note Existing memories are not retroactively scanned Enabling Memory Defense on a bank only affects future retain calls. Memories already in the bank are not re-scanned or modified when you add or change a policy. If you need to scrub a bank that already contains unredacted content, you have to re-ingest the affected memories or remove them manually. :::

Disabled by default

Memory Defense is off on every bank until you set a policy. A bank with no memory_defense field, with enabled: false, or with no sensitive_data rule is treated identically: the extension returns ALLOW and content passes through unchanged. To stop redacting on a bank that has it on, set enabled: false or remove the policy.

Notifications

When an item is redacted or blocked, Hindsight fires a memory_defense.triggered webhook if a webhook on the bank is subscribed to that event type. The payload reports the action taken, the document ID, and which redaction patterns matched — useful for routing security alerts to a SIEM or Slack. Clean items fire no event.

The same redact/block decisions are also recorded as memory_defense entries in the audit log (when audit logging is enabled), with the action and matched pattern labels in the entry metadata.

Patterns covered

The 45 bundled patterns cover the categories below.

AI and LLM providers

Cloud providers

Source control and CI

Payment processors

Communications and email

Commerce

Database connection strings

Private keys, JWTs, and generic credentials

PII (US defaults)