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

# PII Guard

> PII anonymization middleware for agent messages

# PII Anonymization

The `PiiGuard` scrubs personally identifiable information from messages before they reach the LLM, preventing accidental PII exposure in model interactions.

## Configuration

```typescript theme={null}
import { PiiGuard } from "@agentium/core";

const guard = new PiiGuard({
  builtIn: ["email", "phone", "ssn", "creditCard"],
  action: "placeholder", // "redact" | "hash" | "placeholder"
  rehydrate: true,       // restore PII in final output
});
```

## Built-in PII Types

| Type         | Pattern                                       |
| ------------ | --------------------------------------------- |
| `email`      | Standard email addresses                      |
| `phone`      | US phone numbers (with optional country code) |
| `ssn`        | Social Security Numbers (XXX-XX-XXXX)         |
| `creditCard` | Credit card numbers (XXXX-XXXX-XXXX-XXXX)     |
| `ipAddress`  | IPv4 addresses                                |
| `name`       | Two-word proper names (Capitalized)           |

## Actions

| Action        | Example Input      | Example Output    |
| ------------- | ------------------ | ----------------- |
| `placeholder` | `john@example.com` | `[EMAIL_1]`       |
| `redact`      | `john@example.com` | `[REDACTED]`      |
| `hash`        | `john@example.com` | `[HASH_a1b2c3d4]` |

## Integration

### As a beforeLLMCall hook (scrubs every roundtrip)

```typescript theme={null}
const agent = new Agent({
  name: "safe-bot",
  model: openai("gpt-4o"),
  loopHooks: {
    beforeLLMCall: guard.toBeforeLLMCallHook(),
    afterToolExec: guard.toAfterToolExecHook(),
  },
});
```

### As an Input Guardrail

```typescript theme={null}
const agent = new Agent({
  name: "safe-bot",
  model: openai("gpt-4o"),
  guardrails: {
    input: [guard.toInputGuardrail()],
  },
});
```

### Custom Patterns

```typescript theme={null}
const guard = new PiiGuard({
  patterns: [
    { name: "employee_id", regex: /EMP-\d{6}/g },
    { name: "project_code", regex: /PRJ-[A-Z]{3}-\d{4}/g },
  ],
  action: "placeholder",
});
```

## Rehydration

When `rehydrate: true`, the guard maintains a mapping of placeholders to original values. Call `guard.rehydrate(text)` on the final output to restore PII before returning to the user.