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The Regex Detect plugin scans user and assistant messages for specified regex patterns and can either reject requests containing matches or redact the matched content.

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Features

  • Flexible Pattern Matching: Configure multiple regex patterns with optional flags
  • Selective Scanning: Choose to scan only the latest message or all messages in the conversation
  • Reject or Redact: Either block requests containing sensitive data or automatically redact it
  • Custom Messages: Define custom rejection messages for different patterns
  • Configurable Redaction: Use static text or character repetition for redaction

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Use Cases

  • Filter sensitive information (emails, phone numbers, credit cards)
  • Enforce content policies by blocking specific patterns
  • Automatically redact PII (Personally Identifiable Information)
  • Prevent prompt injection attacks by detecting suspicious patterns

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Configuration Options

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patterns (required)

Array of pattern objects to scan for. Each pattern object contains:
  • regex (string, required): The regular expression pattern to match
  • flags (string, optional): Regex flags (e.g., ‘gi’ for global case-insensitive). Default: ‘g’
  • rejectMessage (string, optional): Custom message to return when this pattern is matched

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scanAllMessages (boolean)

  • true: Scans all messages in the array
  • false: Only scans the latest message
  • Default: false

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redactMatches (boolean)

  • true: Redacts matched patterns instead of rejecting the request
  • false: Rejects the request if a match is found
  • Default: false

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redactionText (string)

Text to replace redacted patterns with. Default: [REDACTED]

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redactCharacters (string)

If set, replaces each match with this character repeated to match the length of the original text. Overrides redactionText if both are set.

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Example Configurations

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Block Email Addresses

{
  "patterns": [
    {
      "regex": "\\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Z|a-z]{2,}\\b",
      "flags": "gi",
      "rejectMessage": "Email addresses are not allowed in requests"
    }
  ],
  "scanAllMessages": false,
  "redactMatches": false
}

​
Redact Phone Numbers

{
  "patterns": [
    {
      "regex": "\\b\\d{3}[-.]?\\d{3}[-.]?\\d{4}\\b",
      "flags": "g"
    }
  ],
  "scanAllMessages": true,
  "redactMatches": true,
  "redactionText": "[PHONE]"
}

​
Redact Credit Cards with Character Masking

{
  "patterns": [
    {
      "regex": "\\b\\d{4}[\\s-]?\\d{4}[\\s-]?\\d{4}[\\s-]?\\d{4}\\b",
      "flags": "g"
    }
  ],
  "scanAllMessages": true,
  "redactMatches": true,
  "redactCharacters": "*"
}

​
Multiple Patterns

{
  "patterns": [
    {
      "regex": "\\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Z|a-z]{2,}\\b",
      "flags": "gi",
      "rejectMessage": "Email addresses are not allowed"
    },
    {
      "regex": "\\b\\d{3}-\\d{2}-\\d{4}\\b",
      "flags": "g",
      "rejectMessage": "Social Security Numbers are not allowed"
    }
  ],
  "scanAllMessages": false,
  "redactMatches": false
}

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Response Behavior

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When Rejecting (redactMatches: false)

  • Returns reject: true with a rejection reason
  • Uses custom rejectMessage if provided, otherwise a default message
  • No messages are modified

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When Redacting (redactMatches: true)

  • Returns modified messages array with redacted content
  • Original request continues through the pipeline
  • Debug logs indicate how many matches were redacted

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Common Regex Patterns

  • Email: \b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b
  • US Phone: \b\d{3}[-.]?\d{3}[-.]?\d{4}\b
  • Credit Card: \b\d{4}[\s-]?\d{4}[\s-]?\d{4}[\s-]?\d{4}\b
  • SSN: \b\d{3}-\d{2}-\d{4}\b
  • IP Address: \b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b
  • URL: https?://[^\s]+

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Notes

  • Patterns are tested in order; the first match determines the rejection message
  • Invalid regex patterns are logged in debug output but don’t fail the request
  • The ‘g’ (global) flag is recommended for finding all matches
  • When using redactCharacters, the replacement length always matches the original

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Configuration Schema

{
  "type": "object",
  "title": "Regex Detect Configuration",
  "$schema": "http://json-schema.org/draft-07/schema#",
  "required": [
    "patterns"
  ],
  "properties": {
    "patterns": {
      "type": "array",
      "items": {
        "type": "object",
        "required": [
          "regex"
        ],
        "properties": {
          "flags": {
            "type": "string",
            "title": "Regex Flags",
            "default": "g",
            "description": "Optional regex flags (e.g., 'gi' for global case-insensitive)"
          },
          "regex": {
            "type": "string",
            "title": "Regular Expression",
            "description": "The regex pattern to match (e.g., \\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\\.[A-Z|a-z]{2,}\\b for emails)"
          },
          "rejectMessage": {
            "type": "string",
            "title": "Custom Reject Message",
            "description": "Custom message to return when this pattern is matched"
          }
        }
      },
      "title": "Regex Patterns",
      "minItems": 1,
      "description": "List of regex patterns to scan for"
    },
    "redactMatches": {
      "type": "boolean",
      "title": "Redact Matches",
      "default": false,
      "description": "If true, redacts matched patterns instead of rejecting the request"
    },
    "redactionText": {
      "type": "string",
      "title": "Redaction Text",
      "default": "[REDACTED]",
      "description": "Text to replace redacted patterns with"
    },
    "scanAllMessages": {
      "type": "boolean",
      "title": "Scan All Messages",
      "default": false,
      "description": "If true, scans all messages. If false, only scans the latest message"
    },
    "redactCharacters": {
      "type": "string",
      "title": "Redact Characters",
      "description": "If set, replaces each match with this character repeated to match the original length. Overrides redactionText"
    }
  },
  "description": "Configuration for the Regex Detect plugin"
}
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