feat: add PII detection middleware to community packages

[code-xpertai]

Summary

Adds a PII (Personally Identifiable Information) detection and redaction middleware to the community packages. This middleware helps protect user privacy by detecting and redacting sensitive information in agent messages.

Features

• Multiple built-in detectors: SSN (US Social Security Numbers), email addresses, phone numbers, and credit card numbers
• Custom detector support: Users can provide their own detection logic for specialized PII patterns
• Flexible redaction strategies: hash (base64 hash), mask (character replacement), remove (delete), replace (custom text)
• Configurable options: Control masking characters, replacement text, and length preservation
• Real-time processing: Redacts PII from both user input and model output
• Privacy by design: Helps agents comply with privacy regulations and data protection standards

Implementation Details

• Follows the same patterns as the existing tool-call-limit middleware
• Uses @xpert-ai/plugin-sdk and @nestjs/common for integration
• Supports both built-in and custom detector functions
• Includes comprehensive documentation and usage examples

Usage Example

// Custom detector function (similar to LangChain example)
function detectSSN(content: string): PIIMatch[] {
  const matches: PIIMatch[] = [];
  const pattern = /\d{3}-\d{2}-\d{4}/g;
  let match: RegExpExecArray | null;

  while ((match = pattern.exec(content)) !== null) {
    const ssn = match[0];
    const firstThree = parseInt(ssn.substring(0, 3), 10);
    if (firstThree !== 0 && firstThree !== 666 && !(firstThree >= 900 && firstThree <= 999)) {
      matches.push({
        text: ssn,
        start: match.index ?? 0,
        end: (match.index ?? 0) + ssn.length,
      });
    }
  }
  return matches;
}

// In agent configuration
{
  "type": "PiiMiddleware",
  "options": {
    "detector": detectSSN,
    "strategy": "hash"
  }
}

Files Added

• community/middlewares/pii/ - Complete PII middleware package
  • src/index.ts - Plugin entry point
  • src/lib/pii.ts - Core middleware implementation
  • src/lib/pii.module.ts - NestJS module
  • src/lib/types.ts - Type definitions
  • package.json - Package configuration
  • README.md - Comprehensive documentation
  • tsconfig.json - TypeScript configuration

Testing

• TypeScript compilation successful
• Follows existing middleware patterns
• Ready for integration testing with Xpert AI agents

Dependencies

• Peer dependencies match existing middleware patterns
• No breaking changes to existing codebase
• Compatible with current Xpert AI plugin system