Pattern 4 — Guardrails as Context Hygiene (shadow vs enforce)

snippet11_guardrails_demo.py

import re

def run_guardrails_demo(prompt: str, shadow: bool = True) -> None:
    """Pattern 4: Guardrails as Context Hygiene"""
    print(f"\nInput: {prompt!r}")
    print(f"Mode: {'Shadow (logging only)' if shadow else 'Enforcement'}")
    if shadow:
        print("Shadow mode: logging only (no enforcement).")
        print(f"Response: {prompt}")
        print("(Would log to monitoring system: PII pattern detected)")
    else:
        redacted = re.sub(r"\b\d{3}-\d{2}-\d{4}\b", "<REDACTED-SSN>", prompt)
        print(f"Enforced response: {redacted}")
        if redacted != prompt:
            print("(PII detected and redacted)")