class FacadeDriverGateway:
    def __init__(self, redis_cache: RedisClient, presidio_engine: AnonymizerEngine):
        self.cache = redis_cache
        self.anonymizer = presidio_engine
        self.model_pool = AsyncWorkerPool(max_workers=64)
        
    async def execute_clinical_prompt(self, patient_id: str, graph_context: GraphContext, prompt: str) -> ClinicalResponse:
        # 1. In-Flight Presidio PII Redaction
        sanitized_prompt = self.anonymizer.anonymize(prompt, entities=HEALTHCARE_ENTITIES_12)
        
        # 2. Redis Semantic Cache Check
        cache_key = self.generate_embedding_hash(sanitized_prompt, graph_context.rules_hash)
        if cached := await self.cache.get(cache_key):
            return ClinicalResponse.from_cache(cached)
            
        # 3. Dynamic Model Routing & Execution
        response = await self.model_pool.dispatch_async(sanitized_prompt, context=graph_context)
        
        # 4. Deterministic Schema & Boundary Validation
        assert ClinicalGuardrails.validate_safety_boundaries(response), "Clinical boundary violation"
        await self.cache.set(cache_key, response, ttl=86400)
        return response

class Part11AuditLogger:
    def __init__(self, db_session: AsyncSession, hmac_key: bytes):
        self.db = db_session
        self.hmac_key = hmac_key
        
    async def log_clinical_event(self, patient_id: str, event_type: str, old_val: dict, new_val: dict, actor: str):
        timestamp = datetime.now(timezone.utc)
        payload = json.dumps({"patient_id": patient_id, "old": old_val, "new": new_val, "ts": timestamp.isoformat()})
        
        # Cryptographic SHA-256 HMAC Signature for Tamper Evidence
        signature = hmac.new(self.hmac_key, payload.encode('utf-8'), hashlib.sha256).hexdigest()
        
        audit_record = AuditLog(
            patient_id=patient_id,
            action=event_type,
            old_value=old_val,
            new_value=new_val,
            performed_by=actor,
            performed_at=timestamp,
            hmac_signature=signature
        )
        self.db.add(audit_record)
        await self.db.commit()