Advanced AI Prompt for Multi-tenant SaaS Isolation Patterns

Act as a SaaS Architecture Specialist. Design an airtight multi-tenant data isolation strategy for an enterprise application utilizing API Gateway and DynamoDB, strictly enforcing the [ISOLATION_MODEL] (e.g., Bridge, Silo, or Pool model). Assuming a scale of [TENANT_COUNT], explicitly explain how to implement Fine-Grained Access Control (FGAC) by marrying IAM policy conditions with DynamoDB LeadingKeys. Detail the authorization flow where API Gateway Custom Authorizers extract tenant IDs from validated JWT claims and securely inject them into the backend execution context. Rigorously address [COMPLIANCE_NEEDS] by outlining the strategy for data residency and field-level encryption utilizing tenant-specific AWS KMS Customer Managed Keys.