Policy-Aware Service Mesh Architecture for Regulated Financial Platforms: Runtime Enforcement, Event Governance, and Trust Boundary Isolation

Regulated financial platforms increasingly rely on microservices, event-driven workflows, partner APIs, issuer adapters, and distributed data services to support high-volume consumer and enterprise operations. Existing service mesh architectures provide important capabilities such as mutual TLS, traffic routing, service discovery, retries, and observability; however, they do not fully address the compliance requirements of financial systems where service interactions may cross regulatory, data-sensitivity, partner, issuer, or payment-security boundaries. This paper proposes a policy-aware service mesh architecture for regulated financial platforms. The proposed architecture extends the conventional service mesh model with runtime policy enforcement, data-domain classification, trust-boundary isolation, event payload governance, cryptographic audit logging, and policy-versioned evidence generation. Using co-branded credit card platforms as the reference domain, the paper demonstrates how application services, rewards systems, issuer adapters, partner gateways, compliance services, and AI-assisted operational tools can interact through a mesh that enforces Zero Trust, least privilege, data minimization, and auditability by design. The paper contributes a reference architecture that separates policy decisions from business logic while preserving deterministic runtime enforcement and immutable audit reconstruction.