Codebase architecture review: security hardening, cache TTL, and ADRs

[Copilot]

Full codebase review covering security posture, architecture patterns, and operational readiness. Findings documented in ADRs and a detailed review report; critical issues fixed in-place.

Security Hardening

• Nginx: Added Strict-Transport-Security, Content-Security-Policy, and Referrer-Policy headers
• Docker: Both containers now run as non-root users (appuser for backend, nginx for frontend)
• .gitignore: Added target/, .idea/, .env, OS artifacts — was previously minimal

Cache TTL Implementation

CacheConfig was annotated with @EnableCaching but the body was empty — caches never expired. Added Caffeine with explicit TTL:

@Bean
public CacheManager cacheManager() {
    CaffeineCacheManager cacheManager = new CaffeineCacheManager("transactions", "billing");
    cacheManager.setCaffeine(Caffeine.newBuilder()
            .expireAfterWrite(5, TimeUnit.MINUTES)
            .maximumSize(100));
    return cacheManager;
}

Added com.github.ben-manes.caffeine:caffeine dependency and switched spring.cache.type from simple to caffeine.

Documentation

• docs/architecture/ADR-001 — H2 in-memory DB as primary source, migration path to PostgreSQL
• docs/architecture/ADR-002 — BIAN API circuit breaker pattern and fallback strategy
• docs/architecture/ADR-003 — React + TanStack Query + MUI stack rationale
• docs/code-review/2026-02-09-full-codebase-review.md — 3 P1 (fixed), 5 P2 (documented), 4 P3 findings
• frontend/.env.example — Template for required env vars

Open Items (P2, not addressed here)

• No @ControllerAdvice / global error handler — raw stack traces in error responses
• No Spring profiles — H2 console and Swagger UI enabled unconditionally
• CORS origins hardcoded to localhost — needs env-configurable origins for deployment
• Only 2 backend test classes — service layer untested

Original prompt

perform a review of this code base

Custom agent used: Enterprise Architect Reviewer
System architecture review specialist with Well-Architected frameworks, design validation, and scalability analysis for AI and distributed systems, also covers security reviews, gitops guidelines, and responsible AI practices.

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