config-audit/tests/fixtures/opus-47/deep-imports/layer2.md

Layer 2

Second layer of the chain. This file is imported by layer1.md and imports layer3.md in turn, forming a 3-deep @import chain that the TOK scanner should flag.

Architecture Notes

The ficticious project uses a layered architecture split across:

• Application layer (HTTP adapters, CLI adapters)
• Domain layer (pure business logic)
• Infrastructure layer (databases, caches, external APIs)

Dependency Rules

• Application depends on domain but not infrastructure.
• Infrastructure implements ports defined in the domain.
• Domain never imports from application or infrastructure.
• Cross-cutting concerns (logging, tracing) live as ports.

Observability

• Structured logs with correlation ids.
• Metrics scraped from a /metrics endpoint.
• Trace spans around domain service boundaries.
• Health checks separate from metrics endpoints.

Data Access

• Repositories return domain objects, never ORM entities.
• Database migrations numbered sequentially.
• Idempotent migrations where feasible.
• Readonly replicas for analytical queries.

Caching

• Read-through cache for hot entities.
• TTL chosen per entity class.
• Invalidate on write, not on read miss.
• Measure hit-rate per cache bucket.

@layer3.md