# Layered Architecture

> A convention of stacking presentation, application and persistence layers, each calling only the layer below it.

Record: `architecture:layered-architecture`
Kind: style
Layer: [Structural Core](https://banes-lab.com/records/layer/structural-core.md)
Severity: contextual
Scope: application, system
Canonical: https://banes-lab.com/ontology#architecture-layered-architecture

Listed in [Architecture principles](https://banes-lab.com/api/records/architecture.md), after [Clean Architecture](https://banes-lab.com/records/architecture/clean-architecture.md) and before [Component-Based Architecture](https://banes-lab.com/records/architecture/component-based-architecture.md).

## Repair

- Refactored by: Move Logic, Introduce Service/Repository Boundary
- Detected by: forbidden layer imports
- Violated by: presentation accessing persistence directly
- Measured by: layer violation count
- Enforced by: layer rules

## Requires

- [Layer Separation](https://banes-lab.com/records/lexicon/layer-separation.md)

## Reinforces

- [Separation of Concerns](https://banes-lab.com/records/architecture/separation-of-concerns.md)

## Enables

- [Structured Code Organization](https://banes-lab.com/records/lexicon/structured-code-organization.md)

## Conflicts with

- [Layer Skipping](https://banes-lab.com/records/lexicon/layer-skipping.md)

## In tension with

- [Anemic Layers](https://banes-lab.com/records/lexicon/anemic-layers.md)

## Tensions

- [Layered Architecture / Anemic Layers](https://banes-lab.com/records/tension/anemic-layers-layered-architecture.md)

## Severity

- [contextual](https://banes-lab.com/records/vocabulary/severity-contextual.md)

## Category

- [Codebase / System Architecture Styles](https://banes-lab.com/records/architecture-category/codebase-system-architecture-styles.md)

## Enforced by

- [rules/eslint/closure-no-cross-subsystem-import.eslint.rule.ts](https://banes-lab.com/source/governance/rules/eslint/closure-no-cross-subsystem-import.eslint.rule.ts.md)
- [rules/eslint/closure-no-type-layer-drift.eslint.rule.ts](https://banes-lab.com/source/governance/rules/eslint/closure-no-type-layer-drift.eslint.rule.ts.md)
- [rules/eslint/closure-no-undeclared-type-layer.eslint.rule.ts](https://banes-lab.com/source/governance/rules/eslint/closure-no-undeclared-type-layer.eslint.rule.ts.md)

## Linked from

- [The layer spine](https://banes-lab.com/software-architecture/model/the-layer-spine.md)
- [The direction axis](https://banes-lab.com/software-architecture/model/the-direction-axis.md)
- [Core Modular Design](https://banes-lab.com/ontology/principles/architecture-category-core-modular-design.md)
- [Codebase / System Architecture Styles](https://banes-lab.com/ontology/lexicon/lexicon-category-codebase-system-architecture-styles.md)
- [Severity levels](https://banes-lab.com/ontology/schema/the-vocabulary-severity.md)
- [The resolutions](https://banes-lab.com/ontology/schema/the-resolutions.md)