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ADR 001: Architectural baseline and Clean Architecture principles

Status

Partially superseded — see the note below. The generic content (SRP, DIP, YAGNI) remains as guidance; the compiler architecture decisions live in docs/architecture/overview.md + docs/crates/crate-contracts.md.

Supersession note (2026-09-20, docs audit): this ADR was written as boilerplate (it mentions DTOs, persistence, drivers, "classes") and does not describe the real architecture — a frontend → Core IR → two backends pipeline, with no database, no web frameworks, no classes (Rust). Nothing here was deleted; where this document conflicts with overview.md/crate-contracts, those win (see docs/language/authority-map.md: architecture contracts take precedence as the source of the implemented state).

Context

The project requires high maintainability, strict isolation of business rules from frameworks and external dependencies, and support for unit and integration tests without heavy infrastructure dependencies.

Decision

We adopt Clean Architecture (Ports and Adapters). All dependencies must point toward the core domain. Communication with external infrastructure must occur exclusively through port interfaces.

Consequences

• Positive: Complete in-memory testability; easy replacement of persistence drivers; framework independence.
• Negative: Introduction of intermediate data-mapping layers (DTOs and entities).