ADR-0005: A native config format that is a strict superset, and dependency-cruiser's format accepted as is

• Status: Accepted
• Date: 2026-09-20
• Derives from: design.md § Configuration, § The native format, § The rule language, § Where it would be ignored
• Constrains: architecture.md § Configuration and the rule language
• Implemented by: Wave 1 plan, Wave 2 plan

Context

Every one of the 112 .dependency-cruiser.* files found on GitHub must run on day one, and models trained on dependency-cruiser and ArchUnitNET will write those dialects from memory. A renamed key is an adoption tax paid on every repository and every agent turn.

Decision

• Both formats load into one internal model. A file named .dependency-cruiser.{json,yaml,yml,cjs,js,mjs}, or passed with --config-format dependency-cruiser, is read with dependency-cruiser's semantics and needs no conversion.
• The native format (rulebearing.yaml, also .json, .jsonc, .toml) is a strict superset. Every dependency-cruiser key is legal at the same place with the same meaning. The native format adds languages, defines, rules.dependencies / elements / slices / diagrams / ratchets, the layers and independence shorthands, and the rule metadata fix, examples, owner, expires. It renames nothing.
• Element-rule keys are ArchUnitNET's method names in camelCase, one key per predicate or condition, with all, any, not as the combinators.
• config convert is lossless from dependency-cruiser to native and lossy the other way, and says exactly what it dropped. config lint and config expand exist so nothing is hidden.
• The native schema is published with descriptions at the $schema URL.

Consequences

• rb-config carries two front-ends and one model, and the conformance suite runs the dependency-cruiser front-end against the original specs (ADR-0009).
• A predicate a language cannot answer is a validation error, never a silent false (ADR-0014 states the companion rule for edges).

Alternatives considered

• A new, cleaner rule language. Rejected: the design's adoption analysis shows a new dialect is the first place agents go wrong.
• dependency-cruiser's format only. Rejected: it has no place for element, slice, diagram or ratchet rules, nor for fix and examples.