ArchUnit-style Rules API (Python, Code-first)

[akhundMurad]

Defining architecture rules purely via configuration files becomes hard to maintain as complexity grows.

Many users want to express architecture constraints as code, similar to ArchUnit in the Java ecosystem:

• with IDE autocomplete
• reusable rule definitions
• composable logic

This issue proposes introducing a Python-based rules API, allowing users to write architecture rules in code instead of YAML.

Example (conceptual)

from pacta import rule

@rule
def domain_must_not_depend_on_infrastructure(dep):
    return not dep.from_layer("domain").to_layer("infrastructure")

Why this matters

• Improves developer experience
• Enables reuse and abstraction of rules
• Makes complex rules easier to express and test

Acceptance Criteria

• Users can define rules in Python
• Rules integrate with existing Pacta CLI and CI workflow
• Clear mapping between rule failures and architecture elements
• YAML-based rules remain supported

Out of scope

• Plugin marketplace
• Enterprise rule packs