praxis

Applies Domain-Driven Design with hexagonal (ports & adapters) architecture. Use when designing backend application structure, separating domain from infrastructure, creating testable boundaries, or when user mentions DDD, ports, adapters, hexagonal, or clean architecture.

Designs systems using Event Modeling.

Implement code with TDD following a deterministic state machine (understand → scout → architecture → tdd → simplify → test_quality → complexity → commit). Driven by issues in plan.md.

Design before code. Runs the Discovery state machine (clarify → model → architecture → slice) to produce issues in plan.md. Use when designing a new project, feature, or system.

Applies feature-based architecture for React frontends. Use when designing frontend structure, organizing components, hooks, and features, or when user mentions frontend architecture, React structure, or feature-based design.

Test-driven development (TDD) process used when writing code. Use whenever you are adding any new code, unless the user explicitly asks to skip TDD or the code is exploratory/spike.

Reviews technical proposals against 30 complexity dimensions. Questions necessity of scale, consistency, and resilience. Use when proposing technologies (Kafka, microservices, event sourcing) or designing systems. Pushes for simplest viable approach.

Simplifies and refines code for clarity, readability, and maintainability. Reduces complexity without changing behavior. Use when simplifying, cleaning up, or reducing complexity in code.

Designs software features collaboratively through visual scenarios and iterative refinement. Use when designing features, workflows, or any system before implementation.

Reviews Dockerfiles for build performance, image size, and security issues. Use when optimizing, validating, or improving Dockerfiles.

Zero-downtime pattern for breaking changes. Use when renaming DB columns, changing data types, replacing services/libraries, or modifying public APIs. Applies expand-contract to maintain backward compatibility throughout the migration.

Analyze and improve test code quality using Kent Beck's Test Desiderata framework. Use when analyzing test files, reviewing test code, identifying test quality issues, suggesting test improvements, or when asked to evaluate tests against best practices. Applies to unit tests, integration tests, and any automated test code.

Applies Kent Beck's Thinkies—pattern-based thinking habits that generate ideas. Use when stuck, exploring alternatives, or reframing decisions.