skill-factory

Nullables — testing technique alternative to using mocking libraries. Use when writing unit tests, when code touches external I/O or state (HTTP, databases, files, clock, random) anywhere in its dependency chain, when making a system testable, or when tests are slow or flaky.

Bash script style guide. Always use when writing bash scripts, shell scripts, or CLI bash tools.

Drive a browser from the terminal with playwright-cli: snapshot the page, then act on elements by ref. Use when automating browser interactions, filling web forms, testing UIs, or driving logged-in web apps from the command line.

Facilitates deep, structured learning of a topic — gathering source material, assessing the learner's gaps, then teaching through guided Socratic sessions. Use when someone wants to genuinely study or be tutored on a subject over time, not get a quick answer.

Creates C4 architecture diagrams for designing, documenting, or understanding software architecture. Use when working through system design, mapping existing codebases, or visualizing structure at any level from system landscape down to code.

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.

Presents a proposed approach in progressive confirmable chunks with recommended decisions and alternatives. Use when aligning on a design, plan, or technical approach before implementation.

Iterative code refactoring through progressive lenses via a worker-reviewer agent team.

Launches agent teams with structured roles and task decomposition. Use when asked to create a team, spawn teammates, or coordinate multiple agents in parallel.

Drive feature development using Outside-In TDD with Hexagonal Architecture. Design emerges through inline code, in-memory fakes, interface extraction, and deferred I/O. Use when building features, writing tests, or structuring backend services. Triggers on: TDD, outside-in, hexagonal, ports and adapters, emergent design, acceptance test, component test, walking skeleton, in-memory fakes, component, contract test, adapter, fast tests, sub-second feedback. Language-agnostic (Go, Rust, Python, TypeScript, Java, C#).

Writes Claude Code status line scripts. Use when creating, customizing, or debugging statusline configurations.

Creates process files - text as code instructions for reliable AI workflows. Use when creating new process files.

Designs systems using Event Modeling.

Iterative refinement through multiple passes. Use when the user asks to 'meditate on', 'distill', 'refine', or 'iterate on' something, or proactively when a problem benefits from multiple passes rather than a single attempt.

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

Applies hexagonal (ports & adapters) architecture. Use when designing application structure, separating domain from infrastructure, creating testable boundaries, or when user mentions ports, adapters, hexagonal, or clean architecture.

Refactoring process. Invoke immediately when user or document mentions refactoring, or proactively when code gets too complex or messy.

Creates Claude Code hooks.

Reference patterns for augmented coding with AI. Use when discussing AI coding patterns, anti-patterns, obstacles, context management, steering AI, or looking up Lexler's patterns collection.

Creates git worktrees for parallel development. Use when creating a git worktree, setting up multiple working directories, or working on features in parallel.

Python package and project management with UV. Use when creating Python scripts, initializing projects, or managing dependencies.

Writes approval tests (snapshot/golden master testing) for Python, JavaScript/TypeScript, or Java. Use when verifying complex output, characterization testing legacy code, testing combinations, or working with .approved/.received files.

Scannable BDD tests written in domain language. Use when doing BDD.