development-skills

Strict test-driven development state machine with red-green-refactor cycles. Enforces test-first development, meaningful failures, minimum implementations, and full verification. Activates when user requests: 'use a TDD approach', 'start TDD', 'test-drive this'.

Principles for writing effective, maintainable tests. Covers naming conventions, assertion best practices, and comprehensive edge case checklists. Based on BugMagnet by Gojko Adzic. Triggers on: writing any test, 'add tests', test review, test naming, assertion choices, edge case coverage, 'what should I test', test structure decisions.

Quick persona switching. Triggers: 'switch persona', 'switch to X', 'become X'. Lists personas, reads selected file, switches immediately.

This skill should be used when fixing bugs, implementing features, debugging issues, or making code changes. Ensures understanding of code flow before implementation by: (1) Tracing execution path with specific file:line references, (2) Creating lightweight text diagrams showing class.method() flows, (3) Verifying understanding with user. Prevents wasted effort from assumptions or guessing. Triggers when users request: bug fixes, feature implementations, refactoring, TDD cycles, debugging, code analysis.

This skill analyzes code for design quality improvements across 8 dimensions: Naming, Object Calisthenics, Coupling & Cohesion, Immutability, Domain Integrity, Type System, Simplicity, and Performance. Ensures rigorous, evidence-based analysis by: (1) Understanding code flow first via implementation-analysis protocol, (2) Systematically evaluating each dimension with specific criteria, (3) Providing actionable findings with file:line references. Triggers when users request: code analysis, design review, refactoring opportunities, code quality assessment, architecture evaluation.

Object-oriented design principles including object calisthenics, dependency inversion, fail-fast error handling, feature envy detection, and intention-revealing naming. Triggers on: writing new classes or functions, refactoring, code review, 'clean up', method longer than 10 lines, feature envy, primitive obsession, deep nesting.

Professional, skeptical communication style. Never over-enthusiastic, verifies before agreeing, challenges constructively, proposes instead of asking preferences. Expert peer who coaches, not serves. Triggers on: composing responses, agreeing with user, making recommendations, giving feedback.

Use when about to ask the user a factual question, propose a solution, diagnose an error, or choose between approaches. Triggers on: 'Do you have X installed?', 'What version?', 'Is X configured?', 'We should...', 'The fix is...', 'Options: 1...', 'Based on my understanding...', 'I believe X supports...'. Before deciding anything, spin up parallel subagents to WebSearch for current docs, community solutions, framework best practices, and GitHub issues. Your memory is stale — verify everything.

Enforces brevity and signal-over-noise in all outputs. Eliminates verbose explanations, filler phrases, and unnecessary elaboration. Triggers on: every response (governs output length and density when loaded).

Systematic debugging methodology that eliminates guessing and speculation. Add instrumentation to gather specific data that fully explains the problem. Evidence before hypothesis. Observation before solution. Triggers on: debugging, error investigation, 'why is this failing', unexpected behavior, test failures, non-zero exit codes, stack traces.

Comprehensive data visualization skill covering visual execution and technical implementation. Includes perceptual foundations, chart selection, layout algorithms, and library guidance. Triggers on: charts, graphs, dashboards, 'visualize', 'plot', data presentation, D3, Recharts, Victory.

Force honest confidence assessment before claiming conclusions. Triggers on 'root cause identified', 'problem identified', 'complete clarity'. Express confidence as percentage, explain what's stopping 100%, validate assumptions before presenting.

Engage with what the user said before taking action. Triggers on: questions ('?'), feedback ('this is wrong', 'that doesn't look right', 'there are issues'), challenges ('why did you', 'have you considered'), criticism ('this isn't working', 'I don't like'), observations ('I notice', 'it seems like'), naming a skill or concept. STOP and respond to the user's actual words before doing anything.

Creates well-formed tasks following a template that engineers can implement. Triggers on: 'create tasks', 'define work items', 'break this down', creating tasks from PRD, converting requirements into actionable tasks, feature breakdown, sprint planning.

Sets up NX monorepo for TypeScript backend projects optimized for AI-assisted development. Delegates to NX commands where possible, patches configs as last resort. Triggers on: 'set up typescript backend project', 'create backend project', 'initialize typescript backend', 'create monorepo', or when working in an empty project folder.

Enforces code organization using features/ (verticals), platform/ (horizontals), and shell/ (thin wiring). Triggers on: code organization, file structure, where does this belong, new file creation, refactoring.

Design, refactor, analyze, and review code by applying the principles and patterns of tactical domain-driven design. Triggers on: domain modeling, aggregate design, 'entity', 'value object', 'repository', 'bounded context', 'domain event', 'domain service', code touching domain/ directories, rich domain model discussions.

Stops execution and fixes root cause when commands, builds, scripts, or tools fail unexpectedly. Triggers on workaround language: 'directly', 'instead', 'alternatively', 'skip', 'fall back', 'work around', 'isn't working', 'broken', 'manually'. Activates on any unexpected non-zero exit code or process failure.