mk:development — Development Toolkit

What This Skill Does

Provides reference guides for implementing features: stack-specific code patterns with anti-patterns, opt-in TDD enforcement rules, and a skill lazy-loading system that loads only domain-relevant references.

TDD enforcement is OPT-IN. Default mode (TDD off) skips RED-phase enforcement — use this for prototypes and exploration. Opt into --tdd or MEOWKIT_TDD=1 when shipping production-quality work.

When to Use

• Phase 3 (Build): Implementation guidance and coding standards.
• When the developer agent needs stack-specific patterns.
• Phase 2 (Test): TDD enforcement rules (TDD mode only).

Core Capabilities

Stack-Specific Code Patterns (references/code-patterns.md)

NestJS:

• Module/Controller/Service/DTO: Every feature. Controllers handle HTTP, services handle logic. Anti-pattern: business logic in controllers.
• Guard Usage: @UseGuards(AuthGuard, RolesGuard) on every protected controller. Anti-pattern: relying on middleware alone.
• Pipe Validation: @Body(ValidationPipe) on every input endpoint. Anti-pattern: manual validation in services.
• DTO with Validation: @IsString, @IsNotEmpty, @IsOptional decorators on every DTO. Anti-pattern: raw any types.

Vue 3:

• Composition API with Script Setup: <script setup lang="ts"> with ref, computed. Anti-pattern: Options API in new code, mixing APIs.
• Pinia Store: defineStore with composable-style setup. Anti-pattern: Vuex in new code, local-only state in Pinia.
• Composables: Reusable stateful logic via useX() functions. Anti-pattern: duplicating reactive logic, creating composables for non-reusable logic.

Swift:

• MVVM: ObservableObject ViewModel per screen. Anti-pattern: networking/business logic in Views.
• Async-Await / Combine: async throws for I/O. Anti-pattern: nested completion handlers, blocking main thread.
• Protocol-Oriented Design: Protocol for every service dependency. Anti-pattern: concrete class dependencies preventing testing.

General Rules (all stacks): No any types (unknown + narrow), explicit return types on public APIs, no magic strings (enums/constants), prefer immutability, one concern per file.

On-Demand Skill Loading (references/skill-loader.md)

Only load skills relevant to the current domain. Never load all at once.

Rule	Trigger	Loads
NestJS Backend	.ts with decorators, modules/ dirs	code-patterns (NestJS), adversarial-review, red-green-refactor, general-documentation
Vue Frontend	.vue files, vue/pinia imports	code-patterns (Vue 3), visual-qa, red-green-refactor
Swift/iOS	.swift, .xcodeproj	code-patterns (Swift), red-green-refactor
Database	Migration files, .sql, Supabase	adr-generation
Planning	Design discussion, architecture	scope-challenge, adr-generation
Shipping	Deploy, PR, release, rollback	ship/SKILL.md

Always loaded: session-capture (learnings), tdd-enforcement (test-first in TDD mode).

TDD Enforcement (references/tdd-enforcement.md — TDD mode only)

• Rule 1: No implementation code until failing tests exist.
• Rule 2: Capture failing test output to prove it's running and failing for the right reason.
• Rule 3: Full test suite must pass after implementation — not just new tests.
• Rule 4: Max 3 fix attempts, then escalate to human with all outputs.
• Rule 5: Valid failing test = runs to completion, asserts expected behavior, fails because behavior is not yet implemented. NOT: syntax errors, import errors, skipped tests.

Gotchas

• TDD enforcement blocks exploratory prototyping — strict red-green cycle slows rapid iteration. Default mode (TDD off) is the right choice for prototypes; opt into --tdd for production work.
• 200-line file rule on generated code — auto-generated files (migrations, schemas) exceed limit by design. Exempt them explicitly in plan constraints.

Example Prompts

• "Implement the user registration endpoint using NestJS patterns"
• "Create a Vue 3 checkout component following Composition API patterns"
• "Load the skills I need for this database migration task"
• "Enable TDD mode and implement the payment feature"

Pro Tips

• Run mk:clean-code alongside mk:development — code patterns define structure, clean-code enforces quality.
• The skill-loader prevents context bloat. Let it decide what to load rather than specifying manually.
• For full-stack features (NestJS + Vue), the loader loads both domains — no need to request separately.