---
description: Enforce test-driven development. Scaffold types, write Vitest tests FIRST, then implement the minimum to pass. Ensure 80%+ coverage.
---

# TDD Command

This command invokes the **tdd-guide** agent.

## What This Command Does

1. **Scaffold types** — inputs/outputs first
2. **Write failing tests** (RED) with Vitest
3. **Implement the minimum** (GREEN)
4. **Refactor** while green
5. **Check coverage** (80%+)

## When to Use

- New validators, transformers, stores, components
- Bug fixes (reproducing test first)
- Refactors of existing logic

## Cycle

```
RED → GREEN → REFACTOR → REPEAT
```

## Example

```
User: /tdd Add validation for the full-page name field
```

```typescript
// full-page.validator.test.ts
import { createFullPageSchema } from './full-page.validator';

it('rejects an empty name', () => {
  const schema = createFullPageSchema((k) => k);
  expect(schema.safeParse({ code: 'ABC', name: '' }).success).toBe(false);
});
```

```bash
pnpm --filter web test
pnpm test
pnpm check:all
```

Mock `@repo/core-api` / `apiClient`, not a database. UI in `packages/ui` uses Testing Library.

## Related

Agent: `.cursor/agents/tdd-guide.md`
Skill: `.agents/skills/tdd-workflow/`