**TL;DR**: `/tdd [feature]` - Start test-driven development workflow. Write tests first, verify they fail, then implement.

---

## Usage

```bash
/tdd                    # Start TDD for current task
/tdd add user auth      # TDD for specific feature
/tdd verify             # Verify test is failing
/tdd coverage           # Check coverage report
```

## Workflow

1. **Write failing test** - Define expected behavior
2. **Verify test fails** - Confirm test is valid
3. **Implement minimal code** - Just enough to pass
4. **Verify test passes** - Confirm implementation works
5. **Refactor** - Improve code, keep tests passing
6. **Repeat** - Next test for next behavior

## Example

```python
# Step 1: Write failing test
def test_user_can_login_with_valid_credentials():
    auth = AuthService()
    result = auth.login("user@test.com", "password123")
    assert result.success
    assert result.token is not None

# Step 2: Run and verify it fails
$ pytest tests/test_auth.py -v
FAILED - AuthService not defined

# Step 3: Implement minimal code
class AuthService:
    def login(self, email: str, password: str) -> LoginResult:
        # Minimal implementation to pass test
        ...

# Step 4: Verify test passes
$ pytest tests/test_auth.py -v
PASSED
```

## Coverage Target

Aim for >80% test coverage:

```bash
# Python
pytest --cov=src --cov-report=term-missing tests/

# TypeScript
jest --coverage
npm run test -- --coverage
```

## Integration

This command invokes the **TDD Guide Agent** which:
- Ensures tests are written first
- Verifies tests fail before implementation
- Tracks coverage improvements
- Enforces Red-Green-Refactor cycle
