feat(agent): TDD workflow

.claude/commands/tdd.md

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+Guide test-driven development through RED → GREEN → REFACTOR → REVIEW cycle.
+
+Reference `pytest-patterns` and `tdd-workflow` skills. Use `planner` agent for complex implementations, `refactor-cleaner` agent for cleanup, `code-reviewer` agent for final review.
+
+Task: $ARGUMENTS

.claude/skills/tdd-workflow/SKILL.md

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+---
+name: tdd-workflow
+description: TDD cycle phases (RED → GREEN → REFACTOR → REVIEW) and agent orchestration
+---
+
+# TDD Workflow
+
+## Phases
+
+### Phase 1: RED (Write Failing Test)
+
+1. **Understand requirement** from task description
+2. **Find test location**:
+   - Search existing tests in `tests/` directory
+   - Match structure: `src/server/auth.py` → `tests/server/test_auth.py`
+3. **Write test that fails**:
+   - Test behavior, not implementation
+   - Use descriptive test names
+   - Follow `pytest-patterns` conventions
+4. **Run test to verify failure**:
+   ```bash
+   uv run pytest path/to/test_file.py::test_name -v
+   ```
+
+### Phase 2: GREEN (Minimal Implementation)
+
+**For complex implementations** (multi-file changes, architectural decisions, unclear scope):
+- Use the `planner` agent to create implementation plan
+- Follow the plan to implement minimal code
+
+**For simple implementations** (single function, obvious change):
+- Implement minimal code directly
+
+**Verify test passes**:
+```bash
+uv run pytest path/to/test_file.py::test_name -v
+```
+
+### Phase 3: REFACTOR (Improve Code)
+
+1. **Use `refactor-cleaner` agent** to identify:
+   - Dead code to remove
+   - Duplicated logic to consolidate
+   - Cleanup opportunities
+
+2. **Apply refactorings** while keeping tests green:
+   ```bash
+   uv run pytest path/to/test_file.py -v
+   ```
+
+3. **Verify coverage**:
+   ```bash
+   uv run pytest path/to/test_file.py --cov=src/module/being/tested --cov-report=term-missing
+   ```
+
+### Phase 4: REVIEW (Quality Check)
+
+**Use `code-reviewer` agent** to verify:
+- Security concerns
+- Code quality
+- Test coverage adequacy
+- Adherence to project patterns
+
+## Agent Orchestration
+
+- **planner**: Complex implementations in GREEN phase
+- **refactor-cleaner**: Cleanup in REFACTOR phase
+- **code-reviewer**: Final quality check in REVIEW phase