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name: implement description: | TDD-based implementation workflow for feature development, bug fixes, and code changes. Use when: implementing features, fixing bugs, adding functionality, writing new code, or making any code changes. Triggers: "implement", "add feature", "fix bug", "build", "create", "develop", "write code", "TDD", "test-driven".

Implementation

TDD-based workflow for all code changes.

Workflow

Phase 1: Understand & Plan

1. Explore codebase to understand context and existing patterns
2. Create detailed TodoWrite items for each test case to implement
3. Mark first todo as in_progress

Phase 2: Red-Green-Refactor Cycle

For each todo item:

1. Red: Write failing test
   • Define expected behavior/contract
   • Include concrete examples and edge cases
   • Follow project test naming conventions
2. Run tests - verify new test fails
3. Green: Write minimal code to pass
   • Only implement what's needed to pass the test
   • No premature optimization
4. Run tests - verify all tests pass
5. Refactor: Opportunistic cleanup
   • Clean up touched code if beneficial
   • High test coverage ensures safety
6. Run tests - verify still passing
7. Mark todo completed, next as in_progress

Phase 3: Verify

1. Run full test suite
2. Use available MCP servers or skills for additional verification if applicable
3. Ensure all todos completed

Phase 4: Subagents

Run the following custom subagents parallel:

1. code-simplifier
2. test-reviewer

Guidelines

• Investigate and fix test failures autonomously - do not ask unless stuck
• Explain key decisions only, not every step
• High test coverage enables safe opportunistic cleanup of touched code
• Run tests after each TDD cycle, not just at the end
• Use TodoWrite to track each test case for visibility