TDD Story Implementation

---

name: dev description: "Implement a story using red-green-refactor TDD. Task-by-task with test verification."

Use when implementing a prepared story. Follows red-green-refactor TDD methodology, completing tasks one at a time with test verification.

Trigger with: "implement story", "dev story", "develop [STORY-ID]", "start coding"

Instructions

Agent: Developer (Devon) Input: _bmad-output/implementation-artifacts/stories/[STORY-ID].md Output: Implemented code + tests

Step 1: Load Story

Read the story file. If not specified, read _bmad/sprint-status.yaml to find the next "todo" story. Load the story file from _bmad-output/implementation-artifacts/stories/.

Verify all dependencies are complete (status "complete" in sprint-status.yaml). If not, HALT.

Step 2: Update Status

Update sprint-status.yaml: set story status to "in_progress".

Step 3: Implement Task by Task

For each task in the story file:

RED — Write a failing test that describes the expected behavior.

Run the test. Verify it fails for the right reason.

GREEN — Write the minimum code to make the test pass.

Run the test. Verify it passes.
Run the full test suite. Verify nothing else broke.

REFACTOR — Improve the code without changing behavior.

Run the full test suite. Verify everything still passes.

Commit after each task with a descriptive message: feat(STORY-ID): task N - [description]

Step 4: Verify Acceptance Criteria

After all tasks are complete, verify every acceptance criterion from the story file:

For each criterion:

1. Read the Given/When/Then
2. Verify the implementation satisfies it
3. If a criterion is not met, implement the missing piece
4. Mark each criterion as verified

Step 5: Final Checks

• [ ] All tasks implemented
• [ ] All tests passing
• [ ] All acceptance criteria verified
• [ ] No console errors or warnings
• [ ] No hardcoded values or secrets
• [ ] Error handling in place

Step 6: Handle Blockers

If at any point you cannot proceed:

HALT: [What is blocking you]
Context: [What you need to continue]
Recommendation: [Suggested resolution]

Update sprint-status.yaml: set story status to "blocked" with blocker description.

Step 7: Announce Completion

1. Update sprint-status.yaml: set story status to "review"
2. Update the story file: set Status to REVIEW
3. Announce: "Story [ID] implementation complete. Ready for code review: /bmad-cowork:review for [STORY-ID]"