rubber-duck skill

Invoke @rubber-duck to get an independent second opinion on a plan, implementation, or test suite. This is the same pattern as GitHub Copilot CLI's built-in Rubber Duck feature — a different perspective to catch what the primary agent missed.

When to invoke

Checkpoint	What to pass	What you get back
After Phase 3 (plan complete)	plan.md + test-plan.md	PLAN REVIEW
After complex multi-file implementation	Changed files / diff	CODE REVIEW
After tests written, before running	Test files	TEST REVIEW
Any time you feel uncertain	Anything relevant	Focused critique

How to call it

@rubber-duck Mode: PLAN REVIEW

Plan: <paste plan.md content or path>
Story: <paste story frontmatter + scenarios>

@rubber-duck Mode: CODE REVIEW

Files changed:
- src/scheduler.ts
- src/jobs/notify.ts
- src/queue/index.ts

<paste diff or file content>

@rubber-duck Mode: TEST REVIEW

Test files:
- tests/unit/scheduler.test.ts
- tests/e2e/notify.spec.ts
- features/scheduler.feature

<paste test content>

Verdict handling

Verdict	Orchestrator action
APPROVE	Proceed to next phase
REQUEST_CHANGES	Send findings to the responsible agent for revision; re-review once

CRITICAL findings always block. WARN findings are surfaced to the human for a decision. INFO findings are logged but do not block.

Tips

• You do not need to prepare anything special — just pass the relevant content.
• The rubber duck will not rewrite your code. It only surfaces findings. Acting on them is your job.
• For Copilot CLI users: the built-in /experimental Rubber Duck activates automatically at the same checkpoints. This skill adds equivalent coverage when using Claude Code or OpenCode.