Add adversarial spec and plan review to planning

[rochecompaan]

Summary

Add an adversarial review step for specifications and plans to Patchmill's
planning workflow, before implementation starts.

Motivation

Catching problems at the spec and plan stage saves a lot of churn in later
reviews. Changes at review time are expensive: code must be rewritten, tests
adjusted, and reviewers re-engaged. Changes to a plan are cheap.

Superpower plans contain code blocks. A plan review is therefore essentially a
code review, done before the code exists.

Proposal

• After planning produces a spec and plan, run one or more adversarial
  reviewer passes over them with fresh context.
• Reviewers get the spec, the plan, the issue requirements, and acceptance
  criteria, and look for gaps, contradictions, wrong assumptions, and risky
  design choices.
• Feed review findings back into planning so the plan is revised before any
  implementation begins.

Acceptance criteria

• Planning runs an adversarial review of the spec and plan before
  implementation.
• Review findings are recorded and acted on (plan revised or finding
  explicitly rejected).
• The review step fits the existing Patchmill planning workflow and does not
  block unattended runs on human input.

[rochecompaan]

This was generated by AI during triage.

Triage Notes

Classified as agent-ready.

Why this is ready for automation:

• The workflow change, review inputs, feedback loop, and unattended-run constraint are stated clearly enough for planning.
• The current patchmill-planning wrapper delegates spec and plan creation to the sibling brainstorming and writing-plans skills, whose built-in checks are self-reviews rather than mandatory fresh-context adversarial review passes.
• Reviewer prompt templates already exist at .patchmill/skills/brainstorming/spec-document-reviewer-prompt.md and .patchmill/skills/writing-plans/plan-document-reviewer-prompt.md, providing concrete integration points even though the current skill workflows do not invoke them.
• No reporter clarification or concrete same-repository blocker is required before planning.

Acceptance criteria to preserve:

• Both the completed specification and implementation plan receive fresh-context adversarial review before implementation starts.
• Findings are recorded and each is either incorporated into a revision or explicitly rejected with a rationale.
• Review/revision completes autonomously without waiting for human input.
• The behavior remains integrated with Patchmill's configured planning workflow and artifact paths.

Suggested starting points:

• Define the review and bounded revision loop in .patchmill/skills/patchmill-planning/SKILL.md, reusing or updating the existing reviewer prompt templates rather than creating a parallel workflow.
• Cover installed skill files, skill-pack metadata/update behavior, and planning-skill contract tests in src/workflow/skill-pack.test.ts and related skill-update tests.
• Coordinate the reviewer rubric with Use domain modeling and codebase design in Patchmill planning #173 where appropriate, but do not make this issue depend on that separate planning enhancement.