/harden-plan: pre-code plan quality gate

A shift-left gate. The fix is a plan edit, not a code refactor. This skill takes a WRITTEN plan and runs the /review-pr anti-slop lens against it while the plan is still text.

Reference files

Each reference loads only on the branch that reaches it, some by main, some by a subagent. Loader and firing condition per file:

• ${CLAUDE_SKILL_DIR}/references/subagent-prompts.md holds both Phase 2 prompt templates, Subagent A category analyzer and Subagent B pattern inventory, and the Phase 1 placeholders each takes. Main loads it at the Phase 2 dispatch.
• ${CLAUDE_SKILL_DIR}/references/category-checks.md holds P1-P11, each category's scope, its default severity, its invalidity gate, and one worked example. Subagent A loads it before answering any category. Main never applies these categories itself.
• ${CLAUDE_SKILL_DIR}/references/grill-loop.md holds question-block format, the four response branches, forbidden dismiss reasons, self-heal verification, abort ramps, and the one-at-a-time rule. Main loads it in Phase 4 when findings remain, meaning verdict is not ready-to-code.
• ${CLAUDE_SKILL_DIR}/references/write-back.md holds the external-modification check, the three write-back options, the insertion format, and the write-failure fallback. Main loads it in Phase 5 when PLAN_SOURCE=file.

One reference is not bundled here. ${CLAUDE_SKILL_DIR}/../review-pr/references/repo-map.md holds the repo_map_files and repo_map_exports shell, the one copy this skill shares with /review-pr and /fix-pr-review. Main loads it in Phase 1 when packages/ or apps/ exists.

Usage