Skill Prune

Inverse of /skill-update. Removes content rather than adding it. Run during quarterly maintenance, after engagements, or when scripts/skill_linter.py reports orphans / duplicates.

When to invoke

• Quarterly cadence.
• After scripts/skill_linter.py --check-orphans reports orphan reference files.
• After a SKILL.md or reference file grows past its cap and needs trimming.
• After a de-specialization sweep, to drop content tied to retired challenges.

Prune criteria (the four signals — same shape as /skill-update, inverted)

A reference / scenario / line is a prune candidate when it satisfies any of:

1. Orphan — not linked from any SKILL.md or other reference file in the last 60 days.
2. Referenced only by failed engagements — appeared in attack-chain.md of runs that ended status=BLOCKED, never in a successful chain.
3. Contradicted by newer content — a later scenario / pattern supersedes it; the older entry no longer reflects current technique.
4. Redundant with newer content — same technique covered more clearly elsewhere.