Sync Docs

Check recent code changes (git diff HEAD~5 --name-only), scan the project's documentation system, and report what needs updating.

Checklist items (detect based on directories that actually exist in the project):

1. Knowledge base — Does docs/knowledge/ have new learnings to record?
2. Experiment registry — Are new experiments registered in the registry?
3. Project instructions — Does the CLAUDE.md index table cover all knowledge files?
4. Rules vs knowledge — New learnings default to docs/knowledge/ (dated entries with detail and rationale). Promote to .claude/rules/ only when a constraint is stable, imperative, and reused, and keep the rule to trigger + hard constraint + copy-paste exact values + a > Detail: pointer. Dated experience, measured numbers, and run tags (smoke vN / image tags) stay in knowledge, never in a rule.
5. README — Does the project README match the current code structure?
6. Strategy docs (only if docs/strategy/ exists) — Do vision, roadmap, or paper-outline reflect recent changes? Compare git log activity against strategy doc last-modified dates. Flag docs that haven't been updated in 5+ commits of relevant code changes. Pair with /project-review for full strategic analysis.
7. Rule hygiene — Scan existing .claude/rules/: any rule that has grown into a dated changelog, duplicates the project's main instructions (CLAUDE.md / AGENTS.md), or carries detail that belongs in knowledge → flag for prune. Sync is bidirectional — prune as well as add, not monotonic growth.

Output a checklist marking each item as "needs update" or "up to date". Report only — do NOT auto-modify.