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):

Knowledge base — Does docs/knowledge/ have new learnings to record?
Experiment registry — Are new experiments registered in the registry?
Project instructions — Does the CLAUDE.md index table cover all knowledge files?
Rules — Are there new hard constraints to codify in .claude/rules/?
README — Does the project README match the current code structure?
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.

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

sync-docs