Sibling Sync

Bilateral SYNERGY/UPSTREAM reconciliation across sibling projects. Use when the user wants to sync sibling SYNERGY/UPSTREAM files, compare both sides to surface drift, find reciprocation gaps (entries here but not there, or vice versa), flag stale-aligned rows, detect status drift across sides, surface friction the sibling tracks ABOUT this project (their UPSTREAM-<this-project>.md), or apply a reciprocation batch with --auto-reciprocate. Workflow 3 covers two UPSTREAM pairing modes: shared third-party dependencies AND reciprocal sibling-friction pairs (UPSTREAM-<sibling>.md here ↔ UPSTREAM-<this-project>.md there). NOT for logging entries on this side (use /synergy-tracker workflow 1 (Log a synergy entry)) — sibling-sync compares both sides without writing by default. NOT for upstream → project drift (use /vendor-sync); sibling-sync handles peer-to-peer drift between sibling vp-* projects. Trigger phrases: 'sibling sync', 'compare siblings', 'sync sibling', 'reconcile siblings', 'reciprocation gap', 'sync drift', 'bilateral sync', 'sync SYNERGY', 'sync UPSTREAM both ways', 'auto-reciprocate', 'check sibling drift', 'peer-to-peer drift', 'cross-project drift', 'sibling reconciliation', 'sibling has friction about us', 'what does the sibling say about us', 'reconcile sibling-tracked friction', 'reciprocal upstream friction', 'friction filed against this project', 'sibling follow-up', 'act on sibling drift', 'after sibling-sync', 'follow-up actions', 'what to do about sibling findings'.

mkdir -p ~/.claude/skills/sibling-sync
curl -L https://claudskills.com/skills/sibling-sync/SKILL.md \
  -o ~/.claude/skills/sibling-sync/SKILL.md

@misc{sibling-sync-2026,
  author    = {voxpelli},
  title     = {Sibling Sync [Claude Code skill]},
  year      = {2026},
  publisher = {ClaudSkills},
  url       = {https://claudskills.com/skills/sibling-sync/}
}