Extract the per-machine concurrency lock from sync.sh into a sourceable
lib (.claude/scripts/sync-lock.sh) plus a `run <cmd>` wrapper that locks
the current repo (same lock-dir basename, so it mutually excludes with
sync.sh in the ClaudeTools repo and self-scopes in any project repo).
sync.sh now sources it (behavior identical — verified by review). /scc
routes its commit+push through the locked, rebase-safe sync.sh (and drops
the bare YYYY-MM-DD-session.md filename for the per-session-unique one).
/checkpoint now stages+commits atomically under the repo lock so a
concurrent session in a shared worktree can't be swept in. Closes the
remaining commit paths that bypassed the lock shipped in 6b0ce9a.
Remove /refresh-directives references from save, checkpoint, scc, sync
commands. Trim sync.md from 400+ lines to essentials.
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
