Sync

Sync is the daily-cleanup verb. One command does everything you'd otherwise do across git fetch, git pull, git branch -d, and a manual restack.

What sm sync does, in order

1. Fetch from origin.
2. Fast-forward the local trunk to origin/<trunk>. (Refuses if your trunk has diverged.)
3. Detect merged branches. Any tracked branch whose unique commits are now reachable from trunk is considered merged.
4. Re-parent children of merged branches onto the merged branch's parent (which is usually trunk now). This is what keeps the rest of your stack hanging together when the bottom merges.
5. Delete merged branches locally.
6. Restack survivors. Every remaining tracked branch is rebased onto its (possibly new) parent's tip.
7. Retarget PR bases on GitHub for any branch whose parent changed during step 4 (so reviewers see the new base).

Mental model

Before sync                     After sync (PR #41 merged)

main ── X ── X (origin)         main ──────────── X' (origin, fast-forwarded)
       \                                \
        Y (feat/models PR #41)           Z' (feat/handlers, reparented onto main)
         \
          Z (feat/handlers PR #42)

feat/models is gone locally. feat/handlers now sits directly on trunk, both locally and on GitHub. PR #42's base on GitHub is now main.

When it pauses

If restacking the survivors hits a conflict, sm sync returns a PausedError exactly like sm restack:

⚠ rebase paused on feat/handlers

Resolve, git add, then sm continue — same protocol.

What sm sync is NOT

• It is not git pull --rebase. git pull --rebase only rebases the current branch; sync rebases the whole chain.
• It is not destructive on its own — every branch deletion is gated by "this branch's commits are fully in trunk." If a branch has unique commits left, it survives.
• It does not push. If sync changed your local stack, run sm submit --stack after.

Sync vs. restack

	sm sync	sm restack
Touches origin?	Yes (fetch + retarget PRs)	No
Updates trunk?	Yes (fast-forward)	No
Deletes merged branches?	Yes	No
Rebases descendants?	Yes	Yes
Cost	Higher (network)	Local only

Use sm sync once a day or when something landed on origin. Use sm restack for purely-local churn.

Configuring

There's no flag to disable any of these steps right now. If you want a "fetch only" pass, use git fetch directly; if you want a "restack only" pass, use sm restack.