Next Branch

The next branch

Branch layout

next is the prerelease line for the upcoming editor major. It stays in changesets pre mode (.changeset/pre.json, tag next), so every release from it publishes a -next.N version under the next dist-tag. PRs for the next major target next (--base next). main keeps releasing the current major, and older majors live on maintenance branches (see the backporting skill).

release.yml runs on pushes to both main and next. On next the changesets bot opens "Version Packages (next)" from changeset-release/next.

Syncing main into next

Sync runs one direction only: main into next, never the reverse until the stable cut. It always lands as a two-parent merge through the sync/main-into-next PR, which sync-next.yml opens (or refreshes) after each release of main. Merge that PR with "Create a merge commit". Never squash it, rebase it, or cherry-pick main commits onto next as routine. The merge commit is what records main as an ancestor of next. Without it, the next sync sees the same commits as unmerged, replays them, and hits the same conflicts again.

Timing

Sync only after main's Version Packages PR merges, never before. Until then main still holds pending changesets for a release that has not happened. Syncing then carries those changesets onto next, and the bot proposes prereleases of content that is about to ship stable from main.

sync-next.yml enforces this. It runs on every push to main (and on manual dispatch from main), but it never merges main's tip blindly. It walks back from main's tip along its first-parent history (up to 500 commits) and picks the newest commit with no pending changesets. That commit is the target, and the target is what gets merged. A pending changeset is any .md file anywhere under .changeset/ except README.md files. That includes .changeset/pre/, where changesets v3 keeps prerelease changesets and where pre exit leaves them pending.

For example, after a release commit R, then c1 without a changeset, c2 adding one, and c3, the target is c1. The release and everything up to the first new changeset get synced. The rest waits for the next release.

The workflow skips with a one-line job summary when next does not exist, when no commit within reach is free of pending changesets, or when next already contains the target. So the push that merges Version Packages opens the sync PR, and a feature push re-syncs up to the newest clean commit, which does nothing when next already has it. Every run starts from main's current tip, so a newer run that cancels an older one computes the same or a later target, and nothing is lost.

When the workflow stops

The workflow never overwrites human work on sync/main-into-next. If the branch already contains both next and the target, it leaves the branch alone, so a hand-resolved merge survives later runs. If the branch has commits the workflow did not make and lacks next or the target, it pushes nothing and fails. Otherwise it rebuilds the branch from next and force-pushes with a lease on the SHA it fetched.

It also stops when the merge conflicts, and when its push is rejected. The push error is in the job log. Two likely causes: someone pushed to the branch during the run (the lease caught it), or GitHub refused a workflow file (the app token has no workflows permission, and a clean merge can produce .github/workflows/ contents that exist on neither branch).

In all three cases the report step prints the same commands, with the target filled in, to its own log and to the run summary. For conflicts, the report lists the conflicting files. Keep next's side in the version fields of package.json files and the release headings of CHANGELOG.md files. Everywhere else, both sides changed on purpose, so combine them instead of picking one. Then run the root checks and the affected packages' tests before pushing: tests and lint rules from main can fail against next's code even where Git merged cleanly. Finish in a dedicated worktree, based on origin/sync/main-into-next when the branch exists (so its work is kept) and on origin/next when it does not. Merge the current next first, so a branch that fell behind next catches up, then the target. git worktree add -b refuses to run when a local sync/main-into-next already exists, which protects unpushed work in it: reuse that branch, or delete it once it holds nothing worth keeping.

git fetch origin
git worktree add -b sync/main-into-next \
  ../editor-sync-main-into-next origin/sync/main-into-next
cd ../editor-sync-main-into-next
# if a merge stops on conflicts: resolve them, then
# `git add -A && git commit --no-edit`, then continue
git merge --no-edit origin/next
git merge --no-ff -m "chore: merge main into next" \
  <target>
git push origin sync/main-into-next
# if no sync PR is open:
gh pr create --base next --head sync/main-into-next \
  --title "chore: merge main into next" \
  --body 'Merge with "Create a merge commit".'

<target> is the commit the report names, usually origin/main right after a release.