chore: introduce next integration branch (Phase 1 — additive) (#231)
Adds: - docs/branching.md — beginner contributor guide - docs/adr/XXXX-...md — ADR (will be renamed with issue#) - .github/workflows/auto-backmerge.yml — disabled in Phase 1 - .github/workflows/pr-target-validator.yml — warn-only in Phase 1 - scripts/setup-branch-protection.sh — idempotent gh api script Modifies: - .github/workflows/branch-naming.yml — recognize 'next' - CONTRIBUTING.md — 'Where Do I Open My PR?' section Phase 1 is additive: nothing operational changes until Phase 2 flips auto-backmerge.yml's if:false→true, flips pr-target-validator.yml's WARN_ONLY→false, creates the next branch, and switches the default branch. See the ADR for the migration plan.
This commit is contained in:
Tom Boucher
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docs/adr/230-introduce-next-integration-branch.md
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346
docs/adr/230-introduce-next-integration-branch.md
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# Introduce `next` as a long-lived integration branch
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- **Status:** Proposed
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- **Date:** 2026-05-23
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> **Filename note.** This ADR uses the placeholder (now resolved to `230`) per
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> [CONTRIBUTING.md §Proposing an ADR](../../CONTRIBUTING.md). Before merging,
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> open a `chore:` issue, replace `XXXX` with the assigned issue number, and
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> rename the file accordingly.
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## Context
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Today every contributor branch — `feat/`, `fix/`, `chore/`, `docs/`,
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`refactor/`, `test/`, `perf/`, `ci/`, `revert/` — is cut from `main` and PR'd
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back to `main`. Release branches (`release/X.Y.0`) and hotfix branches
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(`hotfix/X.Y.Z`) are also cut from `main`. As a result:
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1. **`main` moves on every merge.** With ~315 unreleased changesets queued
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and multiple PRs in flight at any time, `main` advances multiple times a
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day.
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2. **GitHub branch protection on `main` requires "branches up to date before
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merging"** (the dominant pattern across mature OSS projects with linear
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history). Every time another PR lands, every in-flight PR must rebase
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before its own merge button enables.
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3. **`release/X.Y.0` accumulates RC-cycle fixes that drift from `main`.**
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When `finalize` opens the merge-back PR, the diff is large and
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contributors who PR'd to `release/*` can't be sure their fix is also
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queued for the next minor.
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4. **`hotfix.yml` cherry-picks `fix:`/`chore:` commits from `main` since the
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prior tag.** This works today only because every fix lands on `main`.
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The pattern is fragile — any deviation (e.g. fix landing on `release/*`)
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is invisible to the picker. v1.42.3 (#3621) shipped a half-state for
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exactly this class of reason.
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The maintainer's stated pain: *"every update doesn't mean the next pr needs
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a rebase"* — i.e. the rebase treadmill from (2), driven by (1).
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## Decision
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Introduce **`next`** as a long-lived integration branch.
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- All work that today targets `main` instead targets `next`, with the sole
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exceptions of `release/X.Y.0` and `hotfix/X.Y.Z` branches, which still
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merge to `main`.
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- `next` is always at-or-ahead of `main`. Any push to `main` (release or
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hotfix merge) triggers an automated back-merge PR `main → next` to keep
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`next` aligned.
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- Branch protection rules differ:
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- **`main`** — strict: 2 reviewer approvals, all CI green, "require
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branches up to date" **ON**, signed commits, restrict push to maintainers
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via PR only.
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- **`next`** — loose: 1 reviewer approval, all CI green, "require branches
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up to date" **OFF**, auto-delete source branches.
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- Default branch (in repo Settings) becomes `next`. `gh pr create` and the
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GitHub web UI then default new PRs to the correct target without a flag.
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### Where each branch type goes
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| Branch prefix | Today's target | New target | Rationale |
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|---|---|---|---|
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| `feat/` | `main` | `next` | Features ship in minor releases |
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| `fix/` | `main` | `next` | Regular fixes ship in minor (or get cherry-picked by hotfix.yml) |
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| `chore/`, `docs/`, `refactor/`, `test/`, `perf/`, `ci/`, `revert/` | `main` | `next` | All same-flow as fixes |
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| `fix/critical-*` | `main` | `main` | Production-down only, auto-back-merges to `next` |
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| `release/X.Y.0` | `main` | `main` (cut from `next`) | Promoted to production on finalize |
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| `hotfix/X.Y.Z` | `main` | `main` (cut from prior tag, cherry-picks from `next`) | Patch releases |
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### Mechanical changes summary
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| Component | Change |
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|---|---|
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| `release.yml` (`create`) | Branch from `next`, not `main` |
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| `release.yml` (`finalize`) | Open merge-back PR to **both** `main` and `next` (was just `main`) |
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| `hotfix.yml` (cherry-pick step) | Cherry-pick from `origin/next`, not `origin/main` |
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| `hotfix.yml` (`finalize`) | Open merge-back PRs to both `main` and `next` (was just `main`) |
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| `branch-naming.yml` | Add `next` to `alwaysValid` list |
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| `auto-branch.yml` | Branch from `next` HEAD instead of `main` HEAD for issue-labeled branches |
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| New `pr-target-validator.yml` | Block PRs targeting `main` from branches that aren't `release/*`, `hotfix/*`, or `fix/critical-*` |
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| New `auto-backmerge.yml` | On push to `main`, open `main → next` PR |
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| Repo settings | Default branch = `next`; squash-merge only on `next`; merge-commit on `main` (preserve tag context) |
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| `scripts/setup-branch-protection.sh` | New: idempotent script to apply both branch protection rule sets via `gh api` |
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## Consequences
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### Positive
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- **Rebase treadmill ends.** PRs targeting `next` are not gated on
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"up-to-date before merge". Concurrent PRs to `next` merge in any order as
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long as they don't conflict on the same lines.
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- **`main` becomes a stable reference.** It changes only on release/hotfix
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merges — a handful of times per week, not multiple times per day. CI on
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`main` runs less; downstream consumers (linked CI, npm tag watchers) see
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fewer transient states.
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- **Hotfix cherry-pick base is unambiguous.** All `fix:`/`chore:` commits
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candidate for a hotfix live on `next`. The cherry-pick filter (today
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hardcoded against `origin/main`) becomes correct-by-construction once
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retargeted to `origin/next`.
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- **RC-only fixes flow back to `next` automatically.** Today a fix that
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lands on `release/1.28.0` to unblock RC2 only makes it to `next`-equivalent
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(i.e. `main`) when finalize back-merges. Under the new model finalize
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back-merges to both `main` and `next`, so an RC fix is never accidentally
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dropped from the next minor.
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- **Default branch switch is one click.** Cost is low; setting takes effect
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for every new PR and clone immediately.
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### Negative
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- **One more concept to teach contributors.** Mitigated by `docs/branching.md`
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+ CONTRIBUTING update + PR-target validator that says "retarget to `next`"
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with a one-line fix instruction.
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- **Hotfix and release workflows need updates.** Patches are inlined below.
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Both are reversible — if a patch causes pain, revert and re-target the
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workflows back to `main`. No on-disk state migration required.
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- **The auto-backmerge PR is a new background-noise source.** It opens
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silently after each release/hotfix push to `main`. Mitigated by labeling
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the PR `automation` and auto-merging if CI passes (configurable in
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`auto-backmerge.yml`).
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- **Existing 315-changeset queue.** Doesn't strictly block this change but
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the next release will be a large one. Recommend cutting `1.28.0` from
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`main` (current behavior, last time) before flipping the default branch
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to `next` — see "Migration" below.
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### Risks not worth the trade-off
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We considered and rejected:
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- **`develop` instead of `next`.** The git-flow nomenclature is established
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but the gitflow model itself is heavier than this project needs (no
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long-lived `release/*` branches per-major, no `support/*` for old majors).
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`next` matches the existing npm dist-tag (`@next`) and is the convention
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for Angular, Next.js, React Native, and others. Use the name that already
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appears in `VERSIONING.md`.
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- **Merge queue.** GitHub's merge queue (GA in 2023) addresses the same
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pain by serializing merges and rebasing+testing automatically. Rejected
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because (a) it doesn't address the parallel work-stream separation that a
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`next` branch gives, (b) it still requires "branches up to date" which we
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want to relax, and (c) the maintainer is a git beginner and merge queue's
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failure modes (split commits, requeued PRs) are harder to debug than a
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conventional model.
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- **Pure trunk-based with feature flags.** Rejected because the project
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publishes to npm and doesn't have a runtime feature-flag system. Feature
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flags would be a larger separate investment.
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## Migration
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This is a phase-gated rollout. Each phase is reversible.
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### Phase 0 — Decide
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1. Open a `chore:` issue: "Introduce `next` integration branch". Get the
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issue number. Rename this ADR file from `XXXX-` to `<issue#>-`.
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2. Review this ADR. Decide on the merge-commit-vs-squash policy for `next`
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(recommended: squash) and for `main` (recommended: merge commit on
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release back-merges, to preserve the tag-commit relationship).
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### Phase 1 — Additive infrastructure (no behavior change)
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The following land on `main` (current model, one last time) before flipping:
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- `docs/branching.md` (new)
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- `docs/adr/<issue#>-introduce-next-integration-branch.md` (this file)
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- `scripts/setup-branch-protection.sh` (new)
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- `.github/workflows/auto-backmerge.yml` (new, disabled with
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`if: false` until phase 2)
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- `.github/workflows/pr-target-validator.yml` (new, in "warning only" mode)
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- `.github/workflows/branch-naming.yml` (update: add `next` to `alwaysValid`)
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- CONTRIBUTING.md update: "Where do I open my PR?" section
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### Phase 2 — Flip
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When the next release is ready to start its RC cycle:
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1. Cut the current planned release (e.g. `1.28.0`) using `release.yml` as
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today — this drains the 315-changeset queue from `main` cleanly.
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2. After `v1.28.0` finalizes and back-merges to `main`, run:
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```bash
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git checkout main && git pull --ff-only
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git checkout -b next && git push -u origin next
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```
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3. Apply branch protection: `bash scripts/setup-branch-protection.sh`.
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4. Settings → Branches → change default branch to `next`.
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5. Re-enable `auto-backmerge.yml` (remove the `if: false`).
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6. Flip `pr-target-validator.yml` from warning-only to enforcing.
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### Phase 3 — Retarget release/hotfix workflows
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Apply these patches once `next` is established and the team has run at
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least one feature PR through it.
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**`release.yml` — branch from `next` (create step):**
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```diff
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@@ create:
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- name: Create release branch
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env:
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BRANCH: ${{ needs.validate-version.outputs.branch }}
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VERSION: ${{ inputs.version }}
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IS_MAJOR: ${{ needs.validate-version.outputs.is_major }}
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run: |
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+ git fetch origin next:next || git fetch origin main:main
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- git checkout -b "$BRANCH"
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+ git checkout -b "$BRANCH" next 2>/dev/null || git checkout -b "$BRANCH" main
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```
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The `|| main` fallback is for the transition window where `next` may not
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yet exist. After Phase 2 the fallback can be removed.
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**`release.yml` — back-merge to both branches (finalize step):**
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```diff
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@@ Create PR to merge release back to main
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- name: Create PR to merge release back to main
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...
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+ - name: Create PR to merge release back to next
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+ if: ${{ !inputs.dry_run }}
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+ continue-on-error: true
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+ env:
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+ GH_TOKEN: ${{ github.token }}
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+ BRANCH: ${{ needs.validate-version.outputs.branch }}
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+ VERSION: ${{ inputs.version }}
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+ run: |
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+ EXISTING_PR=$(gh pr list --base next --head "$BRANCH" --state open --json number --jq '.[0].number' 2>/dev/null || echo "")
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+ if [ -n "$EXISTING_PR" ]; then
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+ gh pr edit "$EXISTING_PR" \
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+ --title "chore: merge release v${VERSION} to next" \
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+ --body "Merge release branch back to next after v${VERSION} stable release (picks up RC-only fixes)." \
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+ || echo "::warning::Could not update next merge-back PR. Open it manually."
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+ else
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+ gh pr create \
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+ --base next \
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+ --head "$BRANCH" \
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+ --title "chore: merge release v${VERSION} to next" \
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+ --body "Merge release branch back to next after v${VERSION} stable release (picks up RC-only fixes)." \
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+ || echo "::warning::Could not create next merge-back PR. Open it manually."
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+ fi
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```
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**`hotfix.yml` — cherry-pick from `next` (with `main` fallback):**
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```diff
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@@ Cherry-pick fix/chore commits from origin/main since base tag
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- - name: Cherry-pick fix/chore commits from origin/main since base tag
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+ - name: Cherry-pick fix/chore commits from origin/next since base tag
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...
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run: |
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set -euo pipefail
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- git fetch origin main:refs/remotes/origin/main
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+ # Prefer next; fall back to main during the transition window or
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+ # for production-down emergencies that landed directly on main.
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+ if git ls-remote --exit-code origin next >/dev/null 2>&1; then
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+ git fetch origin next:refs/remotes/origin/next
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+ SOURCE="origin/next"
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+ else
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+ git fetch origin main:refs/remotes/origin/main
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+ SOURCE="origin/main"
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+ fi
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- CANDIDATES=$(git cherry "$BASE_TAG" origin/main | awk '/^\+ / {print $2}')
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+ CANDIDATES=$(git cherry "$BASE_TAG" "$SOURCE" | awk '/^\+ / {print $2}')
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...
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- ORDERED=$(git log --reverse --format='%H' "$BASE_TAG..origin/main" \
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+ ORDERED=$(git log --reverse --format='%H' "$BASE_TAG..$SOURCE" \
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| grep -F -f <(echo "$CANDIDATES") || true)
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```
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**`hotfix.yml` — back-merge to both branches (finalize step):**
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```diff
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@@ Create PR to merge hotfix back to main
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- name: Create PR to merge hotfix back to main
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...
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+ - name: Create PR to merge hotfix back to next
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+ if: ${{ !inputs.dry_run }}
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+ env:
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+ GH_TOKEN: ${{ github.token }}
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+ BRANCH: ${{ needs.validate-version.outputs.branch }}
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+ VERSION: ${{ inputs.version }}
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+ run: |
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+ EXISTING_PR=$(gh pr list --base next --head "$BRANCH" --state open --json number --jq '.[0].number')
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+ if [ -n "$EXISTING_PR" ]; then
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+ gh pr edit "$EXISTING_PR" \
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+ --title "chore: merge hotfix v${VERSION} back to next" \
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+ --body "Merge hotfix changes back to next after v${VERSION} release."
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+ else
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+ gh pr create \
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+ --base next \
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+ --head "$BRANCH" \
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+ --title "chore: merge hotfix v${VERSION} back to next" \
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+ --body "Merge hotfix changes back to next after v${VERSION} release."
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+ fi
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```
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**`auto-branch.yml` — branch from `next`:**
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```diff
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- // Create branch from main HEAD
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- const mainRef = await github.rest.git.getRef({
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+ // Create branch from next HEAD (fall back to main if next missing)
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+ let baseRef;
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+ try {
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+ baseRef = await github.rest.git.getRef({
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owner: context.repo.owner,
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repo: context.repo.repo,
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- ref: 'heads/main',
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- });
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+ ref: 'heads/next',
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+ });
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+ } catch (e) {
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+ if (e.status !== 404) throw e;
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+ baseRef = await github.rest.git.getRef({
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+ owner: context.repo.owner,
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+ repo: context.repo.repo,
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+ ref: 'heads/main',
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+ });
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+ }
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await github.rest.git.createRef({
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owner: context.repo.owner,
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repo: context.repo.repo,
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ref: `refs/heads/${branch}`,
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- sha: mainRef.data.object.sha,
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+ sha: baseRef.data.object.sha,
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});
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```
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### Phase 4 — Cleanup
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After 2-3 successful releases under the new model:
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- Remove the `|| main` fallbacks from `release.yml` and `hotfix.yml`.
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- Remove `develop` from `branch-naming.yml` `alwaysValid` (it was vestigial;
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the project never used it).
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- Drop warning-only mode from `pr-target-validator.yml`.
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## References
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- `docs/branching.md` — contributor-facing how-to-use-it guide
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- `VERSIONING.md` — semver tiers and npm dist-tag mapping
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- `.github/workflows/release.yml`, `.github/workflows/hotfix.yml` —
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release/hotfix automation that this ADR adjusts
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- `scripts/setup-branch-protection.sh` — bootstrap script for branch
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protection rules
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- [Angular branching model](https://github.com/angular/angular/wiki/Branching-Strategy)
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— closest analogue (`main` + `<version>-next`)
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- [Next.js release flow](https://github.com/vercel/next.js#contributing)
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— uses `canary` as the integration branch with the same shape
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Reference in New Issue
Block a user