changeset.yml

name: Changeset

# Advisory, never blocking. A pull request that ships a release note should add
# a `.changeset/<name>.md`; this job says so when one is missing and gets out of
# the way otherwise.
#
# It used to fail, and the failure did not survive contact with stacked pull
# requests. One change gets ONE changeset, which lives on the bottom branch, so
# the file is *added* in exactly one PR's own diff and inherited by every branch
# above it. A per-PR gate therefore had to reason about stack position to know
# whether an absent changeset was a real omission — via a base-ref guard that
# GitHub's stacked-PR handling made unreliable in both directions, and a
# `skip-changeset` label that got applied to silence the check rather than to
# record "this ships no release note." What was left was a red check people had
# learned to route around, which is worse than no check.
#
# So the question it asks is now the one that has a dependable answer: does a
# changeset exist ANYWHERE in this branch's stack — the full diff against
# `main`, which includes every ancestor branch's commits? If yes, the change is
# covered no matter which PR carries the file. If no, warn, and leave the call
# to the author.

on:
  # No `branches:` filter: the check is advisory, so it should reach every PR in
  # a stack, and a filter is not a dependable way to scope one anyway. It runs
  # everywhere and answers the stack question itself, below. `ready_for_review`
  # is not in the default event set and must be named.
  pull_request:
    types: [opened, reopened, synchronize, ready_for_review]

permissions:
  contents: read

jobs:
  changeset:
    name: Changeset
    runs-on: ubuntu-latest
    steps:
      - uses: actions/checkout@v6
        with:
          fetch-depth: 0 # need `origin/main` to diff the whole stack against

      - name: Look for a changeset in this stack
        env:
          HEAD_SHA: ${{ github.event.pull_request.head.sha }}
          HEAD_REF: ${{ github.head_ref }}
          LABELS: ${{ join(github.event.pull_request.labels.*.name, ',') }}
        run: |
          set -euo pipefail

          # The changesets "Version Packages" PR consumes changesets — removing
          # them is its whole job — so it legitimately has none.
          if [ "$HEAD_REF" = "changeset-release/main" ]; then
            echo "Version Packages PR (changeset-release/main) — no changeset expected."
            exit 0
          fi

          # Kept only to keep deliberate no-release-note PRs (docs, CI, chores,
          # the vale-binaries bot) quiet. It suppresses a warning now, not a
          # failure, so it can no longer be used to force a merge through.
          case ",${LABELS}," in
            *,skip-changeset,*)
              echo "The 'skip-changeset' label is present — no release note expected."
              exit 0
              ;;
          esac

          # Three dots: merge-base of `main` and this head, so the range is
          # everything the stack has added, including the ancestor branches
          # below this PR. A changeset on the bottom branch counts for every PR
          # above it, which is the arrangement this repo asks for.
          #
          # Additions AND modifications, because one change gets one changeset:
          # a stack landing forward finds its release note already on `main` and
          # the right move is to extend that file, not add a second entry for
          # something that ships once.
          FOUND=$(git diff --name-only --diff-filter=AM "origin/main...$HEAD_SHA" -- '.changeset/*.md' \
            | grep -viE '/README\.md$' || true)

          if [ -n "$FOUND" ]; then
            echo "Changeset(s) present in this stack:"
            echo "$FOUND" | sed 's/^/  - /'
            exit 0
          fi

          echo "::warning::No changeset found anywhere in this stack. If this pull request changes published behaviour, run \`pnpm changeset\` on the bottom branch of the stack. If it ships no release note (docs / CI / chore), ignore this or apply the \`skip-changeset\` label."
          {
            echo "### No changeset in this stack"
            echo ""
            echo "Nothing under \`.changeset/\` was added or modified between \`main\` and this branch, including the branches below it."
            echo ""
            echo "- Ships user-visible behaviour → run \`pnpm changeset\` on the **bottom** branch of the stack, so every branch above inherits it."
            echo "- Ships no release note (docs, CI, chore) → nothing to do. Apply \`skip-changeset\` to silence this."
            echo ""
            echo "_This is a warning. It does not block the merge._"
          } >> "$GITHUB_STEP_SUMMARY"