Add OIDC staged-publishing release workflow

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: patocallaghan

.github/workflows/publish.yml

@@ -0,0 +1,73 @@
+# CAVEAT: This repo currently publishes via semantic-release (see `npm run semantic-release`
+# in package.json and the `release` job in .circleci/config.yml). semantic-release cannot emit
+# `npm stage publish`, so this staged-publishing workflow is NOT yet wired into the live release
+# path. Before adopting it, the semantic-release flow must be reconciled with OIDC staged
+# publishing (decide which owns version bump + publish, and remove the duplicate). Also note the
+# Node bump: package.json engines was `>=6.0.0` and CircleCI used Node 12.21 — .nvmrc is now
+# 22.14.0 because npm >= 11.15.0 (staged publishing) requires Node >= 22.14.0.
+name: Publish (staged)
+
+on:
+  release:
+    types: [published]        # cutting a Release creates the tag AND fires this
+
+permissions:
+  contents: read              # workflow default (least privilege); only stage-publish also needs id-token, granted on that job
+
+jobs:
+  verify:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd   # v6.0.2
+        with: { persist-credentials: false }
+      - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version-file: '.nvmrc'      # pin >= 22.14.0
+          package-manager-cache: false     # release-triggered: disable auto-cache (zizmor cache-poisoning)
+      - name: Assert Release tag matches package.json version
+        env:
+          RELEASE_TAG: ${{ github.event.release.tag_name }}
+        run: |
+          PKG="$(node -p "require('./package.json').version")"
+          [ "${RELEASE_TAG#v}" = "$PKG" ] || { echo "tag $RELEASE_TAG != package.json v$PKG"; exit 1; }
+      - name: Refuse releases not on the default branch
+        env:
+          RELEASE_TAG: ${{ github.event.release.tag_name }}
+          DEFAULT_BRANCH: ${{ github.event.repository.default_branch }}
+        run: |
+          git fetch origin "$DEFAULT_BRANCH" --depth=1
+          git merge-base --is-ancestor "$GITHUB_SHA" "origin/$DEFAULT_BRANCH" \
+            || { echo "release $RELEASE_TAG not reachable from $DEFAULT_BRANCH — refusing"; exit 1; }
+
+  stage-publish:
+    needs: verify
+    runs-on: ubuntu-latest
+    permissions:
+      contents: read
+      id-token: write           # OIDC trusted publishing: only this job mints the token
+    steps:
+      - uses: actions/checkout@de0fac2e4500dabe0009e67214ff5f5447ce83dd   # v6.0.2
+        with: { persist-credentials: false }
+      - uses: actions/setup-node@48b55a011bda9f5d6aeb4c2d9c7362e8dae4041e # v6.4.0
+        with:
+          node-version-file: '.nvmrc'
+          registry-url: 'https://registry.npmjs.org'
+          package-manager-cache: false
+      - run: yarn install --frozen-lockfile
+      - run: yarn build
+      - run: npm install -g npm@11.15.0    # npm CLI: staged publishing needs npm >= 11.15.0
+      - name: Resolve dist-tag (a prerelease must never go to `latest`)
+        id: disttag
+        env:
+          PRERELEASE_TAG: next
+        run: |
+          VERSION="$(node -p "require('./package.json').version")"
+          case "$VERSION" in
+            *-*) TAG="$PRERELEASE_TAG" ;;
+            *)   TAG="latest" ;;
+          esac
+          echo "tag=$TAG" >> "$GITHUB_OUTPUT"
+      - name: Stage publish
+        env:
+          DIST_TAG: ${{ steps.disttag.outputs.tag }}
+        run: npm stage publish --tag "$DIST_TAG"

.nvmrc

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+22.14.0