dependabot-news-md-autofill.yaml

name: Dependabot NEWS.md autofill

on:
  pull_request_target:
    branches: [main]
    types: [opened, synchronize, reopened, edited]

permissions:
  contents: write
  pull-requests: read

jobs:
  add-news-entry:
    if: github.actor == 'dependabot[bot]'
    runs-on: ubuntu-latest

    steps:
      - name: Checkout PR head
        uses: actions/checkout@v6
        with:
          # IMPORTANT: checkout the PR branch, not main
          ref: ${{ github.event.pull_request.head.ref }}
          repository: ${{ github.event.pull_request.head.repo.full_name }}
          fetch-depth: 0
          persist-credentials: true

      - name: Compute NEWS.md entry from Dependabot title
        id: news
        shell: bash
        run: |
          set -euo pipefail

          TITLE="${{ github.event.pull_request.title }}"

          # Typical Dependabot titles:
          # "Bump <package> from <old> to <new>"
          if [[ "$TITLE" =~ ^Bump[[:space:]]+(.+)[[:space:]]+from[[:space:]]+([^[:space:]]+)[[:space:]]+to[[:space:]]+([^[:space:]]+)$ ]]; then
            PKG="${BASH_REMATCH[1]}"
            FROM="${BASH_REMATCH[2]}"
            TO="${BASH_REMATCH[3]}"
            ENTRY="* dependabot updating package ${PKG} from version ${FROM} to version ${TO} new"
          else
            # Fallback if title format differs (rare, but happens)
            ENTRY="* dependabot updating dependencies new"
          fi

          echo "entry=$ENTRY" >> "$GITHUB_OUTPUT"

      - name: Insert Dependabot entry under latest Features section
        shell: bash
        run: |
          set -euo pipefail
          ENTRY="${{ steps.news.outputs.entry }}"

          if [[ ! -f NEWS.md ]]; then
            echo "::error file=NEWS.md,line=1,col=1::NEWS.md not found."
            exit 1
          fi

          # If entry already exists anywhere, do nothing
          if grep -Fqx "$ENTRY" NEWS.md; then
            echo "NEWS.md already contains the entry. Skipping."
            exit 0
          fi

          tmp="$(mktemp)"

          # Insert directly after the first "## Features" header
          awk -v entry="$ENTRY" '
            BEGIN { inserted=0 }
            {
              print $0
              if ($0 ~ /^##[[:space:]]+Features[[:space:]]*$/ && inserted == 0) {
                print entry
                inserted=1
              }
            }
            END {
              if (inserted == 0) {
                print ""
                print entry
              }
            }
          ' NEWS.md > "$tmp"

          mv "$tmp" NEWS.md

      - name: Commit and push (only if changed)
        shell: bash
        run: |
          set -euo pipefail

          if git diff --quiet; then
            echo "No changes to commit."
            exit 0
          fi

          git config user.name "github-actions[bot]"
          git config user.email "github-actions[bot]@users.noreply.github.com"

          git add NEWS.md
          git commit -m "Update NEWS.md for Dependabot PR"
          git push