refactor(ci): append commits to refresh PR instead of force-pushing

Switches the refresh workflow off peter-evans/create-pull-request and
onto native gh + git so we can:

- Detect whether an open refresh PR already exists for branch
  chore/refresh-v3-languages.
- If it does, check that branch out, fetch fresh responses, and append
  a new commit on top. Reviewer history (in-line comments, approvals)
  stays intact rather than being invalidated by a force-push each run.
- If it does not, create the branch, commit, push, and open a new PR.
- Skip cleanly when the fetched responses are identical to what is
  already on the branch.

Also adds:

- A concurrency group so cron and manual workflow_dispatch runs cannot
  race for the same branch.
- A comment explaining the workflow_dispatch trigger.
- A link back to the originating Actions run in each commit + PR body.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

Author: Daniel Jones

.github/workflows/refresh-v3-languages.yml

@@ -4,37 +4,107 @@ on:
   schedule:
     # Top of every hour.
     - cron: "0 * * * *"
+  # Allow the job to be triggered manually from the Actions tab.
   workflow_dispatch:
 
 permissions:
   contents: write
   pull-requests: write
 
+concurrency:
+  group: refresh-v3-languages
+  cancel-in-progress: false
+
+env:
+  REFRESH_BRANCH: chore/refresh-v3-languages
+  COMMIT_PATHS: data/v3-languages
+
 jobs:
   refresh:
-    name: Fetch and open PR on diff
+    name: Fetch and update refresh PR
     runs-on: ubuntu-latest
     steps:
-      - name: Checkout
+      - name: Checkout main
         uses: actions/checkout@v5
+        with:
+          fetch-depth: 0
+
+      - name: Detect existing refresh PR
+        id: pr
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          number=$(gh pr list \
+            --base main \
+            --head "$REFRESH_BRANCH" \
+            --state open \
+            --json number \
+            --jq '.[0].number // ""')
+          echo "number=$number" >> "$GITHUB_OUTPUT"
+          if [ -n "$number" ]; then
+            echo "Existing refresh PR: #$number"
+          else
+            echo "No existing refresh PR"
+          fi
+
+      - name: Check out existing refresh branch
+        if: steps.pr.outputs.number != ''
+        run: |
+          git fetch origin "$REFRESH_BRANCH"
+          git checkout -B "$REFRESH_BRANCH" "origin/$REFRESH_BRANCH"
 
       - name: Fetch latest /v3/languages responses
         env:
           DEEPL_AUTH_KEY: ${{ secrets.DEEPL_API_KEY }}
         run: python3 scripts/fetch_v3_languages.py
 
-      - name: Open PR if responses changed
-        uses: peter-evans/create-pull-request@v6
-        with:
-          branch: chore/refresh-v3-languages
-          base: main
-          commit-message: "chore(v3-languages): refresh vended responses"
-          title: "chore(v3-languages): refresh vended responses"
-          body: |
-            Automated refresh of `data/v3-languages/` from `https://api.deepl.com/v3/languages`.
-
-            Triggered by the hourly `refresh-v3-languages` workflow.
-            Merge this PR to update the vended data; downstream generators consume it.
-          add-paths: data/v3-languages/**
-          delete-branch: true
-          labels: automated, v3-languages
+      - name: Detect content changes
+        id: diff
+        run: |
+          if git diff --quiet -- $COMMIT_PATHS; then
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+            echo "No changes in $COMMIT_PATHS; nothing to commit."
+          else
+            echo "changed=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Configure git author
+        if: steps.diff.outputs.changed == 'true'
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+
+      - name: Append commit to existing refresh PR
+        if: steps.diff.outputs.changed == 'true' && steps.pr.outputs.number != ''
+        env:
+          RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+        run: |
+          git add -- $COMMIT_PATHS
+          git commit -m "chore(v3-languages): refresh vended responses
+
+          Run: $RUN_URL"
+          git push origin "$REFRESH_BRANCH"
+
+      - name: Create new refresh PR
+        if: steps.diff.outputs.changed == 'true' && steps.pr.outputs.number == ''
+        env:
+          GH_TOKEN: ${{ github.token }}
+          RUN_URL: ${{ github.server_url }}/${{ github.repository }}/actions/runs/${{ github.run_id }}
+        run: |
+          git checkout -b "$REFRESH_BRANCH"
+          git add -- $COMMIT_PATHS
+          git commit -m "chore(v3-languages): refresh vended responses
+
+          Run: $RUN_URL"
+          git push -u origin "$REFRESH_BRANCH"
+          gh pr create \
+            --base main \
+            --head "$REFRESH_BRANCH" \
+            --title "chore(v3-languages): refresh vended responses" \
+            --body "Automated refresh of \`data/v3-languages/\` from \`https://api.deepl.com/v3/languages\`, opened by the \`refresh-v3-languages\` workflow.
+
+          Subsequent runs append new commits to this PR when the responses change again, so the diff against \`main\` represents the cumulative update. Review the latest state and merge when ready.
+
+          First run: $RUN_URL" \
+            --label automated \
+            --label v3-languages