github: modify github action to have only one comment on previews (#889)

Author: Deflaimun

.github/workflows/build-prev.yml

@@ -15,12 +15,22 @@ jobs:
     steps:
       - uses: actions/checkout@v4
       - uses: pnpm/action-setup@v4
-      - name: Initial preview comment
+      - name: Find or create preview comment
+        uses: peter-evans/find-comment@v3
+        id: find-comment
+        with:
+          token: ${{ secrets.GITHUB_TOKEN }}
+          issue-number: ${{ github.event.pull_request.number }}
+          comment-author: 'github-actions[bot]'
+          body-includes: '### Docs Preview'
+      
+      - name: Create or update initial preview comment
         uses: peter-evans/create-or-update-comment@v4
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           issue-number: ${{ github.event.pull_request.number }}
-          identifier: docs-preview
+          comment-id: ${{ steps.find-comment.outputs.comment-id }}
+          edit-mode: replace
           body: |
             ### Docs Preview
             - Status: ⏳ Creating preview…
@@ -35,19 +45,20 @@ jobs:
           echo "files<<EOF" >> $GITHUB_OUTPUT
           echo "$CHANGED" >> $GITHUB_OUTPUT
           echo "EOF" >> $GITHUB_OUTPUT
+      # 5. Build site (allow failure)
       - name: Build site
         id: build
         run: |
           pnpm run build-prod
         continue-on-error: true
+      # 6. Generate the comment body
       - name: Generate comment body
         id: comment
         run: |
           # compute branch‑based preview URL
           BRANCH="${{ github.event.pull_request.head.ref }}"
           PREVIEW_URL="https://${BRANCH}.documentation-21k.pages.dev"
           LOG_URL="https://github.com/${{ github.repository }}/actions/runs/${{ github.run_id }}"
-          
           if [ "${{ steps.build.outcome }}" = "success" ]; then
             STATUS="✅ Build succeeded"
             LINK="Preview: [${PREVIEW_URL}](${PREVIEW_URL})"
@@ -57,37 +68,27 @@ jobs:
             # always link to last branch preview if available
             LINK="${LINK} | Previous preview: [${PREVIEW_URL}](${PREVIEW_URL})"
           fi
-          
           BODY="### Docs Preview
           - Status: ${STATUS}
           - ${LINK}
           **Changed pages:**"
-          
-          # Process changed files using a more reliable approach
-          if [ -n "${{ steps.changes.outputs.files }}" ]; then
-            echo "${{ steps.changes.outputs.files }}" | while IFS= read -r f; do
-              [ -z "$f" ] && continue
-              REL_PATH="${f#docs/}"
-              NAME=$(basename "${REL_PATH%.*}")
-              URL="${PREVIEW_URL}/${REL_PATH%.*}.html"
-              echo "- [${NAME}](${URL})"
-            done > /tmp/changed_files_list.txt
-            
-            # Read the processed content and append to BODY
-            if [ -f /tmp/changed_files_list.txt ]; then
-              CHANGED_PAGES=$(cat /tmp/changed_files_list.txt)
-              BODY="${BODY}
-          ${CHANGED_PAGES}"
-            fi
-          fi
-          
+          # list each changed file as a page link
+          while IFS= read -r f; do
+            [ -z "$f" ] && continue
+            REL_PATH="${f#docs/}"
+            NAME=$(basename "${REL_PATH%.*}")
+            URL="${PREVIEW_URL}/${REL_PATH%.*}.html"
+            BODY="${BODY}
+          - [${NAME}](${URL})"
+          done <<< "${{ steps.changes.outputs.files }}"
           echo "body<<EOF" >> $GITHUB_OUTPUT
           echo "$BODY" >> $GITHUB_OUTPUT
           echo "EOF" >> $GITHUB_OUTPUT
-      - name: Update preview comment
+      - name: Update preview comment with results
         uses: peter-evans/create-or-update-comment@v4
         with:
           token: ${{ secrets.GITHUB_TOKEN }}
           issue-number: ${{ github.event.pull_request.number }}
-          identifier: docs-preview
+          comment-id: ${{ steps.find-comment.outputs.comment-id }}
+          edit-mode: replace
           body: ${{ steps.comment.outputs.body }}