Comments PR with failed host build log

.forgejo/workflows/auto-update-build.yaml

@@ -85,6 +85,9 @@ jobs:
             echo "  $HOST: ${BUILD_TIMES[$HOST]}"
           done
           
+          # Save failed hosts for the comment step
+          echo "$FAILED_HOSTS" > failed_hosts.txt
+          
           if [ -n "$FAILED_HOSTS" ]; then
             echo "Some builds failed"
             exit 1
@@ -99,6 +102,52 @@ jobs:
           path: build-*.txt
           retention-days: 7
 
+      - name: Comment on PR with build failures
+        if: steps.build.outcome == 'failure'
+        env:
+          PR_TOKEN: ${{ secrets.PR_TOKEN }}
+        run: |
+          set -euo pipefail
+          
+          if [ ! -f failed_hosts.txt ]; then
+            echo "No failed hosts file found"
+            exit 0
+          fi
+          
+          FAILED_HOSTS=$(cat failed_hosts.txt)
+          
+          # Build comment body
+          {
+            echo "## ❌ Build Failed"
+            echo ""
+            echo "The following hosts failed to build:"
+            echo ""
+            
+            for HOST in $FAILED_HOSTS; do
+              LOG_FILE="build-${HOST}.txt"
+              if [ -f "$LOG_FILE" ]; then
+                echo "<details>"
+                echo "<summary><b>${HOST}</b></summary>"
+                echo ""
+                echo '```'
+                tail -n 150 "$LOG_FILE"
+                echo '```'
+                echo ""
+                echo "</details>"
+                echo ""
+              fi
+            done
+          } > comment_body.md
+          
+          # Post comment to PR using jq for proper JSON escaping
+          jq -Rs '{body: .}' comment_body.md > payload.json
+          
+          curl -sf -X POST \
+            -H "Authorization: token $PR_TOKEN" \
+            -H "Content-Type: application/json" \
+            -d @payload.json \
+            "${{ forgejo.api_url }}/repos/${{ forgejo.repository }}/issues/${{ forgejo.event.pull_request.number }}/comments"
+
       - name: Check build result
         run: |
           if [ "${{ steps.build.outcome }}" == "failure" ]; then