pr-check: Auto lock blocked PRs with too many failing builds

.github/workflows/pr-check.yml

@@ -21,7 +21,7 @@ jobs:
           CUTOFF_DATE="2025-05-25T00:00:00Z"
           prs_raw=$(gh pr list --base "new-pr" -L 50 --state open --json number,createdAt,updatedAt,isDraft,labels \
             | jq -r --arg cutoff "$CUTOFF_DATE" '[.
-              [] 
+              []
               | select(
                   .isDraft == false
                   and .createdAt >= $cutoff
@@ -149,6 +149,14 @@ jobs:
               echo "Nothing to do"
               start_build
             fi
+            if [ "$BLOCKED" -eq 1 ] \
+              && label_exists_any "pr-check-blocked" "blocked" \
+              && ! comment_exists_any "$BUILD_SUCCESS_COMMENT" \
+              && [ "$(echo "$PR_COMMENTS" | grep -E -c 'Test build.*failed')" -gt 10 ]; then
+                echo "PR is blocked and too many failing builds. Locking"
+                gh pr comment "$PR_NUM" --body "$LOCKED_COMMENT"
+                gh pr lock "$PR_NUM" || true
+            fi
           done
         env:
           GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
@@ -168,4 +176,9 @@ jobs:
             request title is `Add $FLATPAK_ID` and that all
             [checklist items](https://github.com/flathub/flathub/blob/master/.github/pull_request_template.md)
             in the pull request body are marked as complete.
+          LOCKED_COMMENT: >
+            This pull request is marked as blocked and has too many
+            builds failing. Locking this PR temporarily. Please build
+            it locally following the instructions and push the relevant
+            changes first.
           REVIEW_COMMENT_PARTIAL: "This pull request is temporarily marked as blocked as some"