diff --git a/.github/workflows/score-from-r2.yml b/.github/workflows/score-from-r2.yml
index a6282e1..331a23c 100644
--- a/.github/workflows/score-from-r2.yml
+++ b/.github/workflows/score-from-r2.yml
@@ -15,7 +15,12 @@ name: Score submissions from R2 (private → aggregate)
 # See intake/cloudflare-worker/README.md.
 
 on:
-  workflow_dispatch: {}       # manual trigger (maintainer)
+  workflow_dispatch:          # manual trigger (maintainer)
+    inputs:
+      reset_results:
+        description: "Wipe R2 results/ before scoring (clean the board of stale scored files)"
+        type: boolean
+        default: false
   schedule:
     - cron: "0 16 * * *"      # daily sweep of R2 for new submissions (16:00 UTC).
 
@@ -61,6 +66,12 @@ jobs:
       - name: Pull pending submissions + prior scored detail from R2
         run: |
           mkdir -p incoming results/scored
+          # reset_results (manual): wipe the prior scored detail so the board is rebuilt from
+          # scratch — used to clear stale/test entries that predate a rule change.
+          if [ "${{ github.event.inputs.reset_results }}" = "true" ]; then
+            echo "reset_results: wiping s3://$BUCKET/results"
+            aws s3 rm "s3://$BUCKET/results" --recursive --endpoint-url "$R2_ENDPOINT" || true
+          fi
           # incoming/ = raw submissions to score; results/ = all prior scored detail, so the
           # rebuilt leaderboard reflects the FULL history, not just this batch.
           aws s3 sync "s3://$BUCKET/incoming" ./incoming --endpoint-url "$R2_ENDPOINT"
@@ -102,12 +113,22 @@ jobs:
           MODELS=$(jq 'length' site/results.json)
           BUGS=$(jq '[.[].bugs_found] | add // 0' site/results.json)
           DATE=$(date -u +%Y-%m-%d)
-          TITLE="Update leaderboard — ${MODELS} models, ${BUGS} verified bugs (${DATE})"
-          BR="bot/leaderboard-${{ github.run_id }}"
-          git checkout -b "$BR"
+          [ "$MODELS" = 1 ] && MS="" || MS="s"
+          [ "$BUGS" = 1 ] && BS="" || BS="s"
+          TITLE="Update leaderboard — ${MODELS} model${MS}, ${BUGS} verified bug${BS} (${DATE})"
+          # One rolling branch → at most ONE open leaderboard PR ever. Each run force-updates
+          # it (and its PR) instead of opening a fresh bot/leaderboard-<run_id> PR every time.
+          BR="bot/leaderboard"
+          git checkout -B "$BR"
           git add site/results.json
           git commit -m "$TITLE"
-          git push origin "$BR"
-          gh pr create --base main --head "$BR" \
-            --title "$TITLE" \
-            --body "Automated refresh of \`site/results.json\` from newly scored submissions in private R2. Certificates and rule identities stay private in R2 — only the aggregate counts change here (guarded by \`check_aggregate.py\`). Merging deploys the public site via publish-on-merge."
+          git push -f origin "$BR"
+          EXISTING=$(gh pr list --head "$BR" --state open --json number -q '.[0].number')
+          if [ -n "$EXISTING" ]; then
+            gh pr edit "$EXISTING" --title "$TITLE"
+            echo "Updated existing leaderboard PR #$EXISTING"
+          else
+            gh pr create --base main --head "$BR" \
+              --title "$TITLE" \
+              --body "Automated refresh of \`site/results.json\` from newly scored submissions in private R2. Certificates and rule identities stay private in R2 — only the aggregate counts change here (guarded by \`check_aggregate.py\`). Merging deploys the public site via publish-on-merge. This PR is force-updated by each scoring run, so there is only ever one open leaderboard PR."
+          fi