diff --git a/scripts/ops/hermes_triage_demo.sh b/scripts/ops/hermes_triage_demo.sh
index 5990869c9..042ad60f8 100755
--- a/scripts/ops/hermes_triage_demo.sh
+++ b/scripts/ops/hermes_triage_demo.sh
@@ -147,13 +147,35 @@ for b in json.load(sys.stdin):
     done
   fi
 
+  # The code demo seeds its defect by pushing to master, and the fix only lands
+  # if someone merges the pull request. A demo that ended without a merge - the
+  # usual case, since the point is that nothing merges itself - leaves master
+  # broken, and the next run aborts on "defect already present". Reset has to
+  # undo the seed rather than just report it, or the second demo of the day
+  # fails before it starts.
   if [ -d "$CODE_REPO_DIR/.git" ]; then
     note "restoring the demo repository working state"
-    ( cd "$CODE_REPO_DIR" && git checkout -q master && git pull -q --ff-only 2>/dev/null || true )
+    ( cd "$CODE_REPO_DIR" && git checkout -q master && git fetch -q origin &&
+      git reset -q --hard origin/master ) || note "  could not sync master"
     if grep -q 'percent / 100' "$CODE_REPO_DIR/src/discount.py" 2>/dev/null; then
       note "  src/discount.py is correct; demo is armable"
     else
-      note "  src/discount.py still carries the seeded defect — revert it before demoing"
+      note "  src/discount.py carries the seeded defect; reverting it on master"
+      ( cd "$CODE_REPO_DIR" &&
+        python3 - <<'PY'
+import pathlib, re, sys
+
+path = pathlib.Path("src/discount.py")
+source = path.read_text()
+# Matches the seeded `percent / 10` without also matching a correct
+# `percent / 100`, so re-running reset on a healthy file changes nothing.
+fixed = re.sub(r"percent / 10(?!\d)", "percent / 100", source)
+if fixed == source:
+    sys.exit("unrecognised defect; fix src/discount.py by hand")
+path.write_text(fixed)
+PY
+        git commit -qam "revert: restore the discount divisor" && git push -q origin master &&
+        note "  reverted and pushed; demo is armable" ) || note "  revert failed — fix src/discount.py by hand"
     fi
   else
     note "demo repository not cloned at $CODE_REPO_DIR; skipping"