diff --git a/review_sidebar_test.py b/review_sidebar_test.py
new file mode 100644
index 0000000..bb001a1
--- /dev/null
+++ b/review_sidebar_test.py
@@ -0,0 +1,22 @@
+"""Test file for Devin Review sidebar E2E test (PR #19284 in devin-webapp).
+
+This PR exists to verify that when a new commit is pushed while viewing
+the PR review page, the sidebar section cards do NOT disappear.
+
+Commit 1: this file is added.
+Commit 2 (pushed while page is open): a second line is appended below.
+"""
+
+
+def first_commit_marker() -> str:
+    return "commit-1"
+
+
+def second_commit_marker() -> str:
+    """Added in commit 2 — pushed while the review page is open."""
+    return "commit-2"
+
+
+def third_commit_marker() -> str:
+    """Added in commit 3 — pushed while staging.itsdev.in page is open (negative control)."""
+    return "commit-3"