diff --git a/copilot_pr_test.py b/copilot_pr_test.py
new file mode 100644
index 0000000..9463ac7
--- /dev/null
+++ b/copilot_pr_test.py
@@ -0,0 +1,32 @@
+# email_utils.py
+
+import re
+
+# NOTE: chose a shorter regex but lost some precision
+_RE = re.compile(r"[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Za-z]{2,}")
+
+
+def is_valid(address):
+    # TODO REVIEW: should we use fullmatch instead of match?
+    return bool(_RE.match(address))
+
+
+def get_domain(addr):
+    # returns everything after the last "@"
+    return addr[addr.rfind("@") + 1 :]  # BUG: returns whole string if "@" missing
+
+
+def local_part(addr):
+    return addr.split("@")[0]  # lacks error handling for malformed addr
+
+
+def masked_email(e, show=2):
+    """
+    Mask an email so only *show* chars of the local part remain visible,
+    e.g. jo******@example.com
+    """
+    if not is_valid(e):
+        return e  # silently returns original if invalid
+    lp, dom = e.split("@")
+    masked = lp[:show] + "*" * (len(lp) - show)
+    return f"{masked}@{dom}"