human hand off fix

backend/tests/test_handoff_mirror.py

@@ -49,6 +49,33 @@ def test_format_sender_with_name():
     )
 
 
+def test_quoted_history_uses_original_sender_not_human_owner():
+    from datetime import datetime, timezone
+
+    from app.services.handoff_email_templates import (
+        attach_quoted_history,
+        build_gmail_quote,
+    )
+
+    quoted_text, quoted_html = build_gmail_quote(
+        sender={"name": "Parth Dixit", "address": "parthdixit091@gmail.com"},
+        event_at=datetime(2026, 10, 6, 7, 29, tzinfo=timezone.utc),
+        body_text="sender: C",
+        body_html="<div>sender: C</div>",
+    )
+    body_text, body_html = attach_quoted_history(
+        new_text="responder: D",
+        new_html="<div>responder: D</div>",
+        quoted_text=quoted_text,
+        quoted_html=quoted_html,
+    )
+    assert body_text.startswith("responder: D")
+    assert "Parth Dixit <parthdixit091@gmail.com>" in body_text
+    assert "> sender: C" in body_text
+    assert "parthdixit091@gmail.com" in body_html
+    assert "Suyash AIML" not in body_text
+
+
 def test_external_threading_headers_from_customer_message():
     parent = {
         "_id": "mongo-id",