handoff fixes

backend/tests/test_external_reply_service.py

@@ -1,6 +1,10 @@
 from bson import ObjectId
 
-from app.services.external_reply_service import build_external_reply_plan
+from app.services.external_reply_service import (
+    build_external_reply_plan,
+    internet_message_id_of,
+)
+from app.services.message_ids import canonical_message_id, folded_message_id
 from app.services.thread_service import threading_fields_from_parent
 
 
@@ -55,3 +59,76 @@ def test_external_reply_never_uses_internal_object_id_as_in_reply_to():
     )
     assert str(parent["_id"]) not in (plan.threading.in_reply_to or "")
     assert all(str(parent["_id"]) not in ref for ref in plan.threading.references)
+
+
+def test_handoff_bridge_reply_uses_external_parent_not_human_reply():
+    """Human handoff must thread B against customer A, never private H2."""
+    customer_a = {
+        "_id": ObjectId(),
+        "internet_message_id": "<CAHabc123@mail.gmail.com>",
+        "message_id": "<CAHabc123@mail.gmail.com>",
+        "message_scope": "EXTERNAL",
+        "direction": "inbound",
+        "references": [],
+        "subject": "fresh test",
+    }
+    human_h2 = {
+        "_id": ObjectId(),
+        "internet_message_id": "<H2@gmail.com>",
+        "message_id": "<H2@gmail.com>",
+        "message_scope": "HANDOFF",
+        "direction": "inbound",
+        "in_reply_to": "<H1@gentic.email>",
+        "references": ["<H1@gentic.email>"],
+        "subject": "Re: fresh test",
+    }
+    plan = build_external_reply_plan(
+        parent_external_message=customer_a,
+        body_text="human said B",
+        recipients=["091rabbytes@gmail.com"],
+    )
+    assert plan.threading.in_reply_to == "<CAHabc123@mail.gmail.com>"
+    assert plan.threading.references == ["<CAHabc123@mail.gmail.com>"]
+    assert human_h2["internet_message_id"] not in (plan.threading.in_reply_to or "")
+    assert all(
+        human_h2["internet_message_id"] not in ref for ref in plan.threading.references
+    )
+    assert "<H1@gentic.email>" not in plan.threading.references
+
+
+def test_raw_header_restores_gmail_message_id_case():
+    parent = {
+        "_id": ObjectId(),
+        "internet_message_id": "<cahabc123@mail.gmail.com>",
+        "message_id": "<cahabc123@mail.gmail.com>",
+        "raw_headers": {"message_id": "<CAHabc123@mail.gmail.com>"},
+        "references": [],
+        "subject": "fresh test",
+    }
+    plan = build_external_reply_plan(
+        parent_external_message=parent,
+        body_text="human said B",
+        recipients=["customer@gmail.com"],
+    )
+    assert plan.threading.in_reply_to == "<CAHabc123@mail.gmail.com>"
+    assert plan.threading.references == ["<CAHabc123@mail.gmail.com>"]
+
+
+def test_gmail_message_id_case_is_preserved_for_threading():
+    raw = "<CAHabc123@mail.gmail.com>"
+    assert canonical_message_id(raw) == raw
+    assert folded_message_id(raw) == "<cahabc123@mail.gmail.com>"
+    parent = {
+        "_id": ObjectId(),
+        "internet_message_id": raw,
+        "message_id": raw,
+        "references": [],
+        "subject": "fresh test",
+    }
+    plan = build_external_reply_plan(
+        parent_external_message=parent,
+        body_text="human said B",
+        recipients=["customer@gmail.com"],
+    )
+    assert plan.threading.in_reply_to == raw
+    assert internet_message_id_of(parent) == raw

backend/tests/test_handoff_mirror_policy.py

@@ -0,0 +1,57 @@
+from bson import ObjectId
+
+from app.services.handoff_mirror_policy import (
+    GENERATED_BY_CUSTOMER,
+    GENERATED_BY_HANDOFF_BRIDGE,
+    GENERATED_BY_RELAY_ACK,
+    MESSAGE_ORIGIN_EXTERNAL_CUSTOMER,
+    MESSAGE_ORIGIN_HUMAN_OWNER,
+    is_relay_acknowledgment_message,
+    should_mirror_to_human,
+)
+
+
+def test_should_mirror_customer_inbound():
+    message = {
+        "message_scope": "EXTERNAL",
+        "direction": "inbound",
+        "generated_by": GENERATED_BY_CUSTOMER,
+        "message_origin": MESSAGE_ORIGIN_EXTERNAL_CUSTOMER,
+    }
+    assert should_mirror_to_human(message) is True
+
+
+def test_should_not_mirror_handoff_bridge_outbound():
+    message = {
+        "message_scope": "EXTERNAL",
+        "direction": "outbound",
+        "generated_by": GENERATED_BY_HANDOFF_BRIDGE,
+        "generated_from_handoff_message_id": ObjectId(),
+    }
+    assert should_mirror_to_human(message) is False
+
+
+def test_should_not_mirror_human_origin():
+    message = {
+        "message_scope": "EXTERNAL",
+        "direction": "inbound",
+        "message_origin": MESSAGE_ORIGIN_HUMAN_OWNER,
+    }
+    assert should_mirror_to_human(message) is False
+
+
+def test_is_relay_acknowledgment_detects_legacy_body():
+    message = {
+        "direction": "outbound",
+        "body_text": "Sent to customer:\n\nhuman said B",
+    }
+    assert is_relay_acknowledgment_message(message) is True
+
+
+def test_is_relay_acknowledgment_detects_generated_by():
+    message = {
+        "direction": "outbound",
+        "generated_by": GENERATED_BY_RELAY_ACK,
+        "body_text": "anything",
+    }
+    assert is_relay_acknowledgment_message(message) is True

backend/tests/test_handoff_threading.py

@@ -0,0 +1,82 @@
+"""Integration-style tests for Human Handoff → Customer RFC threading."""
+
+from bson import ObjectId
+
+from app.services.external_reply_service import (
+    build_external_reply_plan,
+    internet_message_id_of,
+)
+from app.services.mail_sender import build_message, sign_message
+from types import SimpleNamespace
+
+
+def test_handoff_bridge_first_reply_threads_against_customer_a():
+    customer_a_id = "<CAHabc123@mail.gmail.com>"
+    customer_a = {
+        "_id": ObjectId(),
+        "internet_message_id": customer_a_id,
+        "message_id": customer_a_id,
+        "message_scope": "EXTERNAL",
+        "direction": "inbound",
+        "references": [],
+        "subject": "fresh test",
+    }
+    plan = build_external_reply_plan(
+        parent_external_message=customer_a,
+        body_text="human said B",
+        recipients=["091rabbytes@gmail.com"],
+    )
+    assert plan.threading.in_reply_to == customer_a_id
+    assert plan.threading.references == [customer_a_id]
+    assert plan.threading.in_reply_to != "<H2@gmail.com>"
+    assert "<H1@gentic.email>" not in plan.threading.references
+
+
+def test_lowercased_stored_id_recovered_via_raw_headers():
+    customer_a_id = "<CAHabc123@mail.gmail.com>"
+    parent = {
+        "_id": ObjectId(),
+        "internet_message_id": "<cahabc123@mail.gmail.com>",
+        "message_id": "<cahabc123@mail.gmail.com>",
+        "raw_headers": {"message_id": customer_a_id},
+        "references": [],
+        "subject": "fresh test",
+    }
+    plan = build_external_reply_plan(
+        parent_external_message=parent,
+        body_text="human said B",
+        recipients=["customer@gmail.com"],
+        parent_internet_id_override=internet_message_id_of(parent),
+    )
+    assert plan.threading.in_reply_to == customer_a_id
+    assert plan.threading.references == [customer_a_id]
+
+
+def test_signed_mime_preserves_threading_headers():
+    customer_a_id = "<CAHabc123@mail.gmail.com>"
+    message = build_message(
+        sender="suyash@gentic.email",
+        recipients=["091rabbytes@gmail.com"],
+        cc=[],
+        subject="Re: fresh test",
+        body_text="human said B",
+        body_html=None,
+        in_reply_to=customer_a_id,
+        references=[customer_a_id],
+        message_id="<B@gentic.email>",
+    )
+    domain = SimpleNamespace(
+        domain_name="gentic.email",
+        dkim_selector="agmail",
+        dkim_private_key="private-key",
+    )
+    from unittest.mock import patch
+
+    with patch(
+        "app.services.mail_sender.dkim.sign",
+        return_value=b"DKIM-Signature: test\r\n",
+    ):
+        signed = sign_message(message, domain)
+
+    assert f"In-Reply-To: {customer_a_id}".encode() in signed
+    assert f"References: {customer_a_id}".encode() in signed

backend/tests/test_human_handoff_service.py

@@ -73,6 +73,7 @@ async def test_resolve_handoff_requires_owner_and_thread_context():
         {
             "_id": message_id,
             "message_id": "<handoff-1@gentic.email>",
+            "message_id_folded": "<handoff-1@gentic.email>",
             "message_scope": MESSAGE_SCOPE_HANDOFF,
         }
     ]

backend/tests/test_mail_sender.py

@@ -41,3 +41,50 @@ async def test_send_via_smtp_uses_configured_client_hostname():
         )
 
     assert send_mock.await_args.kwargs["local_hostname"] == "backend.gentic.email"
+
+
+def test_build_message_sets_in_reply_to_and_references():
+    message = build_message(
+        sender="suyash@gentic.email",
+        recipients=["customer@gmail.com"],
+        cc=[],
+        subject="Re: fresh test",
+        body_text="human said B",
+        body_html=None,
+        in_reply_to="<CAHabc123@mail.gmail.com>",
+        references=["<CAHabc123@mail.gmail.com>"],
+        message_id="<B@gentic.email>",
+    )
+    assert message["Message-ID"] == "<B@gentic.email>"
+    assert message["In-Reply-To"] == "<CAHabc123@mail.gmail.com>"
+    assert message["References"] == "<CAHabc123@mail.gmail.com>"
+    raw = message.as_bytes()
+    assert b"In-Reply-To: <CAHabc123@mail.gmail.com>" in raw
+    assert b"References: <CAHabc123@mail.gmail.com>" in raw
+
+
+def test_signed_mime_preserves_in_reply_to():
+    from unittest.mock import patch
+
+    message = build_message(
+        sender="suyash@gentic.email",
+        recipients=["customer@gmail.com"],
+        cc=[],
+        subject="Re: fresh test",
+        body_text="human said B",
+        body_html=None,
+        in_reply_to="<CAHabc123@mail.gmail.com>",
+        references=["<CAHabc123@mail.gmail.com>"],
+        message_id="<B@gentic.email>",
+    )
+    domain = SimpleNamespace(
+        domain_name="gentic.email",
+        dkim_selector="agmail",
+        dkim_private_key="private-key",
+    )
+    with patch(
+        "app.services.mail_sender.dkim.sign",
+        return_value=b"DKIM-Signature: test\r\n",
+    ):
+        signed = sign_message(message, domain)
+    assert b"In-Reply-To: <CAHabc123@mail.gmail.com>" in signed