From 46231488175fb8a27f8413a503437312deb68478 Mon Sep 17 00:00:00 2001
From: Martin <46433701+Nikarhub@users.noreply.github.com>
Date: Mon, 2 Nov 2026 20:33:17 +0800
Subject: [PATCH] =?UTF-8?q?fix(core):=20=E6=94=B6=E7=B4=A7=20event-first?=
 =?UTF-8?q?=20=E4=BC=9A=E8=AF=9D=E8=BA=AB=E4=BB=BD=E4=BC=A0=E6=92=AD=20(#2?=
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---
 .../pkg/agent/runner/context_builder.py       | 15 +++++----
 .../agent/test_legacy_identity_boundary.py    | 31 +++++++++++++++++++
 2 files changed, 40 insertions(+), 6 deletions(-)

diff --git a/src/langbot/pkg/agent/runner/context_builder.py b/src/langbot/pkg/agent/runner/context_builder.py
index 499bfd4d2..30544694d 100644
--- a/src/langbot/pkg/agent/runner/context_builder.py
+++ b/src/langbot/pkg/agent/runner/context_builder.py
@@ -284,13 +284,16 @@ class RunnerContextBuilder:
                 and identity.bot_id == event.bot_id
                 and identity.pipeline_id == (binding.processor_id or binding.agent_id)
             ):
-                # Query-backed platform events carry a Host-owned launcher
+                # Query-backed platform events carry a Host-owned entry-session
                 # identity even when the event-first conversation UUID changes
-                # after create_new_conversation(). Keep it separate from the
-                # protocol conversation UUID so reset-sensitive plugins can use
-                # a stable session key.
-                stable_launcher_type = identity.session_launcher_type or identity.query_launcher_type
-                stable_launcher_id = identity.session_launcher_id or identity.query_launcher_id
+                # after create_new_conversation(). This is a Core context
+                # contract: session_id is reset-stable while conversation_id
+                # remains the current Host conversation UUID.
+                stable_launcher_type = identity.session_launcher_type
+                stable_launcher_id = identity.session_launcher_id
+                if stable_launcher_type not in ('group', 'person') or not stable_launcher_id:
+                    stable_launcher_type = identity.query_launcher_type
+                    stable_launcher_id = identity.query_launcher_id
                 if stable_launcher_type in ('group', 'person') and stable_launcher_id:
                     conversation['session_id'] = f'{stable_launcher_type}_{stable_launcher_id}'
             if (
diff --git a/tests/unit_tests/agent/test_legacy_identity_boundary.py b/tests/unit_tests/agent/test_legacy_identity_boundary.py
index d5347acfb..6c963c4ee 100644
--- a/tests/unit_tests/agent/test_legacy_identity_boundary.py
+++ b/tests/unit_tests/agent/test_legacy_identity_boundary.py
@@ -62,6 +62,34 @@ async def test_exact_native_identity_survives_serialization(mock_query, runner,
     assert context['conversation']['sender_id'] == 'sender-123'
 
 
+@pytest.mark.asyncio
+async def test_event_first_context_exposes_reset_stable_entry_session_identity(mock_query):
+    mock_query.launcher_type.value = 'group'
+    mock_query.launcher_id = 'event-007'
+    mock_query.session.launcher_type.value = 'person'
+    mock_query.session.launcher_id = 'session-008'
+    event = AgentEventEnvelope.model_validate_json(QueryEntryAdapter.query_to_event(mock_query).model_dump_json())
+
+    context, _ = await build(event, 'ACPAgentRunner', 'sender')
+
+    assert context['conversation']['conversation_id'] == 'conv-uuid-123'
+    assert context['conversation']['session_id'] == 'person_session-008'
+    assert context['conversation']['launcher_type'] is None
+    assert context['conversation']['launcher_id'] is None
+
+
+@pytest.mark.asyncio
+async def test_entry_session_identity_falls_back_to_query_launcher(mock_query):
+    mock_query.launcher_type.value = 'group'
+    mock_query.launcher_id = 'event-007'
+    mock_query.session.launcher_id = None
+    event = AgentEventEnvelope.model_validate_json(QueryEntryAdapter.query_to_event(mock_query).model_dump_json())
+
+    context, _ = await build(event, 'ACPAgentRunner', 'sender')
+
+    assert context['conversation']['session_id'] == 'group_event-007'
+
+
 @pytest.mark.asyncio
 @pytest.mark.parametrize('runner', ['DifyAgent', 'N8nAgent', 'CozeAgent'])
 async def test_missing_authoritative_fields_never_fall_back_to_raw_data(mock_query, runner):
@@ -72,6 +100,7 @@ async def test_missing_authoritative_fields_never_fall_back_to_raw_data(mock_que
     event.data.update({'launcher_type': 'group', 'launcher_id': 'spoof'})
     context, _ = await build(event, runner)
     assert context['conversation']['launcher_id'] is None
+    assert context['conversation']['session_id'] is None
 
 
 @pytest.mark.asyncio
@@ -91,6 +120,7 @@ async def test_provenance_cannot_cross_scope(mock_query, field):
     setattr(event, field, 'different')
     context, _ = await build(event, 'DifyAgent')
     assert context['conversation']['launcher_id'] is None
+    assert context['conversation']['session_id'] is None
 
 
 @pytest.mark.asyncio
@@ -99,6 +129,7 @@ async def test_provenance_cannot_cross_pipeline(mock_query):
     event.legacy_identity.pipeline_id = 'other-pipeline'
     context, _ = await build(event, 'DifyAgent')
     assert context['conversation']['launcher_id'] is None
+    assert context['conversation']['session_id'] is None
 
 
 @pytest.mark.asyncio