fix(embed): isolate browser chat sessions (#2335)

* fix(embed): isolate browser chat sessions

* fix(embed): harden reset and reconnect recovery

tests/unit_tests/platform/test_websocket_session_isolation.py

@@ -0,0 +1,267 @@
+"""Regression tests for isolated embed-widget conversations."""
+
+import asyncio
+from pathlib import Path
+from unittest.mock import AsyncMock, Mock
+
+import pytest
+
+import langbot_plugin.api.entities.builtin.platform.events as platform_events
+from langbot.pkg.platform.sources import websocket_adapter as websocket_adapter_module
+from langbot.pkg.platform.sources.websocket_adapter import WebSocketAdapter, WebSocketMessage, WebSocketSession
+from langbot.pkg.platform.sources.websocket_manager import WebSocketConnectionManager, is_valid_session_id
+
+
+@pytest.mark.asyncio
+async def test_broadcast_only_reaches_connections_in_same_browser_session():
+    manager = WebSocketConnectionManager()
+    first = await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-1',
+        session_type='person',
+        session_id='session-a',
+    )
+    second = await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-1',
+        session_type='person',
+        session_id='session-b',
+    )
+    dashboard = await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-1',
+        session_type='person',
+    )
+
+    await manager.broadcast_to_pipeline(
+        'pipeline-1',
+        {'type': 'response'},
+        session_type='person',
+        session_id='session-a',
+    )
+
+    assert await first.send_queue.get() == {'type': 'response'}
+    assert second.send_queue.empty()
+    assert dashboard.send_queue.empty()
+
+    await manager.broadcast_to_pipeline(
+        'pipeline-1',
+        {'type': 'dashboard-response'},
+        session_type='person',
+        session_id=None,
+    )
+
+    assert await dashboard.send_queue.get() == {'type': 'dashboard-response'}
+    assert first.send_queue.empty()
+    assert second.send_queue.empty()
+
+
+@pytest.mark.asyncio
+async def test_embed_event_uses_stable_session_launcher(monkeypatch):
+    manager = WebSocketConnectionManager()
+    session_id = '31c0f2e9-b115-4ee6-8f15-3e624d6456b1'
+    connection = await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-1',
+        session_type='person',
+        session_id=session_id,
+    )
+    monkeypatch.setattr(websocket_adapter_module, 'ws_connection_manager', manager)
+
+    adapter = WebSocketAdapter.model_construct(ap=Mock(), logger=AsyncMock())
+    adapter.websocket_person_session = WebSocketSession(id='person')
+    adapter.websocket_group_session = WebSocketSession(id='group')
+    received = []
+
+    async def listener(event, _callback_adapter):
+        received.append(event)
+
+    adapter.listeners = {platform_events.FriendMessage: listener}
+    await adapter.handle_websocket_message(
+        connection,
+        {'message': [{'type': 'Plain', 'text': 'hello'}], 'stream': False},
+    )
+    await asyncio.sleep(0)
+
+    assert received[0].sender.id == f'websocket_pipeline-1:{session_id}'
+
+
+@pytest.mark.asyncio
+async def test_embed_group_event_uses_stable_session_launcher(monkeypatch):
+    manager = WebSocketConnectionManager()
+    session_id = '31c0f2e9-b115-4ee6-8f15-3e624d6456b1'
+    connection = await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-1',
+        session_type='group',
+        session_id=session_id,
+    )
+    monkeypatch.setattr(websocket_adapter_module, 'ws_connection_manager', manager)
+
+    adapter = WebSocketAdapter.model_construct(ap=Mock(), logger=AsyncMock())
+    adapter.websocket_person_session = WebSocketSession(id='person')
+    adapter.websocket_group_session = WebSocketSession(id='group')
+    received = []
+
+    async def listener(event, _callback_adapter):
+        received.append(event)
+
+    adapter.listeners = {platform_events.GroupMessage: listener}
+    await adapter.handle_websocket_message(
+        connection,
+        {'message': [{'type': 'Plain', 'text': 'hello'}], 'stream': False},
+    )
+    await asyncio.sleep(0)
+
+    assert received[0].sender.id == f'websocket_pipeline-1:{session_id}'
+    assert received[0].sender.group.id == f'websocketgroup_pipeline-1:{session_id}'
+
+    dashboard = await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-1',
+        session_type='group',
+    )
+    await adapter.handle_websocket_message(
+        dashboard,
+        {'stream': False, 'message': [{'type': 'Plain', 'text': 'dashboard'}]},
+        None,
+    )
+    await asyncio.sleep(0)
+
+    assert received[1].sender.id == f'websocket_{dashboard.connection_id}'
+    assert received[1].sender.group.id == 'websocketgroup'
+
+
+@pytest.mark.asyncio
+async def test_stable_session_launcher_resolves_to_active_connection(monkeypatch):
+    manager = WebSocketConnectionManager()
+    session_id = '31c0f2e9-b115-4ee6-8f15-3e624d6456b1'
+    await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-2',
+        session_type='person',
+        session_id=session_id,
+    )
+    connection = await manager.add_connection(
+        websocket=Mock(),
+        pipeline_uuid='pipeline-1',
+        session_type='person',
+        session_id=session_id,
+    )
+    monkeypatch.setattr(websocket_adapter_module, 'ws_connection_manager', manager)
+
+    adapter = WebSocketAdapter.model_construct(ap=Mock(), logger=AsyncMock())
+    message_source = Mock()
+    message_source.sender.id = f'websocket_pipeline-1:{session_id}'
+
+    assert await adapter._get_message_context(message_source) == ('pipeline-1', session_id)
+    assert await adapter._get_connection_from_target(f'websocketgroup_pipeline-1:{session_id}') is connection
+    assert await manager.get_connection_by_session_id(session_id, 'pipeline-1') is connection
+
+    await manager.remove_connection(connection.connection_id)
+
+    assert await adapter._get_message_context(message_source) == ('pipeline-1', session_id)
+    assert await manager.get_connection_by_session_id(session_id, 'pipeline-1') is None
+
+
+def test_session_ids_must_be_canonical_random_uuids():
+    assert is_valid_session_id('31c0f2e9-b115-4ee6-8f15-3e624d6456b1')
+    assert not is_valid_session_id('session-a')
+    assert not is_valid_session_id('00000000-0000-0000-0000-000000000000')
+
+
+def test_history_read_does_not_allocate_unknown_session():
+    adapter = WebSocketAdapter.model_construct(ap=Mock(), logger=AsyncMock())
+    adapter.websocket_person_session = WebSocketSession(id='person')
+    adapter.websocket_group_session = WebSocketSession(id='group')
+
+    assert adapter.get_websocket_messages('pipeline-1', 'person', 'missing-session') == []
+    assert adapter.websocket_person_session.message_lists == {}
+
+
+def test_history_and_reset_are_scoped_to_browser_session():
+    matching_provider_session = Mock(
+        launcher_type=Mock(value='person'),
+        launcher_id='websocket_pipeline-1:session-a',
+    )
+    matching_group_provider_session = Mock(
+        launcher_type=Mock(value='group'),
+        launcher_id='websocketgroup_pipeline-1:session-a',
+    )
+    other_session = Mock(
+        launcher_type=Mock(value='person'),
+        launcher_id='websocket_pipeline-1:session-b',
+    )
+    ap = Mock()
+    ap.sess_mgr.session_list = [
+        matching_provider_session,
+        matching_group_provider_session,
+        other_session,
+    ]
+    adapter = WebSocketAdapter.model_construct(
+        ap=ap,
+        logger=AsyncMock(),
+    )
+    adapter.websocket_person_session = Mock()
+    adapter.websocket_group_session = Mock()
+
+    session_a = [
+        WebSocketMessage(
+            id=1,
+            role='user',
+            content='private-a',
+            message_chain=[],
+            timestamp='2026-07-13T00:00:00',
+        )
+    ]
+    session_b = [
+        WebSocketMessage(
+            id=1,
+            role='user',
+            content='private-b',
+            message_chain=[],
+            timestamp='2026-07-13T00:00:00',
+        )
+    ]
+    histories = {
+        'pipeline-1:session-a': session_a,
+        'pipeline-1:session-b': session_b,
+    }
+    stream_indexes = {
+        'pipeline-1:session-a': {'response-a': 0},
+        'pipeline-1:session-b': {'response-b': 0},
+    }
+    adapter.websocket_person_session.get_message_list.side_effect = histories.__getitem__
+    adapter.websocket_person_session.message_lists = histories
+    adapter.websocket_person_session.stream_message_indexes = stream_indexes
+    adapter.websocket_group_session.message_lists = {}
+    adapter.websocket_group_session.stream_message_indexes = {}
+
+    assert adapter.get_websocket_messages('pipeline-1', 'person', 'session-a')[0]['content'] == 'private-a'
+    assert adapter.get_websocket_messages('pipeline-1', 'person', 'session-b')[0]['content'] == 'private-b'
+
+    adapter.reset_session('pipeline-1', 'person', 'session-a')
+
+    assert histories['pipeline-1:session-a'] == []
+    assert stream_indexes['pipeline-1:session-a'] == {}
+    assert histories['pipeline-1:session-b'] == session_b
+    assert stream_indexes['pipeline-1:session-b'] == {'response-b': 0}
+    assert ap.sess_mgr.session_list == [matching_group_provider_session, other_session]
+
+    adapter.reset_session('pipeline-1', 'group', 'session-a')
+
+    assert ap.sess_mgr.session_list == [other_session]
+
+
+def test_widget_sends_stable_session_id_to_all_conversation_endpoints():
+    widget_path = Path(__file__).parents[3] / 'src/langbot/templates/embed/widget.js'
+    widget = widget_path.read_text(encoding='utf-8')
+
+    assert 'langbot_embed_session_' in widget
+    assert 'window.sessionStorage' in widget
+    assert 'window.localStorage' not in widget
+    assert 'session_id=' in widget
+    assert widget.count('encodeURIComponent(state.sessionId)') >= 3
+    assert 'loadHistory(true)' in widget
+    assert 'messageVersion !== state.messageVersion' in widget
+    assert 'scheduleHistoryReload();' in widget