fix(line): map LINE mentions to At elements so the at-bot rule works (#2478)

The LINE adapter passed text through as a single Plain component,
ignoring the mention payload (mentions[].index/length/isSelf) that the
Line Messaging API includes in the webhook. As a result:

- At(target=bot_account_id) never appeared in the message chain, so the
  'at-bot' group respond rule silently dropped every @bot mention.
- The bot only replied when the message happened to match the prefix
  rule (e.g. starting with 'ai').

Now LINEMessageConverter reads message.message.mention and builds the
chain per mention position:

- Bot mention (isSelf) -> At(target=bot_account_id) so AtBotRule matches
  the same way as other adapters (dingtalk/lark etc.).
- Other mentions -> At(target=<line user id>, display=<mention text>).
  At.__str__ already prepends '@', so the display text carries no
  double '@' and the rendered text (prefix/regexp rules, quotes,
  session context) is byte-identical to before.
- Missing/out-of-bounds mentions are skipped defensively.

target2yiri becomes an instance method (like wechatpad/aiocqhttp) so
the converters can hold bot_account_id; LINEAdapter passes it in from
its own config.

tests/unit_tests/platform/test_line_session_identity.py

@@ -3,18 +3,25 @@ from __future__ import annotations
 import pytest
 from unittest.mock import MagicMock
 
-from linebot.v3.webhooks import TextMessageContent
+from linebot.v3.webhooks import TextMessageContent, UserMentionee, AllMentionee
 
 from langbot.pkg.platform import botmgr as _botmgr  # noqa: F401
 from langbot.pkg.platform.sources import line
+import langbot_plugin.api.entities.builtin.platform.message as platform_message
+
+BOT_ACCOUNT_ID = 'line-bot-account'
 
 
-def _make_event(*, source_type: str, user_id, group_id=None, room_id=None, message_id: str, text: str = 'hi'):
+def _make_event(
+    *, source_type: str, user_id, group_id=None, room_id=None, message_id: str, text: str = 'hi', mention=None
+):
     event = MagicMock()
     event.timestamp = 1700000000000
-    event.message = MagicMock(spec=TextMessageContent)
-    event.message.id = message_id
-    event.message.text = text
+    message = MagicMock(spec=TextMessageContent)
+    message.id = message_id
+    message.text = text
+    message.mention = mention
+    event.message = message
     event.message.webhook_event_id = f'webhook-{message_id}'
     event.message.timestamp = event.timestamp
 
@@ -30,16 +37,21 @@ def _make_event(*, source_type: str, user_id, group_id=None, room_id=None, messa
     return event
 
 
+def _make_converter(bot_account_id: str = BOT_ACCOUNT_ID) -> line.LINEEventConverter:
+    return line.LINEEventConverter(bot_account_id=bot_account_id)
+
+
 @pytest.mark.asyncio
 async def test_user_message_launcher_id_stable_across_messages() -> None:
     """Two distinct messages from the same LINE user must resolve to the same
     sender id, otherwise every message starts a brand new session (context loss).
     """
+    converter = _make_converter()
     event1 = _make_event(source_type='user', user_id='U-stable-user', message_id='msg-1')
     event2 = _make_event(source_type='user', user_id='U-stable-user', message_id='msg-2')
 
-    result1 = await line.LINEEventConverter.target2yiri(event1, bot_client=None)
-    result2 = await line.LINEEventConverter.target2yiri(event2, bot_client=None)
+    result1 = await converter.target2yiri(event1, bot_client=None)
+    result2 = await converter.target2yiri(event2, bot_client=None)
 
     assert result1.sender.id == 'U-stable-user'
     assert result1.sender.id == result2.sender.id
@@ -48,11 +60,12 @@ async def test_user_message_launcher_id_stable_across_messages() -> None:
 
 @pytest.mark.asyncio
 async def test_group_message_uses_group_id_not_message_id() -> None:
+    converter = _make_converter()
     event1 = _make_event(source_type='group', user_id='U-member', group_id='G-stable-group', message_id='msg-1')
     event2 = _make_event(source_type='group', user_id='U-member', group_id='G-stable-group', message_id='msg-2')
 
-    result1 = await line.LINEEventConverter.target2yiri(event1, bot_client=None)
-    result2 = await line.LINEEventConverter.target2yiri(event2, bot_client=None)
+    result1 = await converter.target2yiri(event1, bot_client=None)
+    result2 = await converter.target2yiri(event2, bot_client=None)
 
     assert result1.sender.group.id == 'G-stable-group'
     assert result1.sender.group.id == result2.sender.group.id
@@ -61,9 +74,186 @@ async def test_group_message_uses_group_id_not_message_id() -> None:
 
 @pytest.mark.asyncio
 async def test_room_message_uses_room_id_and_falls_back_when_user_id_missing() -> None:
+    converter = _make_converter()
     event = _make_event(source_type='room', user_id=None, room_id='R-stable-room', message_id='msg-1')
 
-    result = await line.LINEEventConverter.target2yiri(event, bot_client=None)
+    result = await converter.target2yiri(event, bot_client=None)
 
     assert result.sender.group.id == 'R-stable-room'
     assert result.sender.id == 'R-stable-room'
+
+
+def _plain_texts(chain: platform_message.MessageChain) -> list[str]:
+    return [c.text for c in chain if isinstance(c, platform_message.Plain)]
+
+
+def _ats(chain: platform_message.MessageChain) -> list[platform_message.At]:
+    return [c for c in chain if isinstance(c, platform_message.At)]
+
+
+@pytest.mark.asyncio
+async def test_no_mention_keeps_plain_text() -> None:
+    converter = _make_converter()
+    event = _make_event(source_type='group', user_id='U-member', group_id='G1', message_id='m1', text='hello world')
+
+    chain = await converter.message_converter.target2yiri(event, bot_client=None)
+
+    assert _plain_texts(chain) == ['hello world']
+    assert _ats(chain) == []
+
+
+@pytest.mark.asyncio
+async def test_bot_mention_maps_to_at_with_bot_account_id() -> None:
+    """A @bot mention must become At(target=bot_account_id) so the 'at-bot'
+    group respond rule matches (previously the mention was lost and the message
+    was silently dropped in groups with at-only rules).
+    """
+    mention = MagicMock()
+    mention.mentionees = [
+        UserMentionee(type='user', index=0, length=4, userId='U-bot-user-id', isSelf=True),
+    ]
+    converter = _make_converter()
+    event = _make_event(
+        source_type='group',
+        user_id='U-member',
+        group_id='G1',
+        message_id='m1',
+        text='@BOT hey',
+        mention=mention,
+    )
+
+    chain = await converter.message_converter.target2yiri(event, bot_client=None)
+
+    ats = _ats(chain)
+    assert len(ats) == 1
+    assert ats[0].target == BOT_ACCOUNT_ID
+    assert _plain_texts(chain) == [' hey']
+
+
+@pytest.mark.asyncio
+async def test_other_user_mention_keeps_display_text() -> None:
+    """Mentions of other users keep their display text in the message string,
+    so prefix/regexp rules that match the raw '@Name ...' text still work.
+    """
+    mention = MagicMock()
+    mention.mentionees = [
+        UserMentionee(type='user', index=0, length=6, userId='U-other', isSelf=False),
+    ]
+    converter = _make_converter()
+    event = _make_event(
+        source_type='group',
+        user_id='U-member',
+        group_id='G1',
+        message_id='m1',
+        text='@Alice hello',
+        mention=mention,
+    )
+
+    chain = await converter.message_converter.target2yiri(event, bot_client=None)
+
+    ats = _ats(chain)
+    assert len(ats) == 1
+    assert ats[0].target == 'U-other'
+    # str() of the At component falls back to display when set
+    assert str(chain) == '@Alice hello'
+
+
+@pytest.mark.asyncio
+async def test_bot_mention_triggers_atbot_rule() -> None:
+    """End-to-end: a group message that @mentions the bot must be accepted by
+    the at-bot respond rule (this is the regression that silently dropped
+    '@bot' messages in LINE groups).
+    """
+    from langbot.pkg.pipeline.resprule.rules.atbot import AtBotRule
+
+    mention = MagicMock()
+    mention.mentionees = [
+        UserMentionee(type='user', index=0, length=6, userId='U-bot-user-id', isSelf=True),
+    ]
+    converter = _make_converter()
+    event = _make_event(
+        source_type='group',
+        user_id='U-member',
+        group_id='G1',
+        message_id='m1',
+        text='@RAIQt hi',
+        mention=mention,
+    )
+
+    chain = await converter.message_converter.target2yiri(event, bot_client=None)
+
+    query = MagicMock()
+    query.adapter = MagicMock()
+    query.adapter.bot_account_id = BOT_ACCOUNT_ID
+
+    rule = AtBotRule(ap=MagicMock())
+    result = await rule.match(str(chain), chain, {'at': True}, query)
+
+    assert result.matching is True
+
+
+@pytest.mark.asyncio
+async def test_group_without_bot_mention_still_dropped_by_atbot_rule() -> None:
+    from langbot.pkg.pipeline.resprule.rules.atbot import AtBotRule
+
+    converter = _make_converter()
+    event = _make_event(source_type='group', user_id='U-member', group_id='G1', message_id='m1', text='hello')
+
+    chain = await converter.message_converter.target2yiri(event, bot_client=None)
+
+    query = MagicMock()
+    query.adapter = MagicMock()
+    query.adapter.bot_account_id = BOT_ACCOUNT_ID
+
+    rule = AtBotRule(ap=MagicMock())
+    result = await rule.match(str(chain), chain, {'at': True}, query)
+
+    assert result.matching is False
+
+
+@pytest.mark.asyncio
+async def test_at_all_mention_preserved_as_at_component() -> None:
+    mention = MagicMock()
+    mention.mentionees = [
+        AllMentionee(type='all', index=0, length=4),
+    ]
+    converter = _make_converter()
+    event = _make_event(
+        source_type='group',
+        user_id='U-member',
+        group_id='G1',
+        message_id='m1',
+        text='@All hello',
+        mention=mention,
+    )
+
+    chain = await converter.message_converter.target2yiri(event, bot_client=None)
+
+    ats = _ats(chain)
+    assert len(ats) == 1
+    assert str(chain) == '@All hello'
+
+
+@pytest.mark.asyncio
+async def test_multiple_mentions_sorted_by_position() -> None:
+    mention = MagicMock()
+    # Intentionally out of order to exercise sorting
+    mention.mentionees = [
+        UserMentionee(type='user', index=9, length=4, userId='U-b', isSelf=False),
+        UserMentionee(type='user', index=0, length=4, userId='U-a', isSelf=False),
+    ]
+    converter = _make_converter()
+    event = _make_event(
+        source_type='group',
+        user_id='U-member',
+        group_id='G1',
+        message_id='m1',
+        text='@aaa mid @bbb tail',
+        mention=mention,
+    )
+
+    chain = await converter.message_converter.target2yiri(event, bot_client=None)
+
+    ats = _ats(chain)
+    assert [a.target for a in ats] == ['U-a', 'U-b']
+    assert str(chain) == '@aaa mid @bbb tail'