fix(telegram): restore typing indicator and thread routing for forum General topic

In Telegram forum-enabled groups, the General topic does not include
message_thread_id in incoming messages (it is None). This caused:
1. Messages in General losing thread context — replies went to wrong place
2. Typing indicator failing because thread_id=1 was rejected by Telegram

Fix: synthesize thread_id="1" for forum groups when message_thread_id
is None, then handle it correctly per operation:
- send: omit message_thread_id (Telegram rejects thread_id=1 for sends)
- typing: pass thread_id=1, retry without it on "thread not found"

Also centralizes thread_id extraction into _metadata_thread_id() across
all send methods (send, send_voice, send_image, send_document, send_video,
send_animation, send_photo), replacing ~10 duplicate patterns.

Salvaged from PR #7892 by @corazzione.
Closes #7877, closes #7519.

tests/gateway/test_telegram_thread_fallback.py

@@ -45,6 +45,11 @@ class FakeRetryAfter(Exception):
 
 # Build a fake telegram module tree so the adapter's internal imports work
 _fake_telegram = types.ModuleType("telegram")
+_fake_telegram.Update = object
+_fake_telegram.Bot = object
+_fake_telegram.Message = object
+_fake_telegram.InlineKeyboardButton = object
+_fake_telegram.InlineKeyboardMarkup = object
 _fake_telegram_error = types.ModuleType("telegram.error")
 _fake_telegram_error.NetworkError = FakeNetworkError
 _fake_telegram_error.BadRequest = FakeBadRequest
@@ -52,7 +57,21 @@ _fake_telegram_error.TimedOut = FakeTimedOut
 _fake_telegram.error = _fake_telegram_error
 _fake_telegram_constants = types.ModuleType("telegram.constants")
 _fake_telegram_constants.ParseMode = SimpleNamespace(MARKDOWN_V2="MarkdownV2")
+_fake_telegram_constants.ChatType = SimpleNamespace(
+    GROUP="group",
+    SUPERGROUP="supergroup",
+    CHANNEL="channel",
+)
 _fake_telegram.constants = _fake_telegram_constants
+_fake_telegram_ext = types.ModuleType("telegram.ext")
+_fake_telegram_ext.Application = object
+_fake_telegram_ext.CommandHandler = object
+_fake_telegram_ext.CallbackQueryHandler = object
+_fake_telegram_ext.MessageHandler = object
+_fake_telegram_ext.ContextTypes = SimpleNamespace(DEFAULT_TYPE=object)
+_fake_telegram_ext.filters = object
+_fake_telegram_request = types.ModuleType("telegram.request")
+_fake_telegram_request.HTTPXRequest = object
 
 
 @pytest.fixture(autouse=True)
@@ -61,6 +80,8 @@ def _inject_fake_telegram(monkeypatch):
     monkeypatch.setitem(sys.modules, "telegram", _fake_telegram)
     monkeypatch.setitem(sys.modules, "telegram.error", _fake_telegram_error)
     monkeypatch.setitem(sys.modules, "telegram.constants", _fake_telegram_constants)
+    monkeypatch.setitem(sys.modules, "telegram.ext", _fake_telegram_ext)
+    monkeypatch.setitem(sys.modules, "telegram.request", _fake_telegram_request)
 
 
 def _make_adapter():
@@ -68,6 +89,7 @@ def _make_adapter():
 
     config = PlatformConfig(enabled=True, token="fake-token")
     adapter = object.__new__(TelegramAdapter)
+    adapter.config = config
     adapter._config = config
     adapter._platform = Platform.TELEGRAM
     adapter._connected = True
@@ -82,6 +104,81 @@ def _make_adapter():
     return adapter
 
 
+def test_forum_general_topic_without_message_thread_id_keeps_thread_context():
+    """Forum General-topic messages should keep synthetic thread context."""
+    from gateway.platforms import telegram as telegram_mod
+
+    adapter = _make_adapter()
+    message = SimpleNamespace(
+        text="hello from General",
+        caption=None,
+        chat=SimpleNamespace(
+            id=-100123,
+            type=telegram_mod.ChatType.SUPERGROUP,
+            is_forum=True,
+            title="Forum group",
+        ),
+        from_user=SimpleNamespace(id=456, full_name="Alice"),
+        message_thread_id=None,
+        reply_to_message=None,
+        message_id=10,
+        date=None,
+    )
+
+    event = adapter._build_message_event(message, msg_type=SimpleNamespace(value="text"))
+
+    assert event.source.chat_id == "-100123"
+    assert event.source.chat_type == "group"
+    assert event.source.thread_id == "1"
+
+
+@pytest.mark.asyncio
+async def test_send_omits_general_topic_thread_id():
+    """Telegram sends to forum General should omit message_thread_id=1."""
+    adapter = _make_adapter()
+    call_log = []
+
+    async def mock_send_message(**kwargs):
+        call_log.append(dict(kwargs))
+        return SimpleNamespace(message_id=42)
+
+    adapter._bot = SimpleNamespace(send_message=mock_send_message)
+
+    result = await adapter.send(
+        chat_id="-100123",
+        content="test message",
+        metadata={"thread_id": "1"},
+    )
+
+    assert result.success is True
+    assert len(call_log) == 1
+    assert call_log[0]["chat_id"] == -100123
+    assert call_log[0]["text"] == "test message"
+    assert call_log[0]["reply_to_message_id"] is None
+    assert call_log[0]["message_thread_id"] is None
+
+
+@pytest.mark.asyncio
+async def test_send_typing_retries_without_general_thread_when_not_found():
+    """Typing for forum General should fall back if Telegram rejects thread 1."""
+    adapter = _make_adapter()
+    call_log = []
+
+    async def mock_send_chat_action(**kwargs):
+        call_log.append(dict(kwargs))
+        if kwargs.get("message_thread_id") == 1:
+            raise FakeBadRequest("Message thread not found")
+
+    adapter._bot = SimpleNamespace(send_chat_action=mock_send_chat_action)
+
+    await adapter.send_typing("-100123", metadata={"thread_id": "1"})
+
+    assert call_log == [
+        {"chat_id": -100123, "action": "typing", "message_thread_id": 1},
+        {"chat_id": -100123, "action": "typing", "message_thread_id": None},
+    ]
+
+
 @pytest.mark.asyncio
 async def test_send_retries_without_thread_on_thread_not_found():
     """When message_thread_id causes 'thread not found', retry without it."""