fix: create_poll and get_full_chat on basic groups

Two failures left over from the telethon 1.44 bump (#148).

create_poll raised "Poll.__init__() missing 1 required positional
argument: 'hash'" for every call. 1.44 made `hash` required; a poll
being created has no cached server results, so send 0.

get_full_chat raised "Cannot cast InputPeerChat to any kind of
InputChannel" for basic (non-supergroup) groups, because it always
issued channels.GetFullChannelRequest. Route basic groups to
messages.GetFullChatRequest. ChatFull has no participants_count, so
derive it from the member list; channels are unaffected.

Verified against a live account: basic group returns
{"title": "...", "participants_count": 3}, a channel is unchanged,
and create_poll posts a working poll.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>

Author: sergeychernyshov-code

telegram_mcp/tools/chats.py

@@ -735,17 +735,35 @@ async def get_full_chat(chat_id: Union[int, str], account: str = None) -> str:
         cl = get_client(account)
         await ensure_connected(cl)
         entity = await resolve_entity(chat_id, cl)
-        full = await cl(functions.channels.GetFullChannelRequest(channel=entity))
+
+        # Basic ("legacy") groups are not channels: GetFullChannelRequest cannot
+        # cast an InputPeerChat and raises TypeError. They are served by
+        # messages.GetFullChatRequest instead.
+        if isinstance(entity, (Chat, InputPeerChat)):
+            basic_id = getattr(entity, "chat_id", None) or getattr(entity, "id", None)
+            full = await cl(functions.messages.GetFullChatRequest(chat_id=basic_id))
+        else:
+            full = await cl(functions.channels.GetFullChannelRequest(channel=entity))
 
         chat = full.chats[0] if full.chats else None
         full_chat = full.full_chat
 
+        # Channels carry participants_count on the full object; basic groups only
+        # carry the member list, so count that instead.
+        participants_count = getattr(full_chat, "participants_count", None)
+        if participants_count is None:
+            members = getattr(getattr(full_chat, "participants", None), "participants", None)
+            if members is not None:
+                participants_count = len(members)
+
         result = {
             "id": get_marked_id(chat) if chat else None,
             "title": sanitize_name(getattr(chat, "title", None)) if chat else None,
             "username": getattr(chat, "username", None) if chat else None,
-            "about": sanitize_user_content(full_chat.about or "", max_length=1024),
-            "participants_count": getattr(full_chat, "participants_count", None),
+            "about": sanitize_user_content(
+                getattr(full_chat, "about", None) or "", max_length=1024
+            ),
+            "participants_count": participants_count,
             "linked_chat_id": getattr(full_chat, "linked_chat_id", None),
         }
 

telegram_mcp/tools/messages.py

@@ -1542,6 +1542,9 @@ async def create_poll(
                 PollAnswer(text=TextWithEntities(text=option, entities=[]), option=bytes([i]))
                 for i, option in enumerate(options)
             ],
+            # Telethon 1.44 made `hash` a required argument on Poll. It caches
+            # server-side results, so a poll being created sends 0.
+            hash=0,
             multiple_choice=multiple_choice,
             quiz=quiz_mode,
             public_voters=public_votes,