Telegram allows commenting on a channel post or on a generic supergroup message, thanks to message threads.
Schema:
messageReplyHeader#afbc09db flags:# reply_to_scheduled:flags.2?true forum_topic:flags.3?true quote:flags.9?true reply_to_msg_id:flags.4?int reply_to_peer_id:flags.0?Peer reply_from:flags.5?MessageFwdHeader reply_media:flags.8?MessageMedia reply_to_top_id:flags.1?int quote_text:flags.6?string quote_entities:flags.7?Vector<MessageEntity> quote_offset:flags.10?int = MessageReplyHeader;
messageReplies#83d60fc2 flags:# comments:flags.0?true replies:int replies_pts:int recent_repliers:flags.1?Vector<Peer> channel_id:flags.0?long max_id:flags.2?int read_max_id:flags.3?int = MessageReplies;
message#76bec211 flags:# out:flags.1?true mentioned:flags.4?true media_unread:flags.5?true silent:flags.13?true post:flags.14?true from_scheduled:flags.18?true legacy:flags.19?true edit_hide:flags.21?true pinned:flags.24?true noforwards:flags.26?true invert_media:flags.27?true id:int from_id:flags.8?Peer peer_id:Peer saved_peer_id:flags.28?Peer fwd_from:flags.2?MessageFwdHeader via_bot_id:flags.11?long reply_to:flags.3?MessageReplyHeader date:int message:string media:flags.9?MessageMedia reply_markup:flags.6?ReplyMarkup entities:flags.7?Vector<MessageEntity> views:flags.10?int forwards:flags.10?int replies:flags.23?MessageReplies edit_date:flags.15?int post_author:flags.16?string grouped_id:flags.17?long reactions:flags.20?MessageReactions restriction_reason:flags.22?Vector<RestrictionReason> ttl_period:flags.25?int = Message;
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messages.search#a7b4e929 flags:# peer:InputPeer q:string from_id:flags.0?InputPeer saved_peer_id:flags.2?InputPeer top_msg_id:flags.1?int filter:MessagesFilter min_date:int max_date:int offset_id:int add_offset:int limit:int max_id:int min_id:int hash:long = messages.Messages;Threads are usually automatically created when replying to any message in a group.
For example, all replies to a message with ID 420 are associated to thread with ID 420, unique to this group; this thread ID is contained in the reply_to_top_id field of reply_to messageReplyHeader, along with an eventual reply_to_msg_id, for replies to messages within a thread.
Replies to messages in a thread are part of the same thread, and do not spawn new threads.
When receiving a message from a group that is also the top of a thread (the message with ID 420), the replies optional field will contain a messageReplies constructor, containing the message ID and PTS of the latest reply in the thread, and the message ID of the latest read thread reply, along with the total number of replies in the thread.
Replies to a thread can also be manually fetched using messages.search, providing to top_msg_id the thread ID.
The same messageReplies constructor seen above will also be contained in channel posts, this time containing information about the comment section of a specific channel post, see here ยป for more info.