feat: support Bot API 10.3

[ingvarch]

Adds full Bot API 10.3 support (August 24, 2026), following the existing RichBlock / RichText tagged-union (marshalVariant) and rawRequest patterns.

Rich Messages

• New RichMessageButton and the RichTextButton variant of the RichText union (type: "button").
• New block types in the RichBlock and InputRichBlock unions:
  RichBlockButtons / InputRichBlockButtons,
  RichBlockExpandableBlockQuotation / InputRichBlockExpandableBlockQuotation,
  RichBlockDocument / InputRichBlockDocument, with the matching
  RichBlockType* constants.
• is_compact on RichBlockTable and InputRichBlockTable.
• tg://document?id= links documented for InputRichMessageMedia.

Ephemeral Messages

• New models.EphemeralMessageParameters (receiver_user_id, callback_query_id, replace_callback_query_message).
• The 13 send methods (sendMessage, sendAnimation, sendAudio, sendDocument, sendLivePhoto, sendPhoto, sendSticker, sendVideo, sendVideoNote, sendVoice, sendContact, sendLocation, sendVenue) now take ephemeral_message_parameters instead of receiver_user_id + callback_query_id; the same parameter is added to sendRichMessage.
• rich_message on editEphemeralMessageText (text is now optional, as it is required only when rich_message is not given).
• show_caption_above_media on editEphemeralMessageCaption.
• Upload of new files in editEphemeralMessageMedia: the existing InputMedia form handling already attaches attach:// files; covered by a test that asserts the multipart file part.
• can_send_welcome_messages on ChatAdministratorRights, ChatMemberAdministrator and promoteChatMember.

Reply markup

• New DisabledButton with the disabled field on InlineKeyboardButton.
• force_reply on InlineKeyboardMarkup and ReplyKeyboardMarkup.

General

• can_stop and keep_on_stop on sendMessageDraft and sendRichMessageDraft.
• New MessageGenerationStopped with the stopped_message_generation field on Update and the AllowedUpdateStoppedMessageGeneration constant.
• New CommunityChatJoined with community_chat_joined on Message.
• text, entities and is_private on UniqueGiftInfo.
• README and CHANGELOG bumped to 10.3 (v1.24.0).

Breaking change

ReceiverUserID and CallbackQueryID are removed from the send method params (SendMessageParams, SendPhotoParams, ...). Bot API 10.3 replaced them with EphemeralMessageParameters:

// before
b.SendMessage(ctx, &bot.SendMessageParams{ChatID: id, Text: "hi", ReceiverUserID: uid, CallbackQueryID: cq})

// after
b.SendMessage(ctx, &bot.SendMessageParams{
      ChatID: id,
      Text:   "hi",
      EphemeralMessageParameters: &models.EphemeralMessageParameters{ReceiverUserID: uid, CallbackQueryID: cq},
})

AnswerCallbackQueryParams.CallbackQueryID is unchanged.

[ingvarch]

@negasus Pls review 🙏

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Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 48.35%. Comparing base (d7672bb) to head (8c6bcec).
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Additional details and impacted files

@@            Coverage Diff             @@
##             main     #295      +/-   ##
==========================================
+ Coverage   43.80%   48.35%   +4.54%     
==========================================
  Files          34       34              
  Lines        2785     2827      +42     
==========================================
+ Hits         1220     1367     +147     
+ Misses       1506     1400     -106     
- Partials       59       60       +1     

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[negasus]

Excellent work. I went through this against the official 10.3 documentation rather than just the changelog — pulled the API page and diffed the field tables of every new type against what you wrote — and it holds up completely.

What I verified:

• All 22 changelog items are implemented, nothing missing and nothing invented.
• Field tables match the docs exactly for RichMessageButton (all 11 fields), RichTextButton, RichBlockButtons / InputRichBlockButtons including align, RichBlockDocument (Document) and InputRichBlockDocument (InputMediaDocument, caption ignored), RichBlockExpandableBlockQuotation, DisabledButton, EphemeralMessageParameters, MessageGenerationStopped, CommunityChatJoined — names, types, json tags, optionality, and the discriminator values (expandable_blockquote, buttons, document, button).
• All 14 methods got ephemeral_message_parameters — the 13 send methods plus sendRichMessage, with the old receiver_user_id / callback_query_id removed from exactly those and left in place where the docs still have them (answerCallbackQuery, the editEphemeralMessage* and deleteEphemeralMessage methods). The examples still build.
• The tagged-union additions follow the existing marshalVariant pattern on both the marshal and unmarshal side, for both RichBlock and InputRichBlock.
• go build, go test ./..., go vet, gofmt all clean.

One detail worth calling out because it looked like a slip and is not: can_send_welcome_messages without omitempty on ChatAdministratorRights and ChatMemberAdministrator is correct — that field is required in the docs, while the can_manage_tags / can_manage_topics neighbours are Optional. Nice attention to detail. (It did surface some older drift on our side: can_post_stories, can_edit_stories and can_delete_stories are required in the docs but carry omitempty here. Not yours, I will deal with it separately.)

The tests are the right kind, too — asserting actual multipart field values, including the attach:// part in EditEphemeralMessageMedia, rather than just round-tripping structs.

Merging as is. I am going to adjust the CHANGELOG myself in a follow-up commit: the version and its date are mine to pick when I cut the release, and I need to fold in the #297 entry that landed just before this.

Separately, while checking the tg://document?id= item I found that attachments inside rich messages never reach the multipart form at all — buildRequestForm has no case for InputRichMessage, so it falls through to plain JSON encoding and the attach:// file part is silently dropped. That predates this PR (I reproduced it on main, it has been there since 10.1), so it is not a blocker here, but 10.3 makes it more visible. I will open an issue for it.

[negasus]

Opened #298 for the rich message attachment gap I mentioned — it turned out to cover more than the document case: everything nested inside InputRichMessage is affected, both the Media array and the media-carrying InputRichBlock* types, across sendRichMessage, sendRichMessageDraft, editMessageText and editEphemeralMessageText. Again, not from your changes — it predates them.

I also adjusted the CHANGELOG after merging, as I said I would: dated v1.24.0 to the release day rather than the API release day, folded in #297, and used the [BREAKING] prefix that earlier entries use. And I fixed the older omitempty drift on can_post_stories / can_edit_stories / can_delete_stories that your PR made me notice. Thanks again for the thorough work.