Summary

When streamMode: "partial" is active, Telegram reply threading doesn't work even with replyToMode: "all". The draft stream preview message gets sent without reply_to_message_id, and since the final reply is an edit to that same message, threading is permanently lost.

Closes #17880

lobster-biscuit

Root Cause

createTelegramDraftStream in draft-stream.ts only passes forum topic thread params (message_thread_id) to the initial sendMessage call. It never receives or forwards reply_to_message_id. The call site in bot-message-dispatch.ts doesn't pass it either.

Changes

• Before: draft stream preview sent without reply_to_message_id — replies aren't threaded in partial/block stream mode
• After: replyToMessageId threaded through createTelegramDraftStream and merged into the sendMessage params, gated on replyToMode !== "off"
• replyParams construction follows the same flat ternary style as the existing threadParams pattern (no IIFE)

Tests

• draft-stream.test.ts — 4 new tests:
  • reply-only: replyToMessageId passed without thread
  • reply+thread combo: both reply_to_message_id and message_thread_id present
  • no thread, no reply: params are undefined
  • general topic + reply: reply_to_message_id still set when thread resolves to general topic (id=1)
• bot-message-dispatch.test.ts — 2 additions:
  • existing "streams drafts" test now asserts replyToMessageId: 456 is passed to createTelegramDraftStream
  • new test: replyToMode: "off" → replyToMessageId is undefined
• All existing Telegram tests pass
• pnpm build && pnpm check pass

Greptile Summary

Fixes Telegram reply threading for draft stream preview messages. When streamMode: "partial" (or "block") is active, the initial preview message sent via createTelegramDraftStream was missing reply_to_message_id, causing threading to be permanently lost since the final reply is an edit of that same message.

• Adds replyToMessageId parameter to createTelegramDraftStream and merges it into the sendMessage params alongside existing message_thread_id (forum topic) support
• Computes draftReplyToMessageId in bot-message-dispatch.ts, gated on replyToMode !== "off", consistent with how delivery.ts handles reply threading
• The replyParams construction correctly handles all edge cases: reply-only, reply+thread combo, neither, and general topic (id=1) where message_thread_id is suppressed but reply_to_message_id is preserved
• Well-covered with 4 new tests in draft-stream.test.ts and 2 additions in bot-message-dispatch.test.ts

Confidence Score: 5/5

• This PR is safe to merge — it's a targeted bug fix with thorough test coverage and no risk of regression.
• The change is minimal and focused: threading replyToMessageId through to the draft stream's initial sendMessage call. The replyParams construction correctly handles all edge cases (reply-only, reply+thread, neither, general topic). The gating on replyToMode !== "off" is consistent with the existing delivery path. Six new tests cover the relevant scenarios. No behavioral changes to existing code paths.
• No files require special attention.

_{Last reviewed commit: d0eaad8}