Summary

• include message_thread_id for DM-scoped Telegram threads in buildTelegramThreadParams
• keep existing forum behavior (thread_id=1 still omitted for forum sends)
• update Telegram delivery and draft-stream tests to assert DM topic thread IDs are sent
• update helper tests to cover DM topic inclusion + normalization guardrails

Regression coverage

• src/telegram/bot/helpers.test.ts
• src/telegram/bot/delivery.test.ts
• src/telegram/draft-stream.test.ts

Validation

• pnpm test -- src/telegram

Greptile Summary

This PR fixes Telegram DM topic thread routing by including message_thread_id in API calls for DM-scoped threads. Previously, buildTelegramThreadParams unconditionally dropped thread IDs for DM scope because Telegram private chats historically didn't support topics. Telegram now supports "Topics in Private Chats," so the helper is updated to include message_thread_id when the normalized thread ID is positive, while still omitting non-positive values (0, negative) as invalid.

• buildTelegramThreadParams now returns { message_thread_id: normalized } for DM threads with positive IDs, instead of always returning undefined
• DM thread ID 1 is correctly included (unlike forum scope where 1 is the General topic and must be skipped)
• Tests across delivery, draft-stream, and helpers are updated to assert the new DM topic inclusion behavior
• Edge case normalization (truncation, non-positive values) is preserved and tested

Confidence Score: 5/5

• This PR is safe to merge with minimal risk — it's a targeted behavioral fix with comprehensive test coverage.
• The change is a small, well-scoped fix to a single function (buildTelegramThreadParams) with a clear behavioral rationale (Telegram now supports DM topics). The implementation correctly handles edge cases (non-positive IDs, truncation), maintains forum behavior (General topic id=1 still omitted), and all three test files are updated to cover the new behavior. No new dependencies, no architectural changes, and the diff is minimal.
• No files require special attention.

_{Last reviewed commit: fd055a0}