fix(gateway): preserve Telegram DM topic routing metadata in synthetic notifications

[Dusk1e]

Summary

Preserve Telegram DM topic routing metadata in synthetic gateway notifications.

This change fixes a routing gap where synthetic notifications such as /update, /restart, and startup home-channel messages could bypass the shared Telegram DM topic metadata path and send with only thread_id. For Telegram DM topic lanes, that could route notifications outside the intended topic.

What Changed

• Centralized synthetic thread metadata generation through the same helper logic used by normal thread-aware replies.
• Preserved chat_type in update and restart marker payloads so post-restart notification paths can reconstruct Telegram DM topic routing correctly.
• Added Telegram DM topic fallback metadata for synthetic sends when the target is a DM topic:
  • telegram_dm_topic_reply_fallback
  • direct_messages_topic_id
• Kept home-channel startup notifications on the same metadata path so configured Telegram DM topic homes stay correctly routed.
• Tightened regression coverage to assert the full Telegram DM topic metadata, not just thread_id.

Testing

Focused regression verification:

• tests/gateway/test_update_command.py::TestHandleUpdateCommand::test_writes_pending_marker — passed
• tests/gateway/test_update_command.py::TestHandleUpdateCommand::test_writes_pending_marker_with_thread_id — passed
• tests/gateway/test_update_command.py::TestSendUpdateNotification::test_sends_notification_with_thread_metadata — passed
• tests/gateway/test_update_command.py::TestSendUpdateNotification::test_defers_notification_while_update_still_running — passed
• tests/gateway/test_update_command.py::TestSendUpdateNotification::test_sends_generic_message_when_no_output — passed
• tests/gateway/test_restart_notification.py::test_restart_command_writes_notify_file — passed
• tests/gateway/test_restart_notification.py::test_restart_command_preserves_thread_id — passed
• tests/gateway/test_restart_notification.py::test_send_home_channel_startup_notification_preserves_thread_metadata — passed
• tests/gateway/test_restart_notification.py::test_send_restart_notification_with_thread — passed
• tests/gateway/test_restart_notification.py::test_shutdown_notifications_use_cached_live_thread_source_when_origin_missing — passed

Focused regression result:

• 10 passed

Broader targeted suite command:

pytest tests/gateway/test_update_command.py tests/gateway/test_restart_notification.py -v --timeout-method=thread

Broader targeted suite result:

• 53 collected
• 47 passed
• 6 failed

Remaining failures from the broader targeted suite:

• tests/gateway/test_update_command.py::TestHandleUpdateCommand::test_spawns_setsid
• tests/gateway/test_update_command.py::TestHandleUpdateCommand::test_fallback_when_no_setsid
• tests/gateway/test_update_command.py::TestSendUpdateNotification::test_sends_notification_with_output
• tests/gateway/test_update_command.py::TestSendUpdateNotification::test_strips_ansi_codes
• tests/gateway/test_update_command.py::TestSendUpdateNotification::test_cleans_up_files_after_notification
• tests/gateway/test_update_command.py::TestSendUpdateNotification::test_cleans_up_on_error

Notes

The scoped regression coverage for this fix is green. The remaining failures are outside the routing change itself and should be handled separately.

[kshitijk4poor]

Merged via #36028 — your commit was cherry-picked onto current main with authorship preserved (it was ~320 commits behind, so a salvage was cleaner than rebasing the branch).

This also fixes the /restart + home-channel "Telegram DM topic delivery requires a reply anchor; refusing to send outside the requested topic" failure: the direct_messages_topic_id metadata you added lets _is_private_dm_topic_send route the notification through the anchorless DM-topic path, so no reply anchor is needed.

I added one small follow-up on top: _is_telegram_dm_topic_target now resolves _get_dm_topic_info on the adapter class (type(adapter)) and treats only dict-shaped returns as a declared topic — instance-level getattr was a false positive for MagicMock test doubles. Mirrors the existing guard in _rename_telegram_topic_for_session_title.

Thanks for the fix! 🙏