The auto-reset notice ("◐ Session automatically reset…") was being sent
with metadata=getattr(event, 'metadata', None), which can drop or
mis-route in Telegram forum topics: the event's metadata isn't
guaranteed to carry the originating thread_id, so the notice could leak
into General or another topic.
Use the existing self._thread_metadata_for_source(source) helper, which
already handles thread_id construction plus the Telegram DM topic
reply-fallback shape used everywhere else in the gateway.
Carve-out of #7404. The PR's other hunk (line 7578, queued first
response) is already redundant on main — gateway/run.py:15782 has used
_status_thread_metadata since the _thread_metadata_for_source plumbing
landed.
Closes#7355 (path B; paths A and C closed via prior salvage merges).