Every adapter-side lane (text/photo/album batch dicts, _active_sessions, the
busy guard, /stop /new /reset and clarify replies) derived its session key
before the receiving bot's identity was known, so two bots seeing the same
Telegram chat.id == user.id collided on one agent:main lane and a route to an
unserved profile still reached the default lane's running task.
BasePlatformAdapter._canonicalize pins the RoutingIdentity (via the new
session_identity.canonical_identity seam) as the FIRST statement of
handle_message, _enqueue_text_event, _handle_message_while_active, Telegram
_route_photo_event and every _source_session_key; _drop_unresolved drops a
rejected route at the first seam with one WARNING. Topic recovery copies the
source through replace_source so the identity travels; Slack thread sources go
through build_source so the thread key carries the same provenance.
1654575c6c