The topic-mode helpers (_telegram_topic_mode_enabled,
_recover_telegram_topic_thread_id, _record/_sync_telegram_topic_binding,
_is_telegram_topic_lane/_root_lobby, _normalize_source_for_session_key,
_telegram_topic_new_header, _schedule_telegram_topic_title_rename, and the
base.py _apply_topic_recovery hook) each run a synchronous SessionDB read or
write. They reach the event loop through async handlers, so a contended
state.db froze the loop the same way the handoff watcher did.
These helpers already run off-loop in the run_sync thread-pool closure, so
they are proven thread-safe there. Rather than colour them async, loop-side
callers now invoke them via asyncio.to_thread(...); the executor callers are
unchanged. Inside the helpers the SessionDB handle is unwrapped to the sync
door (getattr(db, '_db', db)) since they always run on a worker thread, and
AIAgent construction + query_session_listing are handed the sync SessionDB
directly. base.py wraps its single _apply_topic_recovery call in to_thread.
The guard is now alias-aware (catches db = getattr(self, '_session_db', None);
db.method(...)) and enforces the offload contract: the offloaded sync helpers
may never be called bare on the loop. Sibling test fixtures wrap their injected
SessionDB in AsyncSessionDB to match how the gateway holds it.
After compression exhaustion the auto-reset created a fresh session but
discarded reset_session()'s return value and left the Telegram topic
binding pointing at the oversized compressed child. The next inbound
message in that topic healed the binding forward and switch_session'd the
freshly-reset lane back onto the bloated transcript, re-triggering
compression exhaustion in a loop with a new session id each time.
Capture the fresh entry and re-sync the topic binding to it so the next
message starts clean. No-op on non-topic lanes.
Regression of the #9893/#10063 auto-reset fix.
Fixes#35809
