The salvaged fix (#58272) guarded the primary network-error reconnect path.
Issue #58270's Scope section names three more unguarded await updater.stop()
sites that can hang identically on a CLOSE-WAIT socket:
- conflict handler (before the retry back-off sleep)
- conflict-retries-exhausted teardown (before the fatal notify)
- disconnect() teardown (would hang gateway shutdown/restart)
Each is now wrapped in asyncio.wait_for(..., _UPDATER_STOP_TIMEOUT) with a
warning on timeout, matching the primary path, so no reconnect/teardown ladder
can wedge on a dead socket.
Also hoist the shared 15.0s bound to a single module constant
_UPDATER_STOP_TIMEOUT (self-documenting + DRY across all 4 sites), and update
the CLOSE-WAIT regression test to patch that constant instead of monkeypatching
asyncio.wait_for process-wide.
Fatal-notify idempotency: bounding the conflict-exhausted teardown stop() adds
an await AFTER _set_fatal_error, which yields the loop and lets a concurrent
retry task (scheduled by an earlier conflict, already suspended past the entry
guard) reach the fatal branch too — double-firing the fatal handler (surfaced
as a Python 3.11 CI failure in test_polling_conflict_becomes_fatal_after_retries).
Snapshot the pre-transition fatal state and only notify on the first transition.
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