The WS-26 `ConnectionGuard` was bound inside its `if let` block, so it
dropped microseconds after insertion instead of living for the
channel-0 dispatcher task — `live_connections()` /
`live_connection_count()` were permanently empty for every session
(review 007 WS-28 [major], reproduced empirically; the handle
retention ADR-048 + review-006 record was aspirational at that commit).
Remediation (review 007 Unit 1):
- bind the guard as an `Option<ConnectionGuard>` in the channel-0
task's frame, mirroring `SessionGuard`'s shape in
`run_channels_session`; the block comment now describes the real
scope
- gate `live_connections_visible_mid_session_and_drain_after_teardown`
— handle visible mid-session (after a completed call proves the
dispatcher is up), drained after teardown; verified to fail against
the pre-fix tree and pass with the fix
Verification: cargo test 454 passed / 0 failed; cargo test
--all-features 582 passed / 0 failed; clippy (both configs) clean; fmt
clean.
Review: docs/reviews/007-ws-data-channel-surface-review.md (WS-28)