Module linearizability 

Linearizability/Isolation conformance: genuinely-overlapping writers and a parked subscriber. Real overlap via tokio::spawn + Barrier (CLAUDE rule 8 — never sequential-then-check).

Functions

check_caught_up_boundary_race

Appends racing the catch-up→live boundary are neither lost nor duplicated, and CaughtUp is still emitted exactly once.

check_concurrent_distinct_streams_all_land

Overlapping appenders on DISTINCT streams never conflict; every event lands; $all holds all of them with strictly increasing positions.

check_concurrent_same_stream_single_winner

N overlapping appenders race the same fresh stream with the same expectation: exactly ONE wins, every loser sees Conflict, and the store holds exactly the winner’s event.

check_wake_after_idle

Wake-after-idle: a subscriber parked at CaughtUp is woken by a later append from another task — the lost-wakeup race the arm-before-rescan discipline exists to prevent.