0263 — The latest-per-key predicate is unbounded, not bounded by the claim's own high

Context. The predicate was originally planned as bounded — the max id for a key at or below the claim’s own high, mirroring how a claim’s range is fixed. But a lease’s high is pinned once and reused identically on every reclaim: after a crash, a newer same-key write landing outside that frozen window would be invisible to a bounded check, so the reclaimed row would look locally latest while actually superseded — and end up with zero completed delivery attempts instead of at least one.

Decision. The predicate is unbounded: “no row with a higher id and the same compaction_key exists, anywhere,” re-evaluated live against current state on every read, including reclaims. The guarantee being upheld is “the current latest value gets delivered, eventually” — what Kafka documents for its own compacted topics — not “every version of a key gets delivered.”

Consequences. readMessages (CURSOR) and FanOut (LIFECYCLE) carry the identical predicate, not merely same-shaped ones; FanOut was never bounded by a claim high anyway, so unbounded fits it better than a bounded version would have. Rejected: bounding by the claim’s high — wrong exactly and only on crash/reclaim.